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Pastoralism is a land‐use system that involves the care and use of grazing livestock and has been more common in areas of low resource availability. In this review, we analyze the impact of pastoralism on biodiversity and ecosystem services across the tropical Andes. This region is the most extensive and populated tropical mountain region in the world and presents a high diversity of biomes, livestock types and management histories. Given that pastoralism is a main land use here, understanding its impacts is important for providing appropriate recommendations for sustainable management. LocationTropical Andes; Venezuela to the north of Argentina and Chile. MethodsTo understand these impacts, we performed a systematic literature search (August 2021) and obtained 103 articles. We created a conceptual framework to map how available research has contributed to our understanding of the main pastoral systems, their associated management strategies and the impact of different grazing intensities on vegetation cover/diversity and ecosystem services. ResultsWe found that research has focused on two leading pastoral systems in the region: bovines in the páramo biome of the northern Andes and camelids in the puna biome of the central Andes. We found important environmental impacts at high grazing intensities for both the puna camelid and páramo bovine pastoral systems, including a decrease in soil organic carbon and an increase in soil compaction, a decrease in above‐ground biomass, plant species richness, and graminoid cover, as well as clear changes in the growth‐form composition of vegetation. ConclusionsGiven these findings, we recommend coordinated research efforts using common methodologies, documenting current and previous land use, including stocking rates, and combining observational and experimental approaches to develop a more integrated understanding of pastoralism's impacts across this diverse and vulnerable region. 

Abstract AimClimate change is transforming mountain summit plant communities worldwide, but we know little about such changes in the High Andes. Understanding large‐scale patterns of vegetation changes across the Andes, and the factors driving these changes, is fundamental to predicting the effects of global warming. We assessed trends in vegetation cover, species richness (SR) and community‐level thermal niches (CTN) and tested whether they are explained by summits' climatic conditions and soil temperature trends. LocationHigh Andes. Time periodBetween 2011/2012 and 2017/2019. Major taxa studiedVascular plants. MethodsUsing permanent vegetation plots placed on 45 mountain summits and soil temperature loggers situated along a ~6800 km N‐S gradient, we measured species and their relative percentage cover and estimated CTN in two surveys (intervals between 5 and 8 years). We then estimated the annual rate of changes for the three variables and used generalized linear models to assess their relationship with annual precipitation, the minimum air temperatures of each summit and rates of change in the locally recorded soil temperatures. ResultsOver time, there was an average loss of vegetation cover (mean = −0.26%/yr), and a gain in SR across summits (mean = 0.38 species m²/yr), but most summits had significant increases in SR and vegetation cover. Changes in SR were positively related to minimum air temperature and soil temperature rate of change. Most plant communities experienced shifts in their composition by including greater abundances of species with broader thermal niches and higher optima. However, the measured changes in soil temperature did not explain the observed changes in CTN. Main conclusionsHigh Andean vegetation is changing in cover and SR and is shifting towards species with wider thermal niche breadths. The weak relationship with soil temperature trends could have resulted from the short study period that only marginally captures changes in vegetation through time.