Research shows the relevance of less abundant species and their evolutionary history
This is the first time that evolutionary diversity, functional diversity and taxonomic diversity have been studied together
The work has focused on 123 arid and semi-arid ecosystems distributed all over the planet
Shrublands dominated by Larrea tridentata species. One of the study areas in Utah, United States
|Eucalyptus savannas in Australia, one of the study areas.
Photo: Santiago Soliveres Codina
Alicante, Tuesday 02 April 2019
University of Alicante researcher Santiago Soliveres along with scientists from the King Juan Carlos University, the National Institute of Agronomic Research of France (INRA) and the Spanish National Research Council (CSIC) is part of a research group that has studied the many aspects of plant biodiversity of 123 arid and semi-arid ecosystems distributed all over the planet. The results recently published in the journal Proceedings of the National Academy of Sciences USA (PNAS) show the relevance of rare species and their evolutionary history in maintaining soil fertility and productivity in arid areas around the world.
Environmental conditions influence the species of plants that live in a given place. For example, if there is a lot of herbivory, they will develop spines to protect themselves. If there is little rainfall, as occurs in much of the Iberian environments, small and thick leaves will grow, as well as stems, to store water. If there is snow, a flattened, circular shape will help them deal with the extra weight they will have to bear.
This variety of functional traits or adaptations is part of biodiversity, but it is not the only one. The number of species or taxonomic diversity is the most widely used measure and a good indicator of how ecosystems change and what consequences can be expected in the future. Also important is its evolutionary diversity, that is, the thousands of years of evolution involved. It is an indicator of their adaptations to past climates, but also of the establishment of their mutual relations or co-evolution with enemies such as pathogens and herbivores.
According to Ramón y Cajal researcher at the UA's Department of Ecology and co-author of the study Santiago Soliveres Codina, they knew that all these aspects of biodiversity were key for ecosystems to work, but their effects had never been studied together. This is important because these many aspects are not necessarily interrelated, nor will they respond equally to climate change. Therefore, their role as a whole, rather than in isolation, must be known in order to better predict the consequences of these changes in diversity. The researcher stressed that this is the first time that evolutionary diversity has been studied as a whole, that is, the number of millions of years that have been accumulated, the diversity of functional traits that identifies the shape adopted by the parts of the plant, and taxonomic diversity or the number of species.
Less abundant species
These scientists have studied ecosystems as diverse as the Iberian esparto grasslands and rosemary fields, the African and Australian savannahs and the Patagonian Pampas. In all of them, several variables have been assessed that, like the recycling of nutrients, the content of organic matter in the soil or the productivity of vegetation, determine the cycles of the three most relevant elements for life: carbon, nitrogen and phosphorus.
Beyond the number of species, this study reveals that less abundant species and their evolutionary diversity are key factors in maintaining the functioning of arid ecosystems.
Interestingly, the functional traits of dominant species determine each function separately; however, their effects have different signs in each of the major nutrients. In other words, no dominant species can maintain high levels of all functions at once, regardless of environmental conditions. This is where less common species come in, since they are capable of providing multiple functions, and the study reveals that it is mainly the evolutionary component of their biodiversity that determines that capacity. The loss of biodiversity that we are suffering directly threatens the capacities of ecosystems that are fundamental to human survival and well-being, as stated by Soliveres Codina. Coordinator of the study and researcher at the Rey Juan Carlos University Yoann LeBagousse-Pinguet concluded that the research, therefore, could help better define biodiversity conservation and management programmes, as well as help choose with which species we can restore to already degraded ecosystems.
“In ecological restoration, this tells us which species to use in each case, it helps managers know which species or families to choose,” UA researcher said.
The global sampling carried out for this research, unique in the world, is part of the BIOCOM project, led by URJC Professor of Ecology Fernando T. Maestre, which is supported by the Starting Grants programme of the European Research Council (ERC).
Le Bagousse - Pinguet, Y.; Soliveres, S.; Gross, N.; Berdugo, M.; Torices, R.; Maestre, F.T. 2019. Phylogenetic, functional and taxonomic richness have both positive and negative effects on ecosystem multifunctionality. Proceedings of the National Academy of Sciences USA, www.pnas.org/cgi/doi/10.1073/pnas.1815727116
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