Abstract
Adequate native grass seed supply is a fundamental requirement for restoring disturbances associated with oil and gas production in West Texas. Knowing the amount and cost of native seed needed would be useful to oil and gas operators, seed producers, and conservation planners. We used projections of potential land impacts from oil and gas development, typical seeding rates, and current market prices to estimate the native grass seed supplies necessary and seed cost for low, medium, and high potential land-alteration scenarios. We estimate that at least 1.0% of the land area in the region has already been altered by oil and gas production, and that an additional 0.6–4.0% will be impacted by oil and gas pad or pipeline construction by 2050. Native seed supply between 112,000–600,000 kg (247,000–1,330,000 lbs.) of pure live seed (PLS) of native grasses valued between US $10–57 million will be needed for restoration to occur on all sites. These estimates provide targets for collaborative efforts focused on developing restoration seed source capacity through partnerships between seed source developers, the seed-production industry, practitioners, and energy producers. Our estimates also illustrate potential cost-savings for energy developers if land impacts can be minimized.
Restoration Recap
Commercial seed supply of locally adapted native grasses is a limiting factor for restoring large-scale disturbances such as those caused by oil and gas production in West Texas.
Estimates of the future scale of land impacts and corresponding estimates of the amount of native seed necessary for restoration would enable seed producers, energy operators, and practitioners to plan for and take action to address these needs.
For restoration seeding to occur on all sites impacted by projected oil and gas development through 2050 in West Texas, native seed supply of 112,000–600,000 kg (247,000–1,330,000 lbs.) of pure live seed (PLS) of native grasses valued at between US $10–57 million would be needed.
To implement restoration at the scale of impact anticipated (0.6–4.1% of land in West Texas by 2050) an additional seed supply of non-grasses is also needed, as well as greater associated restoration infrastructure, such as increased propagation and nursery capacity, educated contractors and staff, and the appropriate equipment.
Estimating capacity for seed-based restoration of native plant communities is an important aspect of conservation in landscapes impacted by expanding energy development. In West Texas (Figure 1), oil and gas (O&G) exploration, production and transport, as well as development of other forms of energy (e.g., utility-scale solar and wind energy) are projected to increase significantly in coming decades (Hastings 2018), even with the current downturn in energy prices (Rhodes 2020). Current capacity and knowledge of methods to restore native vegetation in this area using native plant seeds from the same ecoregion are severely limited (Shackelford et al. 2017). However, reseeding appropriate native grasses to former pad sites and newly constructed energy easements is a common restoration method desired by landowners. One limitation of using native grasses for such restoration is the lack of available commercial seed supply that originates from and is adapted to the same ecoregion as western Texas (Smith et al. 2018).
High-quality genetically appropriate native seed supplies are the basis for successful revegetation and restoration programs (Lippitt et al. 1994) and are increasingly recommended for use in ecosystem restoration in the U.S. (Johnson et al. 2010). Many practitioners report greater success when they use locally adapted, genetically diverse, and high-quality agronomically produced native seeds in restoration (Mortlock 2000). In the face of projected environmental change, many suggest that genetically-appropriate seeds are critical for maintaining evolutionary potential (Broadhurst et al. 2008). For the purposes of this paper, we defined ecotypic seeds as those originating from the study region; such definition may be more narrowly or broadly interpreted depending on the context and region.
While the definition of ecotypic plant materials is a topic of debate, criteria suggested by Jones and Monaco (2009) that incorporate knowledge of empirical performance and geographic origin are met by seed sources with identifiable provenance and performance testing. Recent literature suggests that locally-derived restoration stock may be misguided in the face of rapidly changing environmental conditions (Whitham et al. 2020). One suggestion to ascertain adaptation given by both Whitham et al. (2020) and Jones and Monaco (2009) are field trials in altered environments. In the case of using foundation species such as those commonly utilized for restoration in West Texas (Table 1), field testing throughout the region has identified these genotypes as the best-available commercial seed sources for function in current environmental conditions (C.S. Shackelford, West Texas Native Seeds Project, pers. comm.). Such testing also indicates that more diverse assemblages of locally-sourced populations may have superior performance and adaptive potential in West Texas over some currently-available seed supplies.
