An international team of experts led by Profs. MA Keping and LIU Xiaojuan from the Institute of Botany of the Chinese Academy of Sciences (IBCAS) provide ecological insights from 30 years of global forest biodiversity experiments in a new synthesis of empirical work in the journal Nature Reviews Biodiversity.

Widespread forest destruction and loss of tree species has raised concern about negative impacts on ecosystem services and human well-being. Forests are the most complex and species-rich terrestrial ecosystems and contribute more to global ecological processes such as carbon storage and climate buffering than any other ecosystem. The 2030 targets of the Kunming-Montreal Global Biodiversity Framework explicitly emphasize the urgent need to protect and restore forest biodiversity and ecosystem integrity. But what is the supporting scientific evidence for a relationship between biodiversity and ecosystem integrity? This synthesis work provides answers through the summary of the key findings from global tree biodiversity experiments.

Over the past three decades, scientists have planted experimental plots with different numbers of tree species to test the relationship between tree species richness and forest functioning. They overwhelmingly found that the loss of tree species reduces forest productivity and many other ecosystem functions, complementing findings from observational studies in forests around the globe.

The earliest biodiversity experiments started in the 1990s and focused on herbaceous plants. These were soon to follow by forest biodiversity experiments, which have now proliferated to 45 large-scale experiments established worldwide.

This work highlights the importance of experimental research in revealing the causal relationship between tree species richness (biodiversity) as a driver of ecosystem functions (ecosystem integrity)—something extremely difficult to achieve through observation alone. The synthesis of the experimental evidence shows that the positive effects of tree diversity on multiple ecosystem functions can be explained through mechanisms such as resource partitioning and facilitation between tree species, as well as high diversities of other organisms such as insects, fungi, and microbes. Findings from the longest-running experiments indicate that these positive effects strengthen over time, with findings from natural forests and plantations indicating that these effects are likely to persist in the even longer term.

By integrating scientific insights from experimental and observational research, the review elucidates the multidimensional nature of biodiversity–ecosystem functioning/integrity relationship and its underlying mechanisms. The new perspectives offered are intended to help guide forest management and climate mitigation efforts, providing a scientific foundation for ecological restoration and forest management.