Journal of Resources and Ecology >
Comparison of Methods for Evaluating the Forage-livestock Balance of Alpine Grasslands on the Northern Tibetan Plateau
CAO Yanan, E-mail: caoyanan@hebeu.edu.cn |
Received date: 2020-02-08
Accepted date: 2020-03-20
Online published: 2020-06-16
Supported by
The National Key Research and Development Program of China(2016YFC0502001)
The Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20010201)
The Strategic Priority Research Program of the Chinese Academy of Sciences(XDA19050502)
Copyright
Livestock grazing is one of primary way to use grasslands throughout the world, and the forage-livestock balance of grasslands is a core issue determining animal husbandry sustainability. However, there are few methods for assessing the forage-livestock balance and none of those consider the dynamics of external abiotic factors that influence forage yields. In this study, we combine long-term field observations with remote sensing data and meteorological records of temperature and precipitation to quantify the impacts of climate change and human activities on the forage-livestock balance of alpine grasslands on the northern Tibetan Plateau for the years 2000 to 2016. We developed two methods: one is statical method based on equilibrium theory and the other is dynamic method based on non-equilibrium theory. We also examined the uncertainties and shortcomings of using these two methods as a basis for formulating policies for sustainable grassland management. Our results from the statical method showed severe overgrazing in the grasslands of all counties observed except Nyima (including Shuanghu) for the entire period from 2000 to 2016. In contrast, the results from the dynamic method showed overgrazing in only eight years of the study period 2000-2016, while in the other nine years alpine grasslands throughout the northern Tibetan Plateau were less grazed and had forage surpluses. Additionally, the dynamic method found that the alpine grasslands of counties in the northeastern and southwestern areas of the northern Tibetan Plateau were overgrazed, and that alpine grasslands in the central area of the plateau were less grazed with forage surpluses. The latter finding is consistent with field surveys. Therefore, we suggest that the dynamic method is more appropriate for assessment of forage-livestock management efforts in alpine grasslands on the northern Tibetan Plateau. However, the statical method is still recommended for assessments of alpine grasslands profoundly disturbed by irrational human activities.
CAO Yanan , ZHANG Xianzhou , NIU Ben , HE Yongtao . Comparison of Methods for Evaluating the Forage-livestock Balance of Alpine Grasslands on the Northern Tibetan Plateau[J]. Journal of Resources and Ecology, 2020 , 11(3) : 272 -282 . DOI: 10.5814/j.issn.1674-764X.2020.03.004
Fig. 1 Basic information for the study area. Panel (a) shows the grassland types on the NTP and sampling sites used in this study. Panel (b) shows the spatial distribution of precipitation amounts and Panel (c) shows the change trend of total precipitation during the growing season (GSP). Panel (d) shows the spatial distribution of average temperatures and Panel (e) shows the change trend of the average temperature during the growing season (GSMT). |
Fig. 2 The correlations between the model simulation and field observations of aboveground biomass (AGB). (a) is for aboveground biomass of fenced grasslands (AGBF) and (b) is for aboveground biomass of open grasslands under grazing (AGBG) |
Fig. 3 Inter-annual variations of aboveground biomass (AGB) in alpine grassland on the northern Tibetan Plateau. (a) is for aboveground biomass of fenced grasslands (AGBF), (b) is for aboveground biomass at open grasslands under grazing (AGBG), and (c) is for human-induced aboveground biomass (AGBH). |
Fig. 4 Spatial distribution and change trends for aboveground biomass from 2000 and 2016 on the northern Tibetan Plateau. (a), (c) and (e) show the spatial distribution of aboveground biomass for fenced grasslands (AGBF), for open grasslands under grazing (AGBG) and for human-induced aboveground biomass (AGBH), respectively. (b), (d) and (f) show the change trends for aboveground biomass for fenced grasslands (AGBF), for open grasslands under grazing (AGBG) and for human-induced aboveground biomass (AGBH), respectively. |
Fig. 5 Inter-annual variations of carrying capacity of alpine grasslands on the northern Tibetan Plateau. |
Fig. 6 The carrying capacity of alpine grasslands from 2000 and 2016 for each county of the northern Tibetan Plateau |
Fig. 7 Inter-annual variations of the grazing pressure index on the northern Tibetan Plateau. (a) shows the grazing pressure index obtained by the statical method and (b) shows the grazing pressure index obtained by the dynamic method. |
Fig. 8 The grazing pressure index in each county of the northern Tibetan Plateau between 2000 and 2016. (a) shows the grazing pressure index obtained by the statical method and (b) shows the grazing pressure index obtained by the dynamic method. |
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