Achieving adequate and consistent supplies of native seed is especially important to enable broadscale restoration (Merritt and Dixon 2011). Efforts to estimate the scale of needed restoration, and to plan for necessary seed supplies in advance of demand have occurred throughout the last century (Nixon 1949). Programs aimed at improving native seed supply have resulted in the development of local seed-production initiatives (Smith et al. 2010) that typically produce more viable seeds for restoration than are harvestable from wild populations (Broadhurst et al. 2016).
Two such seed production initiatives exist in our study region: the West Texas Native Seeds Project (Shackelford et al. 2017) and the Permian Basin-Panhandle Native Seed Project. These efforts are modeled after those of the South Texas Natives Project (Smith et al. 2010), which has been effective in generating large supplies of locally adapted seed of many native species and making them commercially available for use in adjacent ecoregions impacted by energy exploration and development.
For example, the availability of native seed for southern Texas has resulted in their considerable use for restoration associated with energy sprawl, especially for restoration of former pad sites (Falk et al. 2017, Lovell et al. 2018) and for revegetation of denuded pipeline rights of ways (ROWs) (Pawelek et al. 2015, Falk et al. 2015, Wester et al. 2019). Increased seed availability, greater knowledge of restoration methodology, and estimates of the potential scale of future land impacts in the Eagle Ford Shale area (Pierre et al. 2015, Wolaver et al. 2018) were important factors in stimulating commercial seed companies to produce needed seed supplies. Producers do have the capacity to meet West Texas energy related seed production needs similarly, but market size estimates are lacking or markets are otherwise small. In this region, traditional markets for native seed sources such as for restoring rangeland habitats, are smaller than in many other regions where extensive seed-based restoration is done. In part, this is related to the extant nature of native plant dominated systems, and modest agriculture and recreation values associated with these semi-arid rangelands
The purpose of this study is to couple estimates of land impacts from future O&G production activities with estimates of native grass seed needed for associated restoration. This study is part of a wider effort to quantify existing landscape alteration from O&G activities and to consider potential future land impacts from fossil and renewable energy development activities in West Texas. Here, we focus on 18 counties impacted by energy development and seek to address the following questions: 1) Given the current and projected energy-development activities, how much land restoration and native grass seed could be needed by 2050 under three development scenarios? 2) Is the current native seed-production infrastructure robust enough to meet this challenge? What on-the-ground activities would be useful for reducing potential landscape alteration and for restoring lands that have undergone disturbance? Ultimately, we seek to provide seed producers with reliable information and business confidence needed to plan for, address, and ensure availability of necessary seed resources for restoration throughout the next three decades.
Methods
Estimate of Land Impacts from Oil and Gas Production Through 2050
Our study area encompasses an 113,310 km2 region of West Texas (Figure 1). Most (80.9%) of the study area is classified as Chihuahuan Desert, with smaller areas classified as Edwards Plateau (9.7%), High Plains (8.2%), Southern Texas Plains (1%), and Arizona/New Mexico Mountains (0.2%) (Omernik and Griffith 2014). The Chihuahuan Desert is the largest North American desert, with annual precipitation increasing from 210–647 mm (PRISM 2012) and potential evapotranspiration decreasing from 1880–1120 mm (Trabucco and Zomer 2009) along a west-to-east gradient. Vegetation biomes are dominated by deciduous shrublands, grasslands, and evergreen shrublands (Elliot et al. 2009–2014), and soils are dominantly Aridisols and Mollisols, with some Entisols (Soil Survey Staff 2019). Oil and gas production and pipeline development is most common in shrublands and grasslands, with lesser impacts in evergreen shrublands as the occurrence of this vegetation type is generally found outside of traditional oil and gas production regions or in undesirable terrain for pipeline construction.
