Long Term Effects Of Prescribed Fire On Nitrogen Availability In Ponderosa Pine Stands In Central Oregon

Download or read book Long-term Effects of Prescribed Fire on Nitrogen Availability in Ponderosa Pine Stands in Central Oregon written by Vicente J. Monleon-Moscardo and published by . This book was released on 1993 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of prescribed burning on the rates of recent litter decomposition, nitrogen and phosphorus release from litter, soil total and inorganic nitrogen pools, and net nitrogen mineralization were determined in ponderosa pine sites that had been burned 0.3, 5 or 12 years earlier. Prescribed burning decreased litter decomposition rates significantly (p>0.1), in the sites burned 0.3 and 12 years previously, although the differences in litter decomposition rates between burned and control plots were small. Nitrogen and P release from recent litter was significantly higher in the plots burned 5 years previously, but there were no significant differences in the plots burned 0.3 or 12 years earlier. Soil inorganic N concentration significantly increased shortly after prescribed burning, but declined thereafter to reach the levels of the control plots at the end of the next growing season. Both inorganic and total soil N pools in soil were significantly lower in the plots burned 5 years previously, and there were no differences in any of the N pools measured for the sites burned 12 years earlier. Prescribed burning did not significantly affect annual net nitrogen mineralization 0.3 years after burning, but net N mineralization decreased significantly in the 5 and 12 year burned plots. The decrease in net nitrogen mineralization is probably caused by a decrease in substrate quantity 5 years after burning, and by changes in substrate quality 12 years after burning. A long-term decrease in net N mineralization in the N-poor ponderosa pine stands of Central Oregon may result in a decrease in long-term site productivity and may explain the observed pattern of long-term decrease in stand growth following prescribed burning.