NWIPB OpenIR
基于“3S”技术的三江源区果洛州草地动态空间分析
Alternative TitleStudies on Grassland Dynamics in Source Area of Three Rivers Using “3S” Technology——A Case Study in Golog Prefecture
于龙
Subtype博士
Thesis Advisor周立
2009-06-02
Degree Grantor中国科学院西北高原生物研究所
Place of Conferral西北高原生物研究所
Keyword三江源区 果洛藏族自治州 “3s” 植被指数 草地生产力 适宜载畜量
Abstract三江源地区自然条件恶劣,生态系统群落结构简单,系统内物质、能量流动缓慢,抗干扰和自我恢复能力低下,是全球生态环境最为敏感和脆弱的地区之一。在全球气候变暖的大背景下,自上世纪60年代以来随着人口的增加,人们对自然资源和畜产品的需求也迅速增加,给三江源区的草场造成很大的生态压力,导致该区生态系统持续退化,生态系统结构和功能受到严重干扰。近年来国家和青海省政府投入大量资金,采取多项措施对三江源区生态环境进行保护与建设。本文以地处黄河源区的果洛藏族自治洲草场为研究对象,借助遥感、地理信息系统和全球定位系统(“3S”),并结合野外地面调查数据,采用计算机监督分类技术解译遥感影像类群,构建植被状态变量与遥感植被指数的统计模型,研究了果洛州近25年来草地覆盖度、生产力、载畜量和土地利用/土地覆盖等的时间和空间变化及景观格局变化,分析了草地生产力与主要气候因子(气温和降水)及人为因素(放牧和草场保护措施)的关系,探讨了草地退化的成因及对策,为今后江河源区的草地可持续发展提供决策支持。 主要研究结果如下: (1) 研究区实测草地植被牧草产量对数值与MODIS植被指数(NDVI、EVI)之间存在着较好的相关性(P<0.001)。不同植被指数与草地生物量对数值的相关性也存在一定差别,EVI与沼泽化草甸的相关性最好(P<0.001);NDVI与高寒典型草甸、高寒草甸草原、高寒干草原和高寒灌丛化草甸的相关性最好(P<0.001)。模型评价绝对误差在17-32%之间,平均相对误差在10-13%之间。依据实际情况确立了以NDVI指数估算全州草地牧草产量的估产模型。 (2) 2005年果洛州鲜草产量自东南半湿润气候区向西北半干旱、干旱区递减;草地生产力从1980s的3605.25kg/ha下降到了2005年的2954.44kg/ha,平均产量下降了18.1%;高产量草地面积在减少,中低产量草地面积在增加。 (3) 2000-2006年间果洛州植被NPP年平均值呈现增加的趋势。NPP与气候因子的分析结果表明:温度是影响该地区NPP变化的主要因素,降水对本区植被的生长也有重要影响,气候变化(暖湿化)总体上有利于草地的恢复。但该区域退化草地面积仍在扩大,草地退化的空间变化特征进一步确定了人类活动是该地区草地退化的主要原因草地退化主要是由于长期过牧造成的。 (4) 果洛州以羊单位表示的理论载畜量呈现出西南高、东北低的空间格局。果洛州2005年样方法计算的理论载畜量为485.31万羊单位,单位可利用草场面积上可承载的家畜量(羊单位/公顷)的大小依次为:久治﹥甘德﹥班玛﹥达日﹥玛沁﹥玛多,平均值为0.78羊单位/公顷。果洛州2005年遥感方法计算的理论载畜量为499.22万羊单位,比样方计算的理论载畜量多出13.1万,总体差别为2.87%,差别较小。单位可利用草场面积上可承载的家畜量(羊单位/公顷)的大小依次为:久治﹥班玛﹥甘德﹥玛沁﹥达日﹥玛多,平均值为0.8羊单位/公顷。基于遥感和GIS影响因子调整后的果洛州2005年最适载畜量为297.15万羊单位,单位可利用草场面积上可承载的家畜量(羊单位/公顷)的大小依次为:久治﹥甘德﹥达日﹥班玛﹥玛沁﹥玛多,平均值为0.39羊单位/公顷。虽然近年来果洛州大量推行草原减畜与生态移民建设,但是超载现象仍然严峻。 (5) 果洛州占主导的土地利用/土地覆盖类型为草地(约占77%)、未利用土地(约占11%)和灌木林地(约占7%),其它约占5%。其中中/低覆盖度草甸所占面积最大,达68%-74%;高覆盖度草地面积约占4.14%-8.84%;未利用土地面积约占11%-12.35%;耕地面积很少,约占全州面积的0.03%。20年间草地覆盖度格局在波动后又呈现出相对稳定的局面。土地利用/土地覆盖变化的类型主要是在草地内部、草地与未利用土地之间的转换。1980-1995-2000年间低覆盖度草地面积呈现出先增加后减少的趋势,而高、中覆盖度草地面积则呈现出先减少后增加的趋势,其它未利用土地、林地、灌丛面积也呈现出先增加后减少的趋势,这与90年代后期气候变化促进植被的恢复以及人为减畜、围栏封育、补播和灭鼠等措施有关,表明生态保护初见成效。 (6) 1980-2005年间整体景观格局情况:1980-2000年间果洛州整体景观的破碎度在减少,2000-2005年间整体景观破碎度下降速率更为明显,表明该地区人类活动减弱,对该区景观的干扰程度在削弱。景观的平均分维数在减小,表明该地区景观中斑块的复杂度在降低。景观的形状指数减少,表明该地区景观的不规则程度或边界长度在下降。该区的多样性指数在下降,均匀度指数在增加,景观结构趋于简单化。
Other AbstractGrasslands have provided fundamental goods and services to humankind for millennia. In many of the Qinghai Plateau’s mountain regions, especially in the source region of the Yellow River (SRYR), pastoralists (livestock herders) have benefited from and maintained alpine grassland biodiversity through sustainable land use practices. In recent decades, however, the increasing demand for natural resources and animal products to cope with sharply rising human populations has placed tremendous pressures on grassland ecosystems. Serious grassland degradation is endangering the fragile environment of this region. Overgrazing caused by an increase the population of humans and domestic livestock in the SRYR, is considered to be the major causes of alpine grassland degradation. So it is important for the local government and pastoralists to know their grassland health conditions and how much livestock their grassland can carry for sustainable utilization of natural resources. In this study, grassland dynamics, including grassland aboveground green biomass (AGGB), net primary productivity (NPP), proper livestock carrying capacity and land use/land cover change in Golog Prefecture, Qinghai, China was monitored by remote sensing (RS), geographic information systems (GIS), and global positioning system (GPS) technologies. The main results are showed as follows: (1) The MODIS-derived vegetation index (NDVI, EVI) data had good relationship with the AGGB data from the ground sampling campaigns. Regional regression model between MODIS-NDVI/EVI and the common logarithm (LOG10) of AGGB was significant (r2 = 0.51, P < 0.001), EVI has the best correlation with alpine swamp meadow; NDVI has the best correlation with typical alpine meadow, alpine