Effect of management activities on forest soil properties in the Rocky Mountains: III. Soil core data

As the demand for forest products and the ability to utilize more fiber increases, less material is being left on the forest floor after harvesting and salvage operations. These operations, in combination with past practices of slash disposal and site preparation, have effectively reduced organic material in and on the forest floor, making coarse woody debris (CWD) management critical (Harvey et al. 1987). CWD is such an important component of a functioning ecosystem that a portion of this material must be maintained after fuels are removed to uphold forest productivity. 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 Airzona) in moist and dry mixed conifer and ponderosa pine forests to address the effects of soil modifications. Depending on the forest, the study sampled stands that were harvested and followed by either no site preparation, such as in the case of whole-tree harvest, prescribed fire, or dozer pile site preparation. Each harvested stand also was paired with an adjacent untreated stand on a similar aspect, slope, and habitat type. This data publication contains soil core data on the following soil horizons: litter, humus, buried wood residue, shallow mineral soil (0 to 10 centimeters (cm)) and deep mineral soil (> 10 cm up to 30 cm). Measurements taken for each data point included layer thickness, percent organic matter, number of mycorrhiza in each horizon (counted later in the laboratory), root weight, moisture content, pH, habitat type, and silvicultural treatment.
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 maintains vegetation in these Rocky Mountain forests. The specific purpose of the soil core samples taken in this portion of our study was to determine how management treatments affected physical and chemical soil properties in five distinct layers of the soil surface including litter, humus, buried wood residue, shallow mineral soil (0 to 10 centimeters (cm)) and deep mineral soil (> 10 cm up to 30 cm). These data, along with the soil chemistry, allowed for a more complete analysis of soil changes due to silvicultural treatment than soil chemistry alone. This study was designed, and the soil data from undisturbed sites was specifically used, to provide recommendations for how much CWD should be left in 14 specific habitat types where timber harvesting and prescribed burns were conducted. The objective was to provide managers with initial recommendations for how CWD should be managed to maintain long-term forest productivity in different forest types of the Rocky Mountains.
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 09/24/2021.