Compensation and colonization offset the impacts of biodiversity loss over time in grasslands

Understanding the long-term impacts of biodiversity loss on ecosystem functioning is a major challenge in ecology. While studies suggest that biodiversity loss exerts increasingly negative impacts over time, it is unclear whether this pattern, observed in artificial assemblages, applies to natural ecosystems. Here, we report findings from a 16-year plant functional group (PFG) removal experiment in the Inner Mongolia grassland, where four levels of PFG richness were established through targeted removals from 2006 to 2009, followed by natural recolonization from 2010 onward. We found that the initially positive biodiversity-productivity relationship (BPR) gradually flattened over time, indicating that the negative impacts of diversity loss diminished. This temporal shift of BPRs was co-regulated by abundance, compensation, and colonization effects, with their relative contributions varying over time. Notably, when the compensatory growth of remaining species and colonization of new species offset productivity decline caused by species removal, the adverse impacts of diversity loss were mitigated. These findings underscore the need to incorporate compensation and colonization dynamics when predicting the long-term ecosystem consequences of biodiversity loss.探明生物多样性丧失对生态系统功能的长期影响，是生态学领域的核心挑战之一。尽管已有研究表明，生物多样性丧失随时间推移会产生愈发强烈的负面影响，但目前尚不清楚这一在人工群落中观测到的规律，是否适用于自然生态系统。本研究依托内蒙古草原开展的一项为期16年的植物功能群（plant functional group, PFG）移除实验：2006年至2009年间，通过针对性物种移除操作构建了4个梯度的植物功能群丰富度处理组，2010年起转为自然再定植过程。研究结果显示，初始呈现正相关的生物多样性-生产力关系（biodiversity-productivity relationship, BPR）随时间推移逐渐趋于平缓，表明多样性丧失的负面影响有所减弱。生物多样性-生产力关系的这一时间动态受丰度效应、补偿效应与定植效应共同调控，且三者的相对贡献随时间发生变化。值得注意的是，当剩余物种的补偿性生长与新物种的定植作用抵消了物种移除引发的生产力下降时，生物多样性丧失的不利影响会得到缓解。本研究结果凸显了在预测生物多样性丧失对生态系统造成的长期后果时，纳入补偿与定植动态过程的必要性。