The Coenotic Role of Acer Negundo in Forests Dominated by Salix Alba in the Valley of Pina River (Belarus)

Abstract

Objective of the research was assessing the influence of A. negundo invasion on the coenotic structure of willow river valley forests in conditions of Belarusian Polesie. Materials and methods. The structure and floristic composition of communities were studied by permanent sample plot, forest valuation, Ramensky and Raunkiaer methods, on 400 m2 plots. Results. All studied communities belong to Salix alba-Rubus caesius association, and had up to 33/100 m2 trees of A. negundo older than 3 years, with the total trunk volume of A. negundo up to 4.75 m3/100 m2. With the increase of A. negundo projection coverage on a plot from 0-13% to 25-46%, Shannon diversity index (SDI) for vascular plants declined from 3.2-3.3 to 2.7-3.0. For the species of lower community level (living ground cover), SDI = 3.1 on the plot without A. negundo trees, and SDI = 2.6 on the plot with the highest A. negundo concentration. The light intensity under A. negundo crowns was 3-8 times lower, than under S. alba. On 5 sample plots 59 vascular plant species were recorded, of which 6 herbaceous species had various degree of gravitation or preference to the crown projections of A. negundo. Conclusion. The communities of Salix alba-Rubus caesius association are favourable for the propagation and growth of A. negundo. Development of A. negundo simplifies the coenotic flora. Along with this negative effect, the possible positive effects of A. negundo growth are: saving soil humidity, prevention of soil erosion, accumulating humus, protecting the neighbouring water bodies.