UBC Theses and Dissertations
A remote-sensing based investigation on the impacts of canopy height differences on microclimate in a burned forest Smith-Tripp, Sarah
Forested canopies buffer seedlings from extreme climate conditions, but whether burned forests maintain this buffering capacity is not well understood. Previously, modeling the impact of a forest canopy on microclimate conditions was difficult because microclimate dynamics occur over fine-spatial scales. Inputs for microclimate modeling thus require high-resolution data. New technology like remotely piloted aircraft (RPAs) and low-cost microclimate sensors allow for a rapid expansion in microclimate modeling. My research capitalized on technological advancements to produce accurate and high spatial resolution descriptions of forest canopies to explain microclimate variation in a sub-boreal forest impacted by variable fire severity. To address a need for standardized microclimate modeling methods, I compare correlations of microclimate metrics to canopy height summarized at different scales of spatial buffers. Results demonstrate that the optimum scale for summarizing canopy height is dependent on the variable of interest – soil moisture is better explained by smaller buffers and temperature by moderately sized spatial buffers. I use these buffers to model the relationship between canopy height and microclimate. I found that growing season near-surface, surface, and soil temperatures increased linearly with decreasing canopy height and cover. Of near-ground temperatures, soil temperature showed the strongest correlation with canopy height, where a reduction of 10 m in canopy height was associated with a 1.5 °C increase in mean growing-season soil temperature. There was a weak negative relationship between canopy height and soil moisture, which I attribute to confounding effects of high evaporation in burned canopies and high transpiration in unburned canopies. My findings underline the importance of including canopy in post-disturbance microclimate models, as differences in soil temperature can impact the distribution of seedlings and other species.
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