【作者】 崔霞；

【导师】 刘勇；

【作者基本信息】 兰州大学 ， 地图学与地理信息系统， 2011， 博士

【摘要】 甘南地区地处青藏高原的东缘,境内草地资源丰富,但气候严酷,生态环境十分脆弱。在过去的几十年中,甘南牧区由于受气候变化及超载过牧等人类活动的强烈影响,导致90%以上的天然草地处于退化状态。因此,及时有效地监测草地植被的生长状况,研究切实可行的草地畜牧业管理措施,不仅对该区草地畜牧业和社会经济的可持续发展具有重要的作用,而且对区域生态环境的建设具有重大的意义。本文通过地面实测生物量数据与17种遥感植被指数的相关性分析,筛选出适宜甘南牧区草地动态变化遥感监测的植被指数,建立了草地生物量和盖度遥感监测模型,分析了甘南草地增强型植被指数和草地生物量的时空变化特点,研究了草地生态恢复力的变化特征,开展了草地分类经营及管理决策。取得如下主要结论：(1)通过多种植被指数和野外实测数据的线性回归分析,确定EVI为监测甘南草地的植被指数。通过精度评价,筛选出甘南草地植被的生物量监测模型为y=3738.073x1.553, (R2= 0.626),盖度监测模型为y=101.664+42.3861n(x)(R2=0.449)。(2)甘南州EVI月际、年际变化表明：从每年的4-6月EVI呈现增长趋势,其中5,6月份EVI增加速度比较快,基本在每年的7月达到最大值(2001年EVI在8月份达到最大值),然后植被指数开始下降。玛曲县和碌曲县的EVI值相对于其它的县较高,舟曲县的EVI值最小。在9年动态变化中,临潭县、夏河县、舟曲县的变化比较明显,临潭县、夏河县、舟曲县、卓尼县草地EVI在9年间有明显增大的趋势。(3)甘南草地生物量9年来有增加趋势,但不显著。对于生物量月际变化来说9年中甘南草地生物量变化呈单峰抛物线分布,草地月际生物量年内变化曲线总体符合草地植被生长的规律。2001-2009年间甘南暖性草丛、温性草原的年最大生物量呈明显上升的趋势(R2=0.529,sig=0.026：R2=0.423,sig=0.058)。(4)甘南草地2001-2009年间恢复力最差的草地占整个甘南草地的33.84%,主要分布在卓尼县、迭部县和临潭县；草地恢复力较差的草地占整个草地的15.35%,主要分布于夏河县北部；草地恢复力较高和草地恢复力最高的草地主要分布在玛曲县、碌曲县、夏河县,分别占整个草地的19.66%和31.15%。卓尼县和迭部县草地恢复力较差,玛曲县和碌曲县草地恢复力最好。甘南草地在夏季恢复力最高。春季和冬季草地的变化比较稳定,夏季草地生长旺盛,良好的水热条件使得草地恢复力有所提高。(5)甘南草地在空间上利用草地分类经营指数划分为保护型草地和适度经营型草地,其中适度经营型草地是甘南草地的主体。保护型草地主要分布在夏河县、玛曲县、迭部县和舟曲县,其中夏河县保护型草地的面积最大。甘南草地保护型草地的面积约为3.45×104ha,占甘南总可利用草地的1.35%；适度经营型草地的面积为252.2×104ha,占总可利用草地面积的98.65%。对于保护型草地,经营策略主要以禁牧和封育为主,使得严重退化的草地能够进行恢复,提高区域草地生态系统的保育能力。适度经营型草地不仅要追求生态效益,同时也要承担经济生产的功能,但是为了不破坏该草地类型的生态环境,应该确定合理的载畜量,采取轮牧等草地管理措施来管理草地。对于保护型草地和适度经营型草地应该采取不同的管理措施,虽然保护型草地不能给牧民带来经济收入,但是这些损失可以通过集约化经营型草地来补偿,保护型草地主要的功能是体现生态和社会价值,在这个区域应该采取禁牧和围栏措施。适度经营型草地可以承载合理的载畜量,轮牧和夏秋季放牧冬季舍饲的措施应该在这个区域实行。更多还原

