Species-rich ecosystems are more stable
Long-term study provides clear evidence for theory for the first timeRead out
Ecosystems that contain many different plant species are not only more productive, they can also better withstand adverse conditions such as climate extremes, diseases and pests than species-poorer systems. This is proven by the results of a recently completed long-term study, now published in Nature. For the first time, it provides enough data to end the 50-year debate on how biodiversity stabilizes ecosystems or not.
The new data is the result of 12 years of research by ecologists David Tilman and Peter Reich of the University of Minnesota and their colleague Johannes Knops of the University of Nebraska. The researchers studied 168 sites in the area of Cedar Creek Long-Term Ecological Research (LTER). Each of these trial plots was planted with one to 16 different species of perennial grasses and other prairie plants, and their productivity and number and duration of survival were observed within those twelve years.
The result confirms the already postulated assumptions: The more diverse the flora on a site and the larger the root mass, the more stable the mini-systems were against disturbances. The root mass plays a role in particular when negative climatic changes occur because they store nutrients and thus act as a buffer. In contrast to field crops, the perennial prairie plants not only have much more root mass, they also do not have to be sown every year.
"This study demonstrates that the stability of a plant community increases as the number of species increases, " explains Martyn Caldwell, head of the National Science Foundation's Department of Environmental Research, who funded the study. "Only long-term field studies can provide this kind of information."
"The prairie's grasslands, which are rich in species, are 240 percent more productive than grasslands of just one species, " explains Tilman. "That's a huge advantage. For example, biomass from such prairies can be used to produce biofuels without having to plow, fertilize, or inject every year, which consumes energy and pollutes the environment. "Display
According to researchers, biodiversity of global ecosystems is decreasing as global population density increases because many complex communities such as forests and prairies have had to give way to fields, buildings or roads. Returning to more biodiversity could be the key, according to Tilman, to regenerate global ecosystems while at the same time using biomass to meet the energy needs of the world's growing population.
(National Science Foundation, 01.06.2006 - NPO)