The influence of stand density and canopy position on sulfur content in needles of Norway spruce (Picea abies L. Karst.)

The mating system was investigated in two neighbouring Norway spruce (Picea abies (L.) Karst.) populations with markedly different stand densities. The amount of outcrossing was estimated using open-pollinated array data at four enzyme loci. Multilocus estimates of the proportion of viable progeny owing to outcrossing were 0.956 and 0.955 for the low- and high-density stand, respectively, indicating that the large reduction in stand density had no impact on outcrossing rates. The multilocus estimate was higher than the mean single-locus estimate only for the low-density stand. The lowering of the mean estimate in the low-density stand is probably a consequence of the clustering of related individuals. The regression of pollen allele frequencies on ovule genotype, which is a direct measure of the effective selfing caused by consanguineous matings, had a significant coefficient for the low-density stand and a nonsignificant one for the high-density stand. This obvservation confirms that the major effect of low-stand density in Norway spruce is the occurrence of consanguineous matings. Key words: mating system, outcrossing rate, inbreeding, Norway spruce, stand density.

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Pruning effect on Norway spruce (Picea abies (L.) Karst.) growth and quality

Forestry Studies / Metsanduslikud Uurimused ◽

10.1515/fsmu-2017-0005 ◽

2017 ◽

Vol 66 (1) ◽

pp. 33-48 ◽

Cited By ~ 2

Author(s):

Endijs Baders ◽

Janis Donis ◽

Guntars Snepsts ◽

Andis Adamovics ◽

Aris Jansons

Keyword(s):

Picea Abies ◽

Norway Spruce ◽

Ring Width ◽

Stand Density ◽

Stand Age ◽

Radial Increment ◽

Annual Increment ◽

Management Activity ◽

Spruce Stands ◽

Occlusion Rate

Abstract Pruning requires significant investment, therefore, the aim of the study was to characterize occlusion of branch wounds and changes in radial increment as well as frequency of browsing damages after pruning of Norway spruce (Picea abies (L.) Karst.) in order to provide data for financial calculations and recommendations for practical forestry. Altogether 1,614 pruned and 4,368 unpruned trees from 45 Norway spruce stands were measured and cored. Degree of wound occlusion and browsing damages were assessed, and additional volume increment estimated in each stand. Pruning resulted in significant increase of length of branch-free section: for unpruned trees it was 0.3 ± 0.07 m, but for pruned 3.4 ± 0.10 m. Branch wounds for most of the trees (68%) were filled with resin (occluded), for lower share of trees (31%) – still open, but for some trees (1%) completely occluded. Branch wound occlusion rate was not affected by differences in stand density, but was significantly affected by stand age: proportion of trees with occluded branch scars increased with age. Trees with occluded branch wounds had a significantly higher increase in tree ring width after the pruning in comparison to the period before pruning than trees with open branch wounds, emphasizing the importance of radial increment in development of branch-free layer of wood. Pruning resulted in minor (−7% or −0.28 ± 0.05 m3 ha−1) reduction of annual increment that was statistically significant only up to 3 years after this forest management activity for stands younger than 17 years and with mean height up to 10.5 m. Pruned trees were significantly more browsed than unpruned (6.1% and 2.7%, respectively).

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Impact of plot size on individual-tree competition measures for growth and yield simulators

Canadian Journal of Forest Research ◽

10.1139/x02-173 ◽

2003 ◽

Vol 33 (3) ◽

pp. 455-465 ◽

Cited By ~ 22

Author(s):

Jari Hynynen ◽

Risto Ojansuu

Keyword(s):

Picea Abies ◽

Norway Spruce ◽

Growth Models ◽

Model Performance ◽

Stand Density ◽

Growth And Yield ◽

Average Radius ◽

Sample Plot ◽

Individual Tree ◽

Plot Size

The study addresses the effect of sample plot size on the bias related to measured stand density. We analyzed the effect of plot size on model coefficients and model performance in the simulation. Alternative growth models were developed for Norway spruce (Picea abies (L.) Karst.) on the basis of data obtained from permanent inventory sample plots of varying size. The competition measures were estimated from small plots with an average radius of 6 m, large plots with an average radius of 10 m, a cluster of three small plots within a stand, and a cluster of three large plots within a stand. The response of the models to competition varied depending on the plot size. Increasing the plot size increased the sensitivity of the models to the variation of overall stand density and the competitive status of a tree. The development of repeatedly measured, unthinned and thinned Norway spruce sample plots was simulated with the models, and the predictions were compared with the observed development. In the unthinned stand, the model with competition measures based on small plots resulted in a higher and more biased prediction of growth and mortality than the models based on larger plots. In the thinned stand, the differences between the models were negligible.

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The elasticity of growth in pure and mixed stands of Norway spruce (Picea abies [L.] Karst.) and common beech (Fagus sylvatica L.)

Journal of Forest Science ◽

10.17221/4721-jfs ◽

2012 ◽

Vol 49 (No. 11) ◽

pp. 491-501 ◽

Cited By ~ 20

Author(s):

H. Pretzsch

Keyword(s):

Picea Abies ◽

Norway Spruce ◽

Fagus Sylvatica ◽

Practical Importance ◽

Stand Density ◽

Maximum Growth ◽

Mixed Stands ◽

Common Beech ◽

Fagus Sylvatica L

This study indicates that the growth of mixed stands with Norway spruce (Picea abies [L.] Karst.) and common beech (Fagus sylvatica L.) is more stable across a range of stand densities than it is in pure forests of the same species. Typical density-growth-relationships are derived from 42 long-term experimental areas with 134 plots in total, the oldest of them under survey since 1870. From these results it is apparent that in pure stands maximum growth can be obtained only at medium stand density, whereas in mixed stands growth is almost unchanged over a range of low, medium and high stand density. The finding that mixed stands may perform a superior growth to pure stands with either decreasing or increasing stand density has often been overlooked but is nevertheless of major practical importance.

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Needle and branch biomass turnover rates of Norway spruce (Picea abies)

Canadian Journal of Forest Research ◽

10.1139/x04-133 ◽

2004 ◽

Vol 34 (12) ◽

pp. 2517-2527 ◽

Cited By ~ 34

Author(s):

P Muukkonen ◽

A Lehtonen

Keyword(s):

Picea Abies ◽

Vertical Distribution ◽

Norway Spruce ◽

Stand Density ◽

Turnover Rates ◽

Single Turnover ◽

Biomass Turnover ◽

Branch Biomass ◽

Species Specific ◽

The Vertical Distribution

Turnover rates of needle and branch biomass, number of needle cohorts, and needle-shed dynamics were modelled for Norway spruce (Picea abies (L.) Karst.) in southern Finland. Biomass turnover rates, vertical distribution, and biomass of the branches were modelled simultaneously. The rate of needle turnover was determined from needle-shed dynamics. The potential litterfall of branches was modelled by combining the vertical distribution of branch biomass and the annual change in height of the crown base. The mean annual turnover rates for needle and branch biomass are 0.10 and 0.0125, respectively. At the age of 5.5 years, 50% of the needles in the needle cohort have been shed. In addition, at the age of 12 years, all needles of the needle cohort have been shed. Turnover of branch biomass was dependent on stand density and tree size. The modelled rates of biomass turnover agreed with measurements of needle and branch litterfall. Many process- or inventory-based models use a single turnover rate for branch litterfall based on literature, and some of the models are fully ignoring the litterfall of branches. Species-specific turnover rates or dynamic litterfall models should be applied when carbon flows in forest stands are modelled.

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