【Abstract】 The Gannan region is located on the northeast of Qinghai-Tibet Plateau, rich in grassland resources but had the severe climatic conditons and the ecological environment is very fragile. In the past decades, natural (climate change) and human factors (overgrazing and deterioration of natural environment) resulting in the degradation of 90% of grasslands in this region. Effective and accurate monitoring of the grassland vegetation changes will not only plays an important role in grassland animal husbandry and sustainable development of social economy and, but also has great significance to the construction of regional ecological environment.This research compared the correlation between 17 vegetation indices and grassland biomass, and found out the suitable VI to monitoring Gannan grassland change. The best VI was used to establish the Gannan grassland biomass/cover monitoring models. The VI and grassland biomass spatial-temporal variation were analyzed. The grassland resilience characteristics and the grassland classification management method were studied. Main conclusions obtained as follows:(1) The linear regression analysis between field survey data and MODIS data showed that the EVI was the best index to simulate the forage dry biomass and cover in the Gannan region from 17 vegetation indices (Ⅵs) evaluated. The results of precision estimation for models showed that the grassland biomass estimated model was:y=3738.073x1.553 (R2=0.626), grassland cover estimated model was:y=101.664+42.3861n(x) (R2=0.449).(2) The EVI monthly and yearly variation showed that:the EVI value increased from April to July during 2001 to 2009 and got the maximum at July except 2001, then the EVI value decreased. Maqu and Luqu had relatively higher EVI value and Zhouqu had the EVI minimum. The variation of EVI during 9 years was more obvious in Lintan, Xiahe, Zhouqu. The EVI increased obviously in Lintan, Xiahe, Zhouqu, Zhouni from 2001 to 2009.(3) The grassland biomass increased slightly from 2001 to 2009. The grassland biomass monthly variation was the single-peak parabola distribution and matched to grassland growth rule. The grassland biomass of warm temperate tussock, temperate steppe increased obviously from 2001 to 2009 (R2=0.529, sig=0.026; R2=0.423, sig=0.058).(4)The grassland with the lowest resilience accounted for 33.84% of the available grassland from 2001 to 2009. These grasslands mainly located in Zhuoni, Diebu and Lintai counties. The grassland with lower resilience mainly located in the northern of Xiahe county and accounted for 15.35% of available grassland in Gannan. Grassland with the highest and higer resilience mainly located in Maqu, Luqu and Xiahe, and accounted for 19.66% and 31.15%, respectively. The resilience of Zhuoni and Diebu counties were lower than other counties. Maqu and Luqu counties had the highest resilience. The grassland in Gannan had the highest resilience in summer and had the relatively stable condition in winter and spring. In fall, the grassland resilience was obviously decreased.(5)The index of classification management of grassland (ICG) was used to subdivide grassland into conservation grassland and moderately productive grassland in the Gannan region where no grassland fell into intensively productive grassland. The moderately productive grassland was the main grassland type in Gannan. Most conservation grassland located in Xiahe, Maqu, Diebu and Zhouqu and the area of conservation grassland in Xiahe was the largest. The area of conservation grassland is 3.45×104ha, accounted for 1.35% of the available grassland while the area of moderately productive grassland is 252.2×104ha accounted for 98.65% of the available grassland. Different management techniques should be applied to conservation, moderately and intensive productive grassland. Although the grassland in conservation sector could not provide the income for resident farmers, these losses can be compensated by the increase income of intensively productive grassland. In this study, grasslands divided into conservation sector can be mainly devoted to ecological and social values in the future. Anti-grazing and fencing had been suggested to restore degraded grasslands in the Gannan regions. The moderately productive grassland was suggested to carry out reasonable carrying capacity and rotational grazing by grazing in the summer and autumn and shelter feeding in winter and spring to achieve the balance between livestock need and forage supply.更多还原