scholarly journals Effects of Thinning Practice, High Pruning and Slash Management on Crop Tree and Stand Growth in Young Even-Aged Stands of Planted Silver Birch (Betula pendula Roth)

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 225
Author(s):  
Jens Peter Skovsgaard ◽  
Ulf Johansson ◽  
Emma Holmström ◽  
Rebecka McCarthy Tune ◽  
Clémentine Ols ◽  
...  

The objective was to quantify the influence of thinning, high pruning and slash management on crop tree and stand growth in young even-aged stands of planted silver birch (Betula pendula Roth). This study was based on two field experiments, aged six and eleven years at initiation and re-measured after six and eight years, respectively. Treatments included the unthinned control, moderate thinning mainly from below (removing 28–33% of standing volume), point thinning to favor 300 trees per ha and with no thinning elsewhere in the plot (removing 16–25%), and heavy thinning leaving 600 evenly distributed potential future crop trees per ha (removing 64–75%). Slash management (extraction or retention) was applied to heavily thinned plots. High pruning removing 30–70% of the green crown was carried out in some plots with point or heavy thinning on 300 or 600 trees per ha, respectively. Stand volume growth increased with increasing pre-treatment mean annual volume increment and decreased with increasing thinning intensity as compared to the unthinned control. LS-means estimates indicated a reduction for moderate thinning by 14%, for point thinning by 12% and for heavy thinning (combined with pruning) by 62%. However, in the youngest experiment, heavy thinning (without pruning) reduced growth by 54%. Combining these results with results from a similar experiment in Canada, the reduction in stand volume growth (RedIv%) depending on thinning removal (RemV%), both expressed as a percentage of the unthinned control, was quantified as RedIv% = −23.67 + 1.16·RemV% (calibration range: 30–83%). For heavy thinning (large quantities of slash), slash extraction resulted in no reduction in stand volume growth as compared to slash retention. The instantaneous numeric reduction in the average stem diameter of the 300 thickest trees per ha (D300) due to thinning was 3.5, 15–21% and 955–11% with moderate, point and heavy thinning, respectively. The subsequent average annual increase in D300 during the observation period was 8.5%, 25 and 18%, respectively. In the youngest experiment, pruning in unthinned plots led to a reduction in the annual increase of D300 by 14%, and heavy thinning in unpruned plots led to an increase by 30%. The growth of pre-selected potential future crop trees increased with increasing thinning intensity. In heavily thinned plots, pruning reduced growth increasingly with increasing pruning severity; LS-means estimates indicated 21% larger growth on stem diameter for unpruned trees and 3% for pruned trees. As an adverse side effect, heavily thinned plots with only 600 trees per ha were at increased risk of windthrow for some years after the thinning intervention. In the oldest experiment, 95–21% of the trees in these plots were damaged by wind.

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 599
Author(s):  
Héloïse Dubois ◽  
Hugues Claessens ◽  
Gauthier Ligot

Forest health problems arising from climate change, pests and pathogens are a threat to the main timber tree species. As a result, silver birch (Betula pendula Roth) has become a precious asset for meeting oncoming forestry challenges in western Europe. However, silviculture guidelines to produce high-value birch logs in this region are lacking. Producing large-sized birch trunks requires crown release, i.e., removing crown competitors around selected target trees. These interventions are currently seldom carried out or else too late when the growth potential of the trees has already diminished. This study set out to ascertain the diameter at breast height (dbh) that could be reached by crown-released birch, determine dbh-associated crown diameters, and further characterize the gain obtained from early crown release on birch dbh growth. We measured 704 birch trees that had undergone crown release in 38 naturally regenerated pure birch stands in southern Belgium and in northeastern France. We then evaluated the variation in stem and crown diameter, and analyzed increments in response to the earliness of the interventions in three subsamples, also compared with control target birch. We found that trees with a dbh of 50 cm could be grown within 60 years. Based on crown diameter, to produce 40, 50 and 60 cm dbh trunk, the distance required between target birch trees at the end of the rotation was around 8, 10 and 12 m. With no intervention and in ordinary dense birch regenerations, the dbh increment was found to decline once the stand reached age 4–7 years. Starting crown release in stands aged 4–5 years can double the dbh increment of target trees and provide a continual gain that may last up to 20 years. When birch crowns are released after 9–12 years, it may already be too late for them to recover their best growth rate. Our contribution should help complete emerging guidelines in support of birch silviculture development.


Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4633
Author(s):  
Aleksandra Ostapiuk ◽  
Łukasz Kurach ◽  
Maciej Strzemski ◽  
Jacek Kurzepa ◽  
Anna Hordyjewska

Silver birch, Betula pendula Roth, is one of the most common trees in Europe. Due to its content of many biologically active substances, it has long been used in medicine and cosmetics, unlike the rare black birch, Betula obscura Kotula. The aim of the study was therefore to compare the antioxidant properties of extracts from the inner and outer bark layers of both birch trees towards the L929 line treated with acetaldehyde. Based on the lactate dehydrogenase test and the MTT test, 10 and 25% concentrations of extracts were selected for the antioxidant evaluation. All extracts at tested concentrations reduced the production of hydrogen peroxide, superoxide anion radical, and 25% extract decreased malonic aldehyde formation in acetaldehyde-treated cells. The chemical composition of bark extracts was accessed by IR and HPLC-PDA methods and surprisingly, revealed a high content of betulin and lupeol in the inner bark extract of B. obscura. Furthermore, IR analysis revealed differences in the chemical composition of the outer bark between black and silver birch extracts, indicating that black birch may be a valuable source of numerous biologically active substances. Further experiments are required to evaluate their potential against neuroinflammation, cancer, viral infections, as well as their usefulness in cosmetology.


Planta ◽  
2005 ◽  
Vol 222 (4) ◽  
pp. 699-708 ◽  
Author(s):  
Heidi Tiimonen ◽  
Tuija Aronen ◽  
Tapio Laakso ◽  
Pekka Saranpää ◽  
Vincent Chiang ◽  
...  

2014 ◽  
Vol 71 ◽  
pp. 32-35 ◽  
Author(s):  
Wojciech Dmuchowski ◽  
Dariusz Gozdowski ◽  
Paulina Brągoszewska ◽  
Aneta Helena Baczewska ◽  
Irena Suwara

2020 ◽  
Vol 11 ◽  
Author(s):  
Giovanbattista D. de Dato ◽  
Angela Teani ◽  
Claudia Mattioni ◽  
Filippos Aravanopoulos ◽  
Evangelia V. Avramidou ◽  
...  

2018 ◽  
Vol 15 ◽  
pp. 28-44
Author(s):  
Dhirendar Kumar Pradhan ◽  
Christine Cahalan ◽  
Sunita Ulak

Climate is one of the major factors that govern the distribution of tree species. Climate change has already affected the growth, structure and distribution of trees and woodlands. Global climate change projections are wetter winters, drier summers and significance changes in temperature regimes in the next few decades. The main objective of this study was to experimentally demonstrate the effects of decline in summer rainfall, as predicted by UKCP09/IPCC, on height and diameter growth in two co-occurring silver birch (Betula pendula Roth) and downy birch (Betula pubescens Ehrh) and provide further understanding of the changes in growth and development in response to a decrease in water availability. One-year-old seedlings were grown in a temperature-controlled greenhouse for eight weeks in a split-plot experimental design. Their height and diameter were measured and analyzed. Result showed that plant height and diameter was significantly reduced with increased water stress. B. pendula showed higher physiological traits indicating that this species can perform better than B. pubescensin water-deficit conditions.


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