Research ArticleStatus of Knowledge Review

Challenges and a Strategy for Successful Restoration of Dry Evergreen Afromontane Forests of Ethiopia

Fisseha Asmelash and Meley Mekonen Rannestad
Ecological Restoration, September 2024, 42 (3) 220-237; DOI: https://doi.org/10.3368/er.42.3.220

ABSTRACT

Dry evergreen Afromontane forests (DAF) once covered most of the Ethiopian highlands. Currently, they are found as a few patches. DAF restoration is a national forest restoration priority in Ethiopia. It has also been identified to be among global ecosystem restoration priorities. There are sufficient data to show DAF restoration from the soil seed bank or seed rain is hardly possible. Planting trees from multiple provenances is important to restore climate-resilient DAF. Therefore, DAF restoration cannot be achieved through natural regeneration alone and must be accomplished by planting characteristic DAF tree species. The poor soil moisture and nutrient conditions in Ethiopia’s dry highlands result in low native tree seedling survival and growth. Hence, proper preparation of the planting sites and after-planting seedling care for at least two years is a reliable mechanism for achieving successful survival and growth. Along with seedling care after planting, four additional mechanisms discussed in this review (i.e., the use of nurse trees/shrubs, design of nursery practices, inoculation with arbuscular mycorrhizal fungi, and application of biochar) have also been shown to be useful. However, they cannot substitute for proper planting site preparation and post-planting seedling care. The complementary use of these five mechanisms could further enhance success. However, there are more questions than answers regarding the effectiveness of the five mechanisms discussed. We hope this review will motivate researchers to engage further to answer some of the important questions regarding restoration success.

Keywords:

Since the Rio Summit in 1992, biodiversity has emerged as a major global agenda. In 2019, the United Nations General Assembly declared 2021–2030 to be the Decade on Ecosystem Restoration (United Nations 2019). Restoring its dry evergreen Afromontane forests (DAF) is perhaps the most important contribution Ethiopia could make to the global restoration effort. Ethiopia possesses, by far, the largest area suitable for DAF restoration in Africa (Yalden 1983, Bussam 2006). In the past, this area was predominantly covered by DAF, but currently only a few of the original forests remain (Teketay and Anders 1995, Friis et al. 2010). By replanting lost and degraded DAF, Ethiopia could restore a significant proportion of the world’s tropical dry forests (Lemenih and Itanna 2004) and could contribute significantly to global biodiversity conservation and climate change mitigation (Strassburg et al. 2020). Restoring the degraded and lost DAF is also among Ethiopia’s national biodiversity priorities (NBSAP 2005). Whereas Ethiopia has committed to restoring forest on 22 million ha of degraded lands by 2030 (MEFCC 2018), DAF restoration, in particular, has been identified as contributing substantially towards the success of this commitment (MEFCC 2018, Pedercini et al. 2021).

In Ethiopia, the practice of DAF restoration goes back to the 15th century when the Menagesh-Suba Forest was restored by wildlings (i.e., naturally regenerating seedlings) from the Wof-Washa Forest (Sertse et al. 2011). In the 1890s (Bekele 2003) and the 1970–80s (Bishaw 2001), there were massive and successful re-greening and community forestry programs, although these endeavors mainly involved planting exotic trees, not native vegetation.

In the past 30 years, mainly since 2000, DAF restoration has centered on exclosures. Exclosures protect restoration sites from livestock and human interference to facilitate regeneration of natural vegetation. Revegetation potentially can be achieved either passively by allowing natural vegetation to recover, or actively through the construction of soil and water conservation structures and supplemental tree planting (Lemenih and Kassa 2014, Haile and Gebregziabher 2020).

Exclosures have resulted in significant positive environmental and socio-economic impacts in Ethiopia (Lemenih and Kassa 2014, Haile and Gebregziabher 2020). However, the Ethiopian dry highlands are nutrient- and moisture-stressed, the soil lacks seeds of native tree species, and recruitment from seed rain is unlikely (Lemenih and Teketay 2004, Lemenih et al. 2005, Aerts et al. 2007, Asmelash et al. 2021c). While theoretically feasible, passive DAF restoration realistically is not possible. When exclosures have been augmented by tree planting, limited species selection (Reubens et al. 2011) and poor seedling survival (Bishaw 2001, Asmelash et al. 2019) have significantly hampered success. Therefore, devising mechanisms for enhancing the survival and growth of characteristic DAF trees is crucial.

DAF restoration programs would be further enhanced through effective management of remnant DAF patches (Lemenih and Teketay 2004). Therefore, before discussing some of the restoration mechanisms that have been tested for establishing tree species characteristic of DAF, we evaluate the conservation status of the remnant DAF. We also review and discuss important forest restoration concepts relevant to DAF restoration. Our objective is to highlight some of the challenges related to DAF restoration and propose a strategy for effective restoration of the plant community.

Methods

We first made a list of DAF occurring in Ethiopia based on an Ethiopian Biodiversity Institute publication (NBSAP 2005), and then conducted Google Scholar searches using the listed DAF names to identify articles pertinent to the Ethiopian DAF patches. Secondly, we downloaded those articles located using the DAF names, and we also downloaded some of the important references cited in those articles. In so doing, we expanded the DAF list and gathered information relevant to DAF restoration. We used the terms: assisted natural regeneration (ANR), dry evergreen Afromontane forests, ecological restoration, ecosystem restoration, nurse trees, priority effect, protected areas, seedlings regeneration, soil seed bank, tropical dry forests, tropical montane forest, vegetation succession, and Ethiopia, to identify most of the references cited in this review by searching Google Scholar and the Society for Ecological Restoration (SER) databases. No exclusion criteria were set; if relevant information regarding DAF restoration was obtained, every article had equal probability of inclusion. When two or more articles provided similar information, those articles published in the most scholarly journals were given priority for citation.

Conservation Status of Ethiopian DAF

Ethiopia’s dry evergreen Afromontane forests are found in the dry highlands (as indicated by the aridity index; Lemenih and Bongers 2011). They are an integral part of the dry evergreen Afromontane forest and grassland complex ecoregion (DAF-G). Floristically, the DAF-G is the second-richest of the ecoregions in Ethiopia (Friis et al. 2010) and is recognized as one of 35 global biodiversity hotspots (Mittermeier et al. 2011, Figure 1). The DAF are found between 1,900 and 3,400 m of elevation in the north, northwest, and central dry highlands; in the southeast, they occur between 1,500 and 2,200 m (Friis et al. 2010). Various researchers have prepared ecological descriptions of the Ethiopian DAF (Friis and Tadesse 1990, Friis 1992, Woldu 1999, Demissew et al. 2004, Friis et al. 2010). In this article, we have used the description by Friis et al. (2010) because it is the most recent and comprehensive (Table 1 and Figure 2).

Figure 1.
Figure 1. A map of the dry evergreen Afromontane forest and grassland complex ecoregion in Ethiopia located in the Horn of Africa. This ecoregion, occurring principally in Ethiopia, was once covered mostly by forest but currently requires massive restoration. Using qGIS, we added the DAF shapefile obtained from Friis et al. (2022) onto the Eastern Afromontane biodiversity hotspot and Africa shapefiles, which are freely available online.
View this table:
Table 1.

Description of the dry evergreen Afromontane forests subtypes in Ethiopia. This table was prepared by extracting information in Friis et al. (2010).

Figure 2.
Figure 2. Forests representing the four dry evergreen Afromontane forests subtypes of Ethiopia: (a = undifferentiated Afromontane forests, b = dry single-dominant Afromontane forests, c = Afromontane wooded grasslands forests, and d = transitional forests between Afromontane forests and Acacia-Commiphora bushlands). These images appear in Friis et al. (2010); used with permission.

According to several vegetation surveys (Ayalew et al. 2006, Woldemichael et al. 2010, Alemu 2011, Benti 2011, Soromessa and Kelbessa 2014, Woldemariam et al. 2016, Woldearegay et al. 2018, Mohammed et al. 2019, Reshad et al. 2019, Yirga et al. 2019), the following tree species are most characteristic of the Ethiopian DAF: Bersama abyssinica Fresen. (Melianthaceae), Ekebergia capensis Sparrm. (Meliaceae), Juniperus procera Hochst. ex Endl. (Cupressaceae), Olea europaea L. subsp. cuspidata (Wall. and G.Don) Cif. (Oleaceae), and Podocarpus falcatus (Thunb.) R.Br. ex. Mirb. (Podocarpaceae). Therefore, these tree species should be included in DAF restoration programs. Moreover, the potential value of other characteristic tree and shrub species listed in Table 1 should also be considered.

There are about 65 DAF remnant patches in Ethiopia as documented by the Ethiopian Biodiversity Institute and other researchers (Table 2). Of these, 24 are designated as a National Forest Priority Area (NFPA). Based on the forests designated as NFPAs (i.e., protected DAF), the conservation status of the Ethiopian DAF has been determined using indices of “protection” and “connectivity” (Joint Research Centre of the European Commission 2021). Protection was computed as the percentage of the area of the protected DAF to the total area of the DAF-G. Connectivity was computed as a factor of 1) the areal extent of protected DAF, 2) ease of dispersal among the protected forests (i.e., the likelihood of the presence of two protected DAFs within 10 km), and 3) network availability (i.e., protected forest in the nearby ecoregion that could serve as a stepping stone) (Saura and de la Fuente 2017, Saura et al. 2017). The DAF protection and connectivity levels were estimated to be 7.43% and 2.79% respectively, much lower than the national averages for Ethiopia’s ecoregions, which are estimated to be 16.03% and 7.8% respectively (Joint Research Centre of the European Commission 2021). However, these figures were computed based on the area of the DAF-G, which includes areas suitable for DAF as well as for grassland. Hence, the actual levels of DAF protection and connectivity could be a bit higher, but still, much lower than the 17% connectivity proposed for effective conservation of important terrestrial areas (United Nations CBD Secretariat 2019).

View this table:
Table 2.

The dry evergreen Afromontane forests of Ethiopia.

According to Hodgson et al. (2011), how well forests are managed (i.e., their ecological “quality”) is an even more important indicator of their conservation status. In Ethiopia, DAF occurs coincident with the densest human population. As a result, degradation and deforestation have been ongoing for centuries (Woldu 1999, Bishaw 2001). Furthermore, for the past few decades, DAF management programs (particularly for the protected DAF tracts), have achieved limited success (Mengistu 2003) as corroborated by studies of forest cover change (Table 3). These data (i.e., protection, connectivity, and forest cover change) clearly indicate that the conservation status of the Ethiopian DAF is not good.

View this table:
Table 3.

Forest cover change reported for some of the dry evergreen Afromontane forests in Ethiopia.

Forest restoration should in no way be an incentive to destroy remnant forests (Chazdon and Laestadius 2016). Protecting and conserving the remnant forests is rather the initial step in forest restoration (DellaSala et al. 2003). Moreover, the presence of natural forest patches nearby greatly helps to ensure the resilience of restored forests by improving connectivity and providing a continuous source of propagules. In turn, the restored forests increase regional connectivity and enhance natural forests’ resilience (Proft et al. 2018). Therefore, future DAF restoration programs in Ethiopia should be augmented with sustainable DAF conservation programs and vice-versa. This is particularly important in the current context because conservation and management of remnant patches receive little attention compared to the massive national campaigns focused on restoration of degraded dry lands through planting trees, shrubs, and herbs.

