Lidar‐derived estimate and uncertainty of carbon sink in successional phases of woody encroachment
Lidar‐derived estimate and uncertainty of carbon sink in successional phases of woody encroachment
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木质侵占连续阶段碳汇的激光雷达估算和不确定性
DOI：
10.1002/jgrg.20088
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
E. Strand
中科院分区：
文献类型：
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作者：
T. Sankey;R. Shrestha;J. Sankey;S. Hardegree;E. Strand
林木侵蚀是一种全球性的现象，它对全球碳汇有贡献。这一贡献的大小需要在区域和地方尺度上进行估计，以解决全球和大陆尺度估计中存在的不确定性，并指导区域政策和管理平衡恢复活动，包括移除木本植物和温室气体减排目标。本研究的目的是估计碳储存在不同的演替阶段的木本入侵。使用激光雷达测量的个别树木，我们提出了高分辨率的估计，在杜松林地地上碳储量。激光雷达点云数据的分割分析确定了四个流域的60，628个杜松树冠。来自激光雷达的树高、树冠覆盖率和密度与85个地块（30 × 30 m）中测量的2613根杜松茎的实地测量结果密切相关。使用回归模型估计单株树木的林地总生物量，其中激光雷达导出的高度和树冠面积作为预测因子（R2 = 0.76，p < 0.001，RMSE = 0.58 kg）。预测的平均地上木质碳储量的研究领域是677克/平方米。碳储量估计的不确定性进行了审查与蒙特卡洛方法，解决主要的误差来源。用不确定性分析预测的平均值、单株树、地上木质碳和相关标准差的范围分别为0.35 - 143.6 kg和0.5 - 1.25 kg。后来的演替阶段的木本入侵，平均而言，两倍的地上碳相对于早期阶段。通过在侵入的早期阶段确定强化处理最有效的优先领域，可以更成功地管理和平衡林地侵蚀与碳储存目标。
Woody encroachment is a globally occurring phenomenon that contributes to the global carbon sink. The magnitude of this contribution needs to be estimated at regional and local scales to address uncertainties present in the global‐ and continental‐scale estimates, and guide regional policy and management in balancing restoration activities, including removal of woody plants, with greenhouse gas mitigation goals. The objective of this study was to estimate carbon stored in various successional phases of woody encroachment. Using lidar measurements of individual trees, we present high‐resolution estimates of aboveground carbon storage in juniper woodlands. Segmentation analysis of lidar point cloud data identified a total of 60,628 juniper tree crowns across four watersheds. Tree heights, canopy cover, and density derived from lidar were strongly correlated with field measurements of 2613 juniper stems measured in 85 plots (30 × 30 m). Aboveground total biomass of individual trees was estimated using a regression model with lidar‐derived height and crown area as predictors (Adj. R2 = 0.76, p < 0.001, RMSE = 0.58 kg). The predicted mean aboveground woody carbon storage for the study area was 677 g/m2. Uncertainty in carbon storage estimates was examined with a Monte Carlo approach that addressed major error sources. Ranges predicted with uncertainty analysis in the mean, individual tree, aboveground woody C, and associated standard deviation were 0.35 – 143.6 kg and 0.5 – 1.25 kg, respectively. Later successional phases of woody encroachment had, on average, twice the aboveground carbon relative to earlier phases. Woody encroachment might be more successfully managed and balanced with carbon storage goals by identifying priority areas in earlier phases of encroachment where intensive treatments are most effective.