UBC Theses and Dissertations
The effects of slashburning on soil mineralizable nitrogen on two sites in the lower Fraser Valley Douglas, Mary-Jane
The effect of slashburning on soil mineralizable nitrogen, expressed both as a concentration (MN) and on a kg ha⁻¹ basis (MNKG), was determined for a hardwood site and a conifer site in the lower Fraser Valley of British Columbia. Burning appeared to reduce both MN and MNKG in the forest floor of the hardwood site; however, the relative proportion of MN to total nitrogen (TN) lost varied between the two plots on this site. This result was attributed to a difference in burning intensity at the two locations. Results were also similar for the mineral soil, but differences were not as distinct. The site was resampled in the second year and differences between treatments were much larger. In the forest floor of the conifer site, the immediate effect of burning was to increase MN but decrease MNKG. MN decreased by the end of the first month after burning, during which a substantial amount of rain fell. In the mineral soil, differences between the two sampling periods were not so distinct. Total nitrogen (TN), organic carbon (OC), and the pH measured in both water (pHH) and in CaCl₂ (pHC) were also measured to determine if any linear relationship existed between these soil variables and mineralizable nitrogen. TN showed a consistent significant linear correlation with MN, while the other soil variables did not. The decrease in MN on these two sites following burning has significant implications for regenerating these sites.
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