近50年气候变化对那曲地区环境承载力的影响

【作者】 秦泗国；

【导师】 钟国辉； 王景升；

【作者基本信息】 西藏大学 ， 生态学， 2009， 硕士

【摘要】 那曲草地地处青藏高原腹地,气候格局、NPP分布以及载畜量大小,直接反映出那曲草地的退化状况。全球气温变暖,导致青藏高原NPP的研究已成为全世界研究的热点。本研究通过在那曲地区布点,建立气象观测站的方法,采集了1955—2004年50年那曲地区的气象数据。那曲地区气温、降水、积温、生长期等气候因子的分析,建立自然植被净第一性生产力模型:NPP=RDI²·P·（1+RDI+RDI²）/（（1+RDI）·（1+RDI²））·exp(-（9.87+6.25RDI）^1/2)模拟那曲地区草地净生产力（NPP）,计算理论载畜量,与实际载畜量进行比较,分析那曲高寒草地退化的关键因子。气象要素总体上与载畜量情况存在着密切联系。牧草生长受光照、热量、水分等主要气象因子的影响,而水分是牧草生长发育的主要限制因子。那曲地区的气候变化呈现气温增高,降水量、相对湿度增加的趋势,有利于牧草的生长以及促进牧业生产的发展。分析那曲地区的草地气候格局变化、草地NPP的年际变化及环境承载力。主要研究结论包括:1)1955—2004年那曲地区50年气候变化趋势的分析,结果表明:那曲地区由东向西地势升高,温度和降水呈减少趋势,平均每升高100m,温度减少0.58℃,生长期减少7天,>0℃积温和>5℃有效积温均减少;随着纬度（或海拔）升高,年均降水量、空气湿度、可能蒸散率（PER）和辐射干燥度（RDI）均呈逐渐减少趋势,但变化均不明显。从而可推测出,那曲地区气候变化在经纬度和海拔梯度上的变化趋势,由东向西,降水量迅速减少,辐射干燥度和可能蒸散率均增加,气候逐渐干旱。2)50年来那曲地区降水和温度增加趋势明显,增速逐渐加快,平均降水量增加了近50mm,升温2℃,升温速度远超全球地表升温平均值0.4⁰.8℃。生长期大幅延长,积温快速增加。随着时间的推移,气温、降水等因子都有增长的趋势,向着有利于牧草生长的方向发展,排除人为干扰因素,将导致那曲草地生产力大幅提升。3)建立那曲地区草地生产力（NPP）的“气候—植被”模型（综合模型）,利用那曲地区50年的气象数据,研究那曲高寒草地生产力的分布格局,呈现出东部高,西部低的态势。而50年来,那曲地区NPP的增长趋势却是中部与西部基本相同,而东部却远小于中部和西部,这与高清竹利用CASA模型得出的结论完全相反。基于卫星遥感研究那曲地区1982—2003年的NDVI动态变化研究表明,反映出草地覆盖和生物量在空间上具有明显的差异性,草地覆盖率呈东部正逐年下降,中部基本持平,而西部却在缓慢增加。由于综合模型是排除人类活动的干扰,从而证明了上述所得结论与高清竹的研究结论并不矛盾。综合考虑各种因素的影响,气候变化（尤其气温和降水）条对那曲地区草地生产力的增长非常重要。4)持续增加的载畜量和不均匀放牧及不合理的管理模式导致那曲高原草地目前全部处于超载状态,经济越发达的地区,超载尤为严重,草地系统退化和沙化是那曲地区草原生态系统普遍存在的现象。更多还原

【Abstract】 Nagqu grassland is at the hinterland of Tibetan plateau. The research on NPP has become one of the focused areas because of globe climate warming causing the grassland degradation in Nagqu. The climate data of grassland （1955-2004） on Nagqu were collected by the method of stationing and established weather observation station in Nagqu areas. The climatic factors were analyzed for temperature, precipitation, accumulated temperature, growth period, etc, and the natural vegetated NPP model is established in Nagqu areas:NPP=RDI²·P·（1+RDI+RDI²）/（（1+RDI）·（1+RDI²））·exp(-（9.87+6.25RDI）^1/2)The crucial factors were analyzed by simulated the net productivity of Nagqu to compare the theoretical loading storage and practical loading storageIn general, the meteorological element exists to close the loading storage. Those mainly meteorological factors of light, heat, water, etc effected the grass growing. Water was the mainly the restricting factor in the period of the grass growing. These climate’s factors of temperature, precipitation, relative humidity had been increasing gradually in Nagqu areas that favored to grow the grass and to develop the animal husbandry. The results of the climate’s pattern, the NPP change and the environmental capacity were analyzed in Nagqu grassland. The mainly results:1) By analyzing 50 years climate in Nagqu areas, The result show that Terrain of altitude increases gradually from east to west causing the temperature and Precipitation decreases gradually, the mean altitude increases 100m and Temperature decreases 0.58℃, the Growth period shortens 7d, the accumulated temperature of >0℃and the active accumulated temperature of >5℃decrease all in Nagqu areas; With the latitude （or altitude） increasing, the annual average Precipitation, the air humidity, the potential evaporating rate （PER） and the radiative aridity （RDI） decreased gradually that changes were not significant. we presumed that the climate drought with Latitude and Longitude（altitude）from east to west in Nagqu areas, Precipitation reduced rapidly, the potential evaporating rate （PER） and the radiative aridity（RDI） increased all.2) For 50 years, Precipitation and Temperature increase significantly in 50 years and the speed accelerates gradually. The average Precipitation increases recent 50mm, Temperature increases recent 2℃. Heating-temperature were well high above the average-heating of 0.4-0.8℃on the surface in the globe. Growth period of plant prolonged so far, the accumulated temperature increased fast. With the passage of time, precipitation and temperature were increasing that were benefit to the growth of forage. its world cause improvement of far the productivity except the human being were interfering in Nagqu grassland.3) Using 50 years Meteorological Data, the“climate-vegetation”model （Comprehensive model） of the productivity in Nagqu grassland were build. The grassland productive patterns were study in Nagqu area that reduced gradually from eastern to western. For 50 years, the western increases the same as the middle at NPP in Nag qu region, and that the eastern is less than theirs. The results are contrary to the Gao Qingzhu’s conclusion of using the CASA model. The grassland cover and biomass in space were obviously Difference by studying on the Urban Dynamic Changes by 1982-2003a NDVI in Nag qu region The grassland coverage decreased gradually in eastern, unchanged in middle and increased in western. The Comprehensive model were removed the interference of the human activity, therefore, the conclusion were not conflict with the Gao Qing zhu’s result. Considering all factors, Climate were very important increasing the grassland productivity in Nagqu areas. 4) The increasing loading storage, the unevening grazing and managing model unreasonable caused all overload state at present in Nagqu grassland. The overloads were particularly serious in the ultra-economic developed region causing the degradation and desertification of the grassland system were commonly （ubiquitous） phenomenon in ecosystem of Nagqu grassland.更多还原