The biodiversity of the Albertine Rift

Abstract

The Albertine Rift is one of the most important regions for conservation in Africa. It contains more vertebrate species than any other region on the continent and contains more endemic species of vertebrate than any other region on mainland Africa. This paper compiles all currently known species distribution information for plants, endemic butterfly species and four vertebrate taxa from the Albertine Rift. The literature on fish species richness and endemism is also reviewed to assess the importance of the larger lakes in the Rift for conservation. We use data from 38 protected and unprotected areas to prioritise sites within the Albertine Rift for conservation based upon their numbers of endemic and globally threatened species. Virunga and Kahuzi Biega National Parks and Itombwe Massif in Democratic Republic of Congo, Bwindi Impenetrable and Kibale National Parks in Uganda, and Nyungwe National Park in Rwanda rank highest in terms of numbers of both endemic and globally threatened species. Six conservation landscapes are described that include most of these sites and it is argued that a focus on these landscapes may be a more holistic method to ensure the safety of the priority areas of the Albertine Rift.

Introduction

The Albertine Rift is the most species rich region for vertebrates on the African continent (Brooks et al., 2001, Plumptre et al., 2003). This part of Africa contains the ‘Mountains of the Moon’ or Rwenzori Massif that includes Africa’s third highest peak, the Virunga Volcanoes made famous by its mountain gorillas, active volcanoes in the Virunga National Park, and Lake Tanganyika – Africa’s deepest lake. The Albertine Rift encompasses much of the western Rift valley down to southern Tanzania and northern Zambia. We define the region as extending from 30 km north of Lake Albert to the southern tip of Lake Tanganyika, including the valley, flanks of the escarpment and associated protected areas, and the range of species endemic to it (Plumptre et al., 2003). Various other publications also recognize the ‘Albertine Rift’ (Poulsen, 1997, Prigogine, 1985): it is an Endemic Bird Area according to BirdLife International (Stattersfield et al., 1998), WWF have defined it as a ‘Global-200’ priority ecoregion (Olson and Dinerstein, 1998, Burgess et al., 2004), and Conservation International (CI) has recognized it as part of the Eastern Afromontane Hotspot in their second global analysis (Brooks et al., 2004). There is much overlap in the definition of the Albertine Rift between these publications, but also some differences in geographical coverage as each analysis has used different criteria to delineate the region. WWF’s Ecoregion focuses primarily on the montane forests and separates moorland from these forests, while BirdLife International’s Endemic bird area is broader and includes the moorlands and highland swamps. CI’s Eastern Afromontane Hotspot is broader still and includes the definition of the Albertine Rift used here (see below).

The Albertine Rift is not only important for its biodiversity but also for its ecological processes and ecosystem services. The savanna parks contained some of the highest biomasses of large mammals recorded on earth in the 1960s (Cornet d’Elzius, 1996). War and poaching have led to major decreases in the numbers of large mammals in these parks but most of the species are still present and could recover to former levels with good protection (Plumptre et al., 2007). The impacts of the browsing and grazing of the elephants, hippopotamuses, buffalos, and antelope species had a major influence on the vegetation of the parks (Delvingt, 1978) and as a result of the decline in numbers of these species it is thought the parks are changing (Eltringham, 1999). The volcanoes in the Virunga National Park are active and influence the ecology of a large portion of this park and its surroundings. The fisheries in some of the lakes are the most productive on the continent and provide a livelihood for many people (Beadle, 1974, Snoeks, 2000) and the rivers and streams flowing from the forests on the mountains provide clean water. In Rwanda, for example, it is estimated that more than 70% of people obtain water that comes from their national parks (Weber, 1989). The spectacular land formations and rich biodiversity of the Albertine Rift mean that it has great potential for tourism. Civil wars and international conflict over the past 30 years have hampered tourism development but when peace comes to the region there is enormous potential to develop world class tourism.

This paper summarises the existing literature on biodiversity surveys within sites in the Albertine Rift. It is the result of a collaborative effort between many different NGOs, protected area authorities and museums that have information about this region. Since 2001 the protected area authorities and their NGO partners have been developing a strategic framework for conservation in the Albertine Rift. At this time a core planning group was established, which developed the strategic framework for conservation in the Albertine Rift, that includes the Albertine Rift Conservation Society, Dian Fossey Gorilla Fund International, Institute for Tropical Forest Conservation, International Gorilla Conservation Programme, Makerere University Institute of Environment and Natural Resources, Wildlife Conservation Society (WCS) and WWF. The compilation of the biodiversity information was one aspect of this planning process and was led by WCS. This paper advances this collaborative effort by using the collated data to prioritise sites in the Albertine Rift for conservation according to their numbers of endemic and globally threatened species.

As part of this planning process a series of meetings were held between February 2001 and March 2003, when the framework was finally developed. During this process it was agreed that the definition of the Albertine Rift should be as inclusive as possible for the moment so that over time it could be refined (Plumptre et al., 2003). The current adopted definition therefore includes all the natural habitats within 100 km east of the border of Democratic Republic of Congo (DRC) and follows the 900 m contour line in eastern DRC, including the protected areas in northern Zambia (Fig. 1). The 900 m contour was selected because there are museum collections at the Royal Museum for Central Africa in Tervuren, Belgium, of Albertine Rift endemic bird species that were found as low as this altitude.

The total area encompassed is around 313,000 km² (Plumptre et al., 2003). The habitats range from the glaciers and rock at the top of the Rwenzori mountains (5100 m), down through alpine moorland (3400–4500 m), Giant Senecio and Lobelia vegetation (3100–3600 m), giant heather (3000–3500 m), raised bogs (3000–4000 m), bamboo forest (2500–3000 m), montane forest (1500–2500 m), to lowland forest (600–1500 m), savanna woodland (600–2500 m) and savanna grassland (600–2500 m). Papyrus and Carex wetlands, together with lakes and streams, have their own unique habitat types varying from the rocky and sandy edges to the benthic and bathypelagic zones in the depths of the lakes. Several very specialised habitats also occur as a result of the volcanic activity in the Virunga National Park, including lava flows and their associated colonising vegetation, hot springs and species adapted to carbon monoxide and methane.