Variable retention forestry in European boreal forests in Russia

Abstract

We explored whether, and to what extent, variable retention (VR) forestry has been applied in European boreal forests in northwestern Russia. Our survey revealed VR since 1910. Between 1910 and the 1960s, the statistics showing how much was retained are largely missing. However, for example, in the 1950s, on a large scale in the Republic of Karelia, up to 200-ha-sized harvesting areas, 18–33%, were retention patches with a mean growing stock of 30–40 m3 ha−1. In the fellings defined as “incomplete clear fellings,” which were the most common final felling type at that time, 11–40% of the growing stock was left. Between the 1960s and the early 1990s, with more efficient harvesting and skidding techniques, conventional clear fellings with a much lower amount of retention were practiced. Concern about the regeneration of harvested areas gradually led to smaller (maximum 50 ha) harvesting areas and the increase of silvicultural activities. Until now, to ensure natural regeneration, patches of understory and 20–25 seed trees (i.e., ca. 15–25 m3) per ha have been left permanently in harvesting areas. Landscape-scale retention for protecting ecosystem functions and biodiversity was legislated in 1978 by preserving key biotopes up to 1000 ha in size. Since 2001, promoted by forest certification, the key biotopes, such as paludified forest patches, buffers around water bodies, and habitats of red-listed species, have also been retained in harvesting areas, together with a dispersed retention of different elements. Quantitative estimates of the amount of key biotopes are largely missing. However, estimates of 1–13% in harvesting areas and 23% in whole managed landscapes have been given. VR applied during the last century has emulated natural disturbances and created diverse uneven-aged forest structures with high amounts of diverse coarse woody debris. We conclude that an analysis of past and current retention practices is essential for estimating the global role of Russian forestry. Further decisions on the general direction of Russian forestry and, specifically, retention practices are important to address the global challenges of biodiversity loss and climate change.