Long Distance Seed Dispersal by Forest Elephants

Abstract

By dispersing seeds long distances, large, fruit-eating animals influence plant population spread and community dynamics. After fruit consumption, animal gut passage time and movement determine seed dispersal patterns and distances. These, in turn, are influenced by extrinsic, environmental variables and intrinsic, individual-level variables. We simulated seed dispersal by forest elephants (Loxodonta cyclotis) by integrating gut passage data from wild elephants with movement data from 96 individuals. On average, elephants dispersed seeds 5.3 km, with 89% of seeds dispersed farther than 1 km. The longest simulated seed dispersal distance was 101 km, with an average maximum dispersal distance of 40.1 km. Seed dispersal distances varied among national parks, perhaps due to unmeasured environmental differences such as habitat heterogeneity and configuration, but not with human disturbance or habitat openness. On average, male elephants dispersed seeds farther than females. Elephant behavioral traits strongly influenced dispersal distances, with bold, exploratory elephants dispersing seeds 1.1 km farther than shy, idler elephants. Protection of forest elephants, particularly males and highly mobile, exploratory individuals, is critical to maintaining long distance seed dispersal services that shape plant communities and tropical forest habitat.

Disturbance sensitivity shapes patterns of tree species distribution in Afrotropical lowland rainforests more than climate or soil

“…However, here we report there are strong human effects across a wide climatic gradient, lending strength to our finding. Human activity has well‐known negative effects on Central African animal communities (Beirne, Nuñez, et al., 2019 ; Koerner et al., 2017 ; Núñez, Froese, et al., 2019 ; Poulsen et al., 2011 , 2017 , 2021 ), and our results suggest that these disturbance gradients are also related to tree community composition, supporting past work suggesting indirect stress on plants and alterations in plant–animal interactions can modify plant community composition (Núñez, Clark, et al., 2019 ; Poulsen et al., 2013 ).…”

Elevation modulates the impacts of climate change on the Brazilian Cerrado flora

“…Both unrestricted and no‐dispersal scenarios are unrealistic, as no plant has either infinite or zero dispersal potential (Cain et al., 2000; Nathan, 2006). The 250 km threshold lies in between unlimited and zero dispersal scenarios and is optimistic given maximal seed dispersal distance tends to be below 100 km (Poulsen et al., 2021, megafauna dispersal). Second, we assumed that only climatic suitability and proximity to an occurrence point constrain the movement of species through the landscape.…”

Seasonality in the equatorial tropics: Flower, fruit, and leaf phenology of montane trees in the highlands of Southwest Uganda

“…For instance, observations in tropical forests show that availability of fruits and other ephemeral resources influence animal abundance and behaviors (Babweteera et al, 2018; Butt et al, 2015; Huang et al, 2012). The abundance of frugivores, critical for the dispersal of many plant species, generally increases when fruiting is abundant (e.g., Gross‐Camp, Masozera, & Kaplin, 2009; Poulsen et al, 2021). Studies in temperate biomes have shown that insect pollinators time their emergence to correspond with local flowering seasons with a general tendency for insects at higher elevations to emerge later than those at lower elevations (Bartomeus et al, 2011; Forrest, 2016; Forrest & Thomson, 2011).…”