MATHEMATICAL MODELING OF THE SPREAD OF ACER NEGUNDO SEEDS IN THE URBAN ENVIRONMENT

Abstract

Acer negundo is an invasive species. It is a serious problem for natural, protected, and other green areas of the cityof Perm. In some areas of small river valleys, it constitutes up to 80% of woody plants, and in public green areas ˗ up to 30%. Inrecent decades, the expansion of Acer negundo has been increasing. Its invasion threatens biodiversity, hinders natural regeneration of other plant species, and deteriorates the appearance of landscaped areas. The rate of distribution of Acer negundo exceeds the possibilities of visual surveys. Thus, the results of such surveys do not provide a reliable picture of the current distribution of the invasive plants and of the potential for their distribution. Our research work aimed to determine the distribution range of Acer negundo seeds by means of modeling. Based on a study of the distribution of Acer negundo in the city of Perm, the range of wind scattering of its seeds was identified. In the valley of the upper reaches of the Uinka River in the Motovilikhinsky District of Perm, the average weight of Acer negundo seeds, the number of seeds per tree, and the seed settling rate were determined. The tree was considered as a point source, for which the rate of discharge of seed quantity was determined, which was estimated as the source power. Further, by mathematical modeling based on Gaussian flare model, the seed dispersal range of the invasive plant was determined and seed flux fields to the soil surface were obtained. All calculations were performed for different conditions of atmospheric stratification and at fixed wind direction. The wind speed was estimated as the highest, with a probability of 5%.It was found that the greatest seed flight distance corresponded to weak and moderately stable stratification of the atmosphere. The distance to the zone of maximum seed deposition was from 35 to 107 m with a wind speed of 7 m/s.These data were prepared for developing a municipal program of phased replacement of Acer negundo in different types of green areas of the city of Perm on the basis of the regional law ‘On Green Areas of the Perm Region’.