Losing even just a few plant species in diverse ecosystems could in the long term reduce biomass production and impair ecosystem sustainability say the authors of a new study published in the international journal, Science.

 

The research, conducted by Professor Peter Reich - jointly affiliated with the University of Western Sydney’s Hawkesbury Institute for the Environment and the University of Minnesota - and a team of international collaborators, found that each plant species plays a role in maintaining a productive ecosystem, especially when a long time horizon is considered.

 

The study examined how the effect of diversity on the productivity of plants changed over the long term in two large independent field experiments at the University of Minnesota’s Cedar Creek Ecosystem Science Reserve in the USA – where Professor Reich and colleagues are conducting the world’s two longest-running biodiversity experiments.

 

The field site has plots with one, four, nine, or 16 different species of plants.  The researchers found every additional species in a plot contributed to a gradual increase in both soil fertility and biomass production over a 14-year period.

 

Lead author on the study, and Foundation Director of the Hawkesbury Institute, Professor Peter Reich says the latest findings highlight the importance of managing for diversity in grasslands, forests, and crops.

 

“Prior shorter-term studies, most about two years long, found that diversity increased productivity, but having more than six or eight species in a plot gave no additional benefit,” says Professor Reich, who is also a professor in the Forest Resources Department at the University of Minnesota.

 

“But we found that over a 14-year time span, all 16 species in our most diverse plots contributed more and more each year to higher soil fertility and biomass production. The take-home message is that when we reduce diversity in the landscape - think of a cornfield or a pine plantation or a suburban lawn - we are failing to capitalize on the valuable natural services that biodiversity provides.”

 

The research was done using long-lived North American prairie plants, but serves as a model system for all vegetation, whether prairie, forest, or row crop.  It also showed how diversity works by demonstrating that different species have different ways to acquire water, nutrients and carbon and maintain them in the ecosystem.