STRUCTURE AND PECULIARITIES OF DEVELOPMENT OF STANDS WITH SOME SHARE OF ASHES IN MARI FORESTS (VOLGA REGION)

Abstract

The goal of the research is to reveal the peculiarities for European ash expansion in Mari forests (upland right bank of the Volga) and development of stands with some share of European ash. An e-database, containing taxation description of stands (more than 3000 stratums, total area - 10166 ha) in the territory of Mari upland pre-Volga area, was chosen to be the material for the analysis. Research results show the structure and peculiarities of development of stands with European ash (Fraxinus exselsior L.). They are offered in the form of mathematical equations. In the studied area, there are stands with European ash in fresh oak forests only (D2 growth conditions). The stands are mainly complex in composition ( 4–5 tree species). The most common species are linden(24,5 %), oak (15,3 %), and birch (12,5 %). The age of trees may be up to 180 year, bonitet class varies from I to V (1,66 mean figure), density varies from 0,3 to 1,0 (0,82 mean figure). The share of ash is higher in young stands ( about 30 %), but in the stands older than 60 years the share of ash is 10–17 %. Little by little, linden tree replaces ash. Besides, it suppresses propagation of birch and asp. Maximum wood stock of ash is found to be at 50 years old (69 m 3 /ha), linden –180 years old (160 m3 /ha). The age of the highest wood stock on the whole is 60 years old (275 m3 /ha). The highest mean annual increment of ash is at the age of 20–25 years old (1,75 m3 /ha), stand on the whole – 20–25 years old (5,75 m3 /ha). Productivity of a stand where ash prevails is higher, than the productivity of stands with some share of ash (at the age of 60 years old, the difference is 41 m3 /ha). It was also defined that the height of trees with some share of ash was close to its biological limit at 60–70 years old (25,8 m), determined by the environment conditions of their growing; after that, it had practically no changes. Maximum of current annual increment in height (50 cm) is at the age of 15–20 years old, then it decreases sharply. The height of stands and current annual increment are higher in the stands where ash prevails. Most differences were found to be at the age 25 - 35 years old. It was concluded it was reasonable to cultivate ash in Mari upland pre-Volga area. However, it is was necessary to improve the technologies of forest tending and to optimize stands species composition.