Supplementary material: Fundamental watersheds and altitudinal tripartition of the mountain cloud forests from Northwestern Argentina (Yungas)

<p>Vegetation zonation along the slopes of a mountain, from low to high altitude, is a well-known pattern in landscape ecology. A similar picture is also described in the field of freshwater ecology. Rivers and streams show different types of habitats between upland and downland site locations. We studied both segmentations of altitudinal gradient in a subtropical hotspot of biodiversity, namely the mountainous rainforest <span>of Yungas from Northwestern Argentina. We assessed the agreement between vegetation stratification (</span>fog grasslands, cloud montane forest and low montane rainforest<span>) and the tripartition of assemblages of mayflies (an ancient group of aquatic insects). The products we offer here accompany the paper of Biotropica entitled </span><em>The inter-forest line could be the master key to track biocoenotic effects of climate change in a subtropical forest</em>.</p> <p>We established a pair of altitudinal cutoffs in each of the watersheds from Argentinean Yungas. They correspond to the upper and lower limits of the middle layer, and they were obtained through an optimization task. The objective function was to maximize the overlap between the extent of such a middle layer and the area classified as cloud montane forest. The upper limit approaches to the treeline, whereas the lower limit is expected to fit the inter-forest line. Interestingly enough, assemblages of aquatic insects can be ordinated along altitudinal transects, but the main distinction occurs at either side of the hypothetical inter-forest line rather than the treeline. This finding is consistent throughout the study area. Map of the three altitudinal floors, as well as the different watersheds, are available as raster files.       </p>