The Science and Practice of Tropical Forest Restoration

According to the Society for Ecological Restoration (SER 2004), restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed. In the case of forests, successful restoration returns structure (i.e., species composition, diversity, and relative abundance), function, and resilience that are comparable to those found in undisturbed natural forests that serve as a reference for comparison (Gann et al. 2019). Reducing disturbance, remediation, reclamation, and rehabilitation are all activities along the restorative continuum—activities allied with forest restoration—while afforestation is not (Gann et al. 2019).

Forest restoration is a site-level activity that is different from forest landscape restoration (Chazdon 2017, César et al. 2020) or re-greening (Reij and Winterbottom 2015), which are landscape-level activities. It is also different from reforestation, which usually requires planting trees or sowing tree seeds (Mansourian 2005). Reforestation qualifies as forest restoration only when the goal is to recover as many of the attributes of the pre-disturbance natural forest as possible (Elliott et al. 2013). Although forest restoration is a site-level activity, for the issues of sustainability and climate resilience, it should be planned at the landscape level and within the context of ecoregional conservation (Morrison et al. 2005, Chazdon 2017; Proft et al. 2018).

In practice, restoration employs knowledge from disciplines including ecology, ecophysiology and functional ecology, phytogeography, genetics, engineering, statistical modeling, and biotechnology (Oliet and Jacobs 2012, Walker et al. 2007, Asmelash et al. 2016, Palmer et al. 2016). However, the theoretical bases of restoration are ecological succession, ecological assembly, and ecological disturbance (White and Jentsch 2004, Hobbs et al. 2007). From the viewpoint of forest ecosystem development, ecological succession can be viewed as ecological assembly in progress (Hobbs and Norton 2004, Walker et al. 2007, Bhaskar et al. 2014, Chang and HilleRisLambers 2016).

Succession takes place when species colonize a site (either passively or through intentional introduction) and then perform differently once established (Pickett et al. 1987). Hence, restorationists can control the colonization of a site and also manipulate the performance of the colonizing species to accelerate succession (Luken 1990, Hobbs and Norton 1996, Parker 1997, Bongers et al. 2006). Similarly, restorationists can remove dispersal filters by introducing appropriate species and can modify abiotic filters (e.g., light, nutrients, and water) and biotic filters (e.g., herbivores, parasites, pathogens, pollinators, symbionts) to accelerate community assembly (Hulvey and Aigner 2014, Kraft and Ackerly 2014, Figure 3). Reducing or eliminating disturbances that caused degradation is an important initial step. Replacing these original disturbances with designed disturbances is crucial for driving succession and assembly (Hobbs and Norton 1996, Bongers et al. 2006, Figure 3).

Figure 3.
Figure 3. Conceptual representation of forest restoration as accelerated succession and assembly. Forest restoration is complete when the community reaches Stage 6 and could start from any of the stages indicated by the numbers 1–5. Forest restoration could be arrested at stages 2 or 4 due to restoration thresholds. Designed disturbance (a special kind of filter manipulation) is required to pass through the thresholds to accelerate succession and assembly. This image was originally found in Whisenant (1999) and Hobbs and Norton (2004). Here, we present it with some modification to fit the current article.

The “priority effect” (i.e., the influence of species that first colonize a site) is also an important consideration in forest restoration (Cortines and Valcarcel 2009, Török et al. 2021). Likewise, facilitation by nurse plants is a concept with a practical application in forest restoration (Bertness and Callaway 1994, Gómez-Aparicio 2009, Gómez-Ruiz et al. 2013, de la Luz Avendaño-Yáñez et al. 2014, Fagundes et al. 2023) including DAF (Aerts et al. 2006 and 2007, Negash and Kagnew 2013, Abiyu et al. 2017).

Based on ecological concepts embedded in and aligned with ecological succession and assembly theories, based on landscape ecology, and documented successful restoration practices, five methods of tropical forest restoration have been recommended. These methods have become widely accepted and are being used as standard methods by multinational organizations that work on forest restoration. Moreover, Chazdon et al. (2021) have grouped a continuum of forest restoration methods into four categories based on the level of intervention each method requires (Table 4, Figure 4).

View this table:
Table 4.

Description of the five tropical forest ecosystems restoration methods proposed by Elliott et al. (2013).

Figure 4.
Figure 4. Forest restoration methods. The figure at the right appeared in Chazdon et al. (2021). We prepared the figure at the left using a similar format by extracting information from Elliott et al. (2013) so that forest restoration methods are presented in a single figure.

Attributes of DAF Restoration

According to several studies, dry Ethiopian highland soils rarely harbor seeds of trees characteristic of DAF (Lemenih and Teketay 2004, Teketay 2005a and b, Reubens et al. 2007, Sileshi and Abraha 2014). Hence, DAF restoration from the soil seed bank is almost impossible. The probability that such tree seeds will naturally arrive at open restoration sites is also very low (Lemenih and Teketay 2004). If the seeds are large and animal dispersed, they may not even move beyond forest edges (Cole et al. 2011). For those few seeds that are dispersed, establishment is also a major problem.

Because the DAF occupies areas with a short growing season, strong wind, depauperate soils, low soil organic carbon, considerable cloud cover, and comparatively low levels of solar radiation, there is a high rate of seeding failure and growth of seedlings that can establish is slow. Revegetation is slow compared to that in the surrounding lowland forests (Guariguata 2005, Dalling et al. 2016).

Moreover, as is the case with many tropical landscapes, the DAF could undergo retrogressive succession. This is a long-term process in which forest structure and function (e.g., moisture, carbon, and nutrient cycling) decline due mainly to the effects of nutrient depletion or unavailability (Walker and Reddell 2007, Peltzer et al. 2010). When such forests are cleared, used for cropland, and then abandoned, soil fertility is further reduced, leading to even higher seedling recruitment failure during restoration (Lemenih et al. 2005, Delelegn et al. 2017, Birhane et al. 2018, Asmelash et al. 2021c).

For these reasons, DAF restoration cannot be achieved through natural regeneration alone and trees must be planted. Fortunately, the same mix of trees can be used in most DAF restoration sites because the Ethiopian DAF do not exhibit clear elevational zonation in species composition (Friis 1992).

Compared to other major forest ecosystems in Ethiopia, DAF restoration could significantly be affected by global climate change (Van Breugel et al. 2016). Climate-induced tree dieback has already been recorded in one of the DAF remnants in northern Ethiopia (Mokria et al. 2015). Due to climate change, 20–85% of the DAF-G in Ethiopia could shift to Combretum-Terminalia woodland (CTW) by 2070 (Van Breugel et al. 2016). CTW is an ecoregion dominated by tree species of the genera Combretum and Terminalia (Combretaceae), which are small- to moderate-sized trees with fairly large deciduous leaves (Friis et al. 2010). In the worst-case scenario, only 15% of the land area currently occupied by DAF would continue to be suitable for DAF restoration. Under the best conditions, however, up to 80% could remain suitable. Regardless, there are three possible options for DAF restoration: 1) restoration based on existing reference sites without regard to the effects of climate change, 2) restoration based on anticipated climatic conditions (e.g., CTW), or 3) restoration of a climate-resilient DAF. Of the latter two, restoration advocates would recommend restoring climate-resilient DAF (Corlett 2016), including restoring the largest possible DAF patches at sites that increase connectivity (Proft et al. 2018). Incorporating species from a variety of provenances would be appropriate for restoring resilient forests (Hubert and Cottrell 2007, Bosselmann et al. 2008, Breed et al. 2013, Gann et al. 2019). Establishing a DAF consortium in Ethiopia would be crucial to facilitate the exchange of tree seedlings and seeds for composite provenance planting in a climate-resilient DAF restoration program.

The DAF are found in the DAF-G ecoregion where grasslands are an integral component of the regional plant community. As a result, there may be cases in which DAF restoration would be implemented on natural grasslands or historical grasslands. The Ethiopian dry highland grasslands have been identified to be among the world’s ecosystems at greatest risk of loss due to afforestation (Veldman et al. 2015, Bond et al. 2019). Therefore, DAF restoration needs to be considered from a regional, ecosystem-based perspective to assess the possible impact of forest restoration on native grasslands.

Potential Mechanisms to Improve Tree Seedling Establishment

As has been described above, the restoration of Ethiopian DAF is hardly achievable through natural regeneration alone; planting trees is essential. Therefore, successful seedling establishment defines the success of restoration projects. In this section, we present potential mechanisms to improve tree establishment, survival, and growth in the dry highlands of Ethiopia. We selected these mechanisms for review because their efficacy has been evaluated previously.

Planting Site Preparation and After-planting Care

The initial step in forest restoration on tropical landscapes with multiple resource limitations is to restore the hydrological properties of the site (Walker and Reddell 2007). The construction of soil and water conservation structures (SWCS) is crucial to improve catchment hydrology (Nyssen et al. 2010, Meaza et al. 2022), soil moisture, and nutrient status in the dry highlands in Ethiopia (Demelash and Stahr 2010, Challa et al. 2016, Tolessa et al. 2021). However, little is known if such improvements are sufficient to improve seedling establishment, survival, and growth. Whereas significant positive effects of micro-basin construction have been reported for the survival and growth of some exotic tree species (Derib et al. 2009, Alem et al. 2020), no significant effect was found in the cases of the native species J. procera and O. europaea subsp. cuspidata (Siyum et al. 2019). Therefore, more research is needed to understand the effects of SWCS (including design alternatives) on DAF tree seedlings.

Based on more than two decades’ research on the biology and restoration of DAF tree species, Negash (2021) concluded there are no shortcuts for DAF restoration. Hence, before tree seedlings are planted, planting pits need to be prepared well and watering ponds should be dug where there is no water source near a restoration site. Care of seedlings after planting for at least two years (i.e., manure application, fencing when appropriate, hoeing, weeding, watering during the dry season, and mulching) is crucial (Negash 2021). With such careful preparation and stewardship, up to 100% survival for some of the most important species’ seedlings has been achieved (Table 5), which otherwise exhibit very low rates of survival and growth at natural and experimental field conditions (Aerts et al. 2006, Abebe et al. 2011, Teketay 2011, Asmelash et al. 2019). Hence, site preparation including SWCS construction and seedling after-care should be the standard for DAF restoration. Other mechanisms, discussed below, could substitute for site preparation and after-care when they are found to produce comparable results or are economically more feasible. In fact, several mechanisms may work synergistically to achieve the best results.

View this table:
Table 5.

Field survival rate of seedlings of some tree species characteristic of dry evergreen Afromontane forests seven months after planting on a degraded dry highland site in central Ethiopia. Survival rates were recorded for quality seedlings raised with desirable traits. Survival rates in the left column were reported by Belude (2007); those in the right column were reported by Tafesse (2007).