The possible future land alteration locations and areal extents were determined by Pierre et al. (2020). They forecast landscape alteration resulting from oil and gas well-pad construction across the entire Permian Basin of Texas and New Mexico, U.S., by projecting recent trends in pad construction and O&G production, at a square kilometer and well-by-well basis, respectively. Using these trends, Pierre et al. (2020) were able to extrapolate the trend lines into the future according to three scenarios, which they called low, medium, and high landscape alteration. The medium alteration was labeled the “Business As Usual” (BAU) case, in which three wells were installed per well pad; the low alteration scenario assumed nine wells per pad (requiring fewer pads and less alteration) and the high alteration scenario assumed one well per pad (requiring more pads and alteration), while assuming these landscape trends through 2050. Using these three scenarios and the number of well pads to be constructed per year, Pierre et al. (2020) determined the direct and indirect land alteration from well-pad construction. With these well-pad estimates, we then estimated the amount of associated alteration from pipeline ROWs required under each scenario, using a pad-to-pipeline alteration ratio of 1.48 based on findings from Pierre et al. (2018) for Permian Basin O&G-related pad and pipeline infrastructure. Our estimated seed needs assumed that 1) all acreage impacted by O&G pads and pipelines will become eventual restoration targets by 2050; 2) well completion and usable lifetime of wells and associated pads will ultimately dictate restoration timing (TPWD 2012, Jones et al. 2015, Thompson et al. 2015); 3) pipelines would likely be reseeded immediately after construction; and, 4) most construction would occur in the earlier years of energy development.
Estimation of Native Seed Supply Needed by 2050
To estimate potential seed use and needed production capacity, we used published data (Table 1) on planting rates of existing seed sources of ten of the most common native grasses found in the West Texas region. These grasses are typically the primary plants desired for use in reseeding mixtures by landowners. We used data for West Texasorigin seed products of these species whenever possible. When this was not available, we used seeding rates and price of the geographically closest available seed source of the same plant species (Table 1). Just three of the ten seed varieties we considered have provenance in our study area and meet our definition of ecotypic seed for the region, but planting rates and prices for future West Texas-specific selections of the same grasses we assume would be similar. Regional seed supplies of the other seven grasses would need to be developed to achieve best results; however, all the species considered are already commonly used in reseeding projects in the study region. Projected seed amounts needed are based on the use of a seeding mixture of these ten grasses, planted at equal portions (10% by pure live seed seeding rate) of the planting mixture, allowing us to make estimates of the economic cost of providing seed to restore the study area. We used commercial seed prices provided by Douglass W. King Seed Co. (San Antonio, TX) for seed varieties in the seed mix for each of the three land-impact scenarios considered.
Results
Estimating Native Seed Supply Needed Through 2050
We estimate the land area impacted under the three (low, medium, and high) impact scenarios, of 0.6, 1.7, and 4.1 % of land within the study region altered by 2050 (Pierre et al. 2020) and potentially suitable for seed-based restoration efforts (Table 2). Based on recommended planting rates for native grasses used, we estimate 112,157; 297,738; and 603,556 kg (247,264; 656,401; and 1,330,614 lbs.) of PLS of these native species would be required to meet reseeding needs under these scenarios (Table 3).
The source of land alteration is relatively projectable, but timing of restoration is more difficult to anticipate. For example, seed producers can be confident of upcoming seed requirements if future trends in the Permian Basin reflect the ratio found by Pierre et al. (2018), where alteration of drilling pads to pipelines is consistently maintained around 1.48:1, the median area of drill pads is ~15,000 m2, and the rate of pad development remains relatively constant through time (even considering the downturn in energy prices during 2020). We anticipate native seeds will be needed at a relatively constant rate, assuming that at least a portion of the drill pads and/or support area will be available for land restoration after the wells are completed (such as from pad-site reductions following drilling) and again once hydrocarbons are no longer being produced at the pad site, and the entire pad is removed. We anticipate that pipeline construction, on the other hand, is likely to be front-loaded in time, as was observed in the Eagle Ford shale play (Pierre et al. 2017). In that region, land alteration from pipeline construction was two times higher than pad construction at the onset of O&G exploration and development. Therefore, if construction plans for pipelines can be used as an indication of future needs for seed producers, then alteration can be more effectively followed by restoration activities.
