Download or read book Temporal and Spatial Changes in Soil Carbon and Nitrogen After Clearcutting and Burning of an Old-growth Douglas-fir Forest written by Joseph A. Antos and published by . This book was released on 2003 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: We used 135 permanent plots (4 m2) nested within 15 blocks (121 m2) to quantify changes in concentration and spatial variation of carbon (C) and nitrogen (N) in the mineral soil (0- to 10-cm depth) after logging and broadcast burning of an old-growth, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forest. Before harvest, surface soils averaged total C of 7.2 percent, total N of 0.19 percent, extractable NH4 +-N of 5.2 Âg/g, extractable NO3 --N of 0.19 Âg/g, and pH of 5.3. Samples collected 9 months after burning showed a 26-percent decline in concentration of total C, but a 5-percent increase in concentration of total N. Concentrations of extractable mineral N (NH4 +-N + NO3 --N) increased to five time initial levels but returned to preharvest levels 1 year later. The coefficient of variation in extractable mineral N more than doubled after burning. Two and 3 years after burning, extractable N showed a significant and increasingly strong negative relation with plant biomass suggesting that N concentration was measurably reduced by plant uptake. Most variation in soil C and N before harvest occurred at small spatial scales (within and among 2- by 2-m plots); logging and broadcast burning had little effect on this pattern.