Diversity of grass vegetation in field shelterbelts transformed into silvoarable agroforestry plantings in the Right-Bank Forest-Steppe of Ukraine

Abstract

Introduction

More than half of Ukraine’s agroforestry fund consists of 60–70-year-old shelterbelts. As these shelterbelts age, their condition deteriorates, and in the absence of silvicultural management, forest edges encroach into adjacent fields, leading to an increase in their width. This expansion results in a more open structure, reducing their amelioration efficiency. To enhance their protective functions, reducing their width is recommended. One potential solution to this issue is the transformation of existing shelterbelts into silvoarable agroforestry plantings.  Such transformation leads to several ecological changes, particularly in the aboveground vegetation cover.

The aim of the study was to assess changes in species and quantitative composition, as well as the prevalence of herbaceous vegetation in shelterbelts that were transformed into linear silvoarable agroforestry plantings.

Materials and Methods

The research was conducted in the northern part of the Right-Bank Forest-Steppe across six sample plots in both wide and transformed shelterbelts. The species composition and degree of projective cover of the aboveground vegetation were analyzed using1?1 m² survey plots with tenfold replication. Phytodiversity of the living aboveground cover was assessed using several ecological indices, including Shannon’s species diversity index, Pielou’s evenness index, and Simpson’s diversity index. The collected data were statistically processed to determine mean values and associated errors.

Results

In classical shelterbelts, the dominance of sylvatic species, along with high projective cover, creates a stable microclimatic environment with high species diversity, which is the result of an environment close to forest phytocoenoses. However, in transformed shelterbelts, ruderal species replace forest vegetation, leading to the formation of agrobiocoenotic plant communities. This suggests that in older shelterbelts with diverse species composition, anthropogenic succession is driving a transition from forest biocenosis to agroforestry ecosystems, accompanied by distinct coenotic changes. An analysis of the coenotic structure of aboveground vegetation revealed that both classical and transformed shelterbelts are characterised by the dominance of sylvatic and ruderal species. However, in classical shelterbelts, sylvatic species accounted for a higher proportion (39.0–49.4%) compared to ruderal species (20.3–42.0%). In contrast, transformed shelterbelts exhibited a clear dominance of ruderal vegetation (22.1-41.3%) over forest species (17.3–31.7%). This shift is attributed to increased light penetration, the dispersal of forest litter, the loss of forest-like microenvironments, and the more open, wind-exposed structure of transformed shelterbelts. In classical shelterbelts, species diversity is influenced by light availability and structural characteristics of the shelterbelts. However, species richness was significantly lower in classical shelterbelts compared to those transformed into silvoarable agroforestry systems.

Conclusions

The transformation of shelterbelts into linear plantings of the silvoarable agroforestry system accelerates successional changes in the aboveground vegetation, leading to desilvatization of herbaceous species and a decline in species diversity. Consequently, transformed shelterbelts experience intensified synanthropization, and are characterised by an increased presence and adaptation of ruderal and meadow vegetation.

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