Primate seed dispersers as umbrella species: a case study from Kibale National Park, Uganda, with implications for Afrotropical forest conservation

Abstract

Almost half of the world's extant primate species are of conservation concern [IUCN, International Union for the Conservation of Nature Red List of Threatened Species, 2008]. Primates are also effective seed dispersers. The implications of and interactions between these two facts are increasingly understood, and data demonstrating the consequences of losing primates for forest ecology are now available from throughout the tropics. However, a reality is that not all species-and the mutualisms among them-can be protected. Conservation managers must make difficult decisions and use shortcuts in the implementation of conservation tactics. Using taxa as "umbrellas" is one such shortcut, although a lack of an operational definition of what an umbrella species is and how to choose one has made implementing this tactic difficult. In this study, I discuss primates as umbrellas by defining a selection index in terms of richness/co-occurrence, rarity, and sensitivity to anthropogenic disturbance. I evaluate the anthropoid assemblage of Kibale National Park, Uganda, in light of the selection index and determine that Cercopithecus is the genus best fitting the criteria for umbrella status. I then evaluate the functional significance-in terms of seed dispersal-of using Cercopithecus monkeys (guenons) as umbrellas. Results from 1,047 hr of observation of focal fruiting trees in Kibale indicate that Cercopithecus ascanius was the most commonly observed frugivore visitor (July 2001-June 2002). These data corroborate earlier data collected in Kibale demonstrating that guenons are highly effective seed dispersers. Patterns of richness/co-occurrence, rarity, and sensitivity observed in Kibale are reflected in Afrotropical forests more generally, with the genus Cercopithecus tending to exhibit greatest richness/co-occurrence with taxonomically similar species, to be neither extremely rare nor ubiquitous, and also to be moderately sensitive to human disturbance. Moreover, in all available evaluations of frugivory in Afrotropical forests, guenons emerge as among the most important seed dispersers relative to other taxa.

The value of disturbance-tolerant cercopithecine monkeys as seed dispersers in degraded habitats

“…For cercopithecine species that are currently threatened, such threats are considered to be serious and solutions to the negative perception of cercopithecines are sought (Riley et al, 2011). However, it is critical that the management of all disturbance-tolerant species be re-evaluated -not only the threatened species -since their conservation could be the first step to the regeneration of degraded Asian and African habitats (Lambert, 2010).…”

Frugivores and seed dispersal (1985–2010); the ‘seeds’ dispersed, established and matured

“…In addition, frugivores indirectly contribute to many other ecosystem services offered by forests to people, including fruit, wood and non-timber forest products, carbon sequestration and forest cover. All of this comes at a modest cost d that of conserving frugivores and their staple resources (Corlett, 2011a;Fleming and Kress, 2011;Lambert, 2011).…”

Primates in 21st century ecosystems: does primate conservation promote ecosystem conservation?

“…Beginning with the classic research of Gautier-Hion et al 30 years ago [Gautier-Hion et al, 1980, 1985, there is still a growing interest in system-wide approaches [e.g. Clark et al, 2001;Gross-Camp et al, 2009;Lambert, 2011;Ratiarison & Forget, 2005]. Not surprisingly, researchers find that primates vary in their seeddispersing capabilities, depending on their diets and the plant species they frequent.…”

“…Lyons et al [2005] proposed that an aggregate of closely related species could play a defining role in an ecosystem, and this might be the case with primates. In this issue, Lambert [2011] develops the view that guenons act as a particularly effective seed-dispersing cohort-and functioning as a cohort of species they could provide an overarching role in ecosystem maintenance.…”