Investigating the relationship between NDVI and LAI in semi-arid grassland in Inner Mongolia using in-situ measurements
Investigating the relationship between NDVI and LAI in semi-arid grassland in Inner Mongolia using in-situ measurements
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DOI：
10.1007/s00704-007-0369-2
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发表时间：
2009-01-01
影响因子：
3.4
通讯作者：
Bernhofer, Ch.
中科院分区：
文献类型：
--
作者：
Fan, L.;Gao, Y.;Bernhofer, Ch.
叶面积指数（LAI）是与植物生物量生产功能相关的关键变量。准确估算叶面积指数对于监测植被动态具有重要意义，而叶面积指数信息对于预测冠层内和冠层下的小气候和各种生物物理过程是必不可少的。传统的叶面积指数测定方法是直接的、破坏性的，费时费力。现代林隙分数技术可以快速、简便地评价叶面积指数，但在低矮植被上的应用存在问题。利用2005年和2006年生长季在内蒙古半干旱草原3个样点进行的植被指数（NDVI）和叶面积指数（LAI）的原位观测，研究了植被指数（LAI）和植被指数（NDVI）的变化规律。在此基础上，建立了一般线性关系和一般指数关系（LAI =-0.0897 +1.424 * NDVI，R = 0.79; LAI = 0.128 * exp（NDVI/0.311），R = 0.77），该关系可用于不同放牧强度的草地和植被覆盖度较高的地区（如湿地）。这些估算叶面积指数的方程适用于正常和干旱气候条件下该地区生长季植被的自然范围。通过简单地应用植被指数和这些关系，该地区的植被状况和牧草产量将快速，无损地估计，这是有益的畜牧业管理和土地可持续利用。
Leaf area index (LAI) is a key variable functionally related to plant biomass production. Accurate estimation of LAI is important for monitoring vegetation dynamics, and LAI information is essentially required for the prediction of microclimate and various biophysical processes within and below canopy. The traditional, direct and destructive method of measuring LAI is time-consuming. Modern gap fraction technique can assess LAI fast and easily, however its application is problematic with vegetations of low stature. Alternatively, NDVI (Normalized Difference Vegetation Index) as a widely used spectral reflectance index has been shown to be a good estimator of LAI and is used to estimate LAI indirectly.In situ measurements of NDVI and LAI at three sites in semi-arid grassland in Inner Mongolia, China were carried out during the growing season in 2005 and 2006. Based on these sites, a general linear and a general exponential relationship (LAI = -0.0897 + 1.424 * NDVI, R = 0.79; LAI = 0.128 * exp(NDVI/0.311), R = 0.77) were developed, which can be used for various grazing intensity grasslands and also for higher vegetation cover area (e.g. wetland) in the region. These equations for estimating LAI are suitable for the natural range of vegetation in this area during the growing season under both normal and dry weather conditions. By simply applying NDVI measurements and these relationships, the vegetation status and grass yield in the area will be rapidly and nondestructively estimated, which is helpful for livestock management and sustainable land use.