Monday, June 4, 2012

Professor David Hooper - Effects of Diversity on Ecosystem Processes: Does it Matter?

Professor Hooper measuring plant productivity

 Professor David Hooper, a professor at Western Washington University, has been receiving a lot of attention, including his most recent article in Nature, for his unique perspective on the relationship between levels of biodiversity and ecosystem services.  What is unique about this aspect of thinking is that many people think that reduced ecosystem services have negative impacts on species, reducing levels of biodiversity, not the other way around. 


           order to further explore this perspective, Professor Hooper and his team at Western Washington University have performed an enormous meta-analysis, looking at 192 studies, which include 574 experiments.  In particular, they examined studies that dealt with a manipulation of species richness, randomized data and looked at a response to a change in ecosystem process rates.  With this wealth of information, Professor Hooper began to evaluate the relationship.  They looked at and analyzed data for several conditions to attempt to illustrate the relevance of this relationship such as plant productivity and species richness of primary producers. When examining this data, they found that with more species lost there were greater impacts on the rates of productivity, as seen the graph below:

This figure not only illustrates that loss of species has a great impact on the ecosystem process of productivity, but it makes a point to emphasize that it is not an negligible impact.  Many people assume that the magnitude of this sort of effects are greatly outshone by those that we are familiar with, such as global warming, invasive species, etc. But, as you can see from the Y-axis on the right of this graph, the resulting loss of productivity due to species loss is actually comparable to many of these other more familiar effects on ecosystem services. 
            While Professor Hooper and his team were definitely concerned with being able to illustrate this relationship, what they really wanted to know was whether it mattered, as evidenced by the title of his presentation.  Hooper said that there were three questions that he wanted to answer with this study with his last question having the most resonance: In terms of how ecosystems are actually changing, does it matter?  In order to really answer this question Professor Hooper emphasized the need to look at how ecosystems are changing.  Professor Hooper suggests that the best way to determine this is to look at the link between ecosystem functions and services.  While his data does suggest that how ecosystems are changing does matter in terms of the effects of species richness, there needs to be much more future research.  In order to evaluate the relevance of this study and to determine whether the species loss patterns are reflected in real life, there needs to be a large increase in the scale of these experiments and a better way to replicate species loss.  It will be exciting to see what Professor Hooper elucidates next. 


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