Hotter, Drier Climate Influences Tropical Tree Cover Loss and Promotes Bracken Fern Dominance within Arrested Successional Patches in Andean Cloud Forests

Document Type

Article

Publication Date

9-2024

Abstract

As rates of deforestation increase, forest fragments face an uncertain future, including trajectories of further degradation or potential regrowth. To understand the processes that lead to tree cover loss in patches undergoing arrested succession, we studied the historical change in tree cover within present-day patches dominated by bracken fern in the Andean Cloud Forests of Peru. We hypothesized that multiscale processes, from regional climate to patch dynamics, have influenced tree cover loss within patches currently dominated by bracken fern. To test these hypotheses, we used a Planet Lab image to identify patches dominated by bracken fern and then paired these patches with 30-years of tree cover loss, derived from the Landsat archive. We assessed pixels when they underwent tree cover loss. From our analysis of 383 patches, we found that 35 % of tree cover loss within bracken fern patches occurred by 2003 and 65 % by 2007, revealing the long-term stability of bracken fern cover after tree cover loss. Survival models indicated that years with higher vapor-pressure deficit resulted in the greatest losses of tree cover in bracken fern patches. We also found that tree cover loss was greater farther from edges and at sites with greater elevation. Our results suggest that the risk of tree cover loss and subsequent transition to bracken-dominated patches will increase in a hotter, drier climate. We conclude that at the patch level, both the regional climate and local factors have negatively impacted the persistence of forest fragments and contributed to the lack of forest recovery.

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