Short communicationConservation of small and medium-sized mammals following native woodland regrowth: A case study in a long-term UNESCO Biosphere Reserve, Argentina
Highlights
► We assessed small and medium-sized mammals response to exclusion in the Monte Desert. ► Protected and unprotected areas preserve different mammals assemblages. ► The relative importance of unprotected areas for supporting mammals diversity.
Introduction
Livestock grazing, deforestation and habitat fragmentation are the major causes of human impacts on biodiversity in drylands and have resulted in desertification, landscape homogenization and loss of plant and animal diversity (Villagra et al., 2009). South American drylands, in particular, are undergoing accelerated degradation due to grazing and deforestation (Villagra et al., 2009). Desert mammals are an important segment of biodiversity conservation showing high diversity and having important effects on the desert ecosystem (e.g., as “keystone species”) (Kelt, 2011; Ojeda et al., 1998).
In the context of land degradation, management of protected areas in which human activities are restricted or prohibited is critical. Although conservation emphasis has been placed on establishing reserves, the importance of surrounding disturbed areas for faunal conservation has been increasingly recognized since protected areas are embedded in a landscape where resource exploitation occurs. Several studies on mammals show that, although some species benefit from being protected against human disturbance, others actually meet their habitat requirements in unprotected areas (Chávez and Ceballos, 2009; Tabeni and Ojeda, 2005).
In this study, we analyzed the composition of a desert assemblage of small and medium-sized mammals and their associated habitats after 50 years of grazing exclusion in a protected area (UNESCO-MaB Reserve of Ñacuñán) and its surrounding grazed matrix (Ojeda et al., 1998). The MaB Reserve of Ñacuñán is embedded within a landscape that is strongly affected by cattle ranching (Villagra et al., 2009). After 50 year-old grazing exclusion, the recovery of the native vascular flora is remarkable, however there is currently no ecological studies that assess the ecological impacts of that protection on the surrounding unprotected rangeland and how it affects desert mammals.
Section snippets
Study area
The study was conducted in the Man and Biosphere (MaB) Reserve of Ñacuñán, Mendoza Province, Argentina (34° 02′S, 67° 58′W, 12,300 ha, 119 km2), and in an adjoining unprotected area under continuous grazing pressure. Both sites belong to the temperate Monte Desert biome, with a marked seasonality of humid summers (mean temperature > 20 °C) and dry winters (mean temperature < 10 °C). Average annual rainfall is 324 mm. It boasts a diverse mosaic of habitats that includes Prosopis flexuosa
Habitat characterization
Sand dunes in the unprotected area had less herbaceous (Welch's approximate t test = −4.71, p < 0.001), shrub (t = −6.45, p < 0.001) and grass cover (t = −2.08, p < 0.05) compared to the protected area. In the Larrea shrubland outside the Reserve, herbaceous (Welch's approximate t test = −5.32, p < 0.001) and grass cover (Welch's approximate t test = −7.89, p < 0.001) were lower than in the Reserve, whereas bare soil cover was higher (Welch's approximate t test = 6.15, p < 0.001). The Prosopis
Discussion
After nearly over 50 years of large herbivore exclusion, our results show significant differences in habitat structure and mammal diversity between areas, suggesting that the mammal assemblage studied is partially protected in the Reserve. Some small rodents like A. molinae and C. musculinus seem to have benefited from this exclosure as it has led to higher plant density and reduced predation risk (Tabeni and Ojeda, 2005). However, the protected area shows a decrease in richness and abundance
Acknowledgments
Thanks to Néstor Viñals, Carlos Vazquez, Manuela Zebunke, Melanie Roth, Cecilia Fernandez and especially to Benjamin Bender for helping us with the fieldwork. We also are most grateful to Nelly Horak and María Eugenia Periago for the English version of the manuscript.
We thank two anonymous reviewers for improving this manuscript with their useful comments.
This work was partially supported by the SETCyP and CONICET Research Grants PICT 03281, PIP 02884 and CONICET doctoral fellowship.
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