Final answer:
Fragmentation leads to increased tree mortality due to edge effects like desiccation, changes in land use, altered ecological processes, and the long-term effects of reduced gene flow resulting in inbreeding depression and loss of genetic diversity.
Step-by-step explanation:
Fragmented areas can lead to increased tree mortality for several reasons. One of the immediate effects of fragmentation is the increase in edge habitat, which can result in increased desiccation due to exposure to wind and sun, making it more difficult for trees to maintain moisture levels. Additionally, fragmentation often involves changes in land use, such as the construction of roads and the use of chemicals like pesticides, which can also lead to the death of trees. Moreover, habitat destruction and fragmentation change ecological processes within fragments, with consequences such as altered species interactions that can cascade to affect vegetation negatively. For example, the loss of large predators can lead to overabundant seed predators and herbivores, altering vegetation composition and reducing tree recruitment. Over time, these isolated patches of vegetation may also suffer from issues such as inbreeding depression and loss of genetic diversity due to hindered gene flow, further compromising their resilience and increasing the risk of tree death.