Based on the NOAA AVHRR-NDVI data from 1981 to 2001, the digitalized China Vegetation Map （1：1,000,000）, DEM, temperature and precipitation data, and field investigation, the spatial patterns and vertical character...Based on the NOAA AVHRR-NDVI data from 1981 to 2001, the digitalized China Vegetation Map （1：1,000,000）, DEM, temperature and precipitation data, and field investigation, the spatial patterns and vertical characteristics of natural vegetation changes and their influencing factors in the Mt. Qomolangma Nature Reserve have been studied. The results show that： （1） There is remarkable spatial difference of natural vegetation changes in the Mt. Qomolangma Nature Reserve and stability is the most common status. There are 5.04% of the whole area being seriously degraded, 13.19% slightly degraded, 26.39% slightly improved, 0.97% significantly improved and 54.41% keeping stable. The seriously and slightly degraded areas, which mostly lie in the south of the reserve, are along the national boundaries. The areas of improved vegetation lie in the north of the reserve and the south side of the Yarlung Zangbo River. The stable areas lie between the improved and degraded areas. Degradation decreases with elevation. （2） Degeneration in the Mt. Qomolangma Nature Reserve mostly affects shrubs, needle-leaved forests and mixed forests. （3） The temperature change affects the natural vegetation changes spatially while the integration of temperature changes, slopes and aspects affects the natural vegetation change along the altitude gradients. （4） It is the overuse of resources that leads to the vegetation degeneration in some parts of the Mt. Qomolangma Nature Reserve.展开更多
1 Introduction On 18 May 1989,the Mt.Qomolangma (Everest)Natural Reserve(abbr.MQNR)in Tibet Autonomous Region formally came into existence and it was listed as World Network of Biosphere Reserves(WNBR)in May 2005.The ...1 Introduction On 18 May 1989,the Mt.Qomolangma (Everest)Natural Reserve(abbr.MQNR)in Tibet Autonomous Region formally came into existence and it was listed as World Network of Biosphere Reserves(WNBR)in May 2005.The MQNR is a comprehensive reserve,which mainly protects alpine ecosystems,plateau natural landscapes,geological remains and Tibetan historical and cultural heritages.展开更多
虽然水生生物大多是变温动物并且温度对化合物的毒性有非常重要的作用,但生态毒理学实验一般在实验室标准温度(20℃)或者生物最适温度下进行。我们调查了适应温度(20℃、24℃和28℃)对镉暴露(0,20和40μg·L^(-1))中大型溞生理和亚...虽然水生生物大多是变温动物并且温度对化合物的毒性有非常重要的作用,但生态毒理学实验一般在实验室标准温度(20℃)或者生物最适温度下进行。我们调查了适应温度(20℃、24℃和28℃)对镉暴露(0,20和40μg·L^(-1))中大型溞生理和亚细胞水平的作用,实验终点包括镉的急性毒性(48 h-EC50)、大型溞的21 d存活率、21 d累积繁殖数(21-d CR)、第一次生育时间(time to first brood,TFB)、能量储存、电子转移活性(electron transport system activity,ETS)、热应激蛋白hsp70和金属硫蛋白(MT)。结果显示:适应温度升高时大型溞的镉耐性降低,20℃、24℃和28℃下的48 h-EC50分别为(40.2±9.9)μg·L^(-1)、(15.6±2.7)μg·L^(-1)和(10.7±1.9)μg·L^(-1);28℃下,大型溞21 d存活率分别比对照(20℃,0μg·L^(-1)镉暴露)降低23%(20μg·L^(-1)镉暴露)和87%(40μg·L^(-1)镉暴露)并且大型溞的21 d累积繁殖数(21-d CR)显著降低。大型溞的能量储存随适应温度的升高而降低,24℃和28℃时分别降低了46%和62%(0μg·L^(-1)镉暴露),48%和60%(20μg·L^(-1)镉暴露)、80%和91%(40μg·L^(-1)镉暴露)。而镉浓度只有达到40μg·L^(-1)时,对大型溞的能量储存有明显影响。适应温度和镉暴露对电子转移系统活性(ETS)没有显著影响。28℃的适应温度和40μg·L^(-1)的镉暴露都能诱导大型溞热应激蛋白hsp70和金属硫蛋白(MT)显著上升,但适应温度(20℃~28℃)和镉暴露(0~40μg·L^(-1))的结合对hsp70先诱导后抑制,MT则一直被诱导上升。总之,生物在不同温度下对毒物的反应存在差异,将不同适应温度下的毒性数据整合到生态危险性评价能够保证生物获得更充分的保护;此外,hsp70和MT的变化是环境压力的综合反应,作为某种污染物的生物标志物时需要综合考虑环境因素。展开更多
