THE FOREST MODELING SERIES FORM-S - APPLICATIONS TO THE SOLLING SPRUCE SITE

The forest model series ForM-S currently includes four modules address ing (1) water fluxes (ForHyM), (2) soil temperature (ForSTeM), (3) ion fluxes (ForIoM), and (4) primary production and nutrient cycling in u pland forest stands (ForSVA). The modules require climate records (air temperature, precipitation volume), total atmospheric ion deposition and descriptive site information as input. The models are designed to capture the dynamics of the simulated processes at monthly (ForHyM, Fo rSTeM, ForIoM) and annual scales (ForSVA). ForHyM and ForSTeM have bee n verified across diverse sites in North America. For the Selling data set, ForHyM closely reproduced hydrologic data (monthly throughfall, f orest-floor percolate, soil percolate) without further calibration. Wi th ForSTeM and ForHyM, snowpack water, soil temperatures, and frost pe netration were simulated. ForIoM simulations compared favourably with the concentration and flux data for individual ion species (H+, K+, Na +, NH4+, Cl-, NO3-, Ca2+, Mg2+, SO42-, Al-x+) in throughfall, forest-f loor percolate and soil percolate after calibrating one or two paramet ers for the forest canopy, the forest floor, the mineral soil. Nutrien t losses, nutrient uptake rates, base cation replenishment rates withi n the soil, and biomass production and accumulation for the main stand compartments (foliage, wood, fine roots, forest floor) were simulated with ForSVA. The resulting calculations about cumulative soil leachin g losses for Ca, Mg, K, NH4-N, NO3-N, and SO4-S were in good agreement with observations.