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Minimum viable population and reserve sizes for naturally regulated grizzly bears in British Columbia

机译:不列颠哥伦比亚省自然监管的灰熊的最低可行种群和保留面积

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Estimating minimum viable population and reserve size is a fundamental cornerstone of conservation biology-but these estimates require representative demographic parameters. For example, "Benchmark" Grizzly Bear (Ursus arctos) Management Units in British Columbia (BC) are defined as unhunted and naturally regulated populations that can serve as population sources to surrounding hunted areas and provide information on natural population processes. Such benchmarks should have a very small probability of becoming threatened (N < 100 animals). The British Columbia Ministry of Environment (BCMOE) recently implemented a plan to establish one benchmark population in each of six different biogeoclimatic zones in the province. How many bears and how large an area for each benchmark remains in question. In this paper I estimate the minimum number of bears and the areal size required to accommodate environmental and demographic stochastic effects that can result in quasi-extinction thresholds of N < 100 animals. Demographic data were compiled from six different grizzly bear studies in North America and mean values and standard deviations were entered into a Leslie matrix to conduct a Population Viability Analysis (PVA). I varied initial population sizes from 100, 150, 200, and 250 animals and carrying capacities from 1/2K, 3/4K, and K. Results indicated that 200-250 bears were required for a sufficiently small probability (P < 0.05) of decline to a quasi-extinction threshold of 27 adult female bears (N < 100 animals total) within 20 years and a mean time to extinction > 20 years. Reserve sizes varied from 8556 km(2) to 17,843 km(2) depending on population density in each benchmark. These minimum viable populations and reserve sizes would protect approximately 12% of the estimated provincial grizzly bear population and would cover approximately 5% of the landmass of BC.
机译:估计最小可行种群和保护区规模是保护生物学的基本基石-但这些估计需要代表性的人口统计学参数。例如,不列颠哥伦比亚省(BC)的“基准”灰熊管理单位被定义为未经狩猎的自然管制种群,可以作为周围狩猎地区的种群来源,并提供有关自然种群过程的信息。此类基准受到威胁的可能性很小(N <100只动物)。不列颠哥伦比亚省环境部(BCMOE)最近实施了一项计划,以在该省六个不同的生物地理气候区中的​​每个地区建立一个基准人口。每个基准有多少熊以及面积有多大仍是一个问题。在本文中,我估计了适应环境和人口随机效应(可能导致N <100只动物的准绝种阈值)所需的最小熊数量和面积。人口统计学数据是从北美的六个不同的灰熊研究中收集而来的,均值和标准差被输入到莱斯利矩阵中以进行种群生存力分析(PVA)。我改变了100、150、200和250只动物的初始种群大小,承载能力从1 / 2K,3 / 4K和K改变。结果表明,需要200-250只熊才能有足够小的概率(P <0.05)在20年内降低到27只成年雌性熊(总共N <100只动物)的准灭绝阈值,平均灭绝时间> 20年。根据每个基准中的人口密度,保护区的大小从8556 km(2)到17,843 km(2)不等。这些最小的可行种群和保护区规模将保护大约12%的省灰熊人口,并覆盖不列颠哥伦比亚省约5%的陆地。

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