Sensitivity of a carbon and productivity model to climatic, water, terrain, and biophysical parameters in a Rocky Mountain watershed

Net primary productivity (NPP) is a key component of the terrestrial carbon cycle and is important in ecological, watershed, and forest management studies, and more broadly in global climate change research. Determining the relative importance and magnitude of uncertainty of NPP model inputs is important for proper carbon reporting over larger areas and time periods. This paper presents a systematic evaluation of the boreal ecosystem productivity simulator (BEPS) model in mountainous terrain using an established montane forest test site in Kananaskis, Alberta, in the Canadian Rocky Mountains. Model runs were based on forest (land cover, leaf area index (LAI), biomass) and climate–water inputs (solar radiation, temperature, precipitation, humidity, soil water holding capacity) derived from digital elevation model (DEM) derivatives, climate data, geographical information system (GIS) functions, and topographically corrected satellite imagery. Four sensitivity analyses were conducted as a controlled series of experiments involving (i) NPP individual parameter sensitivity for a full growing season, (ii) NPP independent variation tests (parameter µ ± 1σ), (iii) factorial analyses to assess more complex multiple-factor interactions, and (iv) topographic correction. The results, validated against field measurements, showed that modeled NPP was sensitive to most inputs measured in the study area, with LAI and forest type the most important forest input, and solar radiation the most important climate input. Soil available water holding capacity expressed as a function of wetness index was only significant in conjunction with precipitation when both parameters represented a moisture-deficit situation. NPP uncertainty resulting from topographic influence was equivalent to 140 kg C ha−1·year−1. This suggested that topographic correction of model inputs is important for accurate NPP estimation. The BEPS model, designed originally for flat boreal forests, was shown to be applicable in mountainous terrain given appropriate image terrain corrections using the SCS+C approach. Rocky Mountain carbon dynamics were simulated with average annual NPP of Kananaskis forests estimated at 4.01 t C ha−1·year−1 and compared favourably with the field plot estimate of 4.24 t C ha−1·year−1 for this area.

[1]  W. Kurz,et al.  Estimating net primary production of forests in the Canadian Prairie Provinces using an inventory-based carbon budget model , 2002 .

[2]  Derek R. Peddle,et al.  Spectral Mixture Analysis of Airborne Remote Sensing Imagery for Improved Prediction of Leaf Area Index in Mountainous Terrain, Kananaskis Alberta , 2000 .

[3]  J. Chen,et al.  A process-based boreal ecosystem productivity simulator using remote sensing inputs , 1997 .

[4]  R. Houghton.  Terrestrial carbon sinks--uncertain explanations. , 2002, Biologist.

[5]  Steven W. Running,et al.  Comparison of available soil water capacity estimated from topography and soil series information , 2005, Landscape Ecology.

[6]  M. G. Ryan,et al.  Growth and maintenance respiration rates of aspen, black spruce and jack pine stems at northern and southern BOREAS sites. , 1997, Tree physiology.

[7]  Ronald J. Hall,et al.  Ground and remote estimation of leaf area index in Rocky Mountain forest stands, Kananaskis, Alberta , 2003 .

[8]  F. Woodward,et al.  Dynamic responses of terrestrial ecosystem carbon cycling to global climate change , 1998, Nature.

[9]  Sylvain G. Leblanc,et al.  Physically based inversion modeling for unsupervised cluster labeling, independent forest classification, and LAI estimation using MFM-5-Scale , 2007 .

[10]  F. Hall,et al.  Improved topographic correction of forest image data using a 3‐D canopy reflectance model in multiple forward mode , 2008 .

[11]  J. Liu,et al.  Mapping evapotranspiration based on remote sensing : An application to Canada ’ s landmass , 2003 .

[12]  S. Running,et al.  A general model of forest ecosystem processes for regional applications I. Hydrologic balance, canopy gas exchange and primary production processes , 1988 .

[13]  T. Singh.  Biomass equations for ten major tree species in the prairie provinces , 1982 .

[14]  E. Boyle,et al.  The global carbon cycle: a test of our knowledge of earth as a system. , 2000, Science.

[15]  Bunkei Matsushita,et al.  Estimation of regional net primary productivity (NPP) using a process-based ecosystem model: How important is the accuracy of climate data? , 2004 .

[16]  W. Schlesinger,et al.  Forest carbon balance under elevated CO2 , 2002, Oecologia.