steppe and dry meadow and alpine shrub meadow. Thinking about difficulties in field sampling and making regression model’s easy to use, we used MODIS-NDVI regression model to predict AGGB in Golog Prefecture. The optimal regression model is: Y = 10(1.303NDVI + 2.575) (r2 = 0.5, P <0.001, df = 37). Regression model’s absolute errors ranged between 17% and 32%, relative errors ranged between 10-13%. (2) Spatially, AGGB decreased from southeast (humid and semi-humid climate) to northwest (arid and semi-arid climate) in 2005. Average AGGB in 1980s was 3605.25kg/ha which decreased to 2954.44kg/ha in 2005, the decreasing rate was 18.1%, among which areas of higher productivity grassland decreased while areas of low to middle productivity grassland increased. (3) Annual NPP increased from 2000 to 2006. Annual NPP had good correlation with annual air temperature than with annual precipitation. For example, in Dari meteorological station, annual temperature had increased significantly (R2=0.35, P<0.001) from 1956 to 2007 while in the same period annual precipitation didn’t change very much (R2=0.0075, P>0.01). Annual NPP in Dari meteorological station had good correlation with annual air temperature (R2=0.61, P<0.05) from 2000 to 2006, but there was very weak correlation between annual precipitation (R2=0.0001, P>0.01). Increasing air temperature associated with increasing air moistures, current climate state was in favor of grassland recover. So it can be see, long time overgrazing is the key factors to result in grassland degradation. (4) Spatially, livestock carrying capacity (in sheet unit) also decreased from southeast (humid and semi-humid climate) to northwest (arid and semi-arid climate) in 2005. Livestock carrying capacity calculated from field sampling, remote sensing images and remote sensing and GIS technologies was 48.53, 49.92 and 29.72 million respectively, it can be carrying 0.78, 0.8, 0.39 sheet unit in per hectare respectively. Though more activities had done to reduce livestock numbers, it was still more than proper livestock carrying capacity. (5) Main grassland use / grassland cover in Golog Prefecture was alpine meadow (77%), unused land (11%) and alpine shrub and forest (7%), others (5%). Low to middle covered meadow occupied 68%-74%, high covered meadow occupied 4.14%-8.84%, arable land occupied 0.03%. From 1980-1995-2000, low covered grassland was increased form 1980 to 1995, and decreased from 1995 to 2000, on the contrary high and middle covered grassland decreased from 1980 to 1995, and increased form 1995 to 2000. (6) The government officials and ecologists in China have realized the on-going degradation of grassland ecosystem in the source region of the Yellow River, most of the studies think the degradation is mainly caused by human activities especially overgrazing. Our results show that the health of grassland ecosystem is declined and overgrazing are still serious in Golog Prefecture. So it is important and urgent to perform some effective management of grassland ecosystem and livestock. Fortunately, some effective management practices e.g. rodent and ruderal weed control, reseeding, establishment of artificial grassland, rational management of grassland, optimizing livestock structure, ecological emigration policy, fencing natural grassland, warm pen construction, establishment of perennial pastures and use of solar energy and integrated countermeasures for the restoration of degraded grasslands have developed in this region. Harnessing of ecological principles and biological processes, the grazing pattern, grazing density, sheep and yaks feedlot fattening, sustainable livestock production system are approached according to serial pilot studies in the region.
Pages125
Language中文
Document Type学位论文
Identifierhttp://210.75.249.4/handle/363003/3106
Collection中国科学院西北高原生物研究所
Recommended Citation
GB/T 7714
于龙. 基于“3S”技术的三江源区果洛州草地动态空间分析[D]. 西北高原生物研究所. 中国科学院西北高原生物研究所,2009.
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