Browsing by Subject "Forest soils"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item The Effects of Biochar, Weed Control, and Irrigation on the Growth and Survival of Jack Pine Seedlings and Native Plant Communities in Northern Minnesota, USA(2019-05) Kelso, SaraClimate change is predicted to result in more frequent and more severe droughts in the northern Midwest region of the United States. This has and will continue to impact forests of the region, especially in regards to establishing regeneration during periods of drought stress. This is leading researchers and land managers to explore adaptive silviculture strategies to promote resilience in their forests. One option hypothesized to improve regeneration success in forest systems is the application of biochar to the soil to increase seedling resistance and resilience to drought conditions Biochar is a bio-based soil amendment created through pyrolysis that has been used for centuries in tropical environments to increase productivity. Since then, biochar has been widely used in agriculture, as it has proven to be effective in increasing nutrient cycling, cation exchange capacity, and water holding capacity of the soil. Additionally, biochar has recalcitrant properties, meaning that it is very slow to degrade and thus is a viable option for sequestering carbon in the soil as a way of off-setting atmospheric emissions. However, there are very few field studies exploring the potential of biochar use in forestry in the Lake States (Minnesota, Wisconsin, and Michigan), USA. Chapter 1 aims to examine the effect that biochar and/or compost has on the growth and survival of jack pine (Pinus banksiana Lamb.) seedlings in northern Minnesota through a series of field experiments. This was done by conducting three field based experiments: 1) quantifying the influence of soil amendment and weed control treatments on survival and growth of jack pine seedlings; 2) quantifying the influence of soil amendments and irrigation when competition was controlled on survival and growth of jack pine seedlings; 3) quantifying the differences in planting stock – bareroot and containerized jack pine seedlings – and soil amendment in relation to jack pine survival and growth. Chapter 2 explores a topdress application treatment of biochar to a recently-harvested pine site. Biochar was spread at two different rates, with two different levels of torrefaction. This was done to learn more about what effects topdressing could have on native plant communities over time. These studies have the potential to help landowners make informed decisions about how to promote drought resilience in their forests, as well as provide a basis for long-term research projects looking into biochar use in the region’s forestry.Item Effects of throughfall reduction and snow removal on soil physical and biogeochemical properties in aspen forests of northern Minnesota, USA(2022-04) Stockstad, AnnaClimate change is projected to alter precipitation patterns across northern latitudes, with decreased snow accumulation and summer rainfall predicted. These changes may alter soil physical and biogeochemical properties, which would have implications for the operability and productivity of forest soils. Reductions in summer and winter precipitation were simulated using a paired-plot design with throughfall reduction and snow removal across four drainage classes at each of three locations in northern Minnesota, USA. Soil temperature and water content were measured every fifteen minutes to a depth of 60 cm, and soil frost depth (winter) and soil strength (summer) were monitored for two years. Soil respiration and extractable nitrogen were measured during two growing seasons, and a laboratory incubation was performed to test the response of carbon and nitrogen fluxes under controlled conditions. Soil temperature and water content increased from well-drained to poorly-drained soils during the winter and growing season, respectively. Snow removal caused large declines in soil temperature and significantly deeper penetration of frost that varied by drainage class, and there were strong relationships between frost depth and freezing degree days. Throughfall reduction had no effect on soil strength, soil respiration, or extractable nitrogen concentrations. Drainage class was a significant, although limited, indicator of soil strength, soil respiration, and extractable nitrogen concentrations. The laboratory incubation confirmed the lack of treatment effect on soil carbon and nitrogen fluxes, and instead showed that drainage class and soil moisture controlled these fluxes. These findings show that the dominant response of forest soils to reduced seasonal precipitation will occur during the winter with decreased soil temperatures and increased frost depth across drainage classes, which has implications for seasonal timber harvesting in northern latitudes under a changing climate.