Ladouceur Emma, Wohlwend Michael, Schutzenhofer Michele R, Chase Jonathan M, Knight Tiffany M
Department of Biology, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada.
Canadian Centre for Climate Change and Adaptation, University of Prince Edward Island, St. Peter's Bay, Prince Edward Island, Canada.
Ecol Appl. 2025 Jun;35(4):e70062. doi: 10.1002/eap.70062.
The need to develop optimal restoration protocols for degraded grasslands has led to experimental research aimed at determining how different restoration treatments influence outcomes for biodiversity. The magnitude and direction of diversity responses to restoration treatments may depend on the spatial scale at which diversity is measured (local, regional), the metric of diversity used (Hill numbers), and the facet of diversity (taxonomic, functional, phylogenetic) considered. We conducted a long-term factorial experiment in a degraded grassland in Missouri, USA, in which we experimentally applied a regionally appropriate biodiverse seed mixture, added soil nutrients to restore soil fertility, and varied the timing in which the invasive plant Lespedeza cuneata entered the community. We used a unified framework of Hill numbers to evaluate how treatments influenced diversity, considering different spatial scales, metrics, and facets (taxonomic, phylogenetic, functional). We find that the timing in which the invasive L. cuneata entered the community had large effects on diversity, while nutrient addition had more limited effects. This was driven by the high dominance of the focal invasive when allowed to invade early in the growing season, suppressing diversity. The positive effects of late invasion increased in magnitude with spatial grain and were higher for taxonomic than phylogenetic and functional facets of diversity. This was largely due to the dominance of the focal invasive, negatively affecting diversity within specific plant families or functional phenotypes across treatments. Under early invasion, nutrients had a negative effect, particularly at local scales, inflating beta diversity in this treatment and resulting in negative to no effect of late invasion on many aspects of beta diversity. Our results demonstrate the importance of looking at a multitude of different measures of diversity to understand the relative effects of ecological restoration treatments combined with invasion timing. Efforts to keep noxious plant invaders out of a system early in restoration approaches better allow desirable, native plants to establish and can have long-term benefits for multiple aspects of diversity.
为退化草原制定最佳恢复方案的需求促使开展了实验研究，旨在确定不同的恢复处理如何影响生物多样性的结果。对恢复处理的多样性响应的幅度和方向可能取决于测量多样性的空间尺度（局部、区域）、所使用的多样性指标（希尔数）以及所考虑的多样性方面（分类学、功能、系统发育）。我们在美国密苏里州的一片退化草原上进行了一项长期析因实验，在实验中我们应用了适合该地区的生物多样种子混合物，添加土壤养分以恢复土壤肥力，并改变入侵植物胡枝子进入群落的时间。我们使用希尔数的统一框架来评估处理如何影响多样性，同时考虑不同的空间尺度、指标和方面（分类学、系统发育、功能）。我们发现入侵的胡枝子进入群落的时间对多样性有很大影响，而添加养分的影响则较为有限。这是由于在生长季节早期允许入侵时，目标入侵物种的高优势度抑制了多样性。后期入侵的积极影响随着空间粒度的增加而增大，并且在分类学方面比系统发育和功能多样性方面更高。这主要是由于目标入侵物种的优势度，对各处理中特定植物科或功能表型内的多样性产生负面影响。在早期入侵的情况下，养分有负面影响，特别是在局部尺度上，使该处理中的β多样性膨胀，导致后期入侵对β多样性的许多方面产生负面或无影响。我们的结果表明，考虑多种不同的多样性测量方法对于理解生态恢复处理与入侵时间相结合的相对影响非常重要。在恢复过程早期努力防止有害植物入侵者进入系统，能更好地让理想的本地植物得以建立，并能对多样性的多个方面产生长期益处。
