Estimation of biophysical characteristics for highly variable mixed-conifer stands using small-footprint lidar
Estimation of biophysical characteristics for highly variable mixed-conifer stands using small-footprint lidar
复制标题
DOI：
10.1139/x06-007
复制
发表时间：
2006-05-01
期刊：
影响因子：
--
通讯作者：
DeGroot, J
中科院分区：
文献类型：
--
作者：
Jensen, JLR;Humes, KS;DeGroot, J
尽管激光雷达数据广泛可从商业承包商获得，但北美的业务使用仍然受到成本和大规模应用的不确定性以及相关模型精度问题的限制。我们分析了从不同物种和结构组成、营林做法和地形的五个不连续地理区域获得的小足迹激光雷达数据是否可以用于单一回归模型，以产生对美国爱达荷州北部内兹佩斯保护区常见森林调查属性的准确估计。在最佳子集多元线性回归过程中，激光雷达得到的高度指标被用作预测变量，以确定是否可以准确地估计一组林分库存变量。利用训练数据和独立子集验证的可接受模型，建立了激光雷达获取的高度度量和现场测量因变量之间的经验关系。然后用所有数据对模型进行拟合，得到最大冠层高度(0.91，3.03 m)、平均冠层高度(0.79，2.64 m)、二次平均胸径(0.61，6.31 cm)、总断面积(0.91，2.99 m(2)/ha)、椭圆形郁闭度(0.80，0.08%)、总材积(0.93，24.65 m(3)/ha)和大锯材(0.75，0.75)等7个生物物理特性的决定系数和均方根误差。28.76米(3)/公顷)。虽然这些回归模型不能在没有额外测试的情况下推广到其他地点，但本研究的结果表明，对于这些类型的针叶混交林，对于结构特征和地形变化很大的林分，使用单一回归模型可以充分估计一些生物物理特性。
Although lidar data are widely available from commercial contractors, operational use in North America is still limited by both cost and the uncertainty of large-scale application and associated model accuracy issues. We analyzed whether small-footprint lidar data obtained from five noncontiguous geographic areas with varying species and structural composition, silvicultural practices, and topography could be used in a single regression model to produce accurate estimates of commonly obtained forest inventory attributes on the Nez Perce Reservation in northern Idaho, USA. Lidar-derived height metrics were used as predictor variables in a best-subset multiple linear regression procedure to determine whether a suite of stand inventory variables could be accurately estimated. Empirical relationships between lidar-derived height metrics and field-measured dependent variables were developed with training data and acceptable models validated with an independent subset. Models were then fit with all data, resulting in coefficients of determination and root mean square errors (respectively) for seven biophysical characteristics, including maximum canopy height (0.91, 3.03 m), mean canopy height (0.79, 2.64 m), quadratic mean DBH (0.61, 6.31 cm), total basal area (0.91, 2.99 m(2)/ha), ellipsoidal crown closure (0.80, 0.08%), total wood volume (0.93, 24.65 m(3)/ha), and large saw-wood volume (0.75, 28.76 m(3)/ha). Although these regression models cannot be generalized to other sites without additional testing, the results obtained in this study suggest that for these types of mixed-conifer forests, some biophysical characteristics can be adequately estimated using a single regression model over stands with highly variable structural characteristics and topography.