Forestry and mensurational characteristics of stands with Picea abies (l.) Karst. in the fir types of forest in the Ivano-Frankivsk region

Abstract

Introduction

Despite the partial loss of biotic stability associated with climate change, Picea abies (L.) Karst. remains one of the most valuable tree species in the forests of the Ukrainian Carpathians. Even in pure secondary stands, Norway spruce generally remains relatively stable up to the age of 50–60 years and accumulates considerable timber volumes. Researchers characterize Picea abies as a fast-growing tree species under rich forest site conditions. Despite ongoing climate change, spruce stands still possess significant resource potential and remain the main source of timber in the Carpathian region. The aim of the study was to investigate the current state and dynamics of silvicultural and mensurational characteristics of spruce stands of different composition and age in silver fir forest types of the Ivano-Frankivsk region.

Materials and Methods

The analysis of silvicultural and mensurational characteristics of stands containing Picea abies within the forest fund of the studied region was carried out using forest inventory data from 2016–2024 provided by the Lviv State Forest Inventory Expedition. The analysis covered 11 silver fir forest types in which Norway spruce is the dominant tree species in both natural and artificial stands. In total, more than 40 thousand forest inventory subcompartments within silver fir forest types were analyzed. The names of forest types are presented according to Gerushynskyy (1996).

Results

The proportion of spruce in forest stands of silver fir forest types varies widely, ranging from 2 to 10 units in stand composition. The largest share of stands was observed where the coniferous species occurred in the composition at 5 and 6 units (14.6% and 17.4%, respectively). At the same time, the area of pure spruce stands in silver fir forest types (10 units) is relatively high (13.6%). The highest timber volumes are concentrated in stands with spruce participation of 6–10 units (2,031.6–2,297.2 thousand m³, or 15.8–17.8%). The largest proportion of stands containing spruce was observed in the age range of 30–70 years (10.9–23%). The highest share of timber stock (13.6–28.1%) is concentrated in stands aged 50–70 years. Within this age range, 7,801.6 thousand m³ of timber have accumulated. Forest stands containing Picea abies are represented by all age groups, from young stands of the first age class to overmature stands. The largest areas are occupied by mature (12,521.4 ha or 32.3%) and middle-aged (10,768.4 ha or 27.8%) stands; somewhat smaller areas are represented by premature stands (8,850.4 ha or 22.9%), while the smallest areas are occupied by overmature stands (4,615.6 ha or 11.9%) and young stands (1,972.4 ha or 5.2%). It is among mature and middle-aged stands that the highest proportion of high-density stands (relative stocking 0.8 and higher) is observed (18.2% and 21.8%, respectively). The largest proportion of the area is occupied by stands of the highest site classes, I and I^a (41.6% and 26.9%, respectively). Stands of site class II occupy a considerably smaller part (19.3%). The timber stocks of stands growing in site classes I and I^a are the highest (10,079 thousand m³ or 78.3%).

Conclusions

Under the conditions of fir and spruce-fir forest types, pure spruce stands are capable of forming substantial timber stocks within a relatively short period, which creates certain prerequisites for the establishment of spruce forest plantations with a shortened rotation period on limited areas. Reducing the timber-growing rotation in such conditions (to 50–60 years) would contribute to maintaining an adequate level of biotic stability of Norway spruce. The presence of highly productive and stable spruce stands in silver fir forest types, some of which exceed 200 years of age, the relatively high stability of spruce up to the age of 50–60 years, its high growth rate, and the accumulation of significant timber volumes in fir and spruce-fir forest types provide grounds to recommend Picea abies as a promising tree species for the establishment of plantation forest stands.

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