Marie Curie Fellowship
Project duration: 
Jul 2007 to Jun 2009

Microbes are the main reason for the degradation of most of plant-derived detritus and soil organic matter (SOM). Therefore, they are very important contributors of CO2 emissions from terrestrial ecosystems to the atmosphere. However, little is known about the ecological basis behind the process of decomposition and the way in which microbial ecology would be affected by climate change.


From an ecological perspective, we know that diversity exerts an important effect on the functionality of ecosystems and its response to temperature. The number of species and its distribution within an ecosystem makes a difference on the way the resources are utilised, because increasing competition leads to a more intense exploration of new niches.

While the link of diversity and functionality has been thoroughly explored on ecosystems, most of this work has been done over the role of the plants or animal kingdom. Comparatively few studies have been made on how microbial community diversity may affect ecosystem functionality. It is generally believed that the high degree of functional redundancy in soils compensates for any given change in environmental-driven changes in microbial community composition. However, a growing number of studies demonstrate how changes in microbial community structure may affect the decomposition rates and nitrogen cycle of soils. Indeed, despite the high degree of functional redundancy on soils, disturbance to microorganisms that are responsible of some key functions, such as degradation of high molecular weight carbohydrates, may affect the functionality of the entire community.

Our results highlighted the role that the microbial community might play on the decomposition of SOM at two Mediterranean ecosystems. After 10 years of climate change simulation in these ecosystems, bacterial diversity and SOM decomposition capacity of soils decreased significantly under drought treatment respect controls. Fungal diversity, however, was not affected. Therefore, fungal community appeared more resilient to climate-induced stress than bacterial community. The decrease in bacterial diversity was associated to lower responses of soils’ microbial decomposition to favourable hydric conditions. Therefore, climate-induced changes in bacterial diversity were associated to changes in the soil functioning. Seasonal variability on SOM decomposition and its response to temperature appeared to be strongly correlated to the variability of fungal community, both in terms of biomass and diversity. While total SOM decomposition was best explained by fungal quantity, the response to temperature was better explained by diversity of the fungal community.

Therefore, microbial diversity might be playing a relevant role in the functioning of soils. Climate induced changes in microbial diversity could therefore affect soil CO2 emissions as well as the current predictions of CO2 emissions from terrestrial ecosystems.



  • Diversitat microbiana del sòl