Nursery Practices to Improve Successful Restoration

Tree seedlings to be out-planted in the dry highlands in Ethiopia should be raised in a manner that will prepare them to overcome the moisture and nutrient limitations they will face in the field. Generally, growing seedlings in pots rather than as bare root stock increases survival (South et al. 2005, Negash 2021). Raising seedlings with a comparably deeper root (Lobet et al. 2014, Trona et al. 2015), bigger collar diameter (Haase 2007, Grossnickle 2012), and higher root-to-shoot or root-to-dry biomass ratios (Comas et al. 2013) is important to increase field survival. Raising seedlings such that they accumulate more non-structural carbohydrates (NSCs) is also helpful (O’Brien et al. 2014).

The identification and implementation of practices that maximize these desirable traits is crucial. NSC accumulation can be enhanced by increasing the leaf area, photosynthetic rate, and root system size by supplying the seedlings with appropriate levels of nutrients and moisture (Villar-Salvador et al. 2015). Using larger diameter pots has been shown to significantly increase seedlings’ root collar diameter (Grossnickle 2012, Abera et al. 2018). Increasing pot depth was found to significantly increase the root collar diameter and the root-to-shoot and root-to-dry biomass ratios (Gülcü et al. 2010). The practice of root pruning commonly used in nurseries to increase root system size should be avoided as much as possible, because it has been shown to significantly reduce field survival (Negash 2021). The nature of the potting soil and the length of time seedlings are held in the nursery are other factors to consider (Table 6). Further evaluation of the effects and economic feasibility of several nursery practices is warranted.

View this table:
Table 6.

Important nursery practices for enhancing field survival of some tree species characteristic of the important dry evergreen Afromontane forests. Table prepared by extracting information found in Negash (2021).

Use of Nurse Trees and Shrubs

Competition and facilitation are the two common interactions in plant communities (Young et al. 2001). Facilitation is an interaction resulting in positive effects on at least one of the interacting species (Bertness and Callaway 1994, Brooker et al. 2008). Hence, the use of facilitative techniques in degraded terrestrial ecosystem restoration is gaining prominence (Gómez-Aparicio 2009, Gómez-Ruiz et al. 2013, de la Luz Avendaño-Yáñez et al. 2014).

Although the theory of facilitation has been informing agroforestry practices for a long time, its application in forest restoration is a recent phenomenon (McIntire and Fajardo 2014). Currently, planting with complementary “nurse” species is among five methods of tropical forest restoration (Elliott et al. 2013). In Ethiopia, nurse trees have been used by farmers for centuries in coffee agroforestry. However, there has not been any documented forest restoration project that has incorporated the nurse plantation method. The few studies carried out to evaluate the potential value of using nurse trees or shrubs in Ethiopian DAF restoration have indicated that the use of nurse vegetation could significantly increase survival and growth (Table 7).

View this table:
Table 7.

Nurse tree/shrub effects reported in the dry highlands in Ethiopia.

Vachellia abyssinica ([Hochst. ex. Benth.] Kyal. & Boatwr.) is among the important nurse tree species for use in DAF restoration. The species’ desirable traits include possession of spines at a young seedling age sufficient to deter herbivores, nitrogen fixation and soil fertility improvement, and drought tolerance (Negash 2021). The survival rate of V. abyssinica on dry highlands in Ethiopia is significantly higher than that of some exotic tree species (Bekele et al. 2021). Another potential nurse plant could be the exotic leguminous tree Acacia decurrens Willd. (Beshir et al. 2022). This species has also been found to produce high-quality charcoal in less than six years (Ferede et al. 2019). Hence, its application as a nurse tree could also significantly increase the economic feasibility of DAF restoration projects. However, serious pest and disease problems associated with using such a nurse plant should not be overlooked (Afework et al. 2024). There are also several other dry highland native Vachellia (formerly Acacia) trees and shrubs with a potential value as nurse species. Large-scale application potential of the nurse trees and shrubs previously identified is also important (Table 7). Croton macrostachyus could be a priority in this regard because it is reported to significantly increase soil fertility, including plant-available phosphorus (Negash 2021). One logical DAF restoration method could be: 1) protect a degraded restoration sites for a few years, 2) remove the re-spouting weedy shrubs, grasses and forbs while leaving trees and shrubs with demonstrated nursing potential, and 3) plant mid- and late-successional tree species’ seedlings.

Arbuscular Mycorrhizal Fungal Inoculation

Arbuscular mycorrhizal fungi (AMF) inoculation has been shown to significantly increase trees seedlings’ field survival (Pouyu-Rojas and Siqueira 2000, Dag et al. 2009, Kapulnik et al. 2010, Karthikeyan and Krishnakumar 2012, Pereira et al. 2021) and growth (Urgiles et al. 2009, Urgiles et al. 2014, Schüßler et al. 2016, Asmelash et al. 2021b). However, inoculation effects depend on the host plant’s responsiveness, the AMF status of the planting material, and the AMF status of the planting sites (Verbruggen et al. 2013). Accordingly, inoculation effects could range from positive to neutral to negative (Johnson et al. 1997).

In the past, few studies have been done to determine the potential benefit of AMF inoculation for DAF restoration in Ethiopia. The simple technique of AMF inoculation resulted in very significant growth improvements of five-month-old seedlings of Cordia africana Lam., an early successional riverine DAF tree species, both on sterile and non-sterile degraded soil. However, seedlings of the mid- and late-successional DAF tree species J. procera and P. falcatus were shown to have low- to negative-AMF responsiveness (Asmelash et al. 2021b). A general trend of a high, medium, and low arbuscular mycorrhizal responsiveness has also been reported for, respectively, early-, mid-, and late-successional tropical tree species elsewhere (Kiers et al. 2000, Zangaro et al. 2003, 2007).

A nursery survey carried out to evaluate the AMF status of planting materials grown for DAF restoration revealed that the nursery stocks were sufficiently colonized (Asmelash et al. 2021a). Regarding the AMF status of planting sites, studies reported contrasting results. While Birhane et al. (2018) and Asmelash et al. (2021c) recorded significant increases in AMF spore abundance and significant reductions in root AMF colonization and infectivity due to site deforestation and degradation, Delegegn et al. (2017) and Birhane et al. (2020) recorded significant reductions of AMF spore abundance and root AMF colonization. Based on these findings, we speculate the AMF inoculation demand of seedlings and sites is low for specific tree species. However, AMF inoculation could be appropriate for selected and AMF-responsive tree species. Therefore, long-term research to investigate the AMF responsiveness of several DAF tree species is crucial. For those AMF-responsive tree species, identifying the most beneficial AMF species or strain(s) is also important.

Biochar Application

Biochar is charcoal used as a soil amendment (McLaughlin et al. 2009, Brockamp and Weye 2020). Biochar application has been shown to significantly increase plant growth and yield (Biederman and Harpole 2013, Kammann et al. 2016, Jeffery et al. 2017), often with a single application (Kätterer et al. 2019, Frimpong et al. 2020). As a result, biochar application could be a promising technology in forest restoration (Thomas and Gale 2015, Palviainen et al. 2020, Grau-Andrés 2021). Considering tropical forests in particular, Román-Dañobeytia et al. (2021), in what is the largest experiment to date, found that biochar application alone and with N-P-K fertilization significantly increased the field survival and growth of tree species with low- and medium-density wood. Biochar’s effects, however, are highly variable and its beneficial effects depend on several factors including application rate and method, feedstock type and pyrolysis temperature/condition, soil conditions, and the plant taxa for which biochar is applied (Thomas and Gale 2015, Joseph et al. 2021). Generally, biochar application is recommended for soils with low cation exchange capacity, soil organic carbon and pH, and with heavier textures (Crane-Droesch et al. 2013)—typical soil conditions in Ethiopia’s dry highlands.

Despite its great potential, there have only been two biochar application studies relevant to DAF restoration in Ethiopia. One of these studies reported no significant application effect on the growth and field survival of O. europaea subsp. cuspidata and Dodonaea angustifolia seedlings (Kayama et al. 2019). On the other hand, the second study reported significant positive effects on the field survival and growth of Faidherbia albida seedlings. Biochar also seemed to enhance the establishment of Vachellia etbica seedlings, but definitive results for this species were compromised by herbivore damage (Kayama et al. 2021). In these two experiments, biochar was applied alone, which may account for observed nonsignificant or low effects. Biochar generally has low N content and its application could require enrichment with organic or inorganic N fertilizers to offset initial N sorption by biochar (Thomas and Gale 2015, Bonanomi et al. 2017).

Conclusion

In this review, we have summarized the scientific and technical issues relevant to DAF restoration. We have also reviewed the literature and gathered data to evaluate the conservation status of the remnant DAF in Ethiopia. We have shown that the conservation status of DAF is not good. Most of these forests have experienced significant reductions in area. Moreover, DAF restoration generally is not possible through natural regeneration alone. Although protection and assisted natural regeneration (ANR) could be very important for DAF restoration, neither is effective unless augmented by tree planting. Framework planting, maximum biodiversity planting, and/or nurse plantation methods are needed, preferably in combination with protection and/or ANR. In some cases, ANR complemented by selective tree species planting could also be a feasible method. In this review, we have presented and discussed five mechanisms for increasing tree seedlings’ establishment, survival, and growth. Proper site preparation and after-planting care is the most effective. The other mechanisms (i.e., modifying nursery practices, incorporating nurse tree and shrubs, inoculating with arbuscular mycorrhizal fungi, and applying biochar) also have potential applications in DAF restoration. However, they cannot replace proper planting site preparation and after-care stewardship. The application of the five mechanisms complementarily could be most effective. However, there are still more questions than answers regarding the effectiveness of these five mechanisms. We hope this review will motivate researchers to engage further to answer some of the important questions.

Socioeconomic factors such as reducing deforestation, avoiding overgrazing, and using exclosures could also help DAF restoration. Successful restoration will require comprehensive and integrated approaches incorporating both ecological and social interventions.

Author Contributions

This project was conceptualized primarily by FA, with contributions by MMR. FA completed the literature review and wrote the original draft; MMR reviewed the draft.

Figure
Coffea arabica is a species of coffee indigenous to Ethiopia and Yemen. L. Brent Vaughan. 1906. Hill’s Practical Reference Library Volume II. NewYork, NY: Dixon, Hanson and Company. The Florida Center for Instructional Technology, fcit.usf.edu.

