The following is the editor's condensed summary of the articles in issue 23.3.
The knowledge on which factors that influences carbon sequestration in the forest is steadily advancing. With this article, we are presented an important component, namely the role of litterfall. Juho Matala and colleagues formulated a general model which shows that litterfall is closely correlated with tree growth, regardless of tree species, stand type or geographical location.
Site index, the measure of the productivity of a stand, is a key factor in forest planning. Easily measured but still reliable estimates are desired by the practical forestry. Jaroslaw Socha presents a model for site index of Norway spruce in the Polish mountains. Elevation was the single most important explaining factor.
Small regeneration areas suffer from the constraints of competition from surrounding trees. Juha Ruuska and colleagues quantified this so called edge-effect on Scots pine regeneration. Small cutblocks, less than 1 hectare, would lead to severe reduction in growth of the pine saplings due to competition from the surrounding stands.
Nitrogen export form a clear-cut is not reduced after harvesting of forest residues, although it could be expected. A model simulation suggested that the lower amount of available nitrogen on harvested sites is compensated by a reduced microbial immobilization of the nitrogen. Ari Laurén and colleagues made the study with the aid of the Finnish model FEMMA.
More green retention trees and wider buffer strips along rivers and lakes. These are probably results of the introduced forest certification schemes in Norway. However, many forest stands still do not meet the certification standards, according to a comparison over time made by Anne Sverdrup-Thygeson and colleagues.
The amount of wild mushrooms varies over time and place, but their abundance can be predicted by the weather. Fredrik Dahl and colleagues in Norway found a relationship with meteorological data. Cloud cover the weeks before mushroom observations was the most important explaining factor.
Simulation with models is gaining increasing importance in Scandinavian forest planning. The new model T, derived for Norwegian conditions, is presented by Terje Gobakken and his colleagues. The model calculates both the growth and the economy of the forest stands.
Missing observations in forest inventories is an obstacle that can lead to biased estimates. Torben Martinussen tackled this issue for Danish inventory data, and derived a method to overcome the bias. It was used to calculate an unbiased estimate of the forest cover in the whole of Denmark.
Log volumes can be estimated with several methods, but they seldom shows the true volume. In this study, Ramazan Özcelik and colleagues compared different estimates, and found two methods that gave less biased and more precise estimates of the volume for two Turkish tree species.
Purely by watching a forest landscape, people may become relieved from stress. Bum-Jin Park and colleagues measured physiological responses on students in Korea who watched a forest with those who watched a city area.