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Abstract It is largely unknown how South America’s Andean forests affect the global carbon cycle, and thus regulate climate change. Here, we measure aboveground carbon dynamics over the past two decades in 119 monitoring plots spanning a range of >3000 m elevation across the subtropical and tropical Andes. Our results show that Andean forests act as strong sinks for aboveground carbon (0.67 ± 0.08 Mg C ha −1 y −1 ) and have a high potential to serve as future carbon refuges. Aboveground carbon dynamics of Andean forests are driven by abiotic and biotic factors, such as climate and size-dependent mortality of trees. The increasing aboveground carbon stocks offset the estimated C emissions due to deforestation between 2003 and 2014, resulting in a net total uptake of 0.027 Pg C y −1 . Reducing deforestation will increase Andean aboveground carbon stocks, facilitate upward species migrations, and allow for recovery of biomass losses due to climate change. 

In this study, we evaluate the effectiveness of indicators for rehabilitation practices in high mountain landscapes that were aimed at increasing grassland palatability and biomass accumulation. Focusing on the department of Huancavelica in Peru, the importance of rehabilitation practiced in this area involves the relationship of alpaca pastoralists and their need to produce wool. Overgrazing in this area has decreased the carrying capacity of the system, which may be problematic for continuing their present levels of grazing. Therefore, rehabilitation practices, including herbivory exclusion, exclusion with added irrigation, and exclusion with water collecting ditches, were installed to increase vegetation biomass and palatability of the vegetation. The effects of the rehabilitation practices were assessed using six indicators: vegetation coverage, species richness, Shannon‐Weiner Diversity Index, below and aboveground biomass, and soil organic matter, which were analyzed using mixed‐effects models. The indicators show that some practices, such as exclusion and ditches, are positively affecting vegetation coverage while negatively affecting species richness. Additionally, biomass showed lower accumulation in areas not excluded from grazing. Therefore, although some of the treatments were initiated as recently as 2013, we can already observe changes in the indicators involving vegetation composition and structure. In the long term, these indicators may allow us to fully understand the effect of the rehabilitation practices on maintaining the carrying capacity of the system. Furthermore, the general approach should be widely applicable in other utilized landscapes.