Variation in Alpine Plant Diversity and Soil Temperatures in Two Mountain Landscapes of South Patagonia

Abstract

Alpine environments and their temporal changes are rarely studied at high latitudes in the southern hemisphere. We analyzed alpine plants, soil temperatures, and growing-season length in mountains of two landscapes of South Patagonia (46° to 56° SL): three summits (814–1085 m a.s.l) surrounded by foothill grasslands in Santa Cruz province (SC), and four summits (634–864 m a.s.l.) in sub-Antarctic forests of Tierra del Fuego province (TF). Sampling followed the protocolized methodology of the Global Observational Research Initiative in Alpine Environments (GLORIA). Factors were topography (elevation and cardinal aspect) and time (baseline vs. re-sampling for plants, five annual periods for temperatures), assessed by univariate and multivariate tests. Plant composition reflected the lowland surrounding landscapes, with only 9 mountain species on 52 totals in SC and 3 on 30 in TF. Richness was higher in re-sampling than baseline, being assemblages more influenced by aspect than elevation. Mean annual soil temperature and growing-season length, which varied with topography, were related to the Multivariate El Niño Southern Oscillation Index (MEI) but did not show clear warming trends over time. We highlight the importance of long-term studies in mountainous regions of extreme southern latitudes, where factors other than warming (e.g., extreme climate events) explain variations.

Compositional shifts of alpine plant communities across the high Andes

“…This highlights the high climatic variability in the Andes induced by differences in local topography, macroclimates and external drivers such as ENSO (Garreaud, 2009; Sklenář et al, 2016). The position of the permanent plots within each summit (one in each of the four main cardinal orientations) and local slope inclinations most likely causes pronounced differences in the thermal input, significantly influencing vegetation physiognomy and composition (Carilla et al, 2018; Lencinas et al, 2021).…”

“…6870 km and an elevational gradient of nearly 4900 m (634 to 5498 m a.s.l.). Summits were classified as subalpine ( n = 5), alpine ( n = 9), subnival ( n = 19) and nival ( n = 12) according to their elevation and latitude (see [Cuesta et al, 2017; Lencinas et al, 2021] for details). The GLORIA‐Andes network established 1 m 2 permanent vegetation plots in the upper area on each summit (i.e.…”

“…The Puna is a seasonal high Andean grassland system that occurs from 8° S to 29–30° S and is characterized by a dry and wet seasonal climate due to a pronounced cold dry season occurring from May through September (Cuesta et al, 2017; Tovar et al, 2022). The Patagonian high Andes occur from 32–39° S to 56° S (northern limit is under discussion), and are characterized by a marked seasonality with a narrow summer window (December–February), when the maximum precipitation is reached (Lencinas et al, 2021).…”