Effect of management activities on forest soil properties in the Rocky Mountains: II. Tree, stump, and downed woody debris data

Site preparation when applied (hand or mechanical methods) in the western United States often has two objectives: 1) modify the soil, litter, or surface vegetation to create microclimates that favor the establishment and growth of desired tree species and 2) to remove excess surface fuel to decrease the fire hazard. Between 1989 and 1992, data were collected from 11 national forests across the Rocky Mountains (Idaho, Montana, and Arizona) in moist and dry mixed-conifer and ponderosa pine forests. Depending on the forest, stands were treated with the following prescriptions over the five-year period (listed by treatment code): 1 = bole removed followed by broadcast burn, 2 = bole removed followed by dozer or grapple pile, 3 = control (undispersed), 4 = whole tree removal (only in 1990 Helena/Deerlodge Forest), and 9 = burned only. Not every treatment was used in each forest.

Each harvested stand was also paired with an adjacent untreated stand on a similar aspect, slope, and habitat type. For each stand in the study, the variable radius plots were used to collect characteristics on trees > 5 inches diameter at breast height (DBH) and to measure and tally stumps. The information gathered from the variable radius plot included tree species, diameter, and height. Brown’s transects (Brown 1971, 1974) were used to collect data on downed woody debris (dwd) and tree and stump density. The information gathered from the Brown’s transects included size and distribution of the sound and rotten wood currently laying on the ground and estimates of the total weights of sound and rotten wood. These data were intended to provide the general characteristics of live and dead wood for each stand after treatment.

The original intent of the study was to summarize the data to an individual stand so returning to each stand for additional sampling in subsequent years was not planned and plot locations were not permanently marked. However, written or diagrammed descriptions of the location of each sample site exist on the sample forms. These descriptions are included with these archived data in case there is a future need to return to the sample areas.The overall purpose of this study was to determine how management practices, such as burning, machine piling, scarifying, and scalping, change the character of the organic-rich surface soil layer; and how this change affects seed sprouting, seed-growth performance, and mycorrhizal development that maintain vegetation in these Rocky Mountain forests.

The specific purpose of the tree, stump, and downed woody debris study was to describe whether the growth of trees, and the amount of stumps or dead woody materials varied significantly on a site if it was dozer piled, prescribe burned, or in an unharvested area. Data collection for this portion of the study included measurements on tree and stump size and basal area for all tree species on the plot. It also included measurements in tons per acre of the downed woody debris (fine and coarse), and of the amount of sound and rotten woody debris laying on the ground.There are six separate data publications containing the data collected to examine the effect of management activities on forest soil properties in the Rocky Mountains: I. understory vegetation; II. tree, stump, and downed woody debris data (variable plots and transects); III. soil core data; IV. soil chemistry data; V. burn and soil surface conditions; and VI. microsite data.

Data were originally published on 08/04/2021. Minor metadata updates were made on 09/27/2021.

在美国西部实施场地准备（手工或机械方法）时，通常有两个目标：一是改良土壤、凋落物或地表植被，以创造有利于期望树种建立和生长的微气候；二是移除过量地表可燃物，以降低火灾风险。在1989年至1992年期间，从落基山脉（爱达荷州、蒙大拿州和亚利桑那州）的11个国家森林中收集了数据，这些数据来自湿润和干燥的针叶混交林和松林。根据森林的不同，在五年的期间内，林分被实施了以下处方（按治疗代码列出）：1 = 切除树干后进行广播燃烧，2 = 切除树干后使用推土机或抓斗堆放，3 = 对照（未分散），4 = 全树砍伐（仅在1990年海伦娜/迪尔洛奇森林），和9 = 仅燃烧。并非每个森林都使用了所有的治疗方法。

每个采伐林分都与一个相邻的未处理林分配对，这些林分在相似的方位、坡度和生境类型上。对于每个研究中的林分，使用了可变半径样地来收集直径大于5英寸胸高（DBH）的树木特征，并测量和统计树桩。从可变半径样地收集的信息包括树种、直径和高度。布朗样带（Brown 1971，1974）被用于收集关于倒木（dwd）和树木及树桩密度的数据。从布朗样带收集的信息包括目前躺在地面上完好的和腐烂的木材的大小和分布，以及完好的和腐烂的木材总重量的估计。这些数据旨在提供每个林分处理后活木和死木的一般特征。

研究的原始目的是将数据汇总到单个林分，因此计划在未来几年返回每个林分进行额外的采样，样地位置也没有永久标记。然而，样本表上存在关于每个样本地点的书面或图示描述。这些描述随存档数据一起提供，以防未来需要返回样本区域。本研究的总体目的是确定管理实践，如焚烧、机械堆放、翻耕和削皮，如何改变富含有机质的表层土壤层的特征；以及这种变化如何影响种子发芽、种子生长表现和菌根发育，这些菌根发育维持了这些落基山脉森林的植被。

树木、树桩和倒木的具体研究目的是描述树木的生长、树桩或死木的数量在推土机堆放、规定焚烧或未采伐区域中是否有显著差异。本部分研究的数据收集包括对样地中所有树种的树木和树桩大小以及基面积进行测量。还包括对每英亩倒木（细和粗）以及地面上完好的和腐烂的木材数量的吨数进行测量。共有六个独立的数据出版物包含用于检验管理活动对落基山脉森林土壤特性的影响的数据：I. 下层植被；II. 树木、树桩和倒木数据（可变样地和样带）；III. 土壤柱数据；IV. 土壤化学数据；V. 焚烧和土壤表面条件；以及VI. 微地点数据。

原始数据于2021年8月4日发布。于2021年9月27日进行了少量元数据更新。