Long-term monitoring of seed dispersal by Asian elephants in a Sundaland rainforest

Asian elephants (Elephas maximus) have inhabited almost all forests in tropical Asia until recently, yet little is known about their role in ecological processes, particularly in the Sundaic forests of Southeast Asia. These forests are peculiar in their phenology, with supra-annual and highly irregular episodes of mast fruiting. Here we present a long-term (six-year) monitoring of the seeds dispersed by elephants in dipterocarp forests of northern Peninsular Malaysia. We conducted monthly dung surveys at two mineral licks (11.3 km apart) frequently visited by elephants. Additionally, we recorded haphazard observations of seeds and seedlings in elephant dung at other locations. We recorded a minimum of 48 morphospecies from at least 25 plant families dispersed by elephants. Elephant seed dispersal was very heterogenous in space, with only 30.3 % of the morphospecies dispersed at both sites (Jaccard dissimilarity index = 0.48). Temporally, elephants dispersed seeds in sporadic pulses of abundance and diversity, without any apparent seasonality (seeds appeared in 19.1 % of 1,284 dung piles and 57.1 % of the 63 months in which we found dung) and with long periods without any seed being dispersed. Nearly half (48 %) of the plants dispersed by elephants belong to a megafaunal dispersal syndrome. Our long-term approach allowed us to unravel an important aspect of Asian elephants’ role and effectiveness in the seed dispersal cycle. Sundaland’s forests are undergoing a rapid loss of their previously common megaherbivores (rhinos and elephants), with profound and long-term consequences for ecosystem functioning.