摘要
东北大兴安岭林草交错区对气候变化和人类活动高度敏感是我国重要的生态脆弱区,研究表征生态环境变化的植被指数时空变化及驱动因子是制定政策、改善生态环境的理论基础。基于此,利用遥感区域分析和地面实证分析对大兴安岭林草交错区的植被变化趋势及影响因子进行分析,并通过重要性指标定量阐述环境因子和人类活动因子影响的相对重要性。结果表明:1982—2015年的植被呈退化趋势(-0.02/10a),最低温度、平均温度和最高温度均呈增温趋势分别为0.13℃/10a、0.16℃/10a和0.20℃/10a,而年平均降水量呈下降趋势(-16.3 mm/10a)。植被NDVI随云量的增加而降低(R_(TMN)=-0.21),并且显著负相关占总面积的24.98%。NDVI随最低温度、平均温度和最高温度的增加而增加(R_(TMN)=0.01、R_(TMN)=0.02和R_(TMN)=0.04)。潜在蒸散对NDVI的影响存在差异,降水量在200—400 mm NDVI与潜在蒸散显著负相关(占总面积18.60%),400 mm以上显著正相关且占总面积16.01%。降水量与NDVI正相关(R_(TMN)=0.03),其中显著正相关占总面积的19.55%,显著负相关仅占总面积的5.31%。降水量是陈巴尔虎旗、新巴尔虎左旗以及鄂温克族自治区西部植被(草地)的主导影响因子,云分量是东部林地的主导影响因子。此外,实证分析结果表明人类活动因子(家畜密度和开垦面积)对NDVI的解释率高于温度和降水,并且人类活动的平均重要性指标(VIP=2.48)高于气候因子(VIP=0.80),气候因子中的降水解释率和重要性均高于温度。因此,气候变暖背景下,东北林草交错区气候呈变暖变干旱趋势,而人类活动因子对植被的影响作用不容忽视,合理调控农牧业是改善林草交错区植被生态系统稳定可持续的重要途径。
The forest-steppe transition ecozone in the Daxing′an Mountains of Northeast China is highly sensitive to climate change and human activities, and it′s an important ecologically fragile area of China. Studying the spatial-temporal changing and driving factors of vegetation index, which characterizes the ecological environment changing is the theoretical basis of policymaking and improving ecological environment. Therefore, we used regional analysis and empirical analysis to analyze the Normalized Difference Vegetation Index(NDVI) dynamic and influence factors, and used variable importance in projection index to quantitatively analyze the relative importance of environmental factors and human activity factors. The results showed that, the NDVI showed a degradation trend(-0.02/10 a) during 1982—2015, the minimum temperature, the mean temperature and the maximum temperature showed a warming trend of 0.13 ℃/10 a, 0.16 ℃/10 a and 0.20 ℃/10 a, respectively, while the annual average precipitation showed a downward trend with time(-16.3 mm/10 a). For the correlation between climate factors and the NDVI, the correlation between NDVI and the minimum temperature, the mean temperature and the maximum temperature was 0.01, 0.02 and 0.04, respectively. The impact of potential evapotranspiration on NDVI varies across regions, when precipitation within 200—400 mm potential evapotranspiration significantly negatively correlated with NDVI(the proportion was 18.60% of the study area), while precipitation above 400 mm potential evapotranspiration significantly positively correlated with NDVI for 16.01% of the study area. Precipitation positively correlated with the NDVI(R = 0.03), including 19.55% of significant positive correlation and 5.31% of significant negative correlation pixels. Precipitation was the dominant influencing factor of the NDVI in Chen Barag Banner, Xin Barag leaf Banner and Ewenki Autonomous Banner(where grass is the main vegetation). Cloud coverage was the dominant influencing factor of eastern woodland. In addition, the empirical analysis results showed that human activity factors(total cultivated area and livestock density) had higher explain rate than temperature and precipitation, and the average importance index of human activity(VIP_(human activity factor)= 2.48) was higher than that of climate factor(VIP_(human activity factor)= 0.80), besides the precipitation explaining rate and VIP value was higher than of temperature. Therefore, under the background of climate warming, the climate of forest-steppe transition ecozone in the Daxing′an Mountains is showing a trend of warming and aridity. The influence of human activities on vegetation dynamic cannot be ignored. Rationally regulated agriculture and livestock is an important way to improve the stability and sustainability of vegetation ecosystem in the forest-steppe ecotone.
作者
袁换欢
王智
徐网谷
游广永
张建亮
YUAN Huanhuan;WANG Zhi;XU Wanggu;YOU Guangyong;ZHANG Jianliang(Nanjing Institute of Environmental Sciences,Ministry of Ecology and Environment,Nanjing 210042,China)
出处
《生态学报》
CAS
CSCD
北大核心
2022年第18期7321-7335,共15页
Acta Ecologica Sinica
基金
国家重点研发计划-公众参与的自然保护地一体化监督平台研究(SQ2020YFF0426320)
生态环境部科研项目-自然保护区监督管理支撑(2110199201502)
生态环境部生物多样性调查、观测和评估项目
中央级公益性科研院所基本科研业务专项-植被物候时空变化及其驱动因子研究(GYZX210507)。
关键词
生态脆弱区
气候因子
人类活动因子
植被变化趋势
变量投影重要性
ecologically fragile region
climate factor
human activities
vegetation dynamic
variable importance in projection
