【作者】 刘卫国；

【导师】 安尼瓦尔·阿木提；

【作者基本信息】 新疆大学 ， 自然地理学， 2007， 博士

【摘要】 本文以过程机理模型为主要研究手段对新疆陆地生态系统碳循环近20年来的时空格局变化及其对气候变化的响应进行了定量估算,旨在通过研究探索新疆陆地生态系统碳收支时空格局和演化规律及其对气候变化的响应机制。依据这一研究目的,我们建立了新疆气候和土壤数据库,并对机理型生态系统模型OLECM进行了相应改进,应用此数据库和模型,对1981～2000年间新疆陆地生态系统碳通量,包括净初级生产力(NPP)、土壤呼吸(HR),净生态系统生产力(NEP)等以及土壤和植被碳储量的时空分布格局进行了较为全面的定量估算,并利用以遥感数据为输入的GLO-PEM模型模拟得到的相同时段内NPP数值与OLECM的NPP结果进行了比较。本文同时对研究区内从上世纪50年代到21世纪初,这一时段内降雨和温度的时空分布格局进行较为深入细致的综合分析。通过研究,主要得到以下几方面的认识:1. 1981～2000年间,新疆陆地生态系统NPP总量波动于0.149～0.195Gt C/yr (1Gt=1015 g)之间,平均约为0.175 Gt C/yr,约占全国NPP总量的约4.87～5.4 %;20年间,NPP在波动中呈现明显的增长趋势(Trend = 0.00142 Gt C/yr2,P<0.01),且具有明显的年际和年代际变化,与20世纪80年代相比,20世纪90年代的NPP总量增加了0.014 Gt C/yr,但区域差异较大,增长趋势明显的地区主要集中在天山北坡一带和昆仑山系一带的部分地区,而在塔城盆地和额尔齐斯河与乌伦古河间地等地区NPP有减少的趋势;NPP时空变化因土地覆被类型的不同而有所差异,绝对增长量最大的是其它林地、林地和居民利用地,增长量分别为64.19 gC/m2、44.48 gC/m2和31.97 gC/m2;与20世纪80年代相比,有1类土地覆被类型在90年代的NPP出现减少,灌丛生态系统绝对增长量为-14.39 gC/m2。不同自然区的NPP时空格局亦有较大差异就空间格局来看,从新疆NPP 80年代到90年代的变化得到,全疆大部分地区NPP都呈增长状态,而NPP下降区分布在准噶尔盆地北部、古尔班通古特沙漠和昆仑山北麓山前平原东段,在10年中NPP呈现降低的状态,其分别降低为1.95 gC/m2、0.55 gC/m2和2.63 gC/m2,罗布洼地为降低最大的地区;伊犁谷地、天山北麓山前平原西段和喀什-莎车三角洲等区域在10年中NPP呈现较大的增长状态,其绝对增长量分别为23.46 gC/m2、38.29 gC/m2和41.58 gC/m2,从结果可得到天山北麓山前平原西段为北疆地区中增长最大的地区及喀什-莎车三角洲为南疆地区中增长最大的地区。2. 1981～2000年间的HR变化范围在0.147～0.211 Gt C/yr之间,平均值为0.173 Gt C/yr,增长趋势为0.013 Gt C/yr2,大大高于NPP的增长趋势,这也决定了研究时段内NEP是一个逐渐减少的趋势。从1981～2000年,年NEP总量变化于-36.4～25.7 Tg C/yr之间,平均约为1.7 Tg C/yr,单位平均值约为1.03 g C/m2/yr,由此可见,近20年,新疆陆地生态系统是一个弱碳汇,年碳吸收量较少,20年总碳吸收量约为33.9 Tg C,约占全国同期总碳吸收量的2.7～3.0%,其中土壤碳增加了13.5 Tg C,植被碳增加了20.4 Tg C;从新疆陆地碳汇和碳源的明显空间差异状况来看,在其20年时期,主要起弱碳汇的作用,尤其是90年代,其碳吸收量占1981～2000年总碳吸收量的70%左右,80年代后期到90年代中期碳吸收量显著增加,尤其是新疆北疆地区NEP从80年代的初期到90年代的末期,NEP一直处于碳汇区域,在90年代初期达到最高随后有较大降低,南疆地区NEP从80年代初期到90年代末期一直处于弱碳源。3.研究时段内,新疆陆地生态系统总的碳储量约为7.49 Gt C,其中植被储量波动于0.146～0.191 Gt C/yr之间,平均约为0.171 Gt C;土壤碳储量波动于6.86～8.06 Gt C/yr之间,平均约为7.32 Gt C。植被碳和土壤碳密度分别约为0.11 kg C/m2和4.5 kg C/m2。新疆土壤碳密度相对较低,一般低于5 kg C/ m2,但在新疆天山山脉等地区,土壤碳密度较高,一般在3～10 kg C/ m2之间;准噶尔盆地西南部等地区,其土壤植被碳可达10～15kg C/ m2左右;而南疆的喀什-莎车三角洲等地区土壤碳密度平均在7～10 kg C/m2;整个昆仑山山系土壤碳密度较小,最大仅有3.3 kg C/m2,最小0.18 kg C/m2,平均在1.2 kg C/m2左右,整个南疆地区土壤碳密度较北疆地区小。新疆陆地植被碳密度的空间分布同土壤碳密度一样具有西北高、东南低的特点,同时也出现塔城盆地地区和伊犁谷地地区的两个高值区,植被碳密度在0.4 kg C/m2左右。在北疆的阿尔泰山区西段等地区,其植被碳密度属于也属次高值区域,为0.3 kg C/m2以上;额尔齐斯河等地区植被碳密度属于一般值区域,在0.15～0.3kg C/m2之间;而北疆的其他地区植被碳密度属于低值区域,在0.07～0.15kg C/m2之间,伊吾-淖毛湖盆地为最小0.07kg C/m2;南疆的尤勒都斯盆地等地区,其植被碳密度属于高值区域,在0.2 kg C/m2以上;喀什-莎车三角洲等地区植被碳密度属于一般值区域,在0.15～0.2kg C/m2之间;而南疆的其他地区植被碳密度属于低值区域,在0.0～0.1kg C/m2之间,整个昆仑山山系最低接近0。4.在50年期间的年降雨量变化曲线整体上也是呈增长的态势,其增长直线为Y=0.4752X+83.771且增长率达到0.4752。新疆地区50年平均降雨量为96.13mm,在年变化曲线中可以得到从50年代末期到80末期降雨量基本在96.13mm水平,但从90年代初期年平均降雨量开始逐渐增多并持续到目前,从2000年到目前年降雨量平均达到108.09mm,其增长量为11.86mm,在21世纪开始降雨量增加是比较快的。在同时间段年平均温度变化曲线整体上也是呈增长的态势,其增长直线为Y=0.02803X+7.2487且增长率达到0.028。新疆地区50年平均温度为7.98℃,在年变化曲线中可以得到从50年代末期到80末期温度基本维持在7.70℃水平,低于50年平均温度,但从90年代初期年平均温度开始逐渐增多并持续到目前,从2000年到目前年温度平均高达8.84℃,其增长量为1.14℃,在21世纪初平均温度增加是比较快的。更多还原

