DOI 10.1515/mammalia-2013-0100 Mammalia 2014; 78(4): 437–449 Noé U. de la Sancha* Patterns of small mammal diversity in fragments of subtropical Interior Atlantic Forest in eastern Paraguay Abstract: The deforestation of eastern Paraguay is a rela- tively recent phenomenon, starting as early as the 1940s. Assuming that larger forest fragments retain mechanisms and patterns of biodiversity resembling the original forests, understanding these patterns is valuable for comparative, management, and conservation purposes. In this study, I document diversity patterns in four of the largest reserves of subtropical rainforest in eastern Paraguay as part of a 3-year field study. Forty grids, totaling 31,600 trap nights per reserve, resulted in 19 captured species. Spearman correlations were used to understand effects of distance to edge, and various diversity metrics and multivariate anal- yses were implemented to compare assemblages between remnants. Trapping revealed an increase in biodiversity toward forest edges. Medium-sized remnants showed the highest diversity (D) and evenness (J). Statistically signifi- cant differences were found between and among forest fragments. Given that biodiversity includes both rich- ness and abundances, high biodiversity metrics are not the best indicator for ecosystem “health,” as population explosions closer to edges result in greater biodiversity. More edge, more biodiversity. Thus, more emphasis needs to be given to understanding the natural history of native fauna and common assemblage patterns when addressing conservation and management strategies. Keywords: biodiversity; deforestation; edge effects; rain- forest fragments. *Corresponding author: Noé U. de la Sancha, Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA; Department of Natural Resources Science, University of Rhode Island, Kingston, RI, USA; and Science and Education, The Field Museum of Natural History, 1400 S. Lake Shore Dr., Chicago, IL 60605, USA, e-mail: delasancha@msn.com Introduction The Atlantic Forest (AF) of South America is a major hotspot for biodiversity, due to its high levels of end- emism and rapid deforestation (Olson and Dinerstein 2002, Galindo-Leal and de Gusmão Camara 2003). There is a plethora of different studies on the AF that examine the effects of habitat fragmentation on small mammals, at varying scales, with different fragment sizes, differ- ent numbers of fragments, and with various surround- ing matrices (see Pardini and Umetsu 2006, de la Sancha 2010) but few studies from the subtropical region of this forest system, in particular, Paraguay (PY). The deforestation of eastern PY has been relatively rapid, dramatic, and recent (Fleytas 2007, Huang et al. 2007), compared to the Brazilian coastal AF, which has a longer history of deforestation (Ribeiro et al. 2009). In PY, the AF has undergone rapid change from forest to cattle pasture and mechanized soy farming, resulting in a rela- tively homogeneous matrix. Most of eastern Paraguayan forest was intact as recently as 1945 (Fleytas 2007); however, by 2003, merely 13.4% of the original forest remained, with most of the deforestation happening in the 1970s (Huang et al. 2009). Since 1980, the planting of cash crops (e.g., soybeans, sugar, and cotton) and cattle ranching further increased deforestation (Nickson 1981, Ríos and Zardini 1989). Poverty, fear of expropriation, and land-rights disputes have exacerbated the pressures on the remaining forest (Nagel 1991, Sanjurjo and Gauto 1996, Cartes 2003, Quintana and Morse 2005, Huang et al. 2009). With few formally published faunal inventories, we have yet to understand the effects this deforestation has had on the fauna of the region (Yahnke et al. 1998). To address this lack of data, I sampled four of the largest remnants left in eastern Paraguay. Non-volant small mammals are good models for land- scape ecology questions because of their short lifespan, small home ranges (Barret and Peles 1999), short reproduc- tive periods, and high diversity. Small mammals are major components of food webs as prey for predators (Pardiñas and Cirignoli 2002, Teta and Contreras 2003, Correa and Roa 2005), and consumers of invertebrates, seeds, fungi, and many sorts of vegetation (Talamoni et al. 2008). Addition- ally, small mammals are important seed (Vieira et al. 2003) and mycorrhizal fungi dispersers (Janos et al. 1995). AF studies suggest that some forest non-volant small mammals have tolerance and limited dispersal abilities into the Authenticated | delasancha@msn.com author's copy Download Date | 10/29/14 5:27 AM