Footnotes

References

  1. ↵
    1. Abera, B.,
    2. A. Derero,
    3. S. Waktole and
    4. G. Yilma
    . 2018. Effect of pot size and growing media on seedling vigour of four indigenous tree species under semi-arid climatic conditions. Forests, Trees and Livelihoods 27(1):61–67.
    OpenUrl
  2. ↵
    1. Abiyu, A.,
    2. D. Teketay,
    3. G. Glatzel,
    4. R. Aerts and
    5. G. Gratzer
    . 2017. Restoration of degraded ecosystems in the Afromontane highlands of Ethiopia: Comparison of plantations and natural regeneration. Southern Forests: A Journal of Forest Science 79(2):103–108.
    OpenUrl
  3. ↵
    1. Aerts, R.,
    2. A. Negussie,
    3. W. Maes,
    4. E. November,
    5. M. Hermy and
    6. B. Muys
    . 2007. Restoration of dry Afromontane forest using pioneer shrubs as nurse-plants for Olea europaea ssp. cuspidata. Restoration Ecology 15(1):129–138.
    OpenUrl
  4. ↵
    1. Aerts, R.,
    2. E. November,
    3. I. Borght,
    4. M. Behailu,
    5. M. Hermy and
    6. B. Muys
    . 2006. Effects of pioneer shrubs on the recruitment of the fleshy fruited tree Olea europaea subsp. cuspidata in Afromontane savanna. Applied Vegetation Science 9:117–126.
    OpenUrl
  5. ↵
    1. Afework, A.,
    2. A.S. Minale and
    3. D. Teketay
    . 2024. Livelihood benefits and challenges of Acacia decurrens-based agroforestry system in Awi Zone highlands, Northwest Ethiopia. Forests, Trees and Livelihoods 33(1):68–88.
    OpenUrl
    1. Ahmed, S.,
    2. D. Lemessa and
    3. A. Seyum
    . 2022. Woody species composition, plant communities, and environmental determinants in Gennemar Dry Afromontane Forest, Southern Ethiopia. Scientifica 2022:7970435.
    OpenUrl
  7. ↵
    1. Alem, S.,
    2. P. Němec and
    3. H. Habrová
    . 2020. Effects of a trench as a moisture harvesting structure on the biomass production and growth of trees planted to restore degraded land, southern Ethiopia. Applied Sciences 10(8560):1–10.
    OpenUrl
  8. ↵
    1. Alemu, S.
    2011. Woody Species Composition, Diversity and Structural Analysis of Angada Forest in Merti Wereda, Arsi Zone of Oromia Region, Ethiopia. MSc Thesis, Addis Ababa University.
  9. ↵
    1. Asmelash, F.,
    2. T. Bekele and
    3. E. Birhane
    . 2016. The potential role of arbuscular mycorrhizal fungi in the restoration of degraded lands. Frontiers in Microbiology 7(1095):1–15.
    OpenUrl
  10. ↵
    1. Asmelash, F.,
    2. T. Bekele and
    3. Z. Belay
    . 2019. Comparative field survival and growth of selected Ethiopian native tree species and the effect of whole soil AMF inoculation. Journal of Horticulture and Forestry 11(2):19–31.
    OpenUrl
  11. ↵
    1. Asmelash, F.,
    2. T. Bekele,
    3. F. Kebede and
    4. Z. Belay
    . 2021a. The arbuscular mycorrhizal fungi status of selected tree nurseries in the Ethiopian highlands. Journal of Forestry Research 32(3):1189–1201.
    OpenUrl
  12. ↵
    1. Asmelash, F.,
    2. T. Bekele,
    3. Z. Belay and
    4. F. Kebede
    . 2021b. Cordia africana Lam. but not Juniperus procera (Hoechst.ex Endl.) and Podocarpus falcatus (Thumb.) Mirb. respond positively to arbuscular mycorrhizal fungi at the early stages of seedling development. Biodiversitas 22(5):2971–2980.
    OpenUrl
  13. ↵
    1. Asmelash, F.,
    2. T. Bekele,
    3. Z. Belay and
    4. F. Kebede
    . 2021c. Soil physicochemical property and arbuscular mycorrhizal fungi resilience to degradation and deforestation of a dry evergreen Afromontane forest in central Ethiopia. Land Degradation and Development 32:3338–3350.
    OpenUrl
    1. Asrat, F.,
    2. T. Soromessa,
    3. T. Bekele,
    4. R.M. Kurakalva,
    5. S.S. Guddeti,
    6. D.R. Smart and
    7. K. Steger
    . 2022. Effects of environmental factors on carbon stocks of dry evergreen Afromontane forests of the Choke Mountain Ecosystem, Northwestern Ethiopia. International Journal of Forestry Research 2022 Article ID 9447946:1–31.
    OpenUrl
  15. ↵
    1. Ayalew, A.,
    2. B. Tamrat and
    3. D. Sebsebe
    . 2006. The undifferentiated Afromontane forest of Denkoro in the central highland of Ethiopia: A floristic and structural analysis. Ethiopian Journal of Science 29:45–56.
    OpenUrl
  16. ↵
    1. Bekele, M.
    2003. Forest Property Rights, the Role of the State, and Institutional Exigency: The Ethiopian Experience. PhD dissertation, Swedish University of Agricultural Sciences.
  17. ↵
    1. Bekele, M.,
    2. L. Habteyohannes,
    3. G. Teshome,
    4. D. Ababu,
    5. M. Minale,
    6. R. Eshetu et al.
    2021. Screening of tree species for fuelwood production in the mid-altitudes of North Shewa, Ethiopia. Journal of Forestry Research 10(248):1–7.
    OpenUrl
  18. ↵
    1. Belude, T.
    2007. Growth Performance of Two Evergreen and Three Deciduous Indigenous Trees of Ethiopia on Degraded Land at Tulu Korma. MSc Thesis, Addis Ababa University.
  19. ↵
    1. Benti, D.B.
    2011. Floristic Composition, Diversity and Structure of Woody Plant Species in Menagesha Suba State Forest, Central Ethiopia. MSc Thesis, Addis Ababa University.
    1. Berhanu, A.,
    2. S. Demissew,
    3. Z. Woldu and
    4. M. Didita
    . 2017. Woody species composition and structure of Kuandisha Afromontane forest fragment in Northwestern Ethiopia. Journal of Forestry Research 28:343–355.
    OpenUrl
    1. Berhanu, A.,
    2. Z. Woldu,
    3. S. Demissew and
    4. S. Melesse
    . 2019. Temporal vegetation cover dynamics in northwestern Ethiopia: Status and trends. Ethiopian Journal of Biological Sciences 18(2):123–143.
    OpenUrl
  22. ↵
    1. Bertness, M.D. and
    2. R. Callaway
    . 1994. Positive interactions in communities. Trends in Ecology and Evolution 9(5):191–193.
    OpenUrl
  23. ↵
    1. Beshir, M.,
    2. F. Yimer,
    3. N. Brüggemann and
    4. M. Tadesse
    . 2022. Soil properties of a Tef-Acacia decurrens-charcoal production rotation system in northwestern Ethiopia. Soil Systems 6(2):44–63.
    OpenUrl
  24. ↵
    1. Bhaskar, R.,
    2. T.E. Dawson and
    3. P. Balvanera
    . 2014. Community assembly and functional diversity along succession post-management. Functional Ecology 28(5):1256–1265.
    OpenUrlCrossRef
  25. ↵
    1. Biederman, L.A. and
    2. S. Harpole
    . 2013. Biochar and its effects on plant productivity and nutrient cycling: A meta-analysis. GCB Bioenergy 5(2):202–214.
    OpenUrl
  26. ↵
    1. Birhane, E.,
    2. K.F. Gebretsadik,
    3. G. Taye,
    4. E. Aynekulu,
    5. M.M. Rannestad and
    6. L. Norgrove
    . 2020. Effects of forest composition and disturbance on arbuscular mycorrhizae spore density, arbuscular mycorrhizae root colonization and soil carbon stocks in a dry Afromontane forest in northern Ethiopia. Diversity 12(4):133–149.
    OpenUrl
  27. ↵
    1. Birhane, E.,
    2. N. Fatumah,
    3. K. Gidey,
    4. A. Zenebe and
    5. S. Mohammed
    . 2018. Vegetation cover density and disturbance affected arbuscular mycorrhiza fungi spore density and root colonization in a dry Afromontane forest, northern Ethiopia. Journal of Forestry Research 29:675–686.
    OpenUrl
  28. ↵
    1. Bishaw, B.
    2001. Deforestation and land degradation in the Ethiopian Highlands: A strategy for physical recovery. Northeast African Studies 8(1):7–25.
    OpenUrl
  29. ↵
    1. Bonanomi, G.,
    2. F. Ippolito,
    3. G. Cesarano,
    4. B. Nanni,
    5. N. Lombardi,
    6. A. Rita et al.
    2017. Biochar as plant growth promoter: Better off alone or mixed with organic amendments? Frontiers in Plant Science 8(Article 1570):1–12.
    OpenUrl
  30. ↵
    1. Bond, W.J.,
    2. N. Stevens,
    3. G.F. Midgley and
    4. C.E. Lehmann
    . 2019. The trouble with trees: Afforestation plans for Africa. Trends in Ecology and Evolution 34(11):963–965.
    OpenUrl
  31. ↵
    1. Bongers, F.,
    2. A. Wassie,
    3. F.J. Sterck,
    4. T. Bekele Ayele and
    5. D. Teketay
    . 2006. Ecological restoration and church forests in northern Ethiopia. Journal of the Drylands 1(1):35–44.
    OpenUrl
  32. ↵
    1. Bosselmann, A.S.,
    2. J.B. Jacobsen,
    3. E.D. Kjær and
    4. B.J. Thorsen
    . 2008. Climate change, uncertainty and the economic value of genetic diversity: A pilot study on methodologies. Forest and Landscape Working Papers, Volume 31–2008:1–58.
    OpenUrl
  33. ↵
    1. Breed, M.F.,
    2. M.G. Stead,
    3. K.M. Ottewell,
    4. M.G. Gardner and
    5. A.J. Lowe
    . 2013. Which provenance and where? Seed sourcing strategies for revegetation in a changing environment. Conservation Genetics 14:1–10.
    OpenUrl
  34. ↵
    1. Brockamp, R.L. and
    2. S.L. Weye
    . 2020. Biochar amendments show potential for restoration of degraded, contaminated, and infertile soils in agricultural and forested landscapes. Pages 209–236 in J.A. Stanturf and M.A. Callaham, Jr. (eds.), Soils and Landscape Restoration. Elsevier.
  35. ↵
    1. Brooker, R.W.,
    2. F.T. Maestre,
    3. R.M. Callaway,
    4. C.L. Lortie,
    5. L.A. Cavieres,
    6. G. Kunstle et al.
    2008. Facilitation in plant communities: The past, the present, and the future. Journal of Ecology 96:18–34.
    OpenUrlCrossRef
  36. ↵
    1. Bussam, R.W.
    2006. Vegetation zonation and nomenclature of African mountains—An overview. Lyonia 11(1):41–66.
    OpenUrl
  37. ↵
    1. César, R.G.,
    2. L. Belei,
    3. C.G. Badari,
    4. R.A. Viani,
    5. V. Gutierrez,
    6. R.L. Chazdon et al.
    2020. Forest and landscape restoration: A review emphasizing principles, concepts, and practices. Land 10(1): 28–2.
    OpenUrl
  38. ↵
    1. Challa, A.,
    2. A. Abdelkadir and
