Simulation modelling of long-term stand dynamics at different scenarios of forest management for coniferous–broad-leaved forests

Abstract

The computer program package FORRUS-S (FORest of RUSsia—Stand) has been developed for simulation modelling of forest ecosystems dynamics. The program package FORRUS-S consists of the model of natural development of multispecies uneven-aged stand, the model of exogenous influence (including sylvicultural activities) and a set of accessory programs (standard GIS, reference databases, modules recoding input and output information, etc.). The available to date set of reference databases allows forecasting of stand dynamics in the zone of mixed coniferous–broad-leaved forests in European Russia. Since within this zone photosynthetic active radiation (PAR) is the main limiting factor, it is recalculated at each step while other factors as soil richness and humidity are considered constant throughout the modelling cycle. Modelling is performed for each cohort separately, i.e. a group of individuals of same species and ontogenetic state. Each cohort is described by a set of biological parameters stored in specially compiled reference databases (biometrics of tree crown, demand for light, gaps in the canopy, crown transparency to light, seed dispersal distance, sprouting ability, growth tables, potential stand quality index, etc.). Growth increment, thinning and natural regeneration are modelled with the step equal to 5 years. The model utilizes the principle of subdivision of the space into discrete three-dimensional elements. This approach makes it possible to consider the available PAR in the zone of active growth in a tree crown, and also to take into account spatial heterogeneity of growth conditions such as relief and soil characteristics. Modelling area can be up to several thousands of hectares. A number of external modules simulating sylvicultural measures can be enabled or disabled at any modelling step. FORRUS-S allows modelling of various scenarios of sylvicultural activity including: (1) natural stand development, (2) complete cycles of sylvicultural measures according to the current regulations and specifications of Russian Forest Service, (3) with infringement of technology specifications (heavy upper thinning and removing the best trees, clear cutting with destroying natural regeneration without planting). A set of tools was developed for analysis of various output databases and forecasted maps produced by means of GIS-technology. Model utilizes the standard input data have traditionally been using in forestry of the Russian Federation (taxation site descriptions, forest stand maps) and available for virtually all Russian territory. Paper describes the results of computational experiments at three scenarios of forest management using sample forest stand in the south of Moscow region.