Patterns of above- and below-ground response of understory conifer release 6 years after partial cutting

2002 ◽  
Vol 32 (2) ◽  
pp. 255-265 ◽  
Author(s):  
Daniel D Kneeshaw ◽  
Harry Williams ◽  
Eero Nikinmaa ◽  
Christian Messier
Keyword(s):  
Root Growth ◽  
Height Growth ◽  
Douglas Fir ◽  
Stem Growth ◽  
Radial Increment ◽  
Growth Responses ◽  
Partial Cutting ◽  
Size Classes ◽  
Clear Cutting ◽  
Advance Regeneration

An increased pressure to use silvicultural techniques not based on clear-cutting followed by planting has led to an interest in systems that take advantage of existing understory seedlings (advance regeneration). Earlier studies have suggested that following harvesting, understory seedlings may experience growth reductions before responding with growth increases. We hypothesize that this "growth shock" following release results because seedlings are ill adjusted to the new growing conditions and that this can be investigated through a comparison of growth in different parts of the tree over a 6-year period. This study compares the growth response of three size classes of lodgepole pine (Pinus contorta Dougl. ex Loud.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings to a partial overstory removal in relatively dry conifer forests of central British Columbia. Growth was evaluated in four parts of the studied trees: radial increment in roots, in the base of the stem, and in branches, as well as leader height growth extension. Our findings show that following release from the overstory, early growth increases were largest in the roots and stems irrespective of the species or the size class. Differences between the species were observed in greater absolute height growth for pine, whereas Douglas-fir invested in greater stem growth, especially in the larger individuals. Important differences also occurred temporally. Both species (and all size classes) responded with an immediate increase in root growth followed, after a 1-year delay, by an increase in stem growth. Branch radial increment (for pine) and leader height growth (both species), however, experienced 2 to 3 year growth reductions before responding. It is therefore suggested that individuals restore the root–shoot balance by greater initial investments to root growth to offset the increased transpiration losses associated with the greater light and higher temperature conditions and the relative changes in the photosynthetic versus nutrient uptake capacity following the canopy opening. Foresters may therefore be able to manipulate tree growth responses by using an appropriate degree of overstory removal or opening size.

Aboveground growth responses of understory Abies lasiocarpa saplings to different release cuts

2003 ◽  
Vol 33 (9) ◽  
pp. 1593-1601 ◽  
Author(s):  
Marek J Krasowski ◽  
Jian R Wang
Keyword(s):  
Radial Growth ◽  
Height Growth ◽  
Abies Lasiocarpa ◽  
Initial Growth ◽  
Growth Responses ◽  
White Birch ◽  
Clear Cutting ◽  
Growth Increments ◽  
Advance Regeneration ◽  
Large Trees

A white birch (Betula papyrifera Marsh.) overstory of a 30+ year old stand was thinned or completely removed, releasing an advance regeneration of subalpine fir (Abies lasiocarpa (Hook.) Nutt.). The overstory was clear-cut (T0), thinned to 600 (T600) or to 1200 (T1200) stems/ha, or left uncut (control). Three years after release, understory responses were best demonstrated by decreasing specific leaf area with increasing release level and by changes to height and radial growth increments. Clear-cutting the overstory stalled the height growth in fir for two seasons and radial growth at the tree base for one season. Compared with the control, the 3-year height increment was proportionally greatest in intermediate trees of T600, and this treatment produced the overall best response in height growth. Complete birch removal produced the best radial growth response despite the initial growth check. However, no release treatment significantly affected the whole tree variables (aboveground biomass, height, diameter at breast height (DBH), live crown ratio) within the studied time frame. Shoot silhouette ratios were lowest in the completely released understory trees, while they were similar to those of the controls in all partial-release treatments. Tree sturdiness (height/DBH ratio) was 80–90 in most treatments except T0, where it declined to below 80. Despite this improvement, large trees in T0 have been damaged by wind and snow.

