Patterns of population differentiation in early traits of development in Elymus glaucus: Implications for restoration

Authors: FONSECA, CAROLINA - California State University; Espeland, Erin; BAXTER, JAMES - California State University

Submitted to: Ecological Restoration
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2014
Publication Date: 12/1/2014
Publication URL: http://handle.nal.usda.gov/10113/60208
Citation: Fonseca, C., Espeland, E.K., Baxter, J. 2014. Patterns of population differentiation in early traits of development in Elymus glaucus: Implications for restoration. Ecological Restoration. 32(4):388-395.

Interpretive Summary: We know that local adaptation to weather, soils, and other habitat factors is common in plants. But, there is little information how much local adaptation prohibits the successful establishment of common restoration species. Establishment (germination, emergence, and early growth) is important for restoration seedings to be successful, and plant populations are known to differ in establishment ability. Restoring large parcels of California grassland requires perennial grass establishment in both riparian (wet) and upland (dry) habitats. To what degree does local adaptation to these two habitats influence early growth traits in commonly used restoration species? In this study, we compared time to germination and early growth rate of riparian, upland and commercial seed sources of Elymus glaucus under contrasting water regimes in a controlled environment. We saw no evidence of local adaptation but did observe population differentiation. Time to germination was significantly shorter for upland seeds compared to riparian or commercial seeds. In addition, the rate of shoot growth for upland plants was significantly higher than riparian or commercial plants. Understanding patterns of differentiation among seed sources, particularly their influence on early establishment will allow us to develop better seed sourcing for more successful restoration seedings.

Technical 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 common restoration 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. Restoring large parcels of California grassland requires perennial grass establishment in both riparian and upland habitats. To what degree does local adaptation to these two habitats influence early growth traits in commonly used restoration species? In this study, we compared time to germination and early growth rate of riparian, upland and commercial seed sources of Elymus glaucus under contrasting water regimes in a controlled environment. In this study, 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 compared to riparian or commercial seeds. In addition, the rate of shoot growth for upland plants was significantly higher than riparian or commercial plants. Understanding patterns of differentiation among seed sources, particularly their influence on early establishment will allow us to develop better seed sourcing for more successful restoration seedings.