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Research article2010Peer reviewed

Natural mortality in thinning and fertilisation experiments with pine and spruce in Sweden

Elfving, Björn

Abstract

Natural mortality in a 30-year period was examined in thinning and fertilisation experiments with 48 blocks in Scots pine (Pinus sylvstris L) and 23 blocks in Norway spruce (Picea alms (L.) Karst) with up to 12 different treatments Of about 90,000 living trees at start of the experiments 18.7% were registered as dead by natural mortality in the 30-year observation period In non-thinned stands about 20% of the volume growth disappeared by natural mortality, in thinned stands about 10% In normally thinned pine stands (repeated thinning from below with moderate intensity) the annual mortality of the basal area at start of an average 7-year period was 0.34% In spruce stands, on more fertile sites, the corresponding figure was about 06%. In an effort to model the mortality, severe damage not leading to final felling was identified in 1.7% of the observation periods. It was assumed that this part of the mortality, representing 24% of the total volume mortality, could be recovered by active thinning The probability for severe damage Increased sharply with stand top height, as shown in a logistic regression The more sparse mortality was expressed as a function of site fertility, stand density, disturbance by thinning and form of treatment (thinned from above or below or non-thinned). The naturally dead trees were approximately of mean size in normally thinned stands while the self-thinning in non-thinned stands tended to occur amongst smaller than average trees. Diagrams were presented for basal area development and stem number reduction in the non-thinned stands. (C) 2010 Elsevier B V. All rights reserved.

Keywords

Self-thinning; Recovery of dead trees; Maximum basal area; Wind-throw

Published in

Forest Ecology and Management
2010, Volume: 260, number: 3, pages: 353-360 Publisher: ELSEVIER SCIENCE BV

    Associated SLU-program

    SLU Future Forests

    UKÄ Subject classification

    Forest Science

    Publication identifier

    DOI: https://doi.org/10.1016/j.foreco.2010.04.025

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/48068