Biodiversity enhances ecosystem multifunctionality in global drylands

This study, entitled "Plant species richness and ecosystem multifunctionality in global drylands," was recently published in the journal Science.

The results of this study indicate that the ability of ecosystems to maintain multiple functions, such as carbon storage and buildup of nutrient pools (multifunctionality) is enhanced and reduced with increases in the number of plant species and average annual temperature, respectively, in drylands worldwide. While small-scale controlled experiments have provided evidence of the positive relationship between biodiversity and multifunctionality over the years, this study is the first in explicitly evaluating such relationship in real ecosystems at a global scale.

The fieldwork of this study has been carried out in 224 dryland ecosystems from all continents except Antarctica, where direct measurements of plant diversity and other biotic and abiotic features of the ecosystem were taken. To assess ecosystem multifunctionality, researchers assessed more than 2600 soil samples for 14 ecosystem functions related to carbon, nitrogen and phosphorus cycling and storage. The functions measured deliver some of the fundamental supporting and regulating ecosystem services (e.g. soil fertility and climate regulation), and are also used to identify the onset of desertification processes.

Drylands constitute some of the largest terrestrial biomes, collectively covering 41% of Earth's land surface and supporting over 38% of the global human population. They are of paramount importance for biodiversity, as host many endemic plant and animal species, and include about 20% of the major centers of global plant diversity and over 30% of the designated endemic bird areas, and are also highly vulnerable to global environmental change and desertification.

"This study provides empirical evidence on the importance of biodiversity to maintain and improve ecosystem multifunctionality in drylands. The quality and quantity of ecosystem services depend on variables such as those we evaluated, and thus the results obtained indicate that increases in the number of plant species could improve the provision of these services. Our findings also suggest that such richness may be particularly important for maintaining ecosystem functions linked to C and N cycling, which sustain carbon sequestration and soil fertility. Because land degradation is often accompanied by the loss of soil fertility, plant species richness may also promote ecosystem resistance to desertification," says Dr. Maestre.

This study emphasizes the need of preserving biodiversity in dryland ecosystems. In this regard, Maestre says that "Our results suggest that the increase in average annual temperature predicted by climate change models will reduce the ability of dryland ecosystems to perform multiple functions related to C, N and P cycling, which are crucial to support life on Earth. Governments worldwide do not agree at the moment about limiting the emission of greenhouse gasses responsible of global warming, but we can contribute to minimize its negative consequences, and to promote the resistance of natural ecosystems against desertification, if we take clear actions to preserve and restore plant biodiversity."

The publication of this study is the outcome of a 5-year research effort, which has involved more than 50 researchers from 30 institutions and 16 different countries. All this work, coordinated and led by Dr. Maestre, has been possible thanks to the support of multiple public and private funding agencies worldwide. Among the support received, the BIOCOM project, awarded to Fernando Maestre by the European Research Council under the Starting Grants program, and the research network EPES, coordinated by Dr. Adrián Escudero and funded by the Science and Technology for Development (CYTED) program, have been fundamental to complete this research endeavor.

The results of this study indicate that the ability of ecosystems to maintain multiple functions, such as carbon storage and buildup of nutrient pools (multifunctionality) is enhanced and reduced with increases in the number of plant species and average annual temperature, respectively, in drylands worldwide. While small-scale controlled experiments have provided evidence of the positive relationship between biodiversity and multifunctionality over the years, this study is the first in explicitly evaluating such relationship in real ecosystems at a global scale.

The fieldwork of this study has been carried out in 224 dryland ecosystems from all continents except Antarctica, where direct measurements of plant diversity and other biotic and abiotic features of the ecosystem were taken. To assess ecosystem multifunctionality, researchers assessed more than 2600 soil samples for 14 ecosystem functions related to carbon, nitrogen and phosphorus cycling and storage. The functions measured deliver some of the fundamental supporting and regulating ecosystem services (e.g. soil fertility and climate regulation), and are also used to identify the onset of desertification processes.

Drylands constitute some of the largest terrestrial biomes, collectively covering 41% of Earth's land surface and supporting over 38% of the global human population. They are of paramount importance for biodiversity, as host many endemic plant and animal species, and include about 20% of the major centers of global plant diversity and over 30% of the designated endemic bird areas, and are also highly vulnerable to global environmental change and desertification. "This study provides empirical evidence on the importance of biodiversity to maintain and improve ecosystem multifunctionality in drylands. The quality and quantity of ecosystem services depend on variables such as those we evaluated, and thus the results obtained indicate that increases in the number of plant species could improve the provision of these services. Our findings also suggest that such richness may be particularly important for maintaining ecosystem functions linked to C and N cycling, which sustain carbon sequestration and soil fertility. Because land degradation is often accompanied by the loss of soil fertility, plant species richness may also promote ecosystem resistance to desertification," says Dr. Maestre.

This study emphasizes the need of preserving biodiversity in dryland ecosystems. In this regard, Maestre says that "Our results suggest that the increase in average annual temperature predicted by climate change models will reduce the ability of dryland ecosystems to perform multiple functions related to C, N and P cycling, which are crucial to support life on Earth. Governments worldwide do not agree at the moment about limiting the emission of greenhouse gasses responsible of global warming, but we can contribute to minimize its negative consequences, and to promote the resistance of natural ecosystems against desertification, if we take clear actions to preserve and restore plant biodiversity."

The publication of this study is the outcome of a 5-year research effort, which has involved more than 50 researchers from 30 institutions and 16 different countries. All this work, coordinated and led by Dr. Maestre, has been possible thanks to the support of multiple public and private funding agencies worldwide. Among the support received, the BIOCOM project, awarded to Fernando Maestre by the European Research Council under the Starting Grants program, and the research network EPES, coordinated by Dr. Adrián Escudero and funded by the Science and Technology for Development (CYTED) program, have been fundamental to complete this research endeavor.