INSTRUMENT FOR INDIRECT MEASUREMENT OF CANOPY ARCHITECTURE
INSTRUMENT FOR INDIRECT MEASUREMENT OF CANOPY ARCHITECTURE
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DOI：
10.2134/agronj1991.00021962008300050009x
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发表时间：
1991-09-01
期刊：
影响因子：
2.1
通讯作者：
NORMAN, JM
中科院分区：
文献类型：
--
作者：
WELLES, JM;NORMAN, JM
叶面积指数（LAI）和叶角分布是植物冠层结构的常用指标，但难以直接测量。 本研究是为了测试一种商用仪器，用于快速确定叶面积指数和叶片倾角信息的“鱼眼”测量光截获。 将该仪器对叶面积指数的估计值与大豆[Glycine max（L.）Merr.]，冬小麦（Triticum aestivum L.），和草原草。 样地的优势草种为印度草[Sorghastrum nutans（L.）Nash]、柳枝稷（柳枝稷L.），和大蓝茎（Andropogon gerardii Vitman）。 该仪器的叶面积指数分辨率优于3%，叶面积指数误差一般小于15%。 天空亮度模式的变化引起的变化，在叶面积指数估计在冬小麦的不到10%，和太阳直接辐射的存在下增加叶面积指数的错误超过30%，在不同物种和叶面积指数的冠层。 在座舱盖中存在间隙的情况下，传感器的方位角视图应减小。 一个简单的测试表明，如果一个树冠的差距是显着的。
Leaf area index (LAI) and leaf angle distribution are widely used indices of vegetative canopy structure that are difficult to measure directly. This study was conducted to test a commercially available instrument for rapidly determining LAI and foliage inclination information from "fisheye" measurements of light interception. The instrument's estimates of LAI are compared with direct measurements in soybean [Glycine max (L.) Merr.], winter wheat (Triticum aestivum L.), and prairie grass. The dominant grass species in the plots were indian grass [Sorghastrum nutans (L.) Nash], switchgrass (Panicum virgatum L.), and big bluestem (Andropogon gerardii Vitman). The instrument's LAI resolution was better than 3%, and its LAI error was generally less than 15%. Variations in sky brightness patterns caused variations in LAI estimates in winter wheat of less than 10%, and the presence of direct solar radiation increased LAI errors to more than 30% in canopies of differing species and LAI. In the presence of gaps in the canopy, the sensor's azimuthal view should be reduced. A simple test indicates if a canopy's gaps are significant.