Some Applications of Stochastic Methods in Investigations on the Dynamics of Ecosystems

This paper describes some possible applications of stochastic methods which may be used in ecological studies. The role of stochastic methods in investigations of the dynamics of ecosystems is gaining in importance. It is a new trend which has arisen in ecological studies, related to the development of methods for the control of the environment. Stochastic methods are very useful for investigating the stability of ecosystems and the criteria of stability of natural systems, especially where the influence of permanent small-scale random disturbances have been noticed. Some criteria have been suggested and examples of use of these criteria are given in this paper. It must also be noted that the complex problems of predicting and controlling processes in natural systems must be solved by mathematical tools which permit analysis of anthropogenic factors without in-situ experimentation

European and United States Case Studies in Application of the CREAMS Model

Several countries require investigation of the complex environmental consequences of agricultural management; therefore, IIASA decided to transfer the physically based CREAMS model program (developed by the US Department of Agriculture) to the Institute. The model was made operational on the Institute's computer and used by scientists from the following countries: Czechoslovakia, FRG, Finland, Poland, Sweden, United Kingdom, United States, and the USSR. The main objective of this work was to perform the quantitative evaluation of the consequences of the agricultural management in different countries. The collateral objective was to make validation studies of the CREAMS model where possible. These studies are completed now, and some of them are included in this volume. They can be divided into three categories: 1. Those where some observed data are available for model validation (Finland, England); 2. Those where some observed data are available for model validation with model extension for simulation (CSSR, FRG, USA); and 3. Those without observed data and only model simulations are generated to examine possible problems associated with management (Sweden, USSR, Poland)

Procedures, Numerical Parameters and Coefficients of the Creams Model: Application and Verification in Czechoslovakia

Problems of agricultural nonpoint source pollution have been investigated by the Resources and Environment Area (Task 2) at IIASA. The CREAMS model has been used as a mathematical aid to arrive at an in-depth understanding of erosion and to predict its influence on agriculture. The CREAMS model was created using data from North America. Investigations of its general use and verification under various conditions were useful. This paper summarizes the results of the verification of this model in a research area in Czechoslovakia and focuses attention on certain points which must be carefully considered during application of this model

The problem of ecosystem stability and some applications of one of the stochastic methods in investigation of this problem

This paper describes some possible applications of one of the stochastic methods which may be used in ecological studies. The role of stochastic methods in investigations of the dynamics of ecosystems is gaining in importance. Stochastic methods are very useful for investigating the stability of ecosystems and the criteria of stability of natural systems, especially where the influence of permanent small-scale random disturbances has been noticed. Some criteria have been suggested and examples of use of these criteria are given