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Competition-based mortality and tree losses. An essential component of net primary productivity
[Display omitted] •Stem volume loss by natural mortality in unmanaged forest stands was analyzed.•Volume losses of 30–40% of total volume production were observed up to an age of 100–150 years.•Average annual biomass loss was 0.8–2.1 t ha−1 (0.4–1.1 tC ha−1).•Loss fraction of gross stand growth incr...
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Published in: | Forest ecology and management 2023-09, Vol.544, p.121204, Article 121204 |
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Main Authors: | , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | [Display omitted]
•Stem volume loss by natural mortality in unmanaged forest stands was analyzed.•Volume losses of 30–40% of total volume production were observed up to an age of 100–150 years.•Average annual biomass loss was 0.8–2.1 t ha−1 (0.4–1.1 tC ha−1).•Loss fraction of gross stand growth increased continuously with stand age.•Trade-off identified between wood utilization and deadwood accumulation for biodiversity.
Even-aged stands can regenerate with many thousand seedlings per hectare before the density declines to just a few hundred trees per hectare 100 years later; management practices can lead to even lower tree numbers due to quality selection and thinning. In other words, during the development of unmanaged stands, the majority of individuals die naturally due to competition. Despite the far-reaching consequences for structural and genetic diversity, dead wood and fuel wood accumulation, we have only limited quantitative knowledge about the continuous mortality of trees and the wood volume loss over longer timespans.
For this study, we used a unique set of 476 unmanaged, monospecific experimental plots of Norway spruce (Picea abies (L.) H. Karst.), silver fir (Abies alba Mill.), Scots pine (Pinus sylvestris L.), European larch (Larix decidua Mill.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)), European beech (Fagus sylvatica L.), and oak (Quercus robur L. and Quercus petraea (Matt.) Liebl.) throughout Europe to analyze the competition-based mortality of trees and its dependency on age and site conditions.
First, we show that the total stem volume production, standing stock, and mortality were continuously increasing until an age of 100–150 years. The accumulated competition-caused stem volume loss at that age amounted to 500–1000 m3 ha−1.
Second, the net growth of the stands (share of the growth that is accumulated in the standing stock) strongly decreased with increasing age even when the gross growth was still high. The proportion of the net growth versus gross growth continuously decreased with increasing age regardless of site quality.
Third, we show a degressive decrease of the annual relative tree number mortality rates from 0.05 to 0.20 in young down to 0.01–0.02 in mature stands. For some species, we found these rates to be site dependent with different directions of the site effect. The interplay of decreasing mortality rates and increasing average volume of the dead trees resulted in unimodal mortality curves over time of th |
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ISSN: | 0378-1127 1872-7042 |
DOI: | 10.1016/j.foreco.2023.121204 |