Bugs in species-rich forests improve productivity

Forests are home to 80 per cent of the world’s plant and animal diversity and are vital for global conservation. However, biodiversity in forests is under serious threat from human activity and climate change. An international research team, including experts from the University of Göttingen in Germany, has shown that forests with higher tree species richness tend to also have a greater diversity of spiders, millipedes, insects and other arthropods.

In addition, they show that these animals play an important role in how tree diversity promotes forest productivity: in forests that have more tree species, arthropods that eat plants are more effectively suppressed by other arthropods. The results were published in Nature Ecology & Evolution in April 2023.

The researchers collected and analysed five years of data about arthropods living on trees in a large forest experiment in southeast China. This was combined with information about tree growth. They then divided the arthropods into plant-eaters, hunters and parasitoids (creatures whose larvae live inside a host, usually killing it).

“The wealth of data on so many different groups of organisms, assembled in the world’s largest tree diversity experiment, allowed us to look more closely at how important biodiversity is for forest ecosystems,” says Professor Andreas Schuldt, a biodiversity researcher from the University of Göttingen, who was involved in the assessment of arthropods and their ecological effects.

The researchers show that the effects of increased tree species richness are consistently positive for arthropod diversity and abundance. In addition, increasing tree diversity can enhance the effect of arthropod hunters and parasitoids in controlling plant-eating arthropods, thereby contributing to increased forest productivity.

Preserving biodiversity in forests
 

This research is the first to show the significance of arthropod diversity in enhancing forest productivity. Schuldt explains: “Species-rich groups, such as arthropods, are declining dramatically due to the degradation of forests and loss of plant diversity. But most studies on the relationships between biodiversity and ecosystem functioning have focused solely on plant diversity, neglecting the diversity impact of life across the food chain. Given the importance of forests to global biodiversity, it is vital to understand these interconnections and take action to protect them.”

Professor Xiaojuan Liu from the Institute of Botany, Chinese Academy of Sciences (IBCAS) in Beijing and leader of the BEF-China experiment says, “This underscores the critical role of conservation efforts to promote and preserve biodiversity in forests”. Dr Yi Li, postdoctoral researcher at IBCAS in Beijing and first author adds: “Optimising forest management for increased carbon capture can be more effective when the diversity of arthropods is promoted together with that of trees.”

(University of Göttingen/wi)

Reference: 

Yi Li et al. Multitrophic arthropod diversity mediates tree diversity effects on primary productivity. Nature Ecology & Evolution. April 2023. Doi: 10.1038/s41559-023-02049-1