    3. T. Mengistu
    . 2016. Effects of graded stone bunds on selected soil properties in the central highlands of Ethiopia. International Journal of Natural Resource Ecology and Management 1(2):42–50.
    OpenUrl
  39. ↵
    1. Chang, C. and
    2. J. HilleRisLambers
    . 2016. Integrating succession and community assembly perspectives. F1000Research 5(F1000 Faculty Rev)2294:1–10.
    OpenUrl
  40. ↵
    1. Chazdon, R.L.,
    2. D.A. Falk,
    3. L.F. Banin,
    4. M. Wagner,
    5. S.J. Wilson,
    6. R.C. Grabowski and
    7. K.N. Suding
    . 2021. The intervention continuum in restoration ecology: Rethinking the active–passive dichotomy. Restoration Ecology e13535.
  41. ↵
    1. Chazdon, R.L.
    2017. Landscape restoration, natural regeneration, and the forests of the future. Annals of the Missouri Botanical Garden 102(5):251–257.
    OpenUrl
  42. ↵
    1. Chazdon, R.L. and
    2. L. Laestadius
    . 2016. Forest and landscape restoration: Toward a shared vision and vocabulary. American Journal of Botany 103(11):1869–1871.
    OpenUrlFREE Full Text
  43. ↵
    1. Cole, R.J.,
    2. K.D. Holl,
    3. C.L. Keene and
    4. R.A. Zahawi
    . 2011. Direct seeding of late-successional trees to restore tropical montane forest. Forest Ecology and Management 261(10):1590–1597.
    OpenUrlCrossRef
  44. ↵
    1. Comas, L.H.,
    2. S.R. Becker,
    3. V.M.V. Cruz,
    4. P.F. Byrne and
    5. D.A. Dierig
    . 2013. Root traits contributing to plant productivity under drought. Frontiers in Plant Science 4:1–16.
    OpenUrl
  45. ↵
    1. Corlett, R.T.
    2016. Restoration, reintroduction, and rewilding in a changing world. Trends in Ecology and. Evolution 31(6):453–462.
    OpenUrl
  46. ↵
    1. Cortines, E. and
    2. R. Valcarcel
    . 2009. Influence of pioneer-species combinations on restoration of disturbed ecosystems in the Atlantic Forest, Rio de Janeiro, Brazil. Revista Árvore 33(5):927936.
    OpenUrl
  47. ↵
    1. Crane-Droesch A.,
    2. S. Abiven,
    3. S. Jeffery and
    4. M.S. Torn
    . 2013. Heterogenous global crop yield response to biochar: A meta-regression analysis. Environmental Research Letters 8(4): 044049.
    OpenUrl
  48. ↵
    1. Dag, A.,
    2. U. Yermiyahu,
    3. A. Ben-Gal,
    4. I. Zipori and
    5. Y. Kapulnik
    . 2009. Nursery and post-transplant field response of olive trees to arbuscular mycorrhizal fungi in an arid region. Crop and Pasture Science 60(5):427–433.
    OpenUrl
  49. ↵
    1. Dalling, J.W.,
    2. K. Heineman,
    3. G. González and
    4. R. Ostertag
    . 2016. Geographic, environmental and biotic sources of variation in the nutrient relations of tropical montane forests. Journal of Tropical Ecology 32(5):368–383.
    OpenUrl
  50. ↵
    1. de la Luz Avendaño-Yáñez, M.,
    2. L.R. Sánchez-Velásquez,
    3. J.A. Meave and
    4. M. del Rosario Pineda-López
    . 2014. Is facilitation a promising strategy for cloud forest restoration? Forest Ecology and Management 329:328–333.
    OpenUrl
  51. ↵
    1. DellaSala, D.A.,
    2. A. Martin,
    3. R. Spivak,
    4. T. Schulke,
    5. B. Bird,
    6. M. Criley et al.
    2003. A citizen’s call for ecological forest restoration: Forest restoration principles and criteria. Ecological Restoration 21(1):14–23.
    OpenUrlFREE Full Text
  52. ↵
    1. Delelegn, Y.T.,
    2. W. Purahong,
    3. A. Blazevic,
    4. B. Yitaferu,
    5. T. Wubet,
    6. H. Göransson and
    7. D.L. Godbold
    . 2017. Changes in land use alter soil quality and aggregate stability in the highlands of northern Ethiopia. Scientific Reports 7(13602):1–12.
    OpenUrl
  53. ↵
    1. Demelash, M. and
    2. K. Stahr
    . 2010. Assessment of integrated soil and water conservation measures on key soil properties in South Gonder, North-Western Highlands of Ethiopia. Journal of Soil Science and Environment 1(7):164–176.
    OpenUrl
  54. ↵
    1. Demissew, S.,
    2. P. Cribb and
    3. F. Rasmussen
    . 2004. Field Guide to Ethiopian Orchids. London: Royal Botanic Gardens, Kew.
  55. ↵
    1. Derib, S.D.,
    2. T. Assefa,
    3. B. Berhanu and
    4. G. Zeleke
    . 2009. Impacts of micro-basin water harvesting structures in improving vegetative cover in degraded hillslope areas of north-east Ethiopia. The Rangeland Journal 31(2):259–265.
    OpenUrl
    1. Duguma, L.A.,
    2. J. Atela,
    3. P.A. Minang,
    4. A.N. Ayana,
    5. B. Gizachew,
    6. J.M. Nzyoka and
    7. F. Bernard
    . 2019. Deforestation and forest degradation as an environmental behavior: Unpacking realities shaping community actions. Land 8(2):26–43.
    OpenUrl
  57. ↵
    1. Elliott, S.,
    2. D. Blakesley and
    3. K. Hardwick
    . 2013. Restoring tropical forests: A practical guide. London: Royal Botanic Gardens, Kew.
    1. Ethiopian Forestry Action Program (EFAP)
    . 1994. Final Report: Volume II—The Challenge for Development, and Volume III—Issues and Action. Ministry of Natural Resources Development and Environmental Protection, EFAP Secretariat, Addis Ababa.
  59. ↵
    1. Fagundes, M.V.,
    2. G.G. Mazzochini and
    3. G. Ganade
    . 2023. The role of plant diversity and facilitation during tropical dry forest restoration. Journal of Ecology 111(6):1231–1241.
    OpenUrl
  60. ↵
    1. Ferede, T.,
    2. A. Alemu and
    3. Y.G. Mariam
    . 2019. Growth, productivity and charcoal conversion efficiency of Acacia decurrens woodlot. Journal of Academia and Industrial Research 8(6):113–120.
    OpenUrl
  61. ↵
    1. Friis, I.
    1992. Forests and forest trees of North-East Tropical Africa: Their Natural Habitats and Distribution Patterns in Ethiopia, Djibouti and Somalia. Royal Botanic Gardens, Kew. Additional Series XV. London: HMSO.
  62. ↵
    1. Friis, I. and
    2. M. Tadesse
    . 1990. The evergreen forests of tropical Northeast Africa. Mitteilungen aus dem Institut für allgemeine Botanik, Hamburg 23a, Proceedings of the Twelfth Plenary Meeting of AETFAT, Symposium II:249–263.
  63. ↵
    1. Friis, I.,
    2. P.V. Breugel,
    3. O. Weber and
    4. S. Demissew
    . 2022. The Western Woodlands of Ethiopia: A Study of the Woody Vegetation and Flora between the Ethiopian Highlands and the Lowlands of the Nile Valley in the Sudan and South Sudan. Scientia Danica. Series B: Biologica, Vol. 9. Copenhagen: Royal Danish Academy of Sciences and Letters.
  64. ↵
    1. Friis, I.,
    2. S. Demissew and
    3. P.V. Breugel
    . 2010. Atlas of the Potential Vegetation of Ethiopia. Copenhagen: Royal Danish Academy of Science and Letters.
  65. ↵
    1. Frimpong, K.A.,
    2. C.A. Phares,
    3. I. Boateng,
    4. E. Abban-Baidoo and
    5. L. Apuri
    . 2020. One-time application of biochar influenced crop yield across three cropping cycles on tropical sandy loam soil in Ghana. Heliyon 7(2)e06267:1–9.
    OpenUrl
  66. ↵
    1. Gann, G.D.,
    2. T. McDonald,
    3. B. Walder,
    4. J. Aronson,
    5. C.R. Nelson,
    6. J. Jonson et al.
    2019. International principles and standards for the practice of ecological restoration. Restoration Ecology 27(S1):S1–S46.
    OpenUrl
    1. Gebeyehu, G.,
    2. T. Soromessa,
    3. T. Bekele and
    4. T. Demel
    . 2019. Species composition, stand structure, and regeneration status of tree species in dry Afromontane forests of Awi zone, northwestern Ethiopia. Ecosystem Health and Sustainability 5(1):199–215.
    OpenUrl
    1. Gebirehiwot H.T.,
    2. A.A. Kedanu,
    3. A.A. Guangul and
    4. M.T. Adugna
    . 2023. Floristic composition, structure, and regeneration status of woody plant species in Hurubu Natural Forest, North Shewa, Oromia Region, Ethiopia. Journal of Landscape Ecology 16(1):86–104.
    OpenUrl
    1. Getachew, H.E. and
    2. A.M. Melesse
    . 2012. The impact of land use change on the hydrology of the Angereb watershed, Ethiopia. International Journal of Water Sciences 1(4):1–7.
    OpenUrl
  70. ↵
    1. Gómez-Aparicio, L.
    2009. The role of plant interactions in the restoration of degraded ecosystems: A meta-analysis across life-forms and ecosystems. Journal of Ecology 97(6):1202–1214.
    OpenUrlCrossRef
    1. Gómez-Ruiz, P.A.,
    2. R. Lindig-Cisneros and
    3. O. Vargas-Ríos
    . 2013. Facilitation among plants: A strategy for the ecological restoration of the high-Andean forest (Bogotá, DC-Colombia). Ecological Engineering 57:267–275.
    OpenUrl
  72. ↵
    1. Grau-Andrés, R.,
    2. M.R.A. Pingree,
    3. M.G. Öquist,
    4. D.A. Wardle,
    5. M-C. Nilsson, and
    6. M.J. Gundale
    . 2021. Biochar increases tree biomass in a managed boreal forest, but does not alter N2O, CH4, and CO2 emissions. GCB Bioenergy 13:1329–1342.
    OpenUrl
  73. ↵
    1. Grossnickle, S.C.
    2012. Why seedlings survive: Importance of plant attributes. New Forest 43:711–738.
    OpenUrl
  74. ↵
    1. Guariguata, M.R.
    2005. Restoring tropical montane forests. Pages 298–305 in S. Mansourian and D. Vallauri (eds.), Forest Restoration in Landscapes. New York, NY: Springer.
  75. ↵
    1. Gülcü, S.,
    2. H.C. Gültekin,
    3. S. Çelik,
    4. Y. Eser and
    5. N. Gürlevik
    . 2010. The effects of different pot length and growing media on seedling quality of Crimean juniper (Juniperus excelsa Bieb.). African Journal of Biotechnology 9(14):2101–2107.
    OpenUrl
  76. ↵
    1. Haase, D.L.
    2007. Morphological and Physiological Evaluations of Seedling Quality. USDA Forest Service Proceedings RMRS-P-50.
  77. ↵
    1. Haile, M. and
    2. D. Gebregziabher
    . 2020. Successful landscape restoration in Abreha We Atsbeha watershed, Tigray, Ethiopia. ETFRN News 60: Restoring African Drylands, Wageningen, the Netherlands: Tropenbos International.