【Abstract】 This study aimed to explore tempo-spatial patterns of XinJiang’s terrestrial carbon budgets and the mechanism of its responses to climate variability and change in past 20 years. For the research purposes, regional climate and soil database have been set up, and the OLECM, which is a process-based biogeochemical model, has been improved and applied. With supports of database and OLECM model, carbon fluxes, such as net primary production (NPP), soil heterotrophic respiration (HR) and net ecosystem production (NEP) from 1981 to 2000 have been quantified. The tempo-spatial pattern of carbon stocks in soils and vegetation has also been described. The paper carried on comprehensive analysising of the thorough delicacy to the spatial pattern of the precipitation and temperature at this period, from 50’s in last century to the beginning of 20 centuries, in the studying area.The estimated results have suggested that:1. During 1981 to 2000, the estimated total terrestrial NPP in XinJiang varied between 0.149 Gt C and 0.195 Gt C, with a mean value of 0.175 Gt C (1 Gt = 1015 g), behaving obvious increasing trend (Trend=0.00142 Gt C/yr2, P<0.001). Comparing to 1980s, the mean annual total NPP in 1990s increased 0.014 Gt C. However, the changes were quite different for regions. Inter-decadal increases were found in TianShang Northen Region, KunLun Mountain and so on.Decreases mainly occurred in the TaCheng Region, ErQiSi River and WuLunGuHe River. For different landcover types, the biggest absolute growth quantity is other woodland, woodland and residentses, which to distinguish for the 64.19 gC/m2, 44.48 gC/m2 and 31.97 gC/m2, comparing to 1980s, decrease was only found in Shrub-land ecosystem is -14.39 gC/m2.Most parts of XinJiang had an inter-decadal increases in total NPP, expect the Northern ZhunGeer basin, the GuerBanTong desert and the Eastern plain of North KunLun Mountain, with a inter-decadal decreases of 1.91 gC/m2, 0.55 gC/m2 and 2.63 gC/m2 and the most of decrease is LuoBuWa region. Yi Lihe Valley, the Western of plain of Northern TianShang Mountain and KaShi-SaChe Delta had a inter-decadal increases in total NPP of 23.46 gC/m2, 38.29 gC/m2 and 41.58 gC/m2, from the result may be found the Western of plain of Northern TianShang Mountain is the most increase of Northern XinJiang and KaShi-SaChe Delta is the another region of Southern XinJiang.2. In the study period, HR fluctuated between 0.147 and 0.211 Gt C/yr, with an average of 0.173 Gt C/yr, increasing at 0.013 Gt C/yr2 (P<0.01). The increasing trend of HR was much higher than that of NPP, which resulted in the decreasing of NEP. In the past 20 years, the estimated total NEP changed between -36.4 to 25.7 Tg C/yr(1 Tg = 1012 g), equivalent of magnitude is 1.036 g C/m2/yr. The mean annual NEP was 1.7Tg C/yr, indicating that XinJiang’s terrestrial ecosystems took up 33.9 Tg C carbon under the climate variations and atmospheric CO2 increases, which accounted for 2.7～3.0% of the China’s total. On the region scale, most parts of XinJiang was carbon balanced, however, the significant difference of carbon sink and releases occurred in the different region of XinJiang from the past 20 years, the Land Ecosystem of XinJiang