In order to test the accuracy of the usually-used fixed calibration factor of the canopy scanner of LAI-2000 for measuring the leaf area index (LAI), a Larix principis-rupprechtii plantation was chosen in the small watershed of Xiangshuihe located at the Liupan Mountains of Ningxia Hui Autonomous Region of NW China, the LAI was measured in October 2010, a period from full canopy to the total fall of needles, by using both the LAI-2000 and litter-fall collection method. Then, a comparison was made between the LAI values determined by the litter-fall collection and that calculated based on the figures read from LAI-2000 and the fixed calibration factor (1.49). It showed that the average of LAI measurements of the 2 methods was very close, with a difference of only 5%. However, the calculated LAI from LAI-2000 was obviously higher than the true values determined by litter-fall collection when the canopy was full of needles; and obviously lower than the true value when the canopy was sparse after needle falling. The reason may be that LAI-2000 takes the projection of twigs as needles. So, a dynamic calibration factor is needed, especially in the seasons when the needle amount and the percentage of twigs projection in crown projection change quickly. Therefore, a statistic relation in a quadratic polynomial form between the 2 series of LAI data was well fitted. This relation can be used for a more accurate estimation of LAI based on the data read from the easily-used canopy scanners like LAI-2000.

2009年,在宁夏六盘山南部林区香水河小流域,调查研究了主要森林类型的生物量及其层次和器官分配。结果表明:不同森林的活体植被总生物量(t·hm-2)差别较大,依次为华山松(102.70)>桦木林(84.42)>山杨林(79.97)>华北落叶松人工林(58.37)>疏林(44.91),按各类森林面积加权平均为78.37,远高于灌丛(20.77)、草地(1.07)和草甸(2.29)。各类森林的枯落物现存量(t·hm-2)为:华北落叶松人工林(18.21)>华山松林(11.99)>桦木林(10.90)>山杨林(7.67)>疏林(7.06),也都远高于灌木林(3.13)、草甸(0.82)和草地(0.49)。森林生物量集中在乔木层(占91.04%),灌木层仅占8.09%,草本层更低至0.87%。森林生物量的器官分配比例:乔木层为树干(54.06%)>枝(21.04%)>根(16.92%)>皮(5.34%)>叶(2.65%);灌木层为枝干(62.68%)>根(30.55%)>叶(6.77%);草本层为地上茎叶(58.82%)>根(41.18%)。乔木层地上与地下生物量比值的平均值为4.49,几种阔叶林都在4.0左右,但华北落叶松林为6.41,华山松林为5.80,都远大于灌木林的2.82、草地的1.89及草甸的1.20。不同林分的生物量均随林龄和林冠郁闭度的增大而几乎线性增加,并随林分密度的增加而增大,但在密度超过900株·hm-2后生物量增速减缓并渐趋其最大值。