A group of researchers, led by Professor MA Keping from the Institute of Botany of the Chinese Academy of Sciences, found that forests with more types of trees usually have a wider variety of arthropods (insects, spiders, and crustaceans).
The researchers demonstrated that a greater variety of trees in a forest can increase productivity by reducing the number of plant-eating insects, spiders, and crustaceans, thanks to the presence of natural predators of these herbivores.
These results were published in Nature Ecology & Evolution, and they highlight how crucial arthropod diversity is in mediating the impact of tree diversity on the productivity of a forest.
The researchers suggest that managing forests to increase productivity will require a focus on both tree diversity and multitrophic diversity. This means taking steps to promote the growth of different types of trees and also supporting the presence of a variety of arthropods, including natural enemies of herbivorous arthropods.
Forests host 80% of the world’s terrestrial plant and animal species, which makes them a crucial element in the preservation of global biodiversity. However, human activities and climate change pose a serious threat to forest biodiversity. The degradation of forests and the loss of plant diversity are causing a significant decline in arthropod populations, which are known for their high species richness.
Most research on the relationship between biodiversity and ecosystem functioning has concentrated on the diversity of plant species, leaving aside the influence of other trophic groups. Consequently, the impact of herbivore and predator diversity on ecosystem functioning remains unclear. Since forests are critical in providing vital ecosystem services and preserving global biodiversity, it is crucial to comprehend these relationships and take action to conserve them.
The researchers analyzed five years of data on aboveground arthropods, including herbivores, predators, and parasitoids, along with tree growth data from a large-scale forest biodiversity experiment in southeastern China called BEF-China. They found that higher tree species richness had a consistently positive effect on the abundance and species richness of herbivores, predators, and parasitoids.
The researchers found that their findings align with a similar study conducted in a grassland biodiversity experiment (the Jena Experiment) and further support the idea that preserving plant diversity is crucial for preserving arthropod diversity.
However, in contrast to the bottom-up control of arthropod diversity by plant diversity in the central European grassland study, plant diversity was found to be the bottom-up control of arthropod diversity. In contrast, this study shows that higher tree diversity can enhance the top-down control of herbivores by their enemies in the species-rich forests of southeastern China. This highlights the importance of considering the specific ecosystem and context when studying biodiversity-ecosystem functioning relationships.
Dr. Li Yi, the first author of the study, said that the study shows how important arthropod diversity is in connecting the effects of tree diversity to primary productivity.
Another study conducted in the same forest areas showed that adding more plant species can increase forest productivity directly. However, this new study demonstrates that increasing plant diversity can also indirectly increase productivity by promoting arthropod diversity and the interactions between different species in the forest.
Prof. LIU Xiaojuan, senior author and leader of the BEF-China management group, said that the study highlights the crucial importance of conservation initiatives targeted at preserving forest biodiversity.
To ensure more accurate results, the researchers collected data over multiple years. The approach accounts for the possibility that various groups of arthropods may be impacted differently each year, said Prof. MA, who is the chairman of the BEF-China platform.
Prof. MA also emphasized the value of the BEF-China platform as an open and international platform for long-term ecological research. The study’s use of multi-year sampling was intended to draw more reliable conclusions and take into account the possibility that different arthropod groups may be affected inconsistently from year to year.
Prof. ZHU Chaodong, an author from the Institute of Zoology of CAS, stated that the BEF-China platform provides valuable opportunities for international research teams and young researchers to explore various directions in ecological research.
Several studies have found that there are fewer arthropods on land now, but not many of them have looked at what this means for ecosystems.
“This study helps us understand how important arthropods are in maintaining the relationship between biodiversity and ecosystem functioning,” said Prof. Bernhard Schmid, a researcher from the University of Zurich.
These important findings can help people understand how to protect the diversity of plants, animals, and microbes in forests.
