Function through Diversity

Pioneering work in China: The largest ever
forest experiment on biodiversity

In the subtropical south of China, on the boundary between the tropical and the temperate climate zones, lies one of the most important biodiversity hotspots in the northern hemisphere. Biodiversity is the technical term for biological diversity and refers to the number of species, the genetic diversity and the variety of habitats. Biodiversity hotspots is a term used to describe areas where the biological diversity is not only very high, but which are also home to a large number of species that cannot be found anywhere else in the world. Many of the plant and animal species that originate from these areas are endangered in their natural habitat and some have already become extinct.

The species diversity of trees and shrubs in the area covered by the study in South China is staggering. In total there are over a thousand different tree species, about five times as many as grow in the whole of Germany. This is why it is here that European and Chinese researchers want to study a question that is of increasing importance in light of global climate change: What contribution does biodiversity in forests make to the stability and role of ecosystems – and how can it be promoted and used?

Forests play a crucial role in many ways, for instance for timber production, soil protection and the water cycle, but they are very poorly suited to experimental investigation due to the long time they take to grow. A forest that is planted today won’t be able to be used and studied until our great-grandchildren are grown up. This is why experimental studies investigating the relationship between biodiversity and its functions in the ecosystem to date have generally been restricted to herbs and grasses. Only very recently have a limited number of experiments been launched in Finland, Germany, Panama and on the island of Borneo.

The experiment in China, however, is unique and is the first of its kind in the species-rich subtropics. It is the first time that a study will encompass trees and shrubs as well as evergreens and deciduous plants simultaneously. Even at the stage of planting the experimental plots, there are already plans to include other groups of organisms in the ecosystem such as fungi, herbivores, predators and decomposers in the course of the experiments, in addition to the plants, as well as investigating both natural forests and monocultures and plantations in the comparative studies.

The loss of valuable soil by erosion is a particularly urgent problem in the subtropics, where heavy rain is frequent. This is especially the case in China, where the rapid pace of economic development in recent years has not only led to a rapid drop in the number of species, but has also resulted in serious atmospheric pollution, severe damage due to erosion, and substantial loss of fertile soil. The measures intended to put a stop to this calamitous development include large-scale reforestation projects, which have also created the opportunity to conduct this experiment. Eighteen European researchers from Germany and Switzerland are participating in the project, including ecologists, forests scientists, and soil scientists, who possess a wealth of expertise in a wide variety of fields, ranging from taxonomy to statistics, and from botany to geographical information systems. They are cooperating with a group of Chinese researchers from a number of institutions, including the Institute of Botany at the Chinese Academy of Sciences and the College of Environmental Sciences at Peking University.

In many individual steps, on more than 300 experimental plots, the researchers will study the relationships between biodiversity and the functions played by a forest. To do so, they are planting thousands upon thousands of saplings of 100 different woody species, 50 tree species and 50 shrub species, 50 of which are evergreens and 50 deciduous species in an area covering some 50 hectares, according to an elaborate plan.

The studies are also of great importance for the commercial use of the forests. On the one hand there is the question of whether greater species diversity in forests provides better protection against erosion than monocultures, and whether increased productivity accompanied by higher biodiversity actually leads to increased carbon fixation, and whether this is thus able to contribute towards the fight against global warming.

Of course, the researchers hope to find answers to these questions within the foreseeable future, but some will be impossible to answer for many years. The large-scale China experiment is very much a far-sighted project that is set to last well into the future. On the one hand, it offers outstanding opportunities for training the next generation of researchers and act as a model for cooperation between continents, and on the other, some of the results may only become evident to our grandchildren or great grandchildren – in just the same way as German forestry continues to benefit from the experiments in forestry conducted in Bismarck’s era, when the so-called long-term monitoring plots were planted.

A profile of the research project

Project name: “The role of tree and shrub diversity for production, erosion control, element cycling, and species conservation in Chinese subtropical forest ecosystems”

Form of research funding: DFG Research Unit (FOR 891)

Duration: 3 (+3) years; commencing in 2008

Study site: Subtropical China (the provinces of Zhejiang and Jiangxi)

Habitat: Forest, plots planted for the experiment and existing control areas

Disciplines involved: Ecology, botany, environmental science, population genetics, forestry, mycology, soil science, and statistics

International cooperation: Trilateral German-Swiss-Chinese cooperation project with complementary, Sino-European appointments to all subprojects.

Special scientific aspects of the project:

• Experimental composition of various levels of diversity in the tree and shrub layer of the forest
• Large pool of woody plant species available and actively used
• Biodiversity as a causal variable for ecosystem functions: Ecosystem stability
• Biodiversity as a causal variable for the role of the ecosystem in: Protection against erosion, productivity, carbon fixation, resistance to invasion
• Comparison with natural systems
• The first study of a biodiversity hotspot in the subtropics
• International consortium in a research network

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