- A study in which the Desertification Research Center (CIDE), a joint center of the CSIC, the UV and the GVA, participates, analyzes the effects of the simultaneous action of two components of global change, defaunation and increased tree mortality, on a fundamental ecosystem service, seed dispersal.
- The work, in which the Universidad Complutense de Madrid and the Helmoholtz Centre for Environmental Research also participate, is published in the journal Ecography.
The study, led by Jose Mª Fedriani, researcher at the Desertification Research Center (CIDE), a joint center of the Spanish National Research Council (CSIC), the University of Valencia and the Generalitat Valenciana, analyzes the combined action of two components of global change, defaunation and increased tree mortality, on seed dispersal, a key ecosystem service closely related to biodiversity. The results of this research, in which the Complutense University of Madrid and the Helmholtz Centre for Environmental Research have also participated, and which have been recently published in the journal Ecography, contribute to improve the prediction of the consequences of global change on the functioning of ecosystems.
Currently, ecosystems are seriously threatened by numerous factors resulting from human activities. Among them, defaunation, understood as the loss of animal species, has profound ecological consequences ranging from the local or even global co-occurrence of species interacting in the same habitat to the loss of environmental functions and services that are critical for humanity. Carbon sequestration, pollination and seed dispersal stand out among these essential services affected. Most plants depend on animals to disperse their seeds. They transport them long distances from the 'mother' plant, and this service is essential for the maintenance and recovery of plant communities. Other components of global change also impact the functioning of humanized ecosystems by promoting the mortality of many tree species. Defaunation and increased tree mortality often occur together in human-altered ecosystems. The isolated effects of each of these factors are known but not the result of their combined action, in which they probably interact to amplify or diminish each other's effects. It is therefore essential to know the effects of the possible interaction between the two disturbances.
“For this study we have used historical data series (over 20 years) in combination with the individual-based simulation model called 'DisPear'. The results show us that both disturbances strongly limited the number of seed dispersal events, both in quantity and quality, and that this impact was not homogeneous in space, i.e., there were important variations among habitats. In addition, we detected an interaction between both disturbances; that is, the combined effect of both disturbances did not correspond to the sum of their isolated effects,” explains Fedriani. This result highlights the importance of investigating the joint impact of the different components of global change on ecosystem functioning.
The work has been carried out in the Doñana National Park, which is home to numerous species of fleshy fruits whose seeds are mainly dispersed by mammals. Specifically, the pyrethrum (Pyrus bourgaeana Decne. Rosaceae) has been used as a study model. This thorny wild pear tree is in strong decline in Doñana and in many other areas of the southern Iberian Peninsula, due to serious problems of natural regeneration. Some of these mammal species (badgers, Meles meles, foxes, Vulpes vulpes), which act as seed dispersers, have locally decreased their numbers due to human activity (poaching, trampling, etc.), so the tree has lost an important part of its dispersers.
More information: J. M. Fedriani, D. Ayllón, T. Wiegand and V. Grimm. Intertwined effects of defaunation, increased tree mortality, and density compensation on seed dispersal. Ecography.
https://onlinelibrary.wiley.com/doi/full/10.1111/ecog.05047
doi: 10.1111/*ecog.05047
CIDE Communication