    1. Hishe, H.,
    2. K. Giday,
    3. J. Van Orshoven,
    4. B. Muys,
    5. F. Taheri,
    6. H. Azadi et al.
    2021. Analysis of land use, land cover dynamics and driving factors in Desa’a Forest in Northern Ethiopia. Land Use Policy 101:105039.
    OpenUrl
  79. ↵
    1. Hobbs, R.J.,
    2. A. Jentsch and
    3. V.M. Temperton
    . 2007. Restoration as a process of assembly and succession mediated by disturbance. Pages 150–167 in L.R. Walker, J. Walker and R.J. Hobbs (eds.), Linking Restoration and Ecological Succession. Springer Series on Environmental Management, New York, NY: Springer.
  80. ↵
    1. Hobbs, R.J. and
    2. D.A. Norton
    . 1996. Towards a conceptual framework for restoration ecology. Restoration Ecology 4:93–110.
    OpenUrl
  81. ↵
    1. Hobbs, R.J. and
    2. D.A. Norton
    . 2004. Ecological filters, thresholds, and gradients in resistance to ecosystem reassembly. Pages 72–95 in V.M. Temperton, R.J. Hobbs, T. Nuttle and S. Halle (eds.), Assembly Rules and Restoration Ecology: Bridging the Gap between Theory and Practice. Washington, DC: Island Press.
  82. ↵
    1. Hodgson, J.,
    2. A. Moilanen,
    3. B. Wintle and
    4. C. Thomas
    . 2011. Habitat area, quality and connectivity: Striking the balance for efficient conservation. Journal of Applied Ecology 48:148–152.
    OpenUrl
  83. ↵
    1. Hubert, J. and
    2. J. Cottrell
    . 2007. The role of forest genetic resources in helping British forests respond to climate change. Information Note. Forestry Commission, Edinburgh, UK.
  84. ↵
    1. Hulvey, K.B. and
    2. P.A. Aigner
    . 2014. Using filter-based community assembly models to improve restoration outcomes. Journal of Applied Ecology 51(4):997–1005.
    OpenUrl
  85. ↵
    1. Jeffery, S.,
    2. D. Abalos,
    3. M. Prodana,
    4. A.C. Bastos,
    5. J.W. van Groenigen,
    6. B.A. Hungate and
    7. F. Verheijen
    . 2017. Biochar boosts tropical but not temperate crop yields. Environmental Research Letters 12(5):053001.
    OpenUrl
  86. ↵
    1. Johnson, N.C.,
    2. J.H. Graham and
    3. F.A. Smith
    . 1997. Functioning of mycorrhizal associations along the mutualism-parasitism continuum. New Phytologist 135:575–586.
    OpenUrlCrossRef
  87. ↵
    1. Joint Research Centre of the European Commission
    . 2021. The Digital Observatory for Protected Areas (DOPA) Explorer 4.1. http://dopa-explorer.jrc.ec.europa.eu (accessed 04/2022).
  88. ↵
    1. Joseph, S.,
    2. A.L. Cowie,
    3. L. Van Zwieten,
    4. N. Bolan,
    5. A. Budai,
    6. W. Buss et al.
    2021. How biochar works, and when it doesn’t: A review of mechanisms controlling soil and plant responses to biochar. GCB Bioenergy 13:1731–1764.
    OpenUrl
  89. ↵
    1. Kammann, C.I.,
    2. B. Glaser and
    3. H.P. Schmidt
    . 2016. Combining biochar and organic amendments. Pages 136–164 in S. Shackley, G. Ruysschaert, K. Zwart and B. Glaser (eds.), Biochar in European Soils and Agriculture: Science and Practice. London: Routledge.
  90. ↵
    1. Kapulnik, Y.,
    2. L. Tsror,
    3. I. Zipori,
    4. M. Hazanovsky,
    5. S. Wininger and
    6. A. Dag
    . 2010. Effect of AMF application on growth, productivity and susceptibility to Verticillium wilt of olives grown under desert conditions. Symbiosis 52(2):103–111.
    OpenUrl
  91. ↵
    1. Karthikeyan, A. and
    2. N. Krishnakumar
    . 2012. Reforestation of bauxite mine spoils with Eucalyptus tereticornis Sm. seedlings inoculated with arbuscular mycorrhizal fungi. Annals of Forest Research 55:207–216.
    OpenUrl
  92. ↵
    1. Kätterer, T.,
    2. D. Roobroeck,
    3. O. Andrén,
    4. G. Kimutai,
    5. E. Karltun,
    6. H. Kirchmann et al.
    2019. Biochar addition persistently increased soil fertility and yields in maize-soybean rotations over 10 years in sub-humid regions of Kenya. Field Crops Research 235:18–26.
    OpenUrl
  93. ↵
    1. Kayama, M.,
    2. B. Abebe and
    3. E. Birhane
    . 2021. Effects of biochar on the growth of Vachellia etbaica and Faidherbia albida planted in Tigray, northern Ethiopia. The Japan Agricultural Research Quarterly 55(4):367–378.
    OpenUrl
  94. ↵
    1. Kayama, M.,
    2. K. Takenaka,
    3. B.A. Tetemke and
    4. E. Birhane
    . 2019. Effects of biochar on the growth of Olea europaea subsp. cuspidata and Dodonaea angustifolia planted in Tigray, northern Ethiopia. Journal of the Japanese Society of Revegetation Technology 45(1):115–120.
    OpenUrl
    1. Kebede, B.,
    2. T. Soromessa and
    3. E. Kelbessa
    . 2016. Floristic composition and community types of Gedo dry evergreen montane forest, West Shewa, Ethiopia. Acta Ecologica Sinica 36(5):392–400.
    OpenUrl
  96. ↵
    1. Kiers E.T.,
    2. C.E. Lovelock,
    3. E.L. Krueger and
    4. E.A. Herre
    . 2000. Differential effects of tropical arbuscular mycorrhizal fungal inocula on root colonization and tree seedling growth: Implications for tropical forest diversity. Ecology Letters 3(2):106–113.
    OpenUrlCrossRef
    1. Kindu, M.,
    2. T. Schneider,
    3. D. Teketay and
    4. T. Knoke
    . 2013. Land use/land cover change analysis using object-based classification approach in Munessa-Shashemene landscape of the Ethiopian highlands. Remote Sensing 5:2411–2435.
    OpenUrl
  98. ↵
    1. Kraft, N.J. and
    2. D.D. Ackerly
    . 2014. Assembly of plant communities. Ecology and the Environment 8:67–88.
    OpenUrl
  99. ↵
    1. Lemenih, M. and
    2. F. Bongers
    . 2011. Dry forests of Ethiopia and their silviculture. Pages 261–272 in S. Günter, M. Weber, B. Stimm and R. Mosandl (eds.), Silviculture in the Tropics. Berlin: Springer-Verlag.
  100. ↵
    1. Lemenih, M. and
    2. F. Itanna
    . 2004. Soil carbon stocks and turnovers in various vegetation types and arable lands along an elevation gradient in southern Ethiopia. Geoderma 123:177–188.
    OpenUrl
  101. ↵
    1. Lemenih, M.,
    2. E. Karltun and
    3. M. Olsson
    . 2005. Assessing soil chemical and physical property responses to deforestation and subsequent cultivation in smallholders farming system in Ethiopia. Agriculture, Ecosystems and Environment 105:373–386.
    OpenUrl
  102. ↵
    1. Lemenih, M. and
    2. H. Kassa
    . 2014. Re-greening Ethiopia: History, challenges and lessons. Forests 5(8):1896–1909.
    OpenUrl
  103. ↵
    1. Lobet, G.,
    2. V. Couvreur,
    3. F. Meunier,
    4. M. Javaux and
    5. X. Draye
    . 2014. Plant water uptake in drying soils. Plant Physiology 164(4): 1619–1627.
    OpenUrlAbstract/FREE Full Text
  104. ↵
    1. Luken, J.O.
    1990. Directing ecological succession. Springer Science & Business Media.
  105. ↵
    1. Mansourian, S.
    2005. Overview of forest restoration strategies and terms. Pages 8–13 in S. Mansourian and D. Vallauri (eds.), Forest Restoration in Landscapes. New York, NY: Springer.
  106. ↵
    1. McIntire, E.J. and
    2. A. Fajardo
    . 2014. Facilitation as a ubiquitous driver of biodiversity. New Phytologist 201(2):403–416.
    OpenUrlCrossRefPubMed
  107. ↵
    1. McLaughlin, H.,
    2. P.S. Anderson,
    3. F.E. Shields and
    4. T.B. Reed
    . 2009. All biochars are not created equal, and how to tell them apart. Digital reprint issued at the North American Biochar Conference, 9–12 August 2009, Boulder, CO, USA.
  108. ↵
    1. Meaza, H.,
    2. W. Abera and
    3. J. Nyssen
    . 2022. Impacts of catchment restoration on water availability and drought resilience in Ethiopia: A meta-analysis. Land Degradation and Development 33(4): 547–564.
    OpenUrl
  109. ↵
    1. Ministry of Environment, Forest, and Climate Change (MEFCC)
    . 2018. National Potential and Priority Maps for Tree-Based Landscape Restoration in Ethiopia (Version 0.0). Federal Democratic Republic of Ethiopia, Ministry of Environment, Forest, and Climate Change, Technical Report, Addis Ababa.
    1. Mekonnen, B.
    2003. An Ecological Study of Biteyu Forest, Gurage Zone, Southern Nations, Nationalities Peoples Region. MS thesis, Addis Ababa University.
    1. Mekonnen A. and
    2. M. Tolera
    . 2019. Carbon stock estimation along altitudinal gradient in Sekele-Mariam dry evergreen montane forest, north-western Ethiopia agriculture. Agriculture, Forestry and Fisheries 8(2):1–48.
    OpenUrl
  112. ↵
    1. Mengistu, M.
    2003. Ethiopia Country Paper. Proceedings of the Tropical Secondary Forest Management in Africa: Reality and Perspectives Workshop, 9–13 December 2002, Nairobi, Kenya. https://www.fao.org/3/j0628e/J0628E50.htm#TopOfPage.
    1. Mideksa, M.
    2009. Assessment of Forest Cover Change Using Remote Sensing and GIS Techniques: Case Study in Adaba-Dodola Forest Priority Area, Ethiopia. MS thesis, Addis Ababa University.
  114. ↵
    1. Mittermeier, R.A.,
    2. W.R. Turner,
    3. F.W. Larsen,
    4. T.M. Brooks and
    5. C. Gascon
    . 2011. Global biodiversity conservation: The critical role of hotspots. Pages 3–22 in F. Zachos and J. Habel (eds.), Biodiversity Hotspots. Berlin: Springer.
  115. ↵
    1. Mohammed, M.,
    2. M. Reshad and
    3. A. Beyene
    . 2019. Woody species richness and diversity following successional stages at Jello-Muktar Dry Afromontane Forest, south-eastern Ethiopia. American Journal of Agriculture and Forestry 7(6):259–269.
    OpenUrl
  116. ↵
    1. Mokria, M.,
    2. A. Gebrekirstos,
    3. E. Aynekulu and
    4. A. Bräuning
    . 2015. Tree dieback affects climate change mitigation potential of a dry Afromontane forest in northern Ethiopia. Forest Ecology and Management 344:73–83.
