International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 175-186 http://ecoevopublisher.com/index.php/ijmec 1 80 large propagators, their effect is limited, especially for large seed species that rely on large animals for propagation (Babweteera and Brown, 2009; Culot et al., 2017). Due to the irreplaceability of the transmission network, the extinction of large mammals cannot be completely replaced by small species (Culot et al., 2017). Figure 1 Schematic diagram of the population and evolution models (Adopted from Kakishima et al., 2015) Image caption: (a) Schematic diagram with two tree species (P1 and P2 on plant layer L0) and the corresponding seed dispersers (birds A1 on layer L1 and squirrels A2 on L2). In each animal layer, the grey cells (U1 and U2) indicate unvisited sites (where animals never visit). (b) An animal (bird) eats a fruit (apple) at the tree (P1) and drops a seed at an unoccupied site (O1) that results in a new apple tree. (c) The fragmentation process repeats at every 6000 MCS, such that (stage I: a single habitat) →3000 MCS→ (stage II: habitat separation and stage III: species differentiation) →3000 MCS→ (stage IV: habitat reunification and resulting species coexistence=stage I) (Adopted from Kakishima et al., 2015) 6.3 Impacts on tree renewal, carbon storage and forest resilience The disruption of the seed propagation process has a chain effect on forest regeneration, carbon storage and long-term resilience. The reduction in dissemination will lead to a decrease in the recruitment rate of large-seed hardwood tree species, which are often key contributors to forest carbon storage (Culot et al., 2017). Empirical studies have shown that deanimalization may reduce plant renewal of certain species by up to 95%, and changes in tree species community composition may endanger the maintenance of carbon storage in tropical forests (Culot et al., 2017). Furthermore, the loss of disseminators weakens the ability of forests to recover from disturbances, thereby threatening biodiversity and ecosystem services (Wandrag et al., 2017; Culot et al., 2017). 7 The Influence of Human Activities on Seed Propagation 7.1 Habitat destruction and fragmentation When habitats are reduced and divided, the number and diversity of seed spreaders are often the first to be affected. Large fruit-eating animals and some highly dependent spreaders are most likely to disappear, which directly leads to shortened transmission distance, increased genetic similarity among communities, and decreased effective population size (Fonturbel et al., 2015; Perez-Mendez et al., 2016; Borah and Beckman, 2024). Meanwhile, the original activity patterns of animals will also be disrupted, seeds will be difficult to deposit in
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