Anthropogenic land-use legacies underpin climate change-related risks to forest ecosystems

Abstract

Forest ecosystems with long-lasting human imprints can emerge worldwide as outcomes of land-use cessation. However, the interaction of these anthropo-genic legacies with climate change impacts on forests is not well understood. Here, we set out how anthropogenic land-use legacies that persist in forest properties , following alterations in forest distribution, structure, and composition, can interact with climate change stressors. We propose a risk-based framework to identify anthropogenic legacies of land uses in forest ecosystems and quantify the impact of their interaction with climate-related stress on forest responses. Considering anthropogenic land-use legacies alongside environmental drivers of forest ecosystem dynamics will improve our predictive capacity of climate-related risks to forests and our ability to promote ecosystem resilience to climate change. Anthropogenic land-use legacies can exacerbate the impacts of climate change on forest ecosystems Humans have exploited forest ecosystems for millennia [1-3]. Given the magnitude of land-cover changes, forest management practices, and plantation establishment over the past few centuries , the footprint of recent humanity now shapes more than 70% of the world's forests [4]. While high-intensity anthropogenic land uses (see Glossary) prevail in tropical and boreal regions [5,6], land-use cessation has also spread unevenly worldwide since the post-1950s great acceleration [7], from large areas and longer time periods in the Global North to scattered, less-extensive patches and shorter time periods in the Global South [8]. As a consequence , forest ecosystems with long-lasting human impacts (Figure 1) can emerge across multiple biomes [9,10]. Although broadly recognised to influence forest dynamics [11], there is still a lack of understanding of how these human imprints may exacerbate the vulnerability of forest ecosystems to climate change [12-14]. However, such understanding is essential to better predict impacts of climate change on forests and define mitigation and adaptation priorities. The response of forest ecosystems to climate change strongly depends on historical factors [15]. Anthropogenic land uses can affect the stability of forest dynamics in response to climate by altering patterns of forest distribution [16], structure [12], and composition [17] (Figure 1). These alterations may result in persistent impacts of land uses on forest properties at different levels (genetic, population, community, and ecosystem). Despite their relevance, the effects of anthropogenic land uses are rarely considered alongside environmental drivers, often hindering our ability to predict climate-change impacts on forests [18]. Given that climate-change stressors Highlights How the long-lasting effects of anthro-pogenic land-uses can exacerbate the impacts of climate change on forest ecosystems is not well understood. Anthropogenic land-use legacies that persist in forest properties following the alteration in forest distribution, structure, and composition can interact with climate change stressors and lead to detrimental ecological effects. Risk-based approaches using the concept of anthropogenic land-use legacy support the identification of highly vulnerable forest ecosystems and the predic-tive understanding of their potential responses to climate change. Current forest properties can be used together with available historical data to identify increased climate change-related risks to forest ecosystems. Appropriate adaptation and mitigation strategies that consider the legacy of anthropogenic land uses will increase forest ecosystem resilience and societal wellbeing in the long-term.