Resumen de Evaluación de servicios ecosistémicos y conflictos asociados a los ungulados silvestres nativos y exóticos
Ecosystem functioning includes all cycling materials and energy, the interactions among organisms and the abiotic system. This functioning has been modified due to human activities, especially the biodiversity, which has provoked alterations of interactions among species. Currently the scientific community has recognized a biodiversity crisis because of human activities, which could affect negatively to human wellbeing by means of losing ecosystems and its components. All those benefits that people obtain from ecosystems are ecosystem services (ES), as for example food, tools, maintenance of habitats or even cultural aspects.
Historically, our species has been linked to many species and among them ungulates deserve a chapter of their own. Ungulates are animal species closely related with human societies. Relations between humans and wild ungulates vary depending of the context. In developing countries ungulate populations are declining whereas in developed countries they are increasing in abundance and distribution. This rewilding process has contributed to the rise negative interactions between humans and between wild ungulates, as for example agriculture or silviculture damage. To avoid or mitigate these conflicts people use different management tools such as fencing or supplementary feeding. So, research about ungulates and their relations with people should be done from a social-ecological perspective.
This thesis focuses on the human-ungulate relations, both positive and negative interactions, and the evaluation of management tools employed to mitigate those negative impacts. Specifically this thesis aims to assess: i) the state of the art of research in human-ungulates relations (Chapter 1); ii) the services and disservices provided by wild ungulates for two stakeholders: scientists and shepherds (Chapter 2); the niche overlap and potential competition between the native Iberian ibex (Capra pyrenaica) and the exotic aoudad (Ammotragus lervia) as a paradigm of conservation conflict (Chapter 3); the effects of supplementary feeding effects on the target species (aoudad), other non-target species and soil properties (Chapters 4 and 5). Finally, in Chapter 6, the results of previous chapters are discussed.
First (Chapter 1), we reviewed scientific publications to establish the state of the art about human-ungulate relations. We showed that most scientific publications approach this relations from the perspective of conflicts, being the ES less considered in that studies. Also, most of the publications included environmental managers and hunters as the main social actors regarding human-ungulate relations. Moreover, management tools employed to mitigate ungulate damages to human interests rarely were evaluated, and lethal control and the use of barriers were the main strategies recommended to mitigate or avoid damages.
In Chapter 2, we approached to the human-ungulate interactions from the perspective of researchers and shepherds and the framework of ecosystem services based on the categories of beneficial nature’s contributions to people (NCP; Díaz et al., 2018) . We examined and compared scientific research and shepherds’ perceptions regarding the provision of NCP by wild ungulates. We reviewed scientific articles of NCP provided by ungulates in Spain and conducted questionnaires regarding NCP to shepherds in farming systems of Spain where domestic and wild ungulates cohabit. Then, we compared whether the scientific priorities match with those perceived by shepherds. Both stakeholders highlighted more detrimental than beneficial NCP, there were some mismatches between scientific priorities and shepherds’ perceptions. Regarding detrimental NCP, soil alteration, damage to silviculture, human safety, traffic collision and human-human conflicts were frequently studied but not mentioned by shepherds. In contrast, shepherds mainly considered vegetation damage, grazing competence, damage to animals with economic interests, crop damage and disease transmission to livestock as important detrimental NCP. Concerning beneficial NCP, whilst hunting was prominent in the publications, shepherds did not conceived it as an important beneficial contribution and considered the regulation of other organisms as an important benefit. These results can have twofold implications. The emphasis on detrimental NCP can reinforce the idea that ungulates can threaten humans rather than contribute to societies’ wellbeing. The fact that research does not address the interests of shepherds can affect the social tolerance towards ungulates as the damages experienced or perceived by shepherds are not studied. Our results show the relevance of considering local knowledge systems of shepherds, something highlighted by the NCP approach.
Regarding Chapter 3, we evaluated the potential competition between the native Iberian ibex and the exotic aoudad measuring the niche overlap under cohabit conditions in the Iberian Peninsula. To do that, we compared the trophic niche by using the content of stable isotopes δ15N and δ13C in the hair, and the environmental niche by modelling habitat based on fine-scale presence records. Then we assessed both species’ co-occurrence to test for spatial segregation. Our results indicated that both species shared a similar trophic niche, showed a similar distribution of suitable areas and that their environmental niches were similar. Moreover, negative spatial association was found between the aoudad and Iberian ibex. So, both species are ecologically similar and suggest that spatial segregation might have favoured their co-existence in semiarid Mediterranean mountains where they cohabit.
In order to clarify the effect of diversionary feeding (i.e. specific use of supplementary feeding to avoid crop damage), in Chapter 4 we evaluated its effect in the spatial behaviour of the aoudad. Also, we assessed the use of the diversionary feeding stations (DFS) by non-target species. Nine aoudads were tracked with GPS/GSM collars to establish their home ranges and the visits to the DFS. We compared the home ranges and the number of GPS locations in the DFS before and meanwhile food was available at them. Moreover, eight DFS were monitored with camera traps to identify which other species used the DFS. We found that home ranges varied for some individuals and that not all the tracked animals used the DFS. The number of locations in the DFS increased when food was available. Furthermore, other fifteen non-target species of birds and mammals used DFS, especially the wild boar. Aoudads and wild boars segregated temporally in their use of the DFS. These results suggest that diversionary feeding had little effect on the spatial behaviour of the aoudad and benefited other conflictive species.
Continuing with the diversionary feeding as a management tool, we evaluated the effect of this tool on semiarid Mediterranean mountain soils, because physicochemical and biological soil properties can be altered due to the concentration of wildlife in areas where food is deposited (Chapter 5). We collected soil samples from three DFS and compared soil characteristics from three areas: feeding stations (FS), contour area (C; surrounding the feeding stations) and a reference soil (RS; not influenced by feeding stations). Our results suggested no effects on soil physical properties. However, we found that diversionary feeding altered electrical conductivity, nutrient concentration, microbial activity and microbial communities at FS, but effects were weaker in the C. Soil functionality could change due to these alterations of soil dynamics.
Finally, Chapter 6 discusses the results presented in this thesis, the limitations of each chapter and the biodiversity conservation implications and future perspectives about wild ungulates and human relations.
