Effect of wild ungulate density on invertebrates in a Mediterranean ecosystem

Abstract

In recent decades, the abundance and distribution of certain big game species, particularly red deer (Cervus elaphus) and wild boar (Sus scrofa), have increased in south central Spain as a result of hunting management strategies. The high density of these ungulate species may affect the abundance of epigeous invertebrates. We tested the relationships between big game abundance and biodiversity, taxon richness, the biomass of invertebrates and their frequency on nine hunting estates and in comparison to ungulate exclusion areas. Ungulate exclusion itself affected invertebrate richness, since lower values were found in the open plots, whereas the highest differences in invertebrate diversity between fenced and open plots was found in areas with high wild boar density. Where wild boar densities were high, the number of invertebrates decreased, while where they were low, red deer had a positive effect on invertebrate abundance. Fenced plots thus seemed to provide refuge for invertebrates, particularly where wild boar were abundant. This study supports the idea that the structure of fauna communities is damaged by high density populations of ungulates, probably due to decreased food availability owing to overgrazing, modified conditions of ecological microniches and direct predation. However, the effects depended on the group of invertebrates, since saprophytic species could benefit from high ungulate abundance. Our findings reflect the need to control ungulate population density under Mediterranean conditions in south–western Europe and to implement ungulate exclusion plots.

Invasive Wild Pigs: A Significant Disturbance in Coastal Forests

“…Although studies are scarce, results from predation studies in the Coastal Plain support further study into the soil impacts of invertebrate consumption by wild pigs [29,30,32]. Significant alterations to soil dynamics resulting from the impacts of wild pigs can have cascading effects on soil chemistry and composition, as has been shown in both their native [50,53,54] and non-native range [29,30,36,42,55].…”

“…Urbanization is associated with: increases in soil temperature, soil moisture dynamics, macroinvertebrates such as earthworms, decomposition rates, nitrogen-mineralization, and nitrification rates, and decreases in microinvertebrate populations, fungal communities, stem density, and leaf litter depths are just a few of the impacts of urbanization [10,12,17,21,23,95]. As explored earlier, wild pigs are associated with increases in soil temperature, decomposition rates, macroinvertebrate populations, nitrogen mineralization, and nitrification rates; they also decrease microinvertebrate populations, leaf litter depth, stem density, and alter fungal communities [31][32][33][34][35][36][37][38]40,[45][46][47][48][49][50][51][53][54][55]. As each of these alterations has cascading impacts on soil dynamics and nutrient cycling, these alterations can result in significant alterations to the function of soil as well as to the composition and distribution of vegetation.…”

Endangered animals and plants are positively or neutrally related to wild boar (Sus scrofa) soil disturbance in urban grasslands

“…Wild boar activities can alter animal communities as well 29 . Arthropods can be affected by predation 30 or habitat modification 31 .…”

Assessing red deer hunting management in the Iberian Peninsula: the importance of longitudinal studies

“…The prevailing management systems in these areas often involve fencing, artificial feeding and translocations ( Rodriguez-Hidalgo et al, 2010 ; Martínez-Jaúregui & Herruzo, 2014 ). Current local densities may reach over 40 ind/km 2 ( Vicente et al, 2007 ; Acevedo et al, 2008 ), which might lead to unsustainable situations, triggering negative effects at different levels of the ecosystem ( Gortázar et al, 2006 ; Carpio et al, 2014a , 2014b ; Perea, Girardello & San Miguel, 2014 ). There is a need to understand the population dynamics of red deer in Mediterranean areas in order to establish sustainable management plans based on scientific knowledge and that are compatible with maximising hunting as a relevant socio-economic activity while impeding the negative impacts of overabundance.…”