Implications of plant functional traits and drought survival strategies for ecological restoration

1. Restoration of degraded grasslands through active revegetation often involves reestablishing populations of native grasses, which must withstand increasing drought stress to persist beyond initial establishment.. In perennial species, superior dehydration tolerance is expected to result in more conservative growth, but this tradeoff has seldom been studied among populations of herbaceous species.
2. We measured seasonal growth and foliar and root functional traits under non-limiting water conditions, followed by recovery after severe drought in four populations of Elymus glaucus, a perennial grass from California’s Mediterranean-climate region. We hypothesized that populations from harsher sites would be more dehydration tolerant, summer dormant, and resource-conservative.
3. Dehydration tolerance and summer dormancy were associated with a more conservative strategy (lower productivity, lower Specific Leaf Area and Specific Root Length), as well as earlier reproductive phenology.
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1. 通过主动植被修复开展退化草地恢复工作时，通常需要重建本土草本植物种群，此类种群需耐受日益加剧的干旱胁迫，方可在初始定植阶段过后持续存活。对于多年生植物而言，更强的脱水耐受性往往会对应更保守的生长策略，但这种生长策略与脱水耐受性之间的权衡关系，在草本植物种群中鲜有研究。
2. 本研究以产自加利福尼亚地中海气候区的多年生草本植物蓝偃麦草（Elymus glaucus）的4个种群为研究材料，首先在水分无限制条件下测定其季节生长特征以及叶片和根系功能性状，随后探究其在严重干旱胁迫后的恢复能力。我们提出假说：生境更为严酷的种群将具备更强的脱水耐受性、更显著的夏季休眠特性以及更保守的资源利用策略。
3. 脱水耐受性与夏季休眠特性均与更保守的资源利用策略显著相关，具体表现为较低的生产力、较小的比叶面积（Specific Leaf Area）和比根长（Specific Root Length），同时伴随更早的生殖物候。