Directed plant species loss reduced community productivity globally

While substantial evidence from biodiversity experiments over the past three decades shows that random species loss reduces community productivity, how productivity is affected by the more realistic scenario of non-random species loss in natural ecosystems remains unclear. Here, we simulated 9 non-random species loss scenarios—directed by different species attributes (that can be categorized into five different aspects including leaf functional traits, evolutionary history characteristic, biogeographical distribution, ecological niche breadth and the integrated prediction of extinction probability) associated with species extinction risk—and evaluated their impacts on community productivity across 54 grassland and forest biodiversity experiments. We found that diversity loss consistently reduced productivity across all non-random species loss scenarios and both in grassland and forest ecosystem, and these negative impacts on productivity strengthened over time. The probability of relative productivity loss surpassing corresponding relative diversity loss (i.e., non-redundancy of biodiversity) was higher in grassland ecosystem than forest ecosystem. While the average effects of non-random species loss were comparable to that of random species loss, the difference between the two sets of scenarios varied substantially across different experiments and ecosystems, with potential to be both over- and under-estimated. Most notably, the productivity decline was more severe when species with lower leaf nitrogen content, more distinct evolutionary history, or more server reduction in suitable habitat were lost first, compared to the random species loss scenario, in most of the experiments. In addition, we found that interspecific interactions were more important than species identities in driving the observed negative impacts of non-random species loss on productivity, especially in forest ecosystem. Our results advance the understanding of the functional consequences of real-world biodiversity loss, demonstrate that realistic diversity loss can severely impair ecosystem functioning in the context of ongoing global changes, and highlight the urgent need for conservation strategies to minish the decreasing trend of global biodiversity.