Pierre Mariotte and colleagues have a paper in the Journal in vol 101:3 titled Subordinate plant species enhance community resistance against drought in semi-natural grasslands. Read the paper here.
The authors have provided a short synopsis of the paper and a photo.
According to the insurance hypothesis, more diverse plant communities are more likely to be resistant to drought but, while many experiments have been carried out to determine the effects of plant diversity on community insurance, the results are still contradictory. In this study, we examined how subordinate species influence community insurance to drought in semi-natural grasslands. First, we manipulated plant communities using a removal experiment of subordinate species. Second, we manipulated water availability by imposing a severe summer drought. This approach was used here to test the diversity-insurance hypothesis by focusing on one key component of diversity, i.e. the presence of subordinate species. Additionally, we also tested the biomass-dependent hypothesis, which predicts that low-productive plant communities allow the persistence of drought-resistant subordinate species and therefore are more resistant to drought than high-productive communities.
Our results showed that subordinate species are more resistant to drought and increased community resistance by enhancing their above-ground biomass production during the imposed drought. Moreover, we demonstrated that plant communities were more resistant in low-productive plots than in high-productive plots and, importantly, that this was due to the increasing biomass of subordinate species when productivity decreased. Findings of this study demonstrated that, independent of plant diversity, the presence of drought-resistant subordinate species increases plant community insurance against drought and hence is important for the functioning of grassland ecosystems.