Savanna herbivore dynamics in a livestock-dominated landscape:: I.: Dependence on land use, rainfall, density, and time
Savanna herbivore dynamics in a livestock-dominated landscape:: I.: Dependence on land use, rainfall, density, and time
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DOI：
10.1016/j.biocon.2007.03.005
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发表时间：
2007-07-01
影响因子：
5.9
通讯作者：
Romanach, Stephanie S.
中科院分区：
文献类型：
--
作者：
Georgiadis, Nicholas J.;Olwero, J. G. Nasser;Romanach, Stephanie S.
如果管理建立在对牲畜为主的景观中野生动物动态的机械性理解的基础上，非洲稀树草原的生态系统过程可以得到更好的保护。对于肯尼亚北部不受保护的稀树草原地区莱基皮亚区，我们使用空间上明确的密度估计来描述影响大型草食动物在三种土地利用类型上动态的因素：喜欢野生动物的商业牧场，实行牧业的社区“团体牧场”，以及其余的(“过渡性”属性)。对于9个野生物种和2个家养物种的21年时间序列，使用线性模型选择将观测到的生物量密度变化的45%(格兰特瞪羚)到95%(平原斑马)归因于土地利用、降雨依赖性、密度依赖性和随时间的趋势。强烈反对整个景观中野生动物和牲畜密度的变化模式，确认了在影响非保护区野生动物丰度的因素中，土地利用是首要的。在整个监测期间，降雨只限制了主要放牧物种(平原斑马和牛)的密度，而大多数其他物种的密度很高。密度的调节作用仅对优势野生放牧和觅食物种(斑马和长颈鹿)有效。除了两个野生物种(斑马和格兰特瞪羚)外，至少在一个土地利用类型上，所有野生物种的数量都有所下降，原因因土地利用方式不同而有所不同。受欢迎的、多样化和丰富的野生食草动物(在有利于野生动物的牧场上平均为1.7吨公里(-2))即使在与略高的牲畜生物量密度(平均2.7吨公里-(12))共享景观时也能蓬勃发展。在不受欢迎的地方，只有少数有弹性的野生物种(例如瞪羚和平原斑马)维持着高密度的牲畜(过渡牧场的平均牲畜密度为4.6吨公里(-2))。维持景观中更高的野生物种多样性将取决于建立一个无围栏的保护区网络，在这些区域中，牲畜密度持续较低或为零，这些区域足够大，足以充当容易被人类和牲畜转移的野生物种的“来源”，并为社区成员带来超过机会成本的好处。(C)2007爱思唯尔有限公司。保留所有权利。
Ecosystem processes in African savannas can be better conserved if management is based on a mechanistic understanding of wildlife dynamics in livestock-dominated landscapes. For Laikipia District, a non-protected savanna region in northern Kenya, we used spatially explicit estimates of density to characterize factors influencing the dynamics of large herbivores on three land-use types: commercial ranches that favor wildlife, communal 'group ranches' practicing pastoralism, and the remainder ('transitional' properties). For 21-year time series of nine wild and two domestic species, linear model selection was used to ascribe between 45% (Grant's gazelle) and 95% (plains zebra) of observed variation in biomass density to land use, rainfall-dependence, density-dependence, and trends over time.Strongly opposing patterns of variation across the landscape in wildlife and livestock densities affirmed the primacy of land use among factors influencing wildlife abundance in non-protected areas. Rainfall limited densities of only the dominant grazing species throughout the monitoring period (plains zebra and cattle), and of most other species while their densities were high. Regulating effects of density were detected only for the dominant wild grazing and browsing species (zebra and giraffe). All but two wild species (zebra and Grant's gazelle) declined on at least one land-use type, for reasons that varied among land uses.Where favored, diverse and abundant wild herbivores (mean of 1.7 t km(-2) on pro-wildlife ranches) can thrive even when sharing the landscape with a slightly higher biomass density of livestock (mean of 2.7 t km-(12)). Where not favored, only a few resilient wild species (e.g. gazelles and plains zebra) persist with high densities of livestock (mean of 4.6 t km(-2) on transitional ranches). Maintaining higher wild species diversity in the landscape will depend on the creation of a network of unfenced conservation areas in which livestock densities are persistently low or zero, which are sufficiently large to act as 'sources' of wild species that are prone to displacement by humans and livestock, and which generate benefits to community members that exceed opportunity costs. (C) 2007 Elsevier Ltd. All rights reserved.