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

This data publication contains chemical results from soil samples collected in a study that was designed to determine how mechanical site preparation and prescribed fire treatments affected the understory vegetation, conifer establishment and growth, and soil physical and chemical properties of each forest. These data were collected in summer months over a five-year period (1989-1993) from 11 national forests located in Montana, Idaho, and Arizona. The treatments (listed by treatment code) applied to the sites included the following: 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. The data in this package focus on results of the chemical analysis of soil cores at each site. Every forest is different when it comes to soil types and nutrient contents in soil. Nutrient levels in the soil also vary from year to year; and treatments of burning, or removal of downed woody debris by mechanical means, can have a significant effect on the resulting soil chemistry and soil properties. Chemical analyses provide an index of nutrient availability or nutrient supply in a given soil at a given time; and the soil extract is designed to evaluate a portion of the nutrients from the same "pool" used by the plant. Chemical analysis can be used to predict the probability of obtaining a profitable response to fertilizer application or to the addition of extra nutrients. Chemical testing also allows managers to know which nutrients and chemicals are in sufficient supply for tree growth and restoration and which elements have been depleted because of disturbance or management activities. A proper soil test can help ensure the application of enough fertilizer to meet the requirements of growing trees while taking advantage of the nutrients already present in the soil. It is important for managers to follow certain recommended steps for soil sampling and testing to develop a fertility management program. In this study, chemical analyses were employed to determine the fertility of soils in the 11 national forests in Idaho, western Montana, and Arizona. These soils had all undergone different treatments to reduce biomass (see list above) and were subjected to major disturbance during the process. Samples were collected and analyzed for the proportion of carbon, hydrogen, and nitrogen remaining in the soil. They were also tested for the proportion of cations, including magnesium (Mg cmol+/Kg), calcium, and potassium. Data within this data publication include stand number, plot type, composite number (from combining like locations), and the soil horizon from which the sample was taken, in addition to the chemical results.
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 surface soil layer, which is rich in organic materials; 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 chemical analyses was to measure the nutrient capacity of these soils after the management treatments on several different forest types. When compared with local control plots, these results would provide a perspective on how removal of the organic materials during treatment affected nutrient availability for biological processes underground. It allowed researchers to make recommendations on how to best maintain nutrients for long-term forest soil productivity in the different forest types of these national forests.
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.