LBA-ECO CD-17 Secondary Forest Survey, Para and Rondonia, Brazil: 2002-2003

This data set provides measurements for diameter at breast height (DBH), tree height, distance from tree stems to the furthest canopy element, and a species survey of secondary forests in Para and Rondonia, Brazil, from 2002-2003. The forest areas were defined as Type A and Type B stands. Measurements were made in the overstory, understory, and midstory of each stand.

Type A stands were sampled intensively, with the goal of providing high-fidelity spatial information about the 3-dimensional structure of the stand. These stands were 60 x 60-m (0.36-ha) areas divided into 10 x 10-m grids of uniform clearing and abandonment history and were identifiable from Landsat images. Type B stands were sampled extensively, with the goal of providing unbiased estimates of biomass, along with some information about the vertical structure of the stand and of spatial variability. These stands were polygons of uniform clearing and afforestation history based on multitemporal Landsat imagery, and varied in size and shape. The Landsat files provide classified land cover for each scene and can be used as a time series to evaluate land cover change over time. Each file is a geolocated land cover map based on 30-m Landsat data. NOTE: There were additional files which could not be archived due to file problems. Data Quality Statement: The Data Center has determined that this data set has missing or incomplete data, metadata, or other documentation resulting in diminished usability of this product.

Known Problems: Some unresolved issues remain where data values are inconsistent with the variable descriptions provided with the data set. The site identification and plot identification values are not consistently used in all three data files. The variables are not adequately described.

本数据集提供了2002-2003年巴西帕拉州（Para）与朗多尼亚州（Rondonia）次生林的多项测量数据，包括胸径（diameter at breast height, DBH）、树高、树干至最远冠层单元的距离，以及物种调查数据。该林区被划分为A型与B型林分，对每个林分的林上层、林下层和中层均开展了测量。
A型林分采用集约采样方案，旨在获取林分三维结构的高精度空间信息。此类林分面积为60×60米（0.36公顷），被划分为10×10米的网格单元，其清理与弃耕历史均一，可通过Landsat影像进行识别。
B型林分采用广泛采样方案，旨在提供无偏的生物量估计值，同时获取林分垂直结构与空间变异性的相关信息。此类林分为基于多时相Landsat影像确定的、清理与造林历史均一的多边形地块，大小与形状各异。Landsat文件提供了每个影像场景的分类土地覆盖数据，可作为时间序列用于评估土地覆盖随时间的变化情况。每个文件均为基于30米分辨率Landsat数据的地理定位土地覆盖图。
注：另有部分文件因文件问题无法完成归档。
数据质量声明：数据中心判定本数据集存在缺失或不完整的数据、元数据（metadata）或其他文档，导致本产品的可用性有所降低。
已知问题：仍存在若干未解决的问题，即数据值与数据集附带的变量描述不一致；所有三个数据文件中未统一使用样地标识与地块标识值；变量描述不够充分。