http://cfs.nrcan.gc.ca/authors/read/20613 Publications by C.-F. Zhang en-ca 2009-01-05 00:00:00 MST 2009-01-05 00:00:00 MST webmaster@nofc.cfs.nrcan.gc.ca http://cfs.nrcan.gc.ca/publications?id=29158 The performances of five carbon (C) and nitrogen (N) cycling models (FLDM, CENTURY, SOMM, DOCDOM and CANDY) were compared for their ability to quantify mass and N remaining in 10 g leaf-litterbags across the wide range of litter types and sites of the Canadian Intersite Decomposition Experiment (CIDET), over a 6-year period. These models differ in their structure and assumptions, number of compartments, predictor variables and coefficients. Calibrated model outputs displayed similar but not identical trends for mass and N remaining, but differed substantially in mass and N contents per model-defined compartments. The quality of fit between model calculations and data varied as follows: FLDM>CENTURY>DOCMOD>CANDY>SOMM for mass remaining (0.73 < r2 < 0.92), and FLDM>DOCMOD>CENTURY>SOMM>CANDY for the changing N concentrations inside the bags (0.40 < r2 < 0.80). FLDM calculations were the most consistent by CIDET site (21), litter type (10), and years of litterbag retrieval (1993–1998). Best-fitted models were used to project mass remaining and N concentrations inside the bags over the next 50 years, using mean July and January air temperatures, and annual precipitation and initial litter composition as independent predictor variables. Projected model outputs converged for mass remaining, but diverged for the N concentrations, i.e., (1±0.5) g and (2±1)% at year 50, respectively. Mon, 05 Jan 2009 http://cfs.nrcan.gc.ca/publications?id=29158 http://cfs.nrcan.gc.ca/publications?id=29127 Tue, 23 Dec 2008 http://cfs.nrcan.gc.ca/publications?id=29127 http://cfs.nrcan.gc.ca/publications?id=28984 Tue, 28 Oct 2008 http://cfs.nrcan.gc.ca/publications?id=28984 http://cfs.nrcan.gc.ca/publications?id=27515 A new Forest Litter Decomposition Model (FLDM) is presented to simulate mass, N and carbon/nitrogen ratios (C/N) according to the 1992-1998 leaf litterbag data of the Canadian Intersite Decomposition Experiment (CIDET). This experiment involved 10 litter types, with litterbags placed on the ground of 18 upland and 3 wetland sites across Canada. The calibrated model, based on first-order reaction kinetics, calculates total mass, N concentration and C/N for each litter type and location using: three compartments (fast, slow, and very slow); four parameters for compartment initialization; three for compartment-based decay; three to assess the climate influence on decay; and one each to determine the rate of N-mineralization and the final C/N ratio. With FLDM, the initial fast fraction is determined from the initial water-extractable and acid-hydrolyzable or acid-unhydrolyzable portions of the litter; the initial ash content determines the ratio between the slow and very slow fractions. Mean July and January air temperatures, and annual precipitation, determine the climate effect on litter decay. Initial N concentration and the upland-wetland difference determine the N-mineralization coefficient. Model performance was fairly consistent by litter type, location, and year: r2 ranged from 0.83 to 0.97, from 0.64 to 0.92 and from 0.54 to 0.93 for mass remaining, N concentration and C/N, respectively. Wed, 17 Oct 2007 http://cfs.nrcan.gc.ca/publications?id=27515 http://cfs.nrcan.gc.ca/publications?id=26955 Fri, 18 May 2007 http://cfs.nrcan.gc.ca/publications?id=26955