The hidden heterogeneity of agricultural landscapes of the Rolling Pampa (Argentina)

Abstract

Extensive agriculture imprints a certain spatial and temporal homogeneity on a landscape and often hides its natural heterogeneity. Moreover, this homogenization may be disconnected from land use capacity, increasing the risk of land degradation. We described the anthropogenic and natural heterogeneity of an agricultural basin of the central Rolling Pampa of Argentina, to assess whether the current land use is consistent with the natural land capacity. First, we mapped and characterized the anthropogenic and natural spatial heterogeneity through two independent analyses, one based on land cover and the other on geomorphological and edaphic variables. Second, we investigated the relationship between anthropogenic and natural heterogeneity by integrating the previous analyses with a third one, focused on vegetation activity (normalized difference vegetation activity index, NDVI). The results showed two anthropogenic landscape units, whereas six natural landscape units were identified. Anthropogenic landscape I was mainly associated with natural landscapes 1, 2 and 3. These landscapes were characterized by large, regularly shaped fields dominated by soybean. Anthropogenic landscape II was associated with natural landscapes 4, 5 and 6, which were characterized by smaller and more irregularly shaped fields and were more diversely cultivated than the other group of landscapes. Anthropogenic landscape I and its three associated natural landscapes had lower average vegetation activity but higher seasonal and inter-annual variation than anthropogenic landscape II and its associated landscapes. In conclusion, on a landscape level, natural heterogeneity may be hidden in agricultural landscapes with highly homogeneous land use, such as the Pampas region. If not taken into consideration, this could increase the risk of land degradation in certain conditions or landscapes.