DOI: 10.5061/dryad.6djh9w126
title: Supplementary material: Fundamental watersheds and altitudinal tripartition of the mountain cloud forests from Northwestern Argentina (Yungas)

description: 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 of Yungas from
 Northwestern Argentina. We assessed the agreement between
 vegetation stratification (fog grasslands, cloud montane forest and low
 montane rainforest) and the tripartition of assemblages of mayflies (an
 ancient group of aquatic insects). The products we offer
 here accompany the paper of Biotropica entitled The
 inter-forest line could be the master key to track biocoenotic effects of
 climate change in a subtropical forest. 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.       
description: <strong>A) </strong>Raster of layers (altitudinal
 tripartition) in the mountain cloud forests from Northwestern Argentina
 (Yungas). Map generated using the Compliance and Commonality index
 (C&C index).  The different strata are delimited by specific
 elevation lines at each hydrographic basin. They embrace to the largest
 possible extent the next vegetation formations, from highlands to
 lowlands: fog grasslands, montane forest and low montane rainforest. The
 treeline matches broadly the upper limit of the intermediate stratum,
 while the lower limit of such a stratum is tied to the inter-forest
 line. <strong>B)</strong>
 Watersheds. Fundamental watersheds from Northwestern Argentina (Yungas).
 They were delimited using a high-resolution DEM of the study area, and
 fulfill the next eligibility criteria: C&C higher than 0.5, extent
 area larger than 5.36 km2 (i.e. &gt; 100 raster cells), maximum
 altitude above the 1,500 m a.s.l. and with raster cells classified in
 either one of three vegetation formations of concern. On average, all
 fundamental watersheds are robust since the mean C&C index is 0.81
 (more than 80% of the middle layer is occupied by montane forest and more
 than 80% of the montane forest falls within the middle layer).