内蒙古草原叶面积指数时空格局与水热影响

The Spatiotemporal Pattern of Leaf Area Index and The Influence of Water and Heat in Inner Mongolia Grassland

叶面积指数(Leaf Area Index,LAI)是表征植被状况的重要参数,与植被的生长和变化状况密切相关。探究内蒙古草原LAI长时间序列时空格局特征及水热条件对LAI的影响,可为准确掌握内蒙古草原分布与生长状况差异提供数据支撑,对了解内蒙古草原生产能力的空间分布特征具有参考价值。基于2000~2019年GEOV2 LAI产品数据集,结合气温和降水资料,选取变化斜率、变异系数和相关性系数3个指标对内蒙古草原LAI展开分析。结果显示,内蒙古草原LAI由东北向西南递减,多年均值为1.34 m^(2)/m^(2),在不同草原类型中,荒漠草原(0.28 m^(2)/m^(2))<典型草原(0.96 m^(2)/m^(2))<草甸草原(2.27 m^(2)/m^(2))<草甸(2.60 m^(2)/m^(2)),且与变异系数呈反比,荒漠草原年际间波动最剧烈。近20 a内蒙古草原LAI呈波动中上升趋势(0.02 m^(2)/m^(2)/a),67.08%区域草原LAI与年降水显著相关,仅4.98%区域草原LAI与年均温显著相关。表明内蒙古草原LAI空间分布具有地带性特征,不同草原类型LAI之间存在明显差异,降水是内蒙古草原LAI的主要影响因素。

Leaf area index(LAI)is an important parameter to characterize the vegetation condition,which is closely related to the growth and change of vegetation.The investigation of the spatiotemporal pattern of LAI in Inner Mongolia grassland over a long time series and the influence of water and heat conditions on LAI can provide data to support an accurate understanding of the differences in the distribution and growth conditions of Inner Mongolia grassland,meanwhile,it is helpful for understanding the spatial distribution characteristics of the production capacity of Inner Mongolia grassland.Based on the GEOV2 LAI product dataset from 2000 to 2019,three indicators,namely slope of variation,coefficient of variation and correlation coefficient,were selected to analyse the grassland LAI in Inner Mongolia in combination with the data of temperature and precipitation.The results show that the LAI of Inner Mongolia grassland decreases from northeast to southwest with a multi-year mean value of 1.34 m^(2)/m^(2),and among different grassland types,desert grassland(0.28 m^(2)/m^(2))<typical grassland(0.96 m^(2)/m^(2))<meadow grassland(2.27 m^(2)/m^(2))<meadow(2.60 m^(2)/m^(2)),and is inversely proportional to the coefficient of variation,with desert grassland showing the sharpest inter-annual fluctuations.Over the past20 years,the LAI of Inner Mongolia grassland showed an increasing trend in fluctuation(0.02 m^(2)/m^(2)/a),67.08%of regional grassland LAI was significantly correlated with annual precipitation,and only 4.98%of regional grassland LAI was significantly correlated with annual mean temperature.These indicate that the spatial distribution of grassland LAI in Inner Mongolia has zonal characteristics,and there are significant differences between different grassland types,and precipitation is the main influencing factor of grassland LAI in Inner Mongolia.