Ken Olaf Storaunet

EPIPHYTIC LICHENS IN NORWEGIAN COASTAL SPRUCE FOREST: HISTORIC LOGGING AND PRESENT FOREST STRUCTURE

Current forestry policies worldwide aim at conserving and restoring biodiversity in managed forests. In this respect, epiphytic lichens have become a focal group in studies of how logging and silvicultural methods can be adjusted to mimic and restore old-growth conditions. We addressed this issue in a retrospective study in the coastal spruce (Picea abies) forest region of central Norway, surveying 31 old forest sites in order to relate a selected group of epiphytic macrolichens (Fuscopannaria ahlneri, Lobaria pulmonaria, L. scrobiculata, Nephroma spp., Platismatia norvegica, Pseudocyphellaria crocata, Ramalina thrausta, and Sphaerophorus globosus) to forest stand characteristics and previous logging history. The lichens were associated with brook ravines, F. ahlneri and P. crocata mostly so, being 10 times more abundant in ravine valley bottoms than on adjacent slopes and plateaus. All species used spruce trees as their main substrate, but L. pulmonaria, L. scrobiculata, and Nephroma spp. preferred scatt...

Using forest stand reconstructions to assess the role of structural continuity for late-successional species

Abstract Historical reconstructions of past forest dynamics and stand structures have been used to establish reference conditions for managing present forest ecosystems. In this study we (1) developed and combined a suite of stand reconstruction techniques to describe past stand characteristics, and (2) applied these stand histories to evaluate the relationship between wood-decay fungi and forest continuity. Ten previous selectively logged stands of Norway spruce (Picea abies L. Karst.), in the middle boreal zone of southeastern Norway, were studied. We reconstructed stand structures during the 20th century using tree-ring series, growth patterns, age structures, and decay classification and datings of stumps and logs. All stands were selectively logged between 1890 and 1965, with a mean logging interval of 25 years. Harvested volumes (1900–1965) constituted 25–99% of present standing volumes and present volumes were 2.6–21 (median 4) times higher than the lowest estimated historic volumes. Dead wood was categorized into eight decay classes, where one is recently fallen, and eight is almost completely decayed. Six fungus species, assumed to indicate dead-wood continuity, were found on logs in decay classes 2–4, all of which were estimated to be

Reconstructing 100-150 years of logging history in coastal spruce forest (Picea abies) with special conservation values in central Norway.

Coastal spruce forests of central Norway harbour a unique assemblage of epiphytic lichens and are given high priority with respect to conservation of biodiversity. To assess the historical impact of logging during the last 100-150 yrs, 31 remnant stands were studied by means of tree-ring analysis of 2199 trees and the decay stage of 1605 stumps. No stands had been clear-cut, but all had been selectively logged at least twice during the last 150 yrs. Total harvested timber volume ranged from 65 to 409 m3ha-1 (31-124% of present-day standing volume) and the selective logging kept standing volume low (40-200 m3ha-1) during 1890-1930. Present-day stand characteristics were strongly correlated with site productivity and topographic position within the ravine valleys. Low amounts of dead wood at sites with high historical logging activity was the only consistent relationship found after covariance of site productivity, topographic position and deciduous trees were taken into account. The results indicate that old-growth stand characteristics, such as reversed J-shaped age distributions and dead wood in advanced decay classes, can be obtained 100-150 yrs after intensive selective logging.

Models to predict time since death of Picea abies Snags

Number of years since death was estimated by dendrochronological cross-dating of 107 standing dead trees (snags) of Norway spruce [Picea abies (L.) Karst.] in a submountainous old-growth forest in south–central Norway. Snag characteristics (size, bark cover, branch order present and variables derived from tree-ring analyses) were used in stepwise linear regression procedures to identify variables that explained time since death. Number of branch orders present (where branches growing directly on the stem were branch order 1, branches growing on order 1 branches were order 2, and so on) explained two-thirds of the variation in time since death. Adding other significant variables, such as diameter, relative height of snags, percentage bark cover and average tree-ring width in the final years before death, increased model precision only moderately. The models were validated by the PRESS statistic, which showed that new observations were predicted fairly well with 65–69% of the variation explained.

Age and growth patterns of old Norway spruce trees in Trillemarka forest, Norway

Abstract Old trees represent key features of old-growth forests and are important elements for maintaining biodiversity. Due to extensive human exploitation of Fennoscandian boreal forests during several centuries, old Norway spruce trees have become exceedingly rare. We analysed 91 spruce trees in Trillemarka Nature Reserve, southern Norway, to investigate (1) the maximum age of living trees, (2) growth rates of different-age trees and (3) growth trends in very old trees. Increment cores were taken from trees in selected old-growth stands located at 700–850 m a.s.l. Twelve spruce trees had an estimated total age of >400 years, the oldest one being 529 years and presumably the oldest known still living Norway spruce in northern Europe. A negative relationship between growth rate (basal area increment) and total age was observed, being most distinct for growth rates at 126–275 years and less marked for early stage growth (26–75 years). Thus, high age apparently was related more to low growth rates at adult and old stages of life rather than at the earlier stage. Among the trees >400 years, many of them did not show growth decrease with advancing age, indicating that ageing did not reduce growth. We conclude that the maximum age of stand-forming Fennoscandian Norway spruce trees would be in the range of 500–600 years.