Based on 2019 price quotes for each of the native seed varieties used in our calculations (Douglass King Seed Company, San Antonio, TX), we estimate cost of native grass seed supply needed for restoration in the study region will range from U.S. $10–57 million from 2017–2050. This range encompasses the three O&G production scenarios (Table 3). Assuming the costs are spread across the time period, we estimate they will be between ~U.S. $319,000 and $1.725 million per year across the entire West Texas study area. This amount is nominal when put in context of the billions being invested for energy development in the study area. Future price changes for native grass seeds could have considerable impacts on these estimates; however predicting such price changes is difficult.
Discussion
Meeting future restoration needs in West Texas will require availability of a larger commercial native seed supplies than is currently available. Ambitious restoration programs require large volumes of seed (Merritt and Dixon 2011); our analysis of potential native seed needs show that between 112,157 and 603,556 kg (or 247,000 and 1.3 million pounds) of native seeds are needed to enable seed-based restoration associated with O&G development through 2050. If we assume uniform needs per year throughout the development of the oil and gas resources over time, seed supply of between 3640–19,500 kg (8,000–43,000 lbs.) per year would be required. Private conversations with established seed companies indicate annual production of seed varieties used in our analysis is approximately 18,300 kg (40,000 lbs.) annually. If restoration activities are spread equally across the time period of our estimates, and appropriate seed selections for West Texas are commercialized, current seed production capacity could suffice. However, such a scenario is unlikely, especially for large-scale infrastructure construction, like that associated with pipelines, which is typically front-loaded in regional development of energy plays. Depending on how much support infrastructure for energy transmission is needed, a more likely scenario is that native seed availability for restoration in this region will often fail to meet future needs without substantial increases in annual native-seed production capacity. To support increases in seed production, we estimated the value of such products when used in the region. Given typical margins for commercially produced native seeds, potential for significant profit and economic gain by supplying oil and gas-related restoration needs in West Texas exists.
Our estimates are probably low for cumulative restoration needs in the region. This is primarily because we only considered O&G development; we did not consider the development scenarios of solar and wind energy resources, or the growth in future electricity transmission-line ROWs that will also impact this region. Though not likely to result in as large of a restoration or seed need as that associated with O&G development, renewable energy development could result in substantial future impacts in this region, depending on how urban centers in Texas adopt renewable energy goals. Another point of uncertainty is that, by 2050, advances in technology (or just exceeding equipment lifespan) may render former renewable energy equipment obsolete (e.g., older wind farms or solar panels). If such sites were not used for future development, these previously utilized areas would likely become restoration targets as well. Like O&G leases and pipeline-easement agreements, most renewable-energy surface leases require the restoration of impacted areas, often including requirements to reseed using appropriate native seed mixes.
Price volatility of oil and gas, particularly amid the Covid-19 pandemic and the uncertainly of global energy markets, could significantly impact the pace of future energy development in West Texas. If development is suppressed by the present economic slowdown, restoration seed needs might also be depressed for the immediate future. The current slowdown in development represents an opportunity for seed-development initiatives and seed producers to catch up to expected future demands. For the long term, development of both O&G and renewable energy resources remains likely.
To meet restoration seed-supply needs for this region, efforts to provide stock seed of regionally collected native species to commercial seed growers is imperative. While three of the seed varieties used in our estimates originate from West Texas and are already being produced by seed companies, the other seven species used in our estimate are not. Continued efforts are needed to collect, increase, and commercialize locally adapted seed with West Texas provenance for use in restoration projects.
Furthermore, our estimates are based on common rangeland restoration seeding rates for these grasses. Many practitioners, including federal agencies such as the USDA Natural Resources Conservation Service (NRCS), recommend sowing native seeds in energy-related reclamation projects at critical area planting rates which are two times higher than the rangeland planting rates (USDA NRCS 2010) used in our estimates. The need for higher seeding rates for native grasses in a semiarid environment is untested. However, if critical area planting rates were utilized, the supply needed and the economic value of that supply could both be double what we report. Restoration of land at this spatial extent and in a semi-arid/arid region of the country will benefit from development and testing of new methods, calling for ongoing partnerships between private industry, research, and government communities.
