Cuarón Alfredo D
Departamento de Ecología de los Recursos Naturales, Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado postal 27-3 (Xangari), Morelia, Michoacán, 58089 México, email
Conserv Biol. 2000 Dec 18;14(6):1676-1692. doi: 10.1111/j.1523-1739.2000.99211.x.
Land-cover changes translate into shifts in habitat available to wildlife species. I analyzed the effects of land-cover changes on habitat availability for 54 mammal species in a 2.7 million-ha area in southern Mexico and northern Guatemala. I considered the regional variability of these changes and the effect of variation in management and development trends. Using cluster analysis, I grouped mammal species into assemblages with similar associations of land-cover type. Based on data from a remote-sensing, land-cover change analysis (1974-1986), I created simple linear Markov models for a heuristic tool to simulate land-cover changes over a 60-year period and to explore temporal trends of change in habitat availability for the mammal species. I used elasticity analyses to identify land-cover transition probabilities critical for these trajectories. Of the 12 land-cover classes considered, four dominated the area: grasslands, tropical secondary vegetation, tropical moist forests, and wetlands. Transition probabilities to and from these four land-cover types were key in determining the availability of habitat for mammals. Thus, the relatedness of mammal species to these land-cover types seems critical for their long-term persistence in the region. According to general simulated trends in fluctuation of habitat availability, I classified species into seven categories: (1) opportunistic and highly adaptable species, occupying most of the area; (2) opportunistic, human-commensal species, with restricted range in the study area; (3) species with stable and moderate habitat availability; (4) species with moderate but increasing habitat availability; (5) species with originally moderate but declining habitat availability; (6) species with already reduced and sharply declining habitat availability; and ( 7) species with declining habitat availability and a restricted range. Markovian trajectories suggest a declining trend of habitat availability for 32 species (59%). Land-cover change trends, however, were highly variable between the nine subregions. As a result, habitat availability for many species varied regionally. Likewise, changes in management and development policies and trends in the study area will lead to contrasting habitat availability for declining and increasing species, but not for the rest of the species. The approach I used is useful for (1) assessment of land-cover changes resulting from different development trends and management practices and (2) exploration of how changes may affect species habitat availability and survival perspectives. This examination can be accomplished for a substantial part of a biota and for entire regions, even in the context of limited information.
土地覆盖变化会转化为野生动物物种可利用栖息地的改变。我分析了墨西哥南部和危地马拉北部一个270万公顷区域内土地覆盖变化对54种哺乳动物栖息地可利用性的影响。我考虑了这些变化的区域变异性以及管理和发展趋势变化的影响。通过聚类分析，我将哺乳动物物种分组为具有相似土地覆盖类型关联的集合。基于遥感土地覆盖变化分析（1974 - 1986年）的数据，我创建了简单的线性马尔可夫模型作为一种启发式工具，以模拟60年期间的土地覆盖变化，并探索哺乳动物物种栖息地可利用性的时间变化趋势。我使用弹性分析来确定对这些轨迹至关重要的土地覆盖转变概率。在所考虑的12种土地覆盖类别中，有四种在该区域占主导地位：草原、热带次生植被、热带湿润森林和湿地。与这四种土地覆盖类型之间的转变概率是决定哺乳动物栖息地可利用性的关键。因此，哺乳动物物种与这些土地覆盖类型的相关性对于它们在该区域的长期存续似乎至关重要。根据栖息地可利用性波动的一般模拟趋势，我将物种分为七类：（1）机会主义且高度适应性强的物种，占据大部分区域；（2）机会主义的人类共生物种，在研究区域内分布范围有限；（3）栖息地可利用性稳定且适中的物种；（4）栖息地可利用性适中但在增加的物种；（5）原本栖息地可利用性适中但在下降的物种；（6）栖息地可利用性已经减少且急剧下降的物种；以及（7）栖息地可利用性下降且分布范围有限的物种。马尔可夫轨迹表明32种物种（59%）的栖息地可利用性呈下降趋势。然而，九个次区域之间的土地覆盖变化趋势差异很大。因此，许多物种的栖息地可利用性存在区域差异。同样，研究区域内管理和发展政策的变化以及趋势将导致栖息地可利用性对减少和增加的物种产生不同影响，但对其他物种则不然。我所使用的方法对于（1）评估不同发展趋势和管理实践导致的土地覆盖变化以及（2）探索这些变化如何影响物种栖息地可利用性和生存前景很有用。即使在信息有限的情况下，这种考察也可以针对生物群的很大一部分以及整个区域来完成。
