Sustainability of Inner Mongolian grasslands: application of the Savanna model
Sustainability of Inner Mongolian grasslands: application of the Savanna model
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DOI：
10.2458/azu_jrm_v56i4_christensen
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发表时间：
2003-07
期刊：
影响因子：
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通讯作者：
L. Christensen;M. Coughenour;J. Ellis;Zuozhong Chen
中科院分区：
文献类型：
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作者：
L. Christensen;M. Coughenour;J. Ellis;Zuozhong Chen
以亚洲典型草原放牧生态系统为例，通过生态系统模拟模型确定阈值和稳定状态，对其可持续性和恢复力进行评价。该分析使用Savanna模型来模拟14种不同载畜率(5.5-59.8auy Km-2)下的空间气候、植被和牲畜放牧动态。评估了放牧对植被的影响，包括对初级生产力、植被组成和根生物量的影响。模拟运行了100年：50年用于检查可持续性，50年用于检查系统的弹性。结果表明，放牧强度(1-g/u；g=放牧区生物量，u=非放牧区生物量)对该系统是可持续的。该地区对放牧强度最高可达0.49，该系统仍以草本植物生产为主。放牧强度大于0.49，加上降雨量少，草本植物净初级生产力和根生物量降低，灌木净初级生产力和根生物量增加。在放牧强度在0.49以上的地区，草本植被无法获得相对于灌木的竞争优势；因此，系统转变为稳定的灌木主导状态，即使没有进一步的放牧，也无法恢复其原始成分。DOI：10.2458/azu_jrm_v56i4_chrisensen
The sustainability and resilience of an Asian typical steppe grazing ecosystem was assessed by determining thresholds and stable states with an ecosystem simulation model. This analysis used the Savanna model to simulate spatial climate, vegetation, and livestock grazing dynamics, at 14 different stocking rates (5.5-59.8 AUY km-2). Grazing effects on vegetation were assessed, including effects on primary production, vegetation composition, and root biomass. Simulations were run for 100 years: 50 years to examine sustainability and 50 years to examine resilience of the system. Results showed that a grazing intensity (1-g/u; g = biomass in grazed area, u = biomass in ungrazed area) of 0.49 was sustainable for this particular system. This region was resilient to grazing up to the intensity of 0.49, where the system remained dominated by herbaceous production. Grazing intensities higher than 0.49, in combination with low precipitation events, resulted in decreased herbaceous net primary production and root biomass, and increased shrub net primary production and root biomass. Herbaceous vegetation was unable to gain a competitive advantage over shrubs in areas where grazing intensities were above 0.49; consequently, the system shifted to a stable shrub-dominated state that could not return its original composition even without further grazing. DOI:10.2458/azu_jrm_v56i4_christensen