[17]  Andrew D. Friend,et al.  A process-based, terrestrial biosphere model of ecosystem dynamics (Hybrid v3.0) , 1997 .

[18]  J. H. Archibald,et al.  Field Guide to Ecosites of Southwestern Alberta , 2002 .

[19]  J. Lassoie.  Humidity and Plants , 1979 .

[20]  L. Swift,et al.  Algorithm for solar radiation on mountain slopes , 1976 .

[21]  Karl Fred Huemmrich,et al.  Remote Sensing of Forest Biophysical Structure Using Mixture Decomposition and Geometric Reflectance Models , 1995 .

[22]  J. Régnière,et al.  Measured and predicted air temperatures at basin to regional scales in the southern Appalachian mountains , 1998 .

[23]  C. Daly,et al.  A Statistical-Topographic Model for Mapping Climatological Precipitation over Mountainous Terrain , 1994 .

[24]  Peter E. Thornton,et al.  Generating surfaces of daily meteorological variables over large regions of complex terrain , 1997 .

[25]  Paul R. Lowe,et al.  The Computation of Saturation Vapor Pressure , 1974 .

[26]  Craig A. Coburn,et al.  SCS+C: a modified Sun-canopy-sensor topographic correction in forested terrain , 2005, IEEE Transactions on Geoscience and Remote Sensing.

[27]  J. Chen,et al.  Net primary productivity distribution in the BOREAS region from a process model using satellite and surface data , 1999 .

[28]  John S. Kimball,et al.  Boreal forest CO2 exchange and evapotranspiration predicted by nine ecosystem process models: Intermodel comparisons and relationships to field measurements , 2001 .

[29]  Josef Cihlar,et al.  Net primary productivity mapped for Canada at 1-km resolution , 2002 .

[30]  P. Teillet,et al.  On the Slope-Aspect Correction of Multispectral Scanner Data , 1982 .

[31]  Werner A. Kurz,et al.  A 70-YEAR RETROSPECTIVE ANALYSIS OF CARBON FLUXES IN THE CANADIAN FOREST SECTOR , 1999 .

[32]  S. Running,et al.  Forest ecosystem processes at the watershed scale: incorporating hillslope hydrology , 1993 .

[33]  R. Houghton,et al.  Continental scale estimastes of the biotic carbon flux from land cover change: 1850 to 1980 , 1995 .

[34]  D. Peddle.  Spectral Mixture Analysis and Geometric-Optical Reflectance Modeling of Boreal Forest Biophysical Structure , 1999 .

[35]  Steven W. Running,et al.  Numerical Terradynamic Simulation Group 5-1994 Testing Forest-BGC Ecosystem Process Simulations Across a Climatic Gradient in Oregon , 2018 .

[36]  W. Ju,et al.  Effects of topography on simulated net primary productivity at landscape scale. , 2007, Journal of environmental management.

[37]  Jing M. Chen,et al.  Daily canopy photosynthesis model through temporal and spatial scaling for remote sensing applications , 1999 .

[38]  Lawrence E. Band,et al.  Effect of land surface representation on forest water and carbon budgets , 1993 .

[39]  Derek R. Peddle,et al.  A Comparison of Spectral Mixture Analysis and Ten Vegetation Indices for Estimating Boreal Forest Biophysical Information from Airborne Data , 2001 .

[40]  Ramakrishna R. Nemani,et al.  Extrapolation of synoptic meteorological data in mountainous terrain and its use for simulating forest evapotranspiration and photosynthesis , 1987 .

[41]  Peter E. Thornton,et al.  Parameterization and Sensitivity Analysis of the BIOME–BGC Terrestrial Ecosystem Model: Net Primary Production Controls , 2000 .

[42]  Jesse A. Logan,et al.  A model for diurnal variation in soil and air temperature , 1981 .

[43]  Josef Cihlar,et al.  Annual carbon balance of Canada's forests during 1895–1996 , 2000 .

[44]  D. Peddle,et al.  Incorporating topographic and climatic GIS data into satellite image analysis of an alpine tundra ecosystem, front range, Colorado rocky mountains , 1995 .

[45]  A. Gillespie,et al.  Topographic Normalization of Landsat TM Images of Forest Based on Subpixel Sun–Canopy–Sensor Geometry , 1998 .