Technical comments on our species richness-multifunctionality paper in Science


The last issue of Science  contains a Technical Comment on our article “Plant species richness and ecosystem multifunctionality in global drylands”, written by Tommaso Jucker & David A. Coomes, together with our reply. These comments discuss how abiotic stress may affect the global relationship between plant species richness and ecosystem multifunctionality that we described in the above mentioned article, which was published in Science on January. I copy below the abstract of both Technical Comments, which summarize their major points:

Comment on “Plant Species Richness and Ecosystem Multifunctionality in Global Drylands”
Tommaso Jucker & David A. Coomes
Maestre et al. (Reports, 13 January 2012, p. 214) reported a general, but weak, positive relationship between plant diversity and ecosystem multifunctionality in global drylands. We show that the strength of this relationship changes consistently along multiple environmental gradients, becoming strongly positive in stressed habitats. This suggests that biodiversity loss may have especially strong consequences in harsh environments.

Response to Comment on “Plant Species Richness and Ecosystem Multifunctionality in Global Drylands”
Fernando T. Maestre, Santiago Soliveres, Nicholas J. Gotelli, José L. Quero & Miguel Berdugo
Jucker and Coomes claim that the relationship between plant species richness (biodiversity) and ecosystem multifunctionality (B-EMf) reported in our study changes along environmental gradients. We point out flaws in their analytical approach and then reanalyze our data to further demonstrate that the B-EMf relationship does not substantially change along environmental gradients.

Jucker & Coomes ask a very interesting question: does the B-EMf relationship change along environmental gradients? They create a new stress index and evaluate how plant species richness affect ecosystem multifunctionality depending on the abiotic stress of the study sites (low, medium and high). They found that this relationship varies depending on the degree of stress, questioning the global relationship we found in our study. In our response we re-analyze the data from Jucker & Coomes, and found important flaws in their calculations of the  stress index, which invalidate their conclusions. We also re-analyze our own data, and found that the inclusion of abiotic stress did not change the findings and conclusions of our original article: there is a significant positive B-EMf relationship in global drylands and that species richness is an important positive predictor of ecosystem multifunctionality.

Our article has received attention from the media (check here for a selection of news about it) and our colleagues since its publication. In addition to the commentary by Jucker & Coomes, our article has received three F1000 evaluations, and has been the subjects of several blog posts (Ted Hart and Bob O´Hara blogs), which led to lively discussions. It also has been cited by reviews on biodiversity recently published in Nature (Cardinale et al. 2012) and Science (Naeem et al. 2012).We certainly welcome this attention and discussion on our work, which we hope will stimulate further studies on the mechanistic basis of the relationships found, and on how we can use, manage and restore biodiversity to improve the structure and functioning in dryland ecosystems. This is an urgent task to fight against desertification and global environmental change, and to improve the livelihood of the millions of people that live in the drylands of the world.

If you are interested on this topic please check also some recent papers from the Maestre lab carried out with biological soil crusts, which explore how different biotic attributes, including species richness, composition and spatial pattern, affect ecosystem functioning:

Maestre et al. (2012, Journal of Ecology), highlighted in the blog of the Journal 
Bowker et al. (2011, Functional Ecology) 
Gotelli et al. (2011, Methods in Ecology and Evolution), see also this video related to the article, and the cover of this issue of the journal.

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