Data from: Intraspecific variation of a dominant grass and local adaptation in reciprocal garden communities along a US Great Plains’ precipitation gradient: implications for grassland restoration with climate change

Identifying suitable genetic stock for restoration often employs a “best guess” approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A. gerardii in reciprocal transplant garden communities across 1150 km precipitation gradient. We measured ecological responses over several time scales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors, and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment-specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations.

筛选适用于生态修复的遗传种质通常采用"经验推测"的策略。若缺乏适应性变异相关研究，生态修复工作可能出现方向性偏差。本研究针对美国中部草原的气候对广泛应用于生态修复的建群禾草——大须芒草（Andropogon gerardii）施加的选择压力及其介导的本地适应效应展开探究。我们将3个地理生态型的大须芒草种植于横跨1150公里降水梯度的互易移栽试验群落中，从多个时间尺度测定其对气候与生物因子的生态响应：包括瞬时气体交换、中期叶绿素吸光度，以及定植率与盖度的长期响应，并检测各生态型是否能够拓展分布范围。结果表明，源自最干旱区域的生态型在低降水条件下盖度最高，提示其在非生物胁迫下存在本地适应。出乎意料的是，在所有生态型定植率与盖度均较低的中生生境中，未检测到各生态型间盖度存在显著差异，这可能源于较强的生物胁迫压力。适应性差异的表达具有极强的生境特异性。基于已观测到的适应性变异，最稳妥的生态修复策略应优先选用本地生态型，尤其适用于干旱区域。鉴于最旱生的生态型在干旱条件下表现更优，且未来干旱事件频发，该生态型可通过自然扩散或人工辅助修复的方式向东拓展分布范围。