Anna-Liisa Sippola

Amount and quality of coarse woody debris in natural and managed coniferous forests near the timberline in Finnish Lapland

Amount and structural characteristics of coarse woody debris (CWD) were studied in 44 stands of old‐growth and managed coniferous forests in Finnish Lapland. The average volume of CWD in old‐growth forests varied from 19 m3 ha−1 in pine forests to 60 m3 ha−1 in herb‐rich spruce‐dominated forests. The volumes of living and dead timber were highly correlated, the most productive sites having the highest volumes. In old‐growth forests about 60–70% of the CWD was logs, 30–40% standing dead trees and snags, and 3.5–7% stumps and branches. The amount of CWD decreased considerably in clear‐cutting, but increased or remained the same in seed‐tree and selective cuttings in the short term. However, the accumulation rate of new dead material was greatly reduced after cutting. In 40‐year‐old seed‐tree cutting areas the new supply of CWD, created by recent disturbance and mortality, was less than 1% of the respective amount in old‐growth forest. All cutting methods reduced standing dead trees and snags considerably.

Wood-decomposing fungi and seed-tree cutting: A 40-year perspective

Abstract The effects of logging on wood-decomposing Basidiomycetes were studied in the boreal forests in northern Finland. The study area consisted of pine forest sites felled 3, 18 and 42 years before our study. The species composition of fungi in cut plots was compared to that of uncut old-growth forest sites. Altogether, 47 species were recorded on 570 logs. The species compositions reflected the amount and quality of coarse woody debris (CWD) available in the stands. In the old-growth stands, the species diversity was high, but the distribution of fungi was strongly affected by the patchy occurrence of CWD. Pioneer white-rot fungi predominated in the 3-year old logging sites. In the 40-year old logging sites, the number of species on the logging waste was 50–60% lower than in the old-growth forests, but the residual CWD from the pre-logging time still hosted a large portion of the species of the virgin forests. The species regarded as old-growth forest indicators showed different ecological tolerance to the effects of logging: the majority was confined only to naturally produced CWD, while some species were able to invade logging waste. The results showed that some polypores known to prefer old-growth forest habitats can survive for decades in managed forests. However, the species diversity of lignicolous fungi after logging greatly depended on the availability and diversity of decaying wood created before the management.

Diversity of polyporous fungi (Polyporaceae) in northern boreal forests: effects of forest site type and logging intensity

The effects of forest site type and logging intensity on polyporous fungi were studied in subxeric, mesic and herb-rich forests and spruce mires in northern Finland. The species richness of polypores did not follow the fertility gradient of the site types, but was connected with the amount and diversity of coarse woody debris (CWD). The total number of species, and the numbers of indicator and threatened species were equal in subxeric pine forests and in more fertile spruce-dominated stands. The species composition of pine-dominated forests differed conspicuously from that of spruce-dominated site types. The total number of species was not affected by logging intensity, but no virgin forest species or threatened species were found on the sites where the number of cut stumps exceeded 150 stumps ha−1. Increasing logging intensity decreased the number of polypore observations, indicating reduced substrate availability. The results stress the importance of protecting not only fertile spruce-dominated stands, but also poorer, pine-dominated forests, and sites with high and diverse CWD content.

Forest Management and Biodiversity

In this paper, some basic questions concerning sampling methods and the interpretation of results in the study of beetles and polypores are discussed. The focus is on the stand-level changes (alpha-diversity), whereas the landscape-level changes (beta-diversity) are discussed only briefly.