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increasingly an acknowledgement that protected areas can and should play a significant role towards poverty reduction among the rural poor (Buta et al, 2014; Chan et al, 2007; Meilby et al, 2014; Scherl et al, 2004; Turner et al, 2012).
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because of the rates at which humans are using resources, modifying natural systems, and increasing in their numbers (Fuggle, 1999; Hooper et al, 2012; Pruitt and Underwood, 2006;
Sandava et al, 2011). In other words, the world is experiencing an environmental crisis.
One facet of the current global environmental crisis is the loss of biodiversity (Russell et al, 2011). Brockington et al (2008: 50) note that “the most urgent imperative voiced by conservationists is the need to preserve biodiversity and combat the extinction crisis”. By even the most conservative estimates, progressive degradation of ecosystem structure and function, with its associated loss of species, is occurring at an alarming rate due to a wide range of human activities (Sandava et al, 2011; Wilshusen et al, 2003). Most scholars and conservation practitioners point to the increasing number of species extinctions as a clear indication of a biodiversity crisis (Belk and Borden, 2008; Dunn et al, 2014; Russell et al, 2011; Wilshusen et al, 2003). In spite of key gains in policy development, political participation, financial support and programme implementation throughout the world; the earth still faces an alarming downturn in its diversity of life (Barrett et al, 2011; Dunn et al, 2014; Galli et al, 2014; Pfund, 2010; Rands et al, 2010; Wilshusen et al, 2003). While extinction has always existed as a natural process, it has currently become a primarily human- sourced phenomenon especially since the second half of the 20th century due to increased human interaction with, and manipulation of, biological resources (Sandava et al, 2011;
Swanson, 1997). Habitat loss and degradation represent the leading threats to species, with the last 30-40 years witnessing major changes in the quantity and quality of tropical forests (Babigumira et al, 2014; Galli et al, 2014; Gardner et al, 2009; Laurance et al, 2014; Sloan et al, 2014; Wilshusen et al, 2003). Pfund (2010) notes that deforestation rates are not decreasing in tropical forests while biodiversity hotspots appear under-protected. It is estimated that one-fifth of all tropical forest cover was lost between 1960 and 1990 (Barrett et al, 2011; Morris, 2010; Wilshusen et al, 2003). A study by the IUCN in 2000 revealed that changes in habitat affected 89% of all threatened birds, 83% of mammals and 91% of threatened plants that were assessed (Babigumira et al, 2014; Brook et al, 2014; Hou et al, 2014; Wilshusen et al, 2003).
The IUCN Red List of Threatened Species has been documenting the threat status of flora and fauna for more than 40 years and is widely considered to be the most comprehensive dataset on the conservation status of species worldwide (Clausnitzer et al, 2009; Galli et al, 2014). The IUCN-World Conservation Union Species Survival Commission has a Red List programme that defines 8 categories of threat on biodiversity (Adams, 2004; Brockington et
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al, 2008; Clausnitzer et al, 2009; Rodrigues et al, 2006). The Red List also assesses the status of living species on the basis of assessments produced by panels of experts who examine the numbers and viability of as many of the world’s organisms as they can (Brockington et al, 2008; Rodrigues et al, 2006). The IUCN Red List has recorded that altogether 360 vertebrates, 373 invertebrates (of which 303 are molusks) and 110 plants are listed to having gone extinct since 1500 (Brockington et al, 2008).
Given the high levels of ignorance surrounding precisely how many species there actually are, it is widely feared that far more species have disappeared, or are threatened than those recorded (Brockington et al, 2008; Galli et al, 2014). This has prompted some conservation biologists and other researchers to come up with higher predicted yearly losses. For example, there are reports indicating that hundreds of thousands of species were being lost annually (Mann, 1991; Sandava et al, 2011). Another prediction by Ehrlich and Wilson (1991) suggested that the loss of tropical forests alone was removing between 4 000 and 40 000 species per year, while Dirzo and Raven (2003) have estimated that over 1 000 extinctions are occurring per million species per year.
Brockington et al (2008), however, note that the study of species extinctions is a very complex science. While it is beyond any doubt that extinctions are occurring, proving that they have occurred is a difficult task (Brockington et al, 2008). The sighting of species that had been declared extinct demonstrates the above challenge (Brockington et al, 2008;
Jeffries, 2006; Seddon et al, 2014). It is even more difficult to state extinction rates as a proportion of existing species simply because the actual number of species on the planet is not known (Brockington et al, 2008).
In addition, the utility of the IUCN Red Lists has been questioned partly as a result of the instability of the definition of species on which the lists depend (Burgman, 2002; Clausnitzer et al, 2009; Galli et al, 2014; Hambler, 2004; Mace, 2004; Possingham et al, 2002; Rodrigues et al, 2006). Some of the criticisms against the Red List Categories are summarised below (Jeffries, 2006: 137):
Bias: The categories contain only known species. The undiscovered ones plus species found but not yet described are omitted. The great majority of species are therefore excluded and the published lists could divert attention from this unknown majority.
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Species based: The Red Lists deal with individual species. There is no attempt to assess the threat to higher taxonomic levels, which may represent more fundamental differences and variety or specialness.
Lack of objectivity: The superficially neat, objective classification is based on expert opinion, and so is subjective. Risk is poorly quantified, such as percentage risk of extinction over a defined time period.
Some criteria are not linked to threat: Red List classification can be based on protection accorded to a species or unhelpful criteria, for example, “insufficiently known” (which applies to most life on the planet). Other potentially useful data such as rate of population decline are not routinely used.
While there may be arguments among conservation biologists concerning the validity of Red Lists and extinction rates, one thing they all, or most of them, agree on is the fact that, at the current rate of human modification and manipulation of the biosphere, there is certainly an impending extinction crisis. While these arguments are important, more effort and resources should be devoted to coming up with measures aimed at reducing the loss of biodiversity.
More comprehensive biodiversity assessments need to be carried out, as much as is possible, so as to come up with more reliable and more useful Red Lists.
The loss of biodiversity is brought about by a complex chain of causal factors and Turpie (2009) identifies proximate and ultimate causes of biodiversity loss (Figure 3.1). The proximate causes of loss include overexploitation of natural resources, invasion by alien species, pollution, climate change, alteration of hydrological systems and habitat alteration and loss (Babigumira et al, 2014; Brook et al, 2014; Butchart et al, 2010; Hou et al, 2014;
Laurance et al, 2014; Rands et al, 2010; Turpie, 2009). These processes are the ones which directly lead to biodiversity loss. On the other hand, the ultimate causes of biodiversity loss are socio-economic in nature and “include market failure and policy distortions which distort the way in which biodiversity losses are accounted for in decision-making; the extremes of wealth and poverty, which lead to destructive patterns of consumption and dependency on natural resources; consumer attitudes and preferences, which are influenced by changing ethics in a modern world; and human population dynamics, which lead to imbalances between the demand for the goods and services provided by biodiversity” (Turpie, 2009: 39).
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Ultimate causes
Proximate causes
Reduction of populations
Figure 3.1: The proximate and ultimate causes of biodiversity loss Source: Turpie (2009: 39)
As Figure 3.1 shows, biodiversity maintenance can be achieved through action at two levels.
Action at the proximate level is necessary to combat losses of biodiversity in the short-term, while action at the ultimate level seeks to prevent future losses and relieve the pressures on biodiversity in the long-term (Turpie, 2009). Ultimately, the successful conservation of biodiversity relies on an in-depth and holistic understanding of the causal chain of biodiversity loss and the most effective points and types of intervention to reverse the process (Brook et al, 2014; Thuillera et al, 2008; Turpie, 2009).