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

Abstract

Climate 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.