Abstract
Restoration of native plant communities is a foundational practice in restoration ecology, but land managers and biologists don’t often take into account the role of intraspecific variation in establishment of restoration seedings. Although ecologists have known for decades that lack of adaptation to local conditions may interfere with the success of ecological restoration, there is little information about the extent to which species demonstrate adaptive divergence among populations. If adaptive divergence occurs for early establishment, knowing which populations have better germination and early growth can maximize restoration performance. Restoration of California grassland requires species establishment in both riparian and upland habitats. To what degree does local adaptation to these habitats influence early growth traits? In this study, we compared time to germination and early growth rate of riparian, upland, and commercial seed sources of blue wild rye (Elymus glaucus) under contrasting water regimes in a controlled environment. Two hypotheses were tested: 1) plants grown from commercial seeds will outperform plants grown from locally-collected seeds under controlled conditions; and 2) plants will demonstrate local adaptation by high performance of riparian sources under high water treatments and high performance of upland sources under low water treatments. We saw no evidence of local adaptation but did observe population differentiation. Time to germination was significantly shorter for upland seeds. In addition, the rate of shoot growth for upland plants was significantly higher than riparian or commercial plants. Understanding if sourcing from similar microhabitats is more important than sourcing from nearby populations will allow us to develop more successful restoration seedings.
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