Author: Nigel Leader-Williams (University of Cambridge – Geography)
Contributors: Peter Damerell (Beijing Forestry University) and Kiragu Mwangi (BirdLife – CLP)
“Biological diversity” is the variability among living organisms including inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part (Article 2 of the Convention on Biological Diversity). The term, more commonly used in the contracted form “biodiversity”, therefore includes diversity within species, between species and of ecosystems (CBD 1992). However, current knowledge of biodiversity is heavily biased towards the species level, particularly of charismatic megafauna, and of components used directly by people. Consequently, various measures of species richness remain the iconic yardstick of biodiversity, and of success in conserving biodiversity, for most conservation scientists (Mace et al. 2012).
While species diversity is very valuable in and of itself in helping to increase the resilience of ecosystems in the face of a changing environment (e.g. Tilman and Downing 1994), there are nevertheless limits to the usefulness of basing conservation strategies on measures of species richness. It was recently estimated that 8.7 ± 1.3 million species occur on Earth. Only 1.2 million of these have been formally identified and described, so 86% of all species estimated to occur on Earth, and 91% of species estimated to occur in the oceans remain undescribed (Mora et al. 2011). As a result, there are significant knowledge gaps regarding the most diverse species groups and the most diverse geographic areas. However, measures of identified species suggest that biodiversity is heterogeneously distributed across Earth based on latitudinal and altitudinal gradients. Furthermore, the greatest concentrations of species diversity in both terrestrial and marine systems occur in tropical biomes. Consequently, several schemes have sought to prioritise conservation action through area-based approaches such as hotspots or ecoregions, that aim to conserve most endemic species per $ of conservation money spent (Olson and Dinerstein 1998; Myers et al. 2000).
Globally, biodiversity is being lost and increasingly threatened through a range of anthropogenic actions. The CBD defines “biodiversity loss” as “the long-term or permanent qualitative or quantitative reduction in components of biodiversity and their potential to provide goods and services, to be measured at global, regional and national levels” (CBD COP VII/30). Over the past few hundred years, it is estimated that species diversity has been reduced at a rate of up to 1,000 times greater than background rates (Lawton and May 1995). This rate of loss is increasing and is projected to reach 10 times that which is currently occurring. Between 10% and 50% of component species of the best-studied taxonomic groups, comprising mammals, birds, amphibians, conifers, and cycads, are threatened with extinction according to the IUCN–World Conservation Union’s Red List (IUCN, 2011). The most important historic drivers behind this current loss of biodiversity were habitat modification, invasive alien species, overexploitation, and chains of extinction, known collectively as the “Evil Quartet” (Diamond 1989). For most ecosystems, the impact of these drivers currently remains constant or is growing (Mace 2010). Furthermore, the most recent threat to emerge, climate change, is likely to worsen over the next 50-100 years, and further exacerbate the effects of earlier threats on biodiversity loss (Thomas et al. 2004).
Many different conservation initiatives have been designed and implemented to address the multiplicity of threats that biodiversity now faces. Though diverse in goals and approach, these can be broadly classified into four categories: (i) protection and management, such as the creation of protected areas and habitat restoration; (ii) law and policy including international treaties and enforcement; (iii) education and awareness, which can range from formal education to moral confrontation; and (iv) changing incentives, a broad category that ranges from economic incentives through to cultural appreciation (Secretariat of the Convention on Biological Diversity, 2010).
In an effort to address the failure of many of these approaches in reducing ongoing declines in biodiversity (Butchart et al. 2010), multi-disciplinary teams have sought to turn the focus of civil society and its policy makers towards the benefits that components of biodiversity bring to people, framed in the concept of “ecosystem services” (see Chapter 3). Syntheses including the Millennium Ecosystem Assessment (2005) and The Economics of Ecosystems and Biodiversity (2010) describe these benefits, demonstrating for decision-makers the importance of biodiversity to the global triple bottom line. Although increasingly comprehensive, these multidisciplinary approaches may not prove silver bullets in promoting the effective conservation of biodiversity (Vira and Adams, 2009). As a result, trade-offs may be important in deciding what to prioritise (Leader-Williams et al. 2010).
Losing biodiversity can reduce resilience within ecosystems, further degrading the natural processes that mitigate biodiversity loss. Furthermore, biodiversity is increasingly being recognised as the foundation of many ecosystem services to which human well-being is intimately linked, as well as proving of considerable economic value in non-traditional accounting systems. Local or functional extinction of different components of biodiversity, or the reduction of populations to the point that they no longer contribute to ecosystem functioning, can have dramatic impacts on the financially valuable ecosystem services upon which people depend. It is therefore vital to gain a better understanding of the linkages between biodiversity and ecosystem services, and how emerging threats to biodiversity such as climate change will affect human well-being (Mace et al. 2012).
Water from the cloud forest in western Ecuador
The cloud forests of western Ecuador harbour many unique species, dependent on the moisture trapped as fog by the aerial vegetation of intact forests. Large swathes of cloud forest have been cleared for pasture or the production of fibre for Panama hats, resulting in the drying up of water catchments. In response, villagers of Loma Alta have exercised their own systems of governance to protect intact forest within the catchment over which they have secure tenure, allowing them to continue the practice of fog capture whilst protecting biodiversity (Becker 1999).
Sustainable use of wildlife in Namibian conservancies
Namibia’s vast wilderness areas and diverse ecosystems are home to many of Africa’s megafauna species. Since independence in 1990, the country has established innovative community-based natural resources management (CBNRM) programmes. Community conservancies now manage wildlife through direct uses, including trophy hunting, photo-tourism, meat harvesting and live game sales. Resulting livelihood benefits and poverty reduction for those living in these conservancies have fostered a deep appreciation of the values of wildlife, and many populations of which have recovered dramatically (Weaver et al. 2012; Abrnsperg-Traun et al. [CITES & CBNRM]; Gland & Cambridge [IUCN]).
- Estimates suggest that many millions more species have yet to be discovered than those that have so far been described for science, while the relationship between biodiversity and ecosystem services remains unclear.
- Pressure on biodiversity and ecosystem services continues to increase, while countless species have probably become extinct before they have even been discovered.
- As a result, the benefits that people obtain from biodiversity are at risk, and ongoing biodiversity loss threatens the improvements in human well-being and health that have been achieved in recent decades.
- Can changes in biodiversity and of ecosystem services be tracked in parallel? Can composite indicators be developed?
- How can civil society and their policy makers be encouraged to value biodiversity and ecosystem services?
- How can the governance of global commons such as biodiversity and ecosystem services be improved?
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Photo: Espadarana Andina & Aldemar Acevedo