    OpenUrl
    1. Molla, E.,
    2. H. Gebrekidan,
    3. T. Mamo and
    4. M. Assen
    . 2010. Patterns of land use/cover dynamics in the mountain landscape of Tara Gedam and Adjacent agro-ecosystem, northwest Ethiopia. Ethiopian Journal of Science 33(2):75–88.
    OpenUrl
  118. ↵
    1. Morrison, J.,
    2. J. Sayer and
    3. C. Loucks
    . 2005. Restoration as a strategy to contribute to ecoregion visions. Pages 41–50 in S. Mansourian and D. Vallauri (eds.), Forest Restoration in Landscapes. New York, NY: Springer.
    1. Muluneh, M.G.,
    2. M.T. Feyissa and
    3. T.M. Wolde
    . 2021. Effect of forest fragmentation and disturbance on diversity and structure of woody species in dry Afromontane forests of northern Ethiopia. Biodiversity and Conservation 30:1753–1779.
    OpenUrl
  120. ↵
    1. National Biodiversity Strategy and Action Plan (NBSAP)
    . 2005. Government of the Federal Democratic Republic of Ethiopia, Institute of Biodiversity Conservation. https://www.cbd.int/doc/world/et/et-nbsap-01-en.pdf.
  121. ↵
    1. Negash, L.
    2021. A Selection of African Native Trees: Biology, Uses, Propagation and Restoration Techniques. Addis Ababa, Ethiopia: Addis Ababa University Press.
  122. ↵
    1. Negash, L. and
    2. B. Kagnew
    . 2013. Mechanisms for the successful biological restoration of the threatened African pencilcedar (Juniperus procera Hochst. ex. Endl., Cupressaceae) in a degraded landscape. Forest Ecology and Management 310:476–482.
    OpenUrl
  123. ↵
    1. Nyssen, J.,
    2. W. Clymans,
    3. K. Descheemaeker,
    4. J. Poesen,
    5. I. Vandecasteele,
    6. M. Vanmaercke et al.
    2010. Impact of soil and water conservation measures on catchment hydrological response—A case in north Ethiopia. Hydrological Processes 24(13):1880–1895.
    OpenUrlCrossRef
  124. ↵
    1. O’Brien, M.J.,
    2. S. Leuzinger,
    3. C.D. Philipson,
    4. J. Tay and
    5. A. Hector
    . 2014. Drought survival of tropical tree seedlings enhanced by non-structural carbohydrate levels. Nature Climate Change 4:710–714.
    OpenUrl
  125. ↵
    1. Oliet, J.A. and
    2. D.F. Jacobs
    . 2012. Restoring forests: Advances in techniques and theory. New Forest 43(5):535–541.
    OpenUrl
  126. ↵
    1. Palmer, M.A.,
    2. J.B. Zedler and
    3. D.A. Falk
    . 2016. Ecological theory and restoration ecology. Pages 3–26 in M.A. Palmer, J.B. Zedler and D.A. Falk (eds.), Foundations of Restoration Ecology. Washington, DC: Island Press.
  127. ↵
    1. Palviainen, M.,
    2. H. Aaltonen,
    3. A. Laurén,
    4. K. Köstera,
    5. F. Berningerc,
    6. A. Ojalad and
    7. J. Pumpanen
    . 2020. Biochar amendment increases tree growth in nutrient-poor, young Scots pine stands in Finland. Forest Ecology and Management 474(5):118362.
    OpenUrl
  128. ↵
    1. Parker, V.T.
    1997. The scale of successional models and restoration objectives. Restoration Ecology 5(4):301–306.
    OpenUrl
  129. ↵
    1. Pedercini, F.,
    2. I.K. Dawson,
    3. R. Kindt,
    4. W. Tadesse,
    5. S. Moestrup,
    6. A. Abiyu et al.
    2021. Priority Landscapes for Tree-based Restoration in Ethiopia. ICRAF Working Paper No 320. World Agroforestry, Nairobi, Kenya. https://doi.org/10.5716/WP21037.PDF.
  130. ↵
    1. Peltzer, D.A.,
    2. D.A. Wardle,
    3. V.J. Allison,
    4. W.T. Baisden,
    5. R.D. Bardgett,
    6. O.A. Chadwick et al.
    2010. Understanding ecosystem retrogression. Ecological Monographs 80(4):509–529.
    OpenUrlCrossRef
  131. ↵
    1. Pereira, S.,
    2. M. Santos,
    3. I. Leal,
    4. M. Tabarelli and
    5. M.G. Santos
    . 2021. Arbuscular mycorrhizal inoculation increases drought tolerance and survival of Cenostigma microphyllum seedlings in a seasonally dry tropical forest. Forest Ecology and Management 492(119213):1–9.
    OpenUrl
  132. ↵
    1. Pickett, S.T.A.,
    2. S.L. Collins and
    3. J.J. Armesto
    . 1987. A hierarchical consideration of causes and mechanisms of succession. Vegetatio 69:109–114.
    OpenUrlCrossRef
  133. ↵
    1. Pouyu-Rojas, E. and
    2. J.O. Siqueira
    . 2000. Arbuscular mycorrhizal and soil fertilization on post-transplant development of outplants of seven forest species. Pesquisa Agropecuária Brasileira 35:103–114.
    OpenUrl
  134. ↵
    1. Proft, K.M.,
    2. M.E. Jones,
    3. C.N. Johnson and
    4. C.P. Burridge
    . 2018. Making the connection: Expanding the role of restoration genetics in restoring and evaluating connectivity. Restoration Ecology 26(3):411–418.
    OpenUrl
  135. ↵
    1. Reij, C. and
    2. R. Winterbottom
    . 2015. Scaling Up Regreening: Six Steps to Success. A Practical Approach to Forest and Landscape Restoration. Washington, DC: World Resources Institute.
  136. ↵
    1. Reshad, M.,
    2. A. Beyene and
    3. M. Mohammed
    . 2019. Woody species richness and diversity at Ades Dry Afromontane Forest of southeastern Ethiopia. American Journal of Agriculture and Forestry 7:44–52.
    OpenUrl
  137. ↵
    1. Reubens, B.,
    2. M. Heyn,
    3. K. Gebrehiwot,
    4. M. Hermy and
    5. B. Muys
    . 2007. Persistent soil seed banks for natural rehabilitation of dry tropical forests in northern Ethiopia. Tropicultura 25(4):204–214.
    OpenUrl
  138. ↵
    1. Reubens, B.,
    2. C. Moeremans,
    3. J. Poesen,
    4. J. Nyssen,
    5. S. Tewoldeberhan,
    6. S. Franzel et al.
    2011. Tree species selection for land rehabilitation in Ethiopia: From fragmented knowledge to an integrated multicriteria decision approach. Agroforestry Systems 82:303–330.
    OpenUrl
  139. ↵
    1. Román-Dañobeytia, F.,
    2. F. Cabanillas,
    3. D. Lefebvre,
    4. J. Farfan,
    5. J. Alferez,
    6. F. Polo-Villanueva et al.
    2021. Survival and early growth of 51 tropical tree species in areas degraded by artisanal gold mining in the Peruvian Amazon. Ecological Engineering 159:106097.
    OpenUrl
  140. ↵
    1. Saura, S.,
    2. L. Bastin,
    3. L. Battistella,
    4. A. Mandrici and
    5. G. Dubois
    . 2017. Protected areas in the world’s ecoregions: How well connected are they? Ecological Indicators 76:144–158.
    OpenUrl
  141. ↵
    1. Saura, S. and
    2. B. de la Fuente
    . 2017. Connectivity as the amount of reachable habitat: Conservation priorities and the roles of habitat patches in landscape networks. Pages 229–254 in S. Gergel and M. Turner (eds.), Learning Landscape Ecology. New York, NY: Springer.
  142. ↵
    1. Schüßler, A.,
    2. C. Krüger and
    3. N. Urgiles
    . 2016. Phylogenetically diverse AM fungi from Ecuador strongly improve seedling growth of native potential crop trees. Mycorrhiza 26:199–207.
    OpenUrl
  143. ↵
    1. Sertse, D.,
    2. O. Gailing,
    3. N.G. Eliades and
    4. R. Finkeldey
    . 2011. Anthropogenic and natural causes influencing population genetic structure of Juniperus procera Hochst. ex Endl. in the Ethiopian highlands. Genetic Resources and Crop Evolution 58:849–859.
    OpenUrl
    1. Shibru, S. and
    2. G. Balcha
    . 2004. Composition, structure and regeneration status of woody species in Dindin Natural Forest, southeast Ethiopia: An implication for conservation. Ethiopian Journal of Biological Sciences 3(1):31–48.
    OpenUrl
  145. ↵
    1. Sileshi, D. and
    2. B. Abraha
    . 2014. Assessment of soil seedbank composition of woody species in Hgumbirda National Forest Priority Area, northeastern Ethiopia. Momona Ethiopian Journal of Science 6(1):25–44.
    OpenUrl
  146. ↵
    1. Siyum, G.E.,
    2. T. Tassew and
    3. A. Gidey
    . 2019. Effect of different moisture harvesting techniques on seedling survivals and growth of trees in degraded lands of southern Tigray. Asian Journal of Research in Agriculture and Forestry 4(1):1–10.
    OpenUrl
  147. ↵
    1. Society for Ecological Restoration (SER)
    . 2004. Primer on Ecological Restoration. Society for Ecological Restoration International, Tucson, AZ.
    1. Society for Ecological Restoration (SER)
    . 2024. Restoration Resource Center database. https://www.ser.org/page/Resources.
    1. Solomon, N.,
    2. H. Hishe,
    3. T. Annang,
    4. O. Pabi,
    5. I. Asante and
    6. E. Birhane
    . 2018. Forest cover change, key drivers and community perception in Wujig Mahgo Waren Forest of northern Ethiopia. Land 7(1):32.
    OpenUrl
  150. ↵
    1. Soromessa, T. and
    2. E. Kelbessa
    . 2014. Interplay of regeneration, structure and uses of some woody species in Chilimo Forest, central Ethiopia. Journal of Science and Technology of the Arts 3(1):90–100.
    OpenUrl
  151. ↵
    1. South, D.B.,
    2. S.W. Harris,
    3. J.P. Barnett,
    4. M.J. Hainds and
    5. D.H. Gjerstad
    . 2005. Effect of container type and seedling size on survival and early height growth of Pinus palustris seedlings in Alabama, USA. Forest Ecology and Management 204(2–3):385–398.
    OpenUrl
  152. ↵
    1. Strassburg, B.B.N.,
    2. A. Iribarrem,
    3. H.L. Beyer,
    4. C.L. Cordeiro,
    5. R. Crouzeilles,
    6. C.C Jakovac et al.
    2020. Global priority areas for ecosystem restoration. Nature 586:724–729.
    OpenUrl
  153. ↵
    1. Tafesse, M.
    2007. Growth Performance of Three Indigenous and One Endemic Tree Species of Ethiopia on Degraded Site in Centralwest Ethiopia. MS thesis, Addis Ababa University.
  154. ↵
    1. Teketay, D.
    2005a. Seed and regeneration ecology in dry Afromontane forests of Ethiopia: I. Seed production-Population structures. Tropical Ecology 46(1):29–44.
    OpenUrl
  155. ↵
    1. Teketay, D.
    2005b. Seed and regeneration ecology in dry Afromontane forests of Ethiopia: II. Forest disturbances and succession. Tropical Ecology 46(1):45–64.
