【作者】 周晓雷；

【导师】 任继周； 傅华；

【作者基本信息】 兰州大学 ， 生态学， 2008， 博士

【摘要】 本文利用历史统计资料(水文、气象、植被)和野外调查的数据，应用高寒草甸系统作为区域生态环境退化的指示剂，来反映气候变化和人类活动对生态环境的影响，对青藏高原东北边缘的水资源变化(地表水系的变化和水资源量的变化)和植被变化(高山草甸退化、草地退化、森林减少)进行研究。并结合ERDAS、MAPINFO、ARCINFO等遥感、GIS软件，通过1982年和2001年2景卫星影像的解译，验证两期湿地变化量。利用遥感图像进行土地利用动态监测，用分类后比较法(Post-Classification Comparison Change Detection)对研究区不同时相(1980，1990，2006年)的图像分别进行分类，然后比较分类结果，找出从某土地利用类型到另一种土地利用类型的信息，获得青藏高原东北边缘土地利用变化信息。采用综合评价方法与分类评价方法相结合的评价方法，建立相应的指标体系和指标权重，利用公式求得青藏高原东北边缘生态环境脆弱度，并作出定性评价。研究结论如下：(1)近40 a来，在强烈的人类活动和区域气候变化的驱动下，青藏高原东北边缘生态环境发生了很大变化。主要体现在生态环境退化、土地利用／土地覆盖发生很大的变化和生态环境脆弱度呈现加剧趋势。(2)通过分析青藏高原东北边缘1956～2004近40 a水文数据，其结果表明，四个不同的汇水区域(玛曲集水区、玛曲——龙羊峡集水区、大夏河集水区和洮河集水区)多年地表水量变化趋势基本一致，最大地表水量出现在上个世纪60年代中期和末期，然后呈下降趋势。从上个世纪90年代初始到2004年，青藏高原东北边缘为严重的兼水年，与20世纪60年代相比，水资源总量减少了29．03％，40多年内，年水资源总量平均减少了14．69％。(3)从上个世纪70年代到80年代总计10年间，青藏高原东北边缘的高山草地、高寒草地和湿地草地面积分别减少了2．26％、3．73％和24．53％。而在80年代至90年代，三类草地面积分别减少了6．64％、24．21％和34．45％，面积减少速度大大提高。同期，高寒草地的覆盖度和河流峡谷平坦地段的灌木草地盖度下降到50～70％，局部地方植被覆盖度不足30％。(4)在研究区，分布有236．10×10~4ha的天然草场，退化草场面积竟占可利用草场面积的83．20％，其中重度和中度草场退化面积分别有81．40×10~4ha和137．00×10~4ha。现有荒漠化草地5．33×10~4ha，盐渍化草地0．55×10~4ha。退化草地产草量下降42％和70％。(5)从上个世纪50年代开始，青藏高原东北边缘林地面积显著持续减少增加。(6)受全球气候变暖的影响，过去40年内，青藏高原东北边缘的呈现出暖化趋势，气温升高了0．70℃，平均每10年上升0．275℃。(7)上世纪80年代同70年代相比，研究区的降雨量变化不明显，90年代比80年代有所减少，90年代与2004年相比变化不明显，总体上各地年降水量有减少趋势。(8)在青藏高原东北边缘，由于冻土层的退化，湖水面积和湖泊河流水量都减少了。湖泊水域面积在1970s～1980s减少了0．54％，而在1980s～1990s减少了9．25％。(9)目前，青藏高原东北边缘的草地处于过畜过牧状态，每羊可利用草地面积仅介于0．45-0．50 ha。(10)根据1980～1990年和1990～2005年两期的土地利用类型转移矩阵研究，表明青藏高原东北边缘的土地利用变化形式发生了很大的变化。(11)1987～2006年间，青藏高原东北边缘生态环境脆弱度指数呈单峰曲线变化，其脆弱度为0．59，属强脆弱区。(12)分析脆弱生态环境脆弱度与各因子的关联度，得到各因子与环境脆弱度的关联序为：产草力>降水量>森林覆盖率>≥10℃的积温>农民人均纯收入>牧业产值占农业总产值的比例>干燥度>成灾面积与受灾面积比>相对1986年降水变化率>人均工业产值>乡镇企业占研究区国内生产总值的比例>人均粮食占有量>非农业人口比例>人口自然增长率>恩格尔系数>非文盲率。(13)综合三类因子的相对贡献率，得到自然因素对环境脆弱度变化影响所占的比重为64．36％，经济因素所占的比重为28．57％，社会因素所占的比重为6．09％。鉴于青藏高原东北边缘生态环境退化，土地利用／土地覆盖的变化以及生态环境脆弱度评价结果，分别提出了青藏高原东北边缘生态环境保护对策、土地资源开发利用建议和脆弱生态环境的保护、整治和修复策略。这些研究结论对于青藏高原东北边缘生态环境的重建、修复和保护具有较大借鉴意义。更多还原

