Climate and microhabitat shape the prevalence of endozoochory in the seed rain of tropical montane forests

Abstract

Endozoochory, the dispersal of seeds by animal ingestion, is the most dominant mode of seed dispersal in tropical forests and is a key process shaping current and future forest dynamics. However, it remains largely unknown how endozoochory is associated with environmental conditions at regional and local scales. Here, we investigated the effects of elevation, climate, and microhabitat conditions on the proportion of endozoochorous plant species in the seed rain of the tropical Andes of southern Ecuador. Over 1 year, we measured seed rain in 162 seed traps on nine 1‐ha forest plots located at 1000, 2000, and 3000 m a.s.l. We recorded climatic conditions (mean annual temperature and rainfall) in each plot and microhabitat conditions (leaf area index and soil moisture) adjacent to each seed trap. In total, we recorded 331,838 seeds belonging to 323 morphospecies. Overall, the proportion of endozoochorous species in the seed rain decreased with elevation. The relative biomass of endozoochorous species decreased with increasing rainfall, whereas the relative seed richness of endozoochorous species increased with increasing temperature and leaf area index. These findings suggest an interplay between climate factors and microhabitat conditions in shaping the importance of endozoochorous plant species in the seed rain of tropical montane forests. We conclude that changing climatic and microhabitat conditions are likely to cause changes in the dominant dispersal modes of plant communities which may trigger changes in the current and future dynamics of tropical forests. Abstract in Spanish is available with online material.

Habitat differences in seed‐dispersing vertebrates indicate dispersal limitation in tropical bracken‐dominated deforested areas

“…After fire or land abandonment, bracken fern, Pteridium spp., frequently colonizes deforested areas and dominates the vegetation for long periods, hindering forest regeneration (Carvalho et al., 2022; Hartig & Beck, 2003; Ssali et al., 2017). Since most tropical forest tree species are dispersed by animals (Acosta‐Rojas et al., 2023; Howe & Smallwood, 1982; Moles et al., 2007), forest regeneration in the deforested areas is highly dependent on seed‐dispersing animals (Catterall, 2018; Costa et al., 2022; Wunderle, 1997). Although the seed rain and seedling recruitment of forest tree species in bracken‐dominated areas is low (Gallegos et al., 2016; Saavedra et al., 2015; Ssali et al., 2018), the properties of seed disperser communities in tropical bracken‐dominated areas have not been studied (but see Maya‐Elizarrarás & Schondube, 2015).…”

Systematic reduction in seed rain of large‐seeded and endozoochorous species in pastures compared to forests along a tropical elevational gradient

“…Tropical elevational gradients are suitable for studying spatial variation in forest restoration dynamics (González et al, 2013;Silveira et al, 2019) because they cover a wide range of abiotic and biotic conditions over a small spatial extent (Bruijnzeel & Veneklaas, 1998;Sanders & Rahbek, 2012). Furthermore, previous studies have shown that the diversity of woody plant species and plant trait composition change along elevational gradients (Aide et al, 1996;Acosta-Rojas et al, 2023). The diversity of seed-dispersal interactions between plants and their animal seed dispersers also changes along tropical mountains (Quitián et al, 2018).…”

Variation in fruit and seed dimensions is better explained by dispersal system than by leaf size in a tropical rainforest

“…In the classic definition, a fruit is a developed carpel that usually helps to protect and disseminate seeds (Gonçalves, 2021). Overall, a large diversity of fruit shapes and functions are present in plant communities (e.g., van Roosmalen, 1985; Acosta‐Rojas et al, 2021; Stevenson, 2023). Within one tropical site, fruits may be represented by dozens of different types, with enormous variation in morphological traits.…”