Effects of scale and scaling in predictive modelling of forest site productivity

Wim Aertsen, Vincent Kint, Bart Muys, Jos Van Orshoven
2012 Environmental Modelling & Software  
29 Site productivity, commonly expressed by site index, is a key indicator of the potential of 30 forested land to deliver ecosystem services like wood production and carbon sequestration. It 31 is an important criterion for decision makers and managers of both production and multi-32 purpose forests. In many situations forest site index cannot be directly measured and must be 33 estimated from site characteristics related to climate, topography and soil, using appropriate 34 models. A major
more » ... ficulty herewith is that the models must capture the spatial and temporal 35 variability of the ecological processes, knowing that the magnitude and the variability of the 36 driving forces and responses may show scale dependencies. Scale is therefore an important 37 issue in successful forest site productivity modelling. 38 In this study, empirical forest site productivity models are evaluated for their scale 39 dependency whereby reference is made to the threefold concept of 'scale' (extent, support, 40 coverage) as proposed by Bierkens et al. (2000) . We also addressed the applicability of 41 models at other extents or other supports than the one they were developed at, i.e. the effect of 42 scaling'. The results show that meaningful site index models for small extents require higher 43 resolution support to catch the short-distance variability, whereas for larger extents a coarser 44 support is sufficient to characterize the variability. Where it regards scaling, it is found that 45 the validity of empirical site index models is restricted to the scale level for which they are 46 calibrated. Also the application of site index models on an extent which is adjacent and not 47 is adapted to the scale of the studied processes and predictions are restricted to the extent for 53 which the model is calibrated. 54 55
doi:10.1016/j.envsoft.2011.11.012 fatcat:unpj3gblk5hknlgzfqhynuqxlu