【Abstract】 Based on the historical statistics data (hydrographical, meteorologic and vegetational) and the field survey data, regarding plant population as the indicator of the regional ecoenvironmental degradation, reflect the effect of the climate change and anthropogenetic activity on the eco-engvironment degradation in the northeastern margin of the Qinghai-Tibetan Plateau. Water resource changes (Changes of Surface Water System, Changes of Water resource amount) and vegetation variation (Alpine meadow degradation, Changes of grassland and forest ecosystem) were studied in this paper. At the same time, applying the ERDAS, MAPINFO, ARCINFO and GIS software, interprete the satellite images of 1982 and 2001 and test the variation amount of wetland.According to the interpretation to the satellite images of 1980, 1990 and 2005 with reference to the historical maps and GPS positioning survey data on-the-spot. Based on the Post-Classification Comparison Change Detection, transfer matrixes of LUCC from 1980 to 1990 and 1990 to 2005 were made and the features of LUCC were analyzed in the northeastern margin of the Qinghai-Tibetan Plateau.In order to evaluate the fragile index of the northeastern margin of the Qinghai-Tibetan Plateau, the intergrative and classified evaluation method was adopted, and index system and index weight were constructed in this paper.Using(?)obtained the ecoenvironmental fragileindex and evauated it.(1)The regional hydrology and ecosystems of the northeastern margin of the Qinghai-Tibetan Plateau have changed over the past 40 years driven by intense human activity and regional climate changes. Annual mean air temperature has increased in the region. Streamflow from the northeastern margin of the Qinghai-Tibetan Plateau has decreased significantly. Overall, a number of Alpine step meadows and Alpine frigid meadows have seriously degraded. Degeneration of vegetation and grassland led to desertification and frequently induced dust storms. With the continuous increase in cultivated land area, grassland area in the region has dropped significantly since the 1960s. At present, degraded grassland occupies about 83% of total usable grassland area. As the number of livestock increased, range condition deteriorated and the carrying capacity was reduced. The forest area in the northeastern margin of the Qinghai-Tibetan Plateau has decreased by 20%, and the local ecosystem has become very fragile.(2)The amount of water resource in the northeastern margin of the Qinghai-Tibetan Plateau has shown a steadily downward trend since 1950s. By analyzing hydrological data (1956 - 2004) of the study areas, the results showed that the multi-year variation of water resource of 4 catchment regions had similar patterns from 1956 to 2004. The maximum occurred at the middle and end of 1960s in all catchment regions, and declined thereafter.(3)From the 1970s to the 1980s the areas of Alpine step meadows, Alpine frigid meadows and swamp meadows in the northeastern margin of the Qinghai-Tibetan Plateau decreased by 2.26, 3.73 and 24.53% respectively, whereas it decreased 6.64, 24.21 and 34.45%, respectively, from 1980s to 1990s.(4)With the continuous increase in cultivated land area and number of livestock, the area of degraded grasslands in the northeastern margin of the Qinghai-Tibetan Plateau had increased significantly since the 1950s. In this region, there was about 2,361,000 ha of natural rangeland, and degraded grassland occupied about 83.20% of total usable grassland area, in which severe and moderate degraded grassland area was 814,000 ha and 1,370,000 ha, respectively; desertified grassland was 53,300 ha, and salt-affected grassland was 5,500 ha. The amount of quality forage declined from 70% to 45%. The areas invaded by noxious weeds had increased from 30% to 55% since 1980s.(5)The area of forest land in the northeastern margin of the Qinghai-Tibetan Plateau has dropped significantly since the 1950s. At the end of 1998, the northeastern margin of the Qinghai-Tibetan Plateau had lost 23,000 ha forest area and 26,270,000 m~3 wood accumulation, representing 35.11% and 32.59% reduction, respectively.(6)Average air temperature showed a fairly rapid increase since 1990s in the northeastern margin of the Qinghai-Tibetan Plateau. The decade of mean air temperature departure was - 0.4 - - 0.3, - 0.3 - - 0.1, - 0.1 - 0 and 0.2 - 0.5℃, for the periods of 1960-1970, 1970-1980, 1980-1990, respectively.(7)Over the past 4 decades the annual precipitation in the headwater area showed no noticeable changes or it remained stable.(8)The increased temperature has caused the degradation of permafrost. In the northeastern margin of the Qinghai-Tibetan Plateau, the lake water area in the region has decreased and water areas of most lakes and rivers were reduced because of permafrost degradation. The lake water area shrank by 0.54% from 1970s to 1980s, and by 9.25% from 1980s to 1990s.(9)At present, the grassland was overstocked and overgrazed, the grassland available per head of sheep ranged from 0.45 to 0.50 ha. Overgrazing resulted in degradation of the grassland ecosystem.(10)Based on the matrix of LUCC, there were significant change of LUCC from 1990 to 2005 in the northeastern margin of the Qinghai-Tibetan Plateau.(11)Environment fragile represented as intensive fragility with index of 0.59 from 1987 to 2005 in the northeastern margin of the Qinghai-Tibetan Plateau.(12)Analyzing the relationship between fragile index of ecoenvironment and fragile factors and knowing the relative sequence between all factors and fragile eco-environmental index is: productive forces of grassland > precipitation > percentage of forest cover > cumulative temperature (≥10℃) > rural per capita net income > the ratio of the income of livestock to the gross income of agriculture > aridity > the ratio of catastrophic area to the calamitious area > the relativity variation rate of precipitation to 1986’s > per capita income of industry > the ratio of capita income of enterprises in townships and towns to capita gross dommestric product > per possession of grain > the ratio of non-farm population to total population > the natural growth rate of population > Engel coefficient > the ratio of non-illiteracy population to illiteracy population.(13)Analyzing the relative contribution of natural fragile factor, economic fragile factor and society fragile, obtain each fragile factor drive proportion is 64.36%, 28.57% and 6.09%. Showing the effect of natural fragile factor on the environment was higher than society and economic fragile factor.To avoid further deterioration of the environment and ecosystems, it is important to establish and implement ecosystem protection countermeasure. Some effective measures are essential in this respect, including technical and political considerations.更多还原