基金the National Basic Research Program of China, No.2005CB422006Social Commonweal Re-search Project of Ministry of Science and Technology of China, No.2005DIA3J106National Natural Science Foundation of China, No.40331006
文摘Based on the NOAA AVHRR-NDVI data from 1981 to 2001, the digitalized China Vegetation Map （1：1,000,000）, DEM, temperature and precipitation data, and field investigation, the spatial patterns and vertical characteristics of natural vegetation changes and their influencing factors in the Mt. Qomolangma Nature Reserve have been studied. The results show that： （1） There is remarkable spatial difference of natural vegetation changes in the Mt. Qomolangma Nature Reserve and stability is the most common status. There are 5.04% of the whole area being seriously degraded, 13.19% slightly degraded, 26.39% slightly improved, 0.97% significantly improved and 54.41% keeping stable. The seriously and slightly degraded areas, which mostly lie in the south of the reserve, are along the national boundaries. The areas of improved vegetation lie in the north of the reserve and the south side of the Yarlung Zangbo River. The stable areas lie between the improved and degraded areas. Degradation decreases with elevation. （2） Degeneration in the Mt. Qomolangma Nature Reserve mostly affects shrubs, needle-leaved forests and mixed forests. （3） The temperature change affects the natural vegetation changes spatially while the integration of temperature changes, slopes and aspects affects the natural vegetation change along the altitude gradients. （4） It is the overuse of resources that leads to the vegetation degeneration in some parts of the Mt. Qomolangma Nature Reserve.
文摘1 Introduction On 18 May 1989,the Mt.Qomolangma (Everest)Natural Reserve(abbr.MQNR)in Tibet Autonomous Region formally came into existence and it was listed as World Network of Biosphere Reserves(WNBR)in May 2005.The MQNR is a comprehensive reserve,which mainly protects alpine ecosystems,plateau natural landscapes,geological remains and Tibetan historical and cultural heritages.
文摘虽然水生生物大多是变温动物并且温度对化合物的毒性有非常重要的作用,但生态毒理学实验一般在实验室标准温度(20℃)或者生物最适温度下进行。我们调查了适应温度(20℃、24℃和28℃)对镉暴露(0,20和40μg·L^(-1))中大型溞生理和亚细胞水平的作用,实验终点包括镉的急性毒性(48 h-EC50)、大型溞的21 d存活率、21 d累积繁殖数(21-d CR)、第一次生育时间(time to first brood,TFB)、能量储存、电子转移活性(electron transport system activity,ETS)、热应激蛋白hsp70和金属硫蛋白(MT)。结果显示:适应温度升高时大型溞的镉耐性降低,20℃、24℃和28℃下的48 h-EC50分别为(40.2±9.9)μg·L^(-1)、(15.6±2.7)μg·L^(-1)和(10.7±1.9)μg·L^(-1);28℃下,大型溞21 d存活率分别比对照(20℃,0μg·L^(-1)镉暴露)降低23%(20μg·L^(-1)镉暴露)和87%(40μg·L^(-1)镉暴露)并且大型溞的21 d累积繁殖数(21-d CR)显著降低。大型溞的能量储存随适应温度的升高而降低,24℃和28℃时分别降低了46%和62%(0μg·L^(-1)镉暴露),48%和60%(20μg·L^(-1)镉暴露)、80%和91%(40μg·L^(-1)镉暴露)。而镉浓度只有达到40μg·L^(-1)时,对大型溞的能量储存有明显影响。适应温度和镉暴露对电子转移系统活性(ETS)没有显著影响。28℃的适应温度和40μg·L^(-1)的镉暴露都能诱导大型溞热应激蛋白hsp70和金属硫蛋白(MT)显著上升,但适应温度(20℃~28℃)和镉暴露(0~40μg·L^(-1))的结合对hsp70先诱导后抑制,MT则一直被诱导上升。总之,生物在不同温度下对毒物的反应存在差异,将不同适应温度下的毒性数据整合到生态危险性评价能够保证生物获得更充分的保护;此外,hsp70和MT的变化是环境压力的综合反应,作为某种污染物的生物标志物时需要综合考虑环境因素。