    OpenUrl
  156. ↵
    1. Teketay, D.
    2011. Natural regeneration and management of Podocarpus falcatus (Thunb.) Mirb. in the Afromontane forests of Ethiopia. Pages 325–337 in S. Günter, M. Weber, B. Stimm and R. Mosandl (eds.), Silviculture in the Tropics. Berlin: Springer.
  157. ↵
    1. Teketay, D. and
    2. G. Anders
    . 1995. Soil seed banks in dry Afromontane forests of Ethiopia. Journal of Vegetation Science 6:777–786.
    OpenUrl
  158. ↵
    1. Thomas, S.C. and
    2. N. Gale
    . 2015. Biochar and forest restoration: A review and meta-analysis of tree growth responses. New Forest 46(5–6):931–946.
    OpenUrl
  159. ↵
    1. Tolesa, A.,
    2. S. Mammo and
    3. E. Bohnett
    . 2021. Effects of soil and water conservation structures on selected soil physicochemical properties: The case of Ejersa Lafo District, Central Highlands of Ethiopia. Applied and Environmental Soil Science 2021:9910237.
    OpenUrl
    1. Tolessa, T.,
    2. F. Senbeta, and
    3. M. Kidane
    . 2017. The impact of land use/land cover change on ecosystem services in the central highlands of Ethiopia. Ecosystem Services 23:47–54.
    OpenUrlCrossRef
    1. Tolla, T.,
    2. T. Soromessa,
    3. T. Richard,
    4. P. Dick,
    5. S. Leta,
    6. M. Argaw et al.
    2022. Estimation and mapping of Asabot Monastery Dry Afromontane Forest carbon stock under diverse land-use scenarios. Pages 91–110 in M. Kindu, T. Schneider, A. Wassie, M. Lemenih, D. Teketay and T. Knoke (eds.), State of the Art in Ethiopian Church Forests and Restoration Options. Cham: Springer.
    1. Török, P.,
    2. L.A. Brudvig,
    3. J. Kollmann,
    4. J.N. Price and
    5. B. Tóthmérész
    . 2021. The present and future of grassland restoration. Restoration Ecology 29:e13378.
    OpenUrl
  163. ↵
    1. Trona, S.,
    2. G. Bodnerb,
    3. F. Laioc,
    4. L. Ridolfic and
    5. D. Leitner
    . 2015. Can diversity in root architecture explain plant water use efficiency? A modeling study. Ecological Modeling 312:200–210.
    OpenUrl
  164. ↵
    1. United Nations
    . 2019. United Nations Decade on Ecosystem Restoration. https://www.cbd.int/restoration/UNDER.shtml.
  165. ↵
    1. United Nations CBD Secretariat
    . 2019. Strategic Plan for Biodiversity 2011–2020, including Aichi Biodiversity Targets. https://www.cbd.int/sp/targets/.
  166. ↵
    1. Urgiles, N.,
    2. P. Loján,
    3. N. Aguirre,
    4. H. Blaschke,
    5. S. Günter,
    6. B. Stimm, and
    7. I. Kottke
    . 2009. Application of mycorrhizal roots improves growth of tropical tree seedlings in the nursery: A step towards reforestation with native species in the Andes of Ecuador. New Forest 38:229–239.
    OpenUrl
  167. ↵
    1. Urgiles, N.,
    2. A. Strauß,
    3. P. Loján and
    4. A. Schüßler
    . 2014. Cultured arbuscular mycorrhizal fungi and native soil inocula improve seedling development of two pioneer trees in the Andean region. New Forest 45:859–874.
    OpenUrl
  168. ↵
    1. Van Breugel, P.,
    2. I. Friis,
    3. S. Demissew,
    4. J.P.B. Lillesø and
    5. R. Kindt
    . 2016. Current and future fire regimes and their influence on natural vegetation in Ethiopia. Ecosystems 19(2):369–386.
    OpenUrl
  169. ↵
    1. Veldman, J.W.,
    2. G.E. Overbeck,
    3. D. Negreiros,
    4. G. Mahy,
    5. S.L. Stradic,
    6. G.W. Fernandes et al.
    2015. Where tree planting and forest expansion are bad for biodiversity and ecosystem services. Bio-Science 65(10):1011–1018.
    OpenUrlCrossRef
  170. ↵
    1. Verbruggen, E.,
    2. M.G.A. van der Heijden,
    3. M.C. Rillig and
    4. E.T. Kiers
    . 2013. Mycorrhizal fungal establishment in agricultural soils: Factors determining inoculation success. New Phytologist 197(4):1104–1109.
    OpenUrlCrossRefPubMed
  171. ↵
    1. Villar-Salvador, P.,
    2. M. Uscola and
    3. D.F. Jacobs
    . 2015. The role of stored carbohydrates and nitrogen in the growth and stress tolerance of planted forest trees. New Forests 46:813–839.
    OpenUrl
  172. ↵
    1. Walker, J. and
    2. P. Reddell
    . 2007. Retrogressive succession and restoration on old landscapes. Pages 69–89 in L.R. Walker, J. Walker and R.J. Hobbs (eds.), Linking Restoration and Ecological Succession. London: Springer.
    1. Walker, L.R.,
    2. J. Walker and
    3. R.D. Moral
    . 2007. Forging a new alliance between succession and restoration. Pages 1–18 in L.R. Walker, J. Walker and R.J. Hobbs (eds.), Linking Restoration and Ecological Succession. London: Springer.
  174. ↵
    1. Whisenant, SG.
    1999. Repairing Damaged Wildlands: A Process-Orientated, Landscape-Scale Approach. Cambridge, UK: Cambridge University Press.
  175. ↵
    1. White, P.S. and
    2. A. Jentsch
    . 2004. Disturbance, succession, and community assembly in terrestrial plant communities. Pages 342–366 in V.M. Temperton, R.J. Hobbs, T. Nuttle and S. Halle (eds.), Assembly Rules and Restoration Ecology: Bridging the Gap between Theory and Practice. Washington, DC: Island Press.
  176. ↵
    1. Woldearegay, M.,
    2. Z. Woldu, and
    3. E. Lulekal
    . 2018. Species diversity, population structure and regeneration status of woody plants in Yegof Dry Afromontane Forest, northeastern Ethiopia. European Journal of Advanced Research in Biological and Life Sciences 6(4):20–34.
    OpenUrl
  177. ↵
    1. Woldemariam, G.,
    2. S. Demissew and
    3. Z. Asfaw
    . 2016. Woody species composition, diversity and structure of Kumuli Dry Evergreen Afromontane Forest in Yem District, southern Ethiopia. Journal of Environment and Earth Science 6(3):1–13.
    OpenUrl
  178. ↵
    1. Woldemichael, L.K.,
    2. T. Bekele and
    3. S. Nemomissa
    . 2010. Vegetation composition in Hugumbirda-Gratkhassu National Forest Priority Area, South Tigray. Momona Ethiopian Journal of Science 2:27–48.
    OpenUrl
  179. ↵
    1. Woldu, Z.
    1999. Forests in the vegetation types of Ethiopia and their status in the geographical context. Pages 1–38 in S. Edwards, A. Demissie, T. Bekele and G. Haas (eds.), Forest Generic Resources Conservation: Principles, Strategies and Actions. Proceedings of the National Forest Genetic Resource Conservation Strategy Development Workshop, 21–22 June 1999. Institute of Biodiversity Conservation and Research and German Technical Cooperation. Addis Ababa, Ethiopia.
    1. Worku, B.B.,
    2. E.B. Hizkias, and
    3. S.M. Dawud
    . 2022. Diversity, structural, and regeneration analysis of woody species in the Afromontane Dry Forest of Harego, northeastern Ethiopia. International Journal of Forestry Research 2022 (Article 7475999):1–20.
    OpenUrl
    1. Yahya, N.,
    2. T. Bekele,
    3. O. Gardi and
    4. J. Blaser
    . 2020. Forest cover dynamics and its drivers of the Arba Gugu forest in Eastern Highlands of Ethiopia during 1998–2015. Remote Sensing Applications: Society and Environment 20:100378.
    OpenUrl
    1. Yahya, N.,
    2. B. Gebre and
    3. G. Tesfaye
    . 2019. Species diversity, population structure and regeneration status of woody species on Yerer Mountain Forest, Central Highlands of Ethiopia. Tropical Plant Research 6(2):206–213.
    OpenUrl
  183. ↵
    1. Yalden, D.W.
    1983. The extent of high ground in Ethiopia compared to the rest of Africa. Ethiopian Journal of Sciences 6:35–39.
    OpenUrl
    1. Yineger, H.,
    2. E. Kelbessa,
    3. T. Bekele and
    4. E. Lulekal
    . 2008. Floristic composition and structure of the dry Afromontane forest at Bale Mountains National Park, Ethiopia. Ethiopian Journal of Sciences 31:103–120.
    OpenUrl
  185. ↵
    1. Yirga, F.,
    2. M. Marie,
    3. S. Kassa and
    4. M. Haile
    . 2019. Impact of altitude and anthropogenic disturbance on plant species composition, diversity, and structure at the Wof-Washa Highlands of Ethiopia. Heliyon 5:1–13.
    OpenUrl
  186. ↵
    1. Young, T.P.,
    2. J.M. Chase and
    3. R.T. Huddleston
    . 2001. Community succession and assembly: Comparing, contrasting and combining paradigms in the context of ecological restoration. Ecological Restoration 19(1):5–18.
    OpenUrlFREE Full Text
  187. ↵
    1. Zangaro, W.,
    2. F.R. Nishidate,
    3. J. Vandresen,
    4. G. Andrade and
    5. M.N. Nogueira
    . 2007. Root mycorrhizal colonization and plant responsiveness are related to root plasticity, soil fertility and successional status of native woody species in southern Brazil. Journal of Tropical Ecology 23(1):53–62.
    OpenUrl
  188. ↵
    1. Zangaro, W.,
    2. S.M.A. Nisizaki,
    3. J.C.B. Domingos and
    4. E.M. Nakano
    . 2003. Mycorrhizal response and successional status in 80 woody species from South Brazil. Journal of Tropical Ecology 19:315–324.
    OpenUrl
    1. Zewde, B.
    1998. Forests and forest management in Wällo in historical perspective. Journal of Ethiopian Studies 31(1):87–122.
    OpenUrl
    1. zur Heide, F.
    2012. Feasibility study for a Lake Tana biosphere reserve, Ethiopia. Bundesamt für Naturschutz (BfN)/Federal Agency for Nature Conservation. Bonn, Germany. https://www.nabu.de/imperia/md/content/nabude/international/machbarkeitsstudie_lake_tana.pdf.
Back to top

In this issue

Print
Download PDF
Article Alerts
Email Article
Citation Tools
Challenges and a Strategy for Successful Restoration of Dry Evergreen Afromontane Forests of Ethiopia
Fisseha Asmelash, Meley Mekonen Rannestad
Ecological Restoration Sep 2024, 42 (3) 220-237; DOI: 10.3368/er.42.3.220
Twitter logo Facebook logo Mendeley logo
Bookmark this article

Jump to section

Keywords