Using VEGNET In-Situ Monitoring LiDAR (IML) to Capture Dynamics of Plant Area Index, Structure and Phenology in Aspen Parkland Forests in Alberta, Canada
Using VEGNET In-Situ Monitoring LiDAR (IML) to Capture Dynamics of Plant Area Index, Structure and Phenology in Aspen Parkland Forests in Alberta, Canada
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使用 VEGNET 原位监测激光雷达 (IML) 捕获加拿大艾伯塔省阿斯彭公园森林的植物面积指数、结构和物候动态
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发表时间：
2014
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通讯作者：
D. Culvenor
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作者：
Carlos Portillo;A. Sánchez;D. Culvenor
使用密度计和数字半球照片来估算植物面积指数(PAI)通常包括仪器定位、定向和数据分析带来的偏差和误差。作为这些方法的替代方法，我们使用了现场监测LiDAR系统，该系统基于优化的PAI提取原理和算法，以固定的角度提供PAI和植物面积体积密度(PAVD)的间接测量。该仪器从2013年9月26日至10月17日在杨树公园森林落叶期间连续安装了22个晚上。总共进行了85次扫描(每晚~4次)。落叶期间测得的PAI从1.27下降到0.67，这与文献报道的值一致。PAVD剖面可以区分每一森林层PAI的贡献。通过四种方式捕捉物候变化：命中次数、最大累积PAI值和绝对值、PAVD剖面的时间序列和每一森林层的PAI值。我们还发现，VEGNET、IML、冠层PAI和MODIS的LAI值呈现出相似的下降趋势，相差2%-15%。我们的结果表明，VEGNET IML在森林结构的快速表征和在与地球观测卫星兼容的时间频率下对PAI/LAI进行地面验证方面具有巨大的潜力。
The use of ceptometers and digital hemispherical photographs to estimate Plant Area Index (PAI) often include biases and errors from instrument positioning, orientation and data analysis. As an alternative to these methods, we used an In-Situ Monitoring LiDAR system that provides indirect measures of PAI and Plant Area Volume Density (PAVD) at a fixed angle, based on optimized principles and algorithms for PAI retrieval. The instrument was installed for 22 nights continuously from September 26 to October 17, 2013 during leaf-fall in an Aspen Parkland Forest. A total of 85 scans were performed (~4 scans per night). PAI measured decreased from 1.27 to 0.67 during leaf-fall, which is consistent with values reported in the literature. PAVD profiles allowed differentiating the contribution of PAI per forest strata. Phenological changes were captured in four ways: number of hits, maximum cumulative and absolute PAI values, time series of PAVD profiles and PAI values per forest strata. We also found that VEGNET IML Canopy PAI and MODIS LAI values showed a similar decreasing trend and differed by 2%–15%. Our results indicate that the VEGNET IML has great potential for rapid forest structural characterization and for ground validation of PAI/LAI at a temporal frequency compatible with earth observation satellites.