For best results, many restoration ecologists recommend the use of more species-diverse seed blends than those used in our estimates, though such mixes may be more costly. We did not include any non-grass plants in our analyses. These plants, which are critically important to wildlife, are even more region and soil-specific, and estimating their seed costs based on currently available species from adjacent regions is difficult. Flowering forbs are of great importance for restoration of pollinator habitat and species of concern such as the monarch butterfly (Danaus plexippus). Some federal agencies recommend that restoration seed mixes contain 30–85% flowering forbs by composition (USDA NRCS 2008). However, to our knowledge, no seed supplies of such plants are yet available for West Texas. It can be expected that use of forbs, legumes, or semi-woody vegetation suitable for O&G restoration applications will increase cost substantially over the use of native grasses alone.
Along with seed supply, other restoration needs must concomitantly be addressed for successful broadscale restoration to occur in West Texas. For this paper, our analyses and estimates were restricted to native seed supply, as it is relatively simple to calculate based on available knowledge. Just as important, contractors, seeding equipment, and skilled labor also must be at capacity for the scale of restoration needs indicated in our estimates to occur. At present, this regional capacity does not exist. Also, such expertise and equipment will add significant cost to the restoration enterprise in the region. Custom planting of native seeds on pipeline ROWs, for example, ranges between U.S. $25–550 per acre in South Texas, depending on the application method utilized (drill, broadcast, or hydroseeding; see Pawelek et al. 2015). Often, these services represent far greater restoration cost than native seeds because of the low number of practitioners available to perform such services in West Texas. If we consider the high end of the restoration cost range and the high-impact scenario (Table 2), total all-in costs could approach $310 million over the 30-year timeline being considered, or around $10 million per year.
Seed and restoration application costs represent one of many economic factors in O&G development, and they may or may not be of imperative concern to energy companies at projected levels over such a long-term horizon. However, potential cost savings of millions in U.S. dollars over the coming decades could be realized with O&G development scenarios that minimize the long-term land footprint in the region. In addition, the use of old or obsolete O&G pad sites for solar (Devitt et al. 2020) or wind energy, or the colocation of pipelines, transmission lines, and roadways could have advantages for minimizing the amount and cost of restoration ultimately required in the region. Diligent planning to reduce redundancy and increase overlap (or siting along roadways) in pipeline and power-line infrastructure alone could significantly reduce landscape alteration and increase monetary savings. Drilling multiple well bores from single pad sites, as has been done in shale plays throughout North America, also present opportunities for significant cost savings.
In any case, seed-based native plant restoration, as increasingly required by landowners in easement and surface-use agreements, is often left to the end of the project, when access to cash-flow and investment capital may be less favorable than at the beginning of capital-intensive projects. Planning for the ultimate restoration need in the construction of new O&G infrastructure may be of use to those seeking to identify and address long-term economic obligations. The same can certainly be considered for renewable-energy projects. Without planning such as this, supply of appropriate native plant materials is unlikely to be available, resulting in the continued use of maladapted native seeds or introduced plants that will have little benefit to ecosystems found in the greater West Texas region.
This analysis of future O&G-related land impacts, associated native-seed supply needs for restoration, and related economic concerns represents one of many aspects impacting the sustainable future of ecosystems of West Texas in the face of accelerated energy development of all kinds: O&G, solar, and wind. Similar analyses may be helpful for addressing other supply-and-demand needs associated with energy sprawl in other regions facing similar development, and where minimizing long-term impacts on native plant communities and land uses are important. Such an exercise may enable communities and resource planners to more accurately assess the total impact of intense energy development. Assessments of potential demand at large scales will be increasingly important to ensuring that adequate supplies of locally adapted and genetically appropriate native seeds are available for seed-based restoration projects.
Acknowledgments
This work was supported by a grant to The University of Texas, Bureau of Economic Geology from the Cynthia and George Mitchell Foundation. The authors thank Tim Fulbright, Humberto Perotto, and Alfonso Ortega, and three anonymous referees for their review of the manuscript to improve it. This is Caesar Kleberg Wildlife Research Institute manuscript #19–113.
