Productivity and plant species richness

Before we can even begin to hope to reduce the dramatic loss of species the world is currently experiencing, we need to first have a clear understanding of where we should and should not expect biodiversity to be high or low.

Humans depend on high levels of ecosystem biodiversity, but due to climate change and changes in land use, biodiversity loss is now greater than at any time in human history. A leading global initiative is underway to determine whether there are widespread and consistent patterns in plant biodiversity. Sixty-two scientists from 19 countries spanning six continents studied the relationships between plant biomass production and species diversity. 

In a new study they show that a consistent biological rule governing the link between plant biomass and species richness in grassland ecosystems: plant species diversity is generally greatest at intermediate levels of plant biomass. The humped-back model suggests that plant diversity peaks at intermediate productivity. At low productivity only few species can tolerate environmental stress, and at high productivity only a few highly competitive species can dominate.

In this study, we were asking a very simple question: is there a consistent 'rule' governing how grassland plant diversity varies with local productivity? We are trying to determine how many regions of the world operate in the context of biodiversity patterns. Leaning under the hood [of a car] without any clear vision of what parts should be connected will cause all sorts of frustration. It is much easier to make the necessary adjustments once you learn how the system operates.

The results of these findings help unveil how natural systems operate and have global ramifications for the management and conservation of grassland biodiversity. 

As the underlying causes of biodiversity loss are highly contentious, this will be an active area of research for decades. We are hopeful that by understanding the core relationships between land productivity and biodiversity, we can then refine management recommendations for land users with the goal of enhancing both economic and environmental outcomes.