It seems hard to imagine elephants delicately tending a garden, but these pachyderms may well be the world’s heaviest horticulturists and considered gardeners of the forests.
Elephants in Africa and Asia eat copious amounts of fruit when it is available. The seeds pass through their intestines and after being expelled – sometimes many kilometers away – they germinate a new plant, if the conditions are favorable.
This process is known to ecologists as “seed dispersal,” and scientists have long studied the “gardening” ability of monkeys, birds, bats, and rodents.
However, recently researchers have begun to document the seed dispersal ability of the world’s largest land animal – the elephant – proving that this species may be among the most important tropical gardeners on the planet.
“In our paper, we show that African forest elephants are the best seed dispersers – they disperse a vast number of seeds, from a wide diversity of plants, very effectively […]
Asian and African savanna elephants also disperse many seeds [… ] but they appear to be less frugivorous (fruit eaters),” Ahimsa Campos-Arceiz, the coauthor of a recently published paper in Acta Oecologica on seed dispersal by African and Asian elephants, tells mongabay. com, in an interview.
Stephen Blake, the other coauthor of the study, says that in this context, the behavior of different elephant species has more to do with habitat than species preferences.
“African savanna elephants don’t normally disperse many seeds, but put them in the Kibale forest in Uganda, where there is access to fruit, and they will become formidable seed dispersers,” Blake explains. “No large mammal that is a generalist in its diet is going to turn down a good meal of fruit if it is available.”
Blake and Campos-Arceiz point out in their study that some plant species depend completely on elephants for their dispersal, just as some orchids depend entirely on a single pollinating insect for propagation.
“The best documented case is the relationship between Balanites wilsonianae the savanna elephant in Uganda. Several studies have found that elephants consume and disperse many Balanites seeds and that no other animal disperses these seeds,” explains Campos-Arceiz.
However, Blake adds that “the cumulative impact of dispersal by elephants” is more important than their connection to a single species: “Of course, the decrease in the amount of some trees because of the disappearance of elephants is detrimental, but if Balanites becomes extinct, it is unlikely to have a major impact on the forest ecosystem.
However, if elephants are extinct, it will mean that the competitive balance of many species, arguably over 100 in Central Africa, will favor those that are dispersed by abiotic (i.e. non-biological, such as wind) factors. This is a fundamental factor from an ecological point of view.
One of the reasons elephants are so important in a forest ecosystem is that, unlike many other species, they are able to disperse seeds away from the parent tree (the one that produces the seeds).
According to researchers, Asian elephants spread seeds within a radius of 1km to 6km, while, in the Congo, forest elephants are able to spread seeds over a radius of up to 57km.
“These are really unprecedented dispersal distances for large forest seeds. most seed dispersing animals in tropical forests release seeds only about 10 or 100 meters from the source,” explains Campos-Arceiz.
Despite their ecological importance, Asian and African elephants are threatened.
While a few African savanna elephant populations are still stable, Blake says that all African forest elephant populations – the largest frugivorous animals in the world – are in “rapid decline because of poaching.”
Asian elephants face pressures from poaching, in addition to human-elephant conflict and habitat loss.
“The number of Asian elephants is rapidly declining and today they exist mainly in small, fragmented populations. Asian elephants have lost most – probably more than 95% – of the territorial extent they historically occupied. […]
Today, one out of every three Asian elephants is a captive animal,” explained Campos-Arceiz, who says the priority in Asian elephant conservation is dealing with the emergence of human-elephant conflict.
Blake says that the economic, educational and social situation has become so poor in Central Africa that drastic measures may be necessary for forest elephants to survive.
“I’m afraid that a strong non-politically correct mindset must be imposed in national parks until there is a new world order of assessing the value of natural resources…there simply isn’t a financial incentive or other benefits to get local communities interested in conserving elephants [… ] but the challenge is how to do this, with the constantly decreasing funds and increasing external threats, which are moving closer to the edges of national parks every day,” Blake says, adding that “a land use plan that respects the needs of species that traverse very wide spaces, such as elephants, strong enforcement of laws, and socioeconomic, political, and environmental stability are among the possible solutions, but Central Africa (as well as the rest of the world) is a long way from achieving these things.”
Blake believes that the plight of the seed-dispersing elephant is in some ways emblematic of broader planetary problems, such as conservation, environment, consumption, and even philosophical problems.
“We need to generate larger ideals in the population that go beyond the next car and a big house as a life goal…we need to get people thinking about the connection between buying a cheap product and why it’s cheap,” Blake says.
“Elephants are simply another natural resource that involves human greed on the one hand, and human need on the other.
Somehow we need people to refamiliarize themselves with nature, or they will have no idea of the interrelationship between cause and effect.
This philosophical shift will be too late for the elephants, that’s if it actually happens, and with the estimated 9 billion people in the world soon, the tsunami will simply sweep away the last noble wilderness areas and take, in the process, their natural resources, elephants, and everything else.”
What if Blake is right, and the elephants disappear for good from the forests they once dominated?
“Overall, we can expect a loss of biodiversity and a simplification of forest structure and function,” Campos-Arceiz explained succinctly. And then the gardener will have abandoned his piece of land, leaving it exposed to a growing monoculture of weeds.
