Exposição das florestas da Amazônia à velocidade das mudanças climáticas

Abstract

Climate change is occurring at an accelerated rate and, as a result, species must produce adaptive responses to survive. The redistribution of biodiversity is one of the most anticipated effects for tropical species, as they have narrow thermal niches that make them less able to adapt to new environmental conditions. Evidence has already been observed in many Amazonian taxonomic groups, however, it remains uncertain whether the species will be able to follow up future climate changes. The amazon is among the global regions most exposed to long distances to climates analogs and to the emergence of new climate conditions. Along with this, the advance of deforestation may restrict the amount of habitats favorable to the distribution of species in the future, in addition to impairing connectivity to areas with a similar climate. Protected areas (PAs) can contribute to the redistribution of Amazonian biodiversity as climate havens, representing an important connectivity strategy between present and future climates, but they may be insufficient, given the speed of climate change promoted by human activities. Climate velocities represent a method to quantify the rate at which species must change their distribution in order to preserve their current climatic adaptation characteristics. In this work, the speed of climate change in the Amazon biome is investigated, based on climatic analogues between the present and the future, from the directions of advancement (present-future) and retreat (future-present), emphasizing the network of PAs in the region. The median climatic velocity of these areas was compared with that of unprotected areas (UAs), in order to verify the effectiveness of PAs in maintaining favorable climatic conditions for the adaptation of species in future climate change scenarios. In addition, the climatic refuges of the Amazon biome were identified and the impact of deforestation on these areas was quantified. To achieve these objectives, data from annual air temperature and precipitation averages with a spatial resolution of 10 km were used, in order to describe the current (1970-2000) and future (2041-2060) mesoclimates. The results show that the effects of the recoil speed will be greater in magnitude and spatial extension. Despite this, the network of PAs will be less exposed to the impacts of the recoil speed than UAs - emphasizing the importance of these areas as a tool in conservation. In contrast, for impacts related to the speed of advancement, the PA network will be slightly more exposed than PAs - indicating that the current spatial layout of the PA network is still not the most suitable for minimizing the impacts of climate change. It was also found that climatic refuges occupy only 7% of the Amazon biome, and are distributed along the edges of the biogeographic limit. In just 12 years, deforestation has caused a loss of more than 5% of these areas. In view of this scenario, it is necessary to further limit the loss of forests and include climate refuges in the conservation agendas of the Amazon, in order to enhance the conservation of the biota of Amazonian forests under climate change scenarios.