干旱区生态环境知识资源中心

We describe the altitudinal variation in species richness, turnover and species composition of small mammals through field surveys along 4 transects ranging from tropical rainforests at 500 m to high Andean deserts at 4 000 m in northwestern Argentina. The elevation pattern of richness for all small mammals decreases with altitude, mainly due to the high diversity of bats in the lowlands. For the terrestrial small mammals there was a clear curvilinear pattern of richness with a peak near the upper tree line at 2 700 m. The maximum values of the species turnover rates were located in the upper part of the gradient at 3 500 m. The composition of small mammals communities in every single elevation transect was consistent with the phytogeographic scheme, with species characteristics of montane rainforest, temperate cloud forests and high Andean steppes. The analysis of the 4 altitudinal transects together revealed that elevation is the. main source of variation in species composition. Latitudinally, the 2 northernmost transects, similar between each other, differed from the 2 southernmost, mainly at intermediate elevation, where a high concentration of endemic rodents has been documented.