O. Janne Kjønaas
Seniorforsker
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Lisa Fagerli Lunde Tone Birkemoe Anne Sverdrup-Thygeson Johan Asplund Rune Halvorsen O. Janne Kjønaas Jenni Nordén Sundy Maurice Inger Skrede Line Nybakken Håvard KauserudSammendrag
Boreal forests are important carbon sinks and host a diverse array of species that provide important ecosystem functions.Boreal forests have a long history of intensive forestry, in which even-aged management with clear-cutting has been thedominant harvesting practice for the past 50–80 years. As a second cycle of clear-cutting is emerging, there is an urgentneed to examine the effects of repeated clear-cutting events on biodiversity. Clear-cutting has led to reduced numbers ofold and large trees, decreased volumes of dead wood of varied decay stages and diameters, and altered physical andchemical compositions of soils. The old-growth boreal forest has been fragmented and considerably reduced. Here,we review short- and long-term (≥50 years) effects of clear-cutting on boreal forest biodiversity in four key substrates:living trees, dead wood, ground and soil. We then assess landscape-level changes (habitat fragmentation and edge effects)on this biodiversity. There is evidence for long-term community changes af
Forfattere
Johan Asplund Jenni Nordén O. Janne Kjønaas Rieke Lo Madsen Lisa Fagerli Lunde Tone Birkemoe Eivind Kverme Ronold Milda Norkute Ulrika Jansson Damian Petkovic Karlsen Anne Sverdrup-Thygeson Inger Skrede Ine-Susanne Hopland Methlie Sundy Maurice Ulrik Geiran Botten Regine Jusnes Krok Håvard Kauserud Line NybakkenSammendrag
The history of forestry in Fennoscandia spans five centuries, with clear-cutting being the dominant practice since the mid-20th century. This has led to a significant transformation of the forest landscape. In this study we investigated long-term effects of clear-cutting on forest structure and dead wood volumes. We established twelve pairs of spruce forest sites in southeastern Norway, each pair constituting of a mature, previously clear-cut stand and its near-natural counterpart with similar edaphic factors. The near-natural stands had 2.8 times higher volumes of dead wood and a larger proportion of dead wood in late stages of decay. The near-natural stands had on average 36.8 ± 9.1 m3 ha−1 of downed dead wood and 24.1 ± 6.2 m3 ha−1 of standing dead wood. Corresponding numbers for the previously clear-cut stands were 10.2 ± 2.8 m3 ha−1 and 11.9 ± 3.7 m3 ha−1. Forests with lower volumes of dead wood often also had lower connectivity of old spruce forests, which potentially have further negative effects on biodiversity. Furthermore, near-natural stands displayed greater tree size heterogeneity, resulting in a wider variation in light conditions. While no difference was observed in living tree volume, we found only weak evidence for higher basal area in the previously clear-cut stands, which had a higher stem density with more slender stems and shorter crowns. Our findings suggest that managed forests do not develop structures typical of near-natural forests before they become mature for logging. We stress the importance of a thorough site selection for studies of management effects, as forest management history may be confounded with productivity and other edaphic factors. Experimental designs like ours are vital for testing how differences in structure and deadwood volumes, driven by forest management, translate into variations in biodiversity, carbon sequestration and ecosystem functioning in future studies.
