Extracts from Campos-Arceiz and Stephen Blake’s interview:
"In our paper we show that African forest elephants are the ultimate seed dispersers—they disperse vast numbers of seeds of a high diversity of plants in a very effective way Asian and African savanna elephants also disperse many seeds but seem to be less frugivorous [i.e. fruit-eating]," Ahimsa Campos-Arceiz, co-author of a recent paper on African and Asian elephant seed dispersal in Acta Oecologica, told mongabay.com in an interview. Stephen Blake, the study's other co-author, says that the behavior of different elephant species, in this context, has more to do with habitat than species' preference.
"African savannah elephants don’t disperse many seeds usually, but stick them in the Kibale forest in Uganda where fruit is accessible, and they become formidable seed dispersers," Blake explains, "no large-bodied generalist feeding mammal is going to refuse a good fruit feed if it is available."
Blake and Campos-Arceiz highlight in their study some plant species likely depend entirely on elephants for their dispersal, much as some orchids depend wholly on a single insect pollinator for propagation.
"The best documented case is the relationship of Balanites wilsoniana and savanna elephants in Uganda. Several studies have found that elephants consume and disperse lots of Balanites seeds, that no other animal disperses these seeds," explains Campos-Arceiz.
However, Blake adds that the "cumulative impact of elephant dispersal" is more important than their connection to one species: "a few trees declining because elephant disappear is of course detrimental, but Balanites going extinct will be unlikely to have massive impact on the forest ecosystem. However, elephants going extinct means that the competitive balance of many many species, arguably over 100 in central Africa will be tipped in favor of species poor abiotically [i.e. non-biologically, such as wind] dispersed species. That is the key point from an ecological perspective."
Despite their ecological importance, elephants in Asia and Africa are threatened. While some populations of savannah elephants in Africa are stable, Blake says Africa's forest elephants—the world's biggest frugivores—are in "steep decline due to poaching ".
Asian elephants face pressures from poaching in addition to human-elephant conflict and habitat loss.
"Asian elephants are rapidly declining and now they exist mainly in small and fragmented populations. Asian elephants have lost most—probably over 95%—of their range in historical ranges. […] Nowadays, one out of three Asian elephants is a captive animal," explains Campos-Arceiz, who says that priority in Asian elephant conservation is dealing with rising human-elephant conflict.
In central Africa, Blake says the economic, education, and social situation has become so poor that if forest elephants are to survive drastic measures may be needed.
"I am afraid a very un-politically correct fortress mentality needs to be imposed inside national parks until there is a new world order for valuation of natural resources…there simply isn’t the financial incentive or other benefits to get local communities interested in conserving elephants […] but how to do this with ever decreasing funds and ever increasing external threats getting closer to park borders every day is the challenge," Blake says,adding that "land use planning that respects the needs of wide ranging species like elephants, strong law enforcement, and socio-economic, political and environmental stability are among potential answers, but Central Africa (just like the rest of the world for that matter) is a long way from these things."
Blake believes that the plight of the seed-dispersing elephant is in some ways emblematic of the globe's wider conservation, environmental, consumption and even philosophical problems.
"We need to generate some higher ideal in the general public beyond the next car and big house life goal…we need to make people think of the connection between their buying a cheap product and the reasons why it is cheap," says Blake. "Elephants are simply one more natural resource that is being caught up in human greed on the one hand and human need on the other. We somehow need people to become reacquainted with nature, or they can have no clue as the interrelatedness of cause and effect. This philosophical change will be way too late for elephants if it ever comes, and with 9 billion people estimated to be here soon, the tsunami is just going to sweep over the last great wilderness areas and take their natural resources with it, elephants and all."
And if Blake is right and 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 explains succinctly.
And so, the gardener has abandoned their plot leaving it to an expanding monoculture of weeds.