Cover stories: Volume 110 Issue 2

The cover image for our February issue features a Female Asian elephant foraging in a dipterocarp forest of Peninsular Malaysia. This image relates to the research article: The ability to disperse large seeds, rather than body mass alone, defines the importance of animals in a hyper-diverse seed dispersal network, by Lisa Ong, Kim McConkey and Ahimsa Campos-Arceiz.

Here the author Lisa Ong tells us the story behind the image.

^{Female Asian elephant (Elephas maximus) foraging in a dipterocarp forest of Peninsular Malaysia. Large and threatened vertebrates like elephants, gibbons, and hornbills, play irreplaceable roles in ecosystem processes, such as seed dispersal, that are rarely evaluated at the community level. Photograph by Lisa Ong (using high optical zoom).}

A walk in the Malaysian rainforest is often accompanied by a cacophony of insects, and the pulsating calls of gibbons from a far distance. Observing wild elephants and other elusive animals in the forest is rare, even for ecologists who have been studying their behaviour and functional roles. This cover photo features a captive Asian elephant, brought specially to the Krau Nature Reserve for observation of her feeding choices (for a different study). The relationship between elephants and their mahouts at the Kuala Ganda National Elephant Conservation Centre made such direct feeding observations in short distances possible. Wild elephants have been absent from Krau since the early 1990s, when they were translocated out of the reserve to reduce the conflicts with humans. For one more time, the Krau forest was filled with rumbles of pleasure and trumpets of joy and distress of the pachyderms!

^{Families of wild elephants occasionally feed in forest edges along the highway that divides the Belum Temengor Complex in two large forest fragments – Belum with primary forest (as above), and the Temengor forest where selective logging is permitted.}

Wild elephants still roam freely in many forests of Peninsular Malaysia, including the Royal Belum State Park, the study area of our recently published paper. We have lost almost half the world’s Asian elephant population since the beginning of 1900s (currently less than 50,000). Yet, the endangered elephants present the only feasible choice for us to study the functional role of megaherbivores in Peninsular Malaysia (estimated population of less than 1500 in the wild). Facing challenges of defaunation and the decline in populations, we sought non-conventional methods to study the ecological impact of elephants and their interactions with other species at a community level.

***^{Interviews with the local indigenous people, Orang Asli, on frugivory and seed dispersal interactions.}***

The Belum-Temengor complex is home to several groups of indigenous people, the ‘Orang Asli’, who have inhabited the region’s forests since ~ 55,000 years ago. Tapping into the realm of knowledge of the Temiar and Jahai sub-ethnic groups enabled us to describe the web of interactions between plants of diverse traits and major animal taxa, including that of several large-bodied animals. Large vertebrates are absent from most studied seed-dispersal networks because most network studies have been conducted in regions where the largest frugivores are already extinct.

^{The Seed dispersal network of Belum-Temengor and its four modules, comprising 164 plant species and 34 animal taxa. Plants are represented as circles and animals as squares. (Figure from published paper).}

For the first time, we have a glimpse at the structure of a seed dispersal network in a tropical rainforest of the Sundaic region, which allowed us to understand how major groups of seed dispersers, together, can regenerate a forest. We included the contributions of synzoochoric dispersers – animals capable of dispersing seeds by carrying them in their mouth. Rodents, for example, may facilitate seed dispersal through hoarding, bats are capable of carrying fruits exceeding their body weights, and most birds and deer regurgitate larger seeds than they defecate.

Our results showed that seed dispersers particularly important to the plant and animal communities are predominantly animals capable of dispersing larger seeds, including small rodents. Large-bodied animals were strong interactors within modules, of which, elephants served as a seed dispersal ‘hub’. Amongst animals of different diets, frugivores were influential seed dispersal generalists that help maintain the community’s resilience against extinction.

The sad news: many animals we identified as the most important are currently threatened. Their functionalities can be degraded before the species are fully lost. The survival of the Asian elephants, gibbons, binturongs, hornbills, and sun bears, is under dire threat from conflicts with people, and their protection or reintroduction should be of top conservation priority as highly interactive umbrella species.

Lisa Ong, Chinese Academy of Sciences & Center for Integrative Conservation, China.

Read the full research article here: The ability to disperse large seeds, rather than body mass alone, defines the importance of animals in a hyper-diverse seed dispersal network.