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Encyclopedia of biodiversity encyclopedia of biodiversity, (7 volume set) ( PDFDrive ) 5040

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Wildlife Management species, the long-term monetary income from a sustained yield may be less than the yield offered by the economic market on regular investments (Clark, 1976) In other words, economically, a greater profit can be realized by selling licenses to hunt the entire population and investing the profits than by limiting the number of licenses to a sustained yield that will ensure the continued existence of the population Thus, in recent years considerable effort has been directed at assessing the economic value of wildlife for nonconsumptive uses such as tourism and conservation (Fennell, 2008) Endangered Species and Reducing the Risk of Extinction With the biodiversity crisis coming into focus during the second half of the twentieth century, the science of conservation began to evolve Initially, conservation to preserve an endangered species and wildlife management were treated as separate sciences Eventually, the sciences merged in the area where they overlap (wildlife), and managing wildlife populations for conservation became an integral part of wildlife management Topics such as management for recovery and sustainability, the dynamics of small population (especially as impacted by demographic, genetic, and stochastic environmental processes), fragmentation, and the importance of populations to the integrity of the ecosystem and biodiversity became a central focus of wildlife management In terms of management for conservation, Caughley and Gunn (1996) recognized two central paradigms: the small population paradigm and the declining population paradigm The sensitivity of small wildlife populations to extinction was first recognized and expressed in 1938 in a book written by the famous American ecologist Allee In his book (Allee, 1938), Allee writes: ‘‘The general conclusion seems to be that different species have different minimum populations below which the species cannot go with safety, and that in some instances this is considerably above the theoretical minimum of one pair.’’ Four types of stochastic processes (Shaffer, 1981) play an important role in the dynamics of small populations and contribute to their increased risk of extinction: demographic stochasticity, genetic stochasticity (including loss of genetic variance and inbreeding depression), environmental stochasticity, and catastrophes The accelerated loss and fragmentation of wildlife habitat during the second half of the twentieth century restricted many wildlife populations and required that management steps be taken to minimize these stochastic effects The size of refuges and other areas set aside for conserving wild populations must be large enough to support a population equal to or larger than the minimum viable population (MVP) (Belovsky, 1987) Corridors connecting small populations are currently considered important (Bennett, 1999), but their effectiveness has not yet been fully demonstrated Where the establishment of corridors is not feasible, translocation has been implemented For instance, in South Africa, mountain zebras are translocated by airlift between isolated populations Habitat improvement and resource supply during limiting periods of harsh environmental conditions are also being used 405 to minimize population declines and reduce the impact of stochastic processes and risk of extinction The management of declining species requires that the cause of decline be identified and managed directly or indirectly Human-related decline of wildlife populations in the twentieth century can be attributed to three main factors: overharvesting, loss and fragmentation of habitat, and the introduction of alien species With the improved control of harvest by science and legislation, loss of habitat and fragmentation became the major causes of wildlife population declines This process has highlighted the importance of considering space in wildlife management Management efforts have been concentrated on land allocation for conserving wildlife and securing refuges and linkages (corridors) between patches (fragments) of adequate habitat Roads and fencing are some of the major causes of fragmentation, and special overpasses, underpasses, and gates have been developed to ensure wildlife movement Managing Wildlife for Conserving the Integrity of Ecosystems and Landscapes Wildlife populations are important for maintaining biodiversity in the system of which they are a part Many wild populations are critical for the functioning of the entire community Beavers (Castor canadensis) are a classic example of how a single species engineers change in the ecosystem beneficial to many other species Prairie dogs (Cynomys spp.) are another example Thus, in many instances, populations are managed in order to sustain species richness of the ecosystem of which they are a part For example, research has shown that both overgrazing and undergrazing will reduce plant species richness This is known as the intermediate disturbance hypothesis (Connell, 1978) In certain cases, herbivore populations are managed to maintain the diversity of the plant community Elk (Cervus elaphus) populations were regularly controlled to maintain the existing landscape in Yellowstone National Park Wolves (Canis lupus) were reintroduced (Fritts and Carbyn, 1995) into Yellowstone with the hope that they would control the elk population thus restoring cottonwood stands along the river-banks The control, however, was not manifested by direct predation, but rather by changes in the behavior of elk that avoided the riverbanks due to the increased risk imposed by the newly present wolves (Ripple and Beschta, 2004) The use of focal species as a tool to manage ecosystems gained popularity in the 1990s but has waned in the past decade The underlying assumption is that by managing the focal species, the entire system, or a significant part of it, can be secured Indicator, keystone, and umbrella species are the main types that have been suggested as focal species through which systems can be monitored, conserved, or managed Indicator species are species that testify to the well-being (health) of the entire ecosystem These species are the first to respond to deterioration of the ecosystem, since they are more sensitive By monitoring and managing the indicator species population only we can estimate and protect the welfare of the entire ecosystem We assume that as long as the status of the

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