is weak carbon sink in the period, particularly in 90s , its carbon absorbs was 70% of the total quantity of sink from 1981 to 2000, from the later of 80s to the middle of 90s the absorb was began to grown clearly, the most growth was in the Northern of XinJiang last now. Meantime in the Southern of XinJiang is a weak sink status of CO2 absorb.3. In the past 20 years, the total terrestrial carbon stocks in XinJiang was about 7.49 Gt C, of which the stocks in vegetation varied in the range of 0.146～0.191 Gt C/yr with an average of 0.171 Gt C, and stocks in soils changed from 6.86 Gt C to 8.06 Gt C, with an average of 7.32 Gt C. The vegetations and soils carbon density was 0.11 kg/m2 and 4.5 kg/m2 respectively. The higher soil carbon density occurred in Southern of Zhun Geer basin and Yi Lihe valley, where soils carbon density is higher than 10～15 kg C/ m2 even higher than 30 kg C/m2,the parts of NanJiang of XinJiang of the highest soil carbon is such as KaShi-SaChe Delta with a value 7～10 kg C/ m2, the whole Kun Lunshang mountain is the smallest place with the mean value 1.2 kg C/ m2 and the highest is only 3.3 kg C/ m2, the smallest is 0.18 kg C/ m2.Nationally, the soils carbon density increased from southeast of XinJiang to northwest. The spatial distribution of vegetation carbon density also showed the decreasing trend from northwest to southeast and has two higher values regions locating at northwest where are the Ta Cheng basin and the Yi Lihe valley with a value 0.4 kg C/ m2. Nationally, lawns played a major role in terrestrial ecosystem carbon budgets. The smaller vegetation carbon density occurred in Southern of XinJiang with the mean value 0.0～0.1kg C/ m2and the whole Kun Lunshang mountain is the smallest place with near to 0 kg C/m2.4.The year rainfall variety curve that is a rising trend during the period of 50 years, its growning straight line as Y=0.4752 X+83.771 with a growth rate R 0.4752.The average rainfall of 50 years of Xinjiang is a 96.13 mm, can get in year change curve from the later of the 50’s to the later of 80’s the same level of ainfalls of the 96.13mm, but from the initial of 90’s, the year average rainfall start increasing and keeping on gradually currently, but attain the mean level with 108.09 mm equally currently from 2000, its growning quantity got to the 11.86 mms, the rainfall is starting to risign quickly in 21 centuries.The year mean temperature variety curve that is a rising trend during the period of 50 years, its growning straight line as Y=0.02803 X+7.2487 with a growth rate R 0.028.The average temperature of 50 years of Xinjiang is a 7.98℃, can get in year change curve from the later of the 50’s to the later of 80’s the same level of temperature of the 7.70℃, but from the initial of 90’s, the year average temperature start increasing and keeping on gradually currently, but attain the mean level with 8.84℃equally currently from 2000, its growning quantity attained to the 1.14℃, the mean temperature is starting to risign quickly in 21 centuries.更多还原