Ten-year growth and survival of Douglas-fir seedlings treated with plant growth regulating substances at transplant

2000 ◽  
Vol 30 (11) ◽  
pp. 1778-1787 ◽  
Author(s):  
C F Scagel ◽  
R G Linderman ◽  
R K Scagel
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Douglas Fir ◽  
Growth Responses ◽  
Indole Butyric Acid ◽  
Growth And Survival ◽  
Growing Seasons ◽  
Tree Survival ◽  
Stock Types ◽  
The Cost

Commercially available plant growth regulators (PGRs) or moisture retention gels, applied to the roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) before planting, can modify indole-3-acetic acid (IAA) levels in roots, root growth responses, and tree survival. We treated two different 1+0 stock types (PSB313B and PSB323) of Douglas-fir with indole-butyric acid (IBA), ethephon (Ethrel®), alginate, or a combination of IBA and alginate. New root growth and IAA levels in roots were measured 2 weeks after planting, and aboveground growth and tree survival were monitored over 10 growing seasons after planting. Treatment with IBA or the combination of IBA and alginate increased IAA conjugate and free IAA levels in roots, root growth, and tree survival. Alginate treatment alone increased new root growth and tree survival, but did not increase free IAA levels in roots. Ethrel® treatment increased free IAA levels and root growth, but had no effect on IAA conjugates or tree survival. A cost analysis suggests that use of certain PGRs or alginate decreases the cost required to attain target stocking and increased tree size. Our results suggest that application of PGRs or other root-promoting materials to the roots of Douglas-fir before planting has the potential to be a cost-beneficial method for increasing root growth and tree survival.

Ten-year results of strip clear-cutting in Quebec black spruce stands

2000 ◽  
Vol 30 (1) ◽  
pp. 59-66 ◽  
Author(s):  
David Pothier
Keyword(s):  
Picea Mariana ◽  
Black Spruce ◽  
Height Growth ◽  
Clear Cutting ◽  
Advance Regeneration ◽  
Spruce Stands ◽  
Harvesting Method ◽  
Cost Efficient ◽  
One Year ◽  
Cutting System

Regeneration of first-cut strips in a two-cut system of strip clear-cutting was compared to that of large clear-cutting in four different areas representative of the black spruce (Picea mariana (Mill.) BSP) stands of the boreal forest of Quebec. Seedlings were more evenly distributed in clearcut strips than in large clearcuts. Differences of about 10 000 black spruce seedlings per hectare and 20% of stocking were observed in favour of clearcut strips compared to large clearcuts. Black spruce stocking was about 14% larger on lowland than on upland sites but height growth was better on upland sites. A regeneration problem similar to that of large clearcuts was observed when the second strips were cut. One year after cutting these second strips, winter harvesting resulted in a 23% gain in black spruce stocking as compared to summer harvesting. Even if black spruce stocking marginally increased during the years following winter harvesting, the height advantage of the preserved advance growth justifies the application of this harvesting method. The strip clear-cutting system effectively improved the stocking of former black spruce stands but if the stocking level of advance growth is adequate, careful harvesting to preserve advance regeneration should be the preferred method since it would be more cost-efficient.

Douglas-fir and white fir advance regeneration for renewal of mixed-conifer forests

1993 ◽  
Vol 23 (7) ◽  
pp. 1427-1437 ◽  
Author(s):  
Steven D. Tesch ◽  
Ed J. Korpela
Keyword(s):  
Mediterranean Climate ◽  
Height Growth ◽  
Douglas Fir ◽  
Regression Equations ◽  
Site Class ◽  
Class V ◽  
Advance Regeneration ◽  
White Fir ◽  
Mixed Conifer Forests ◽  
Site Classes

Stem analysis of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and white fir (Abiesconcolor (Gord. & Glend.) Lindl.) advance regeneration 20 years after overstory removal showed that both species can respond in height growth to become dominant components of future stands on medium- to low-quality sites with a Mediterranean climate. Average annual height growth of both species nearly doubled on site classes III and IV during the first 5 years after release and continued to increase over the 20-year period of observation. Trees on the poorer site class V responded more slowly, but achieved similar 5-year periodic annual height growth after 20 years. Regression analyses indicated that prerelease height growth and site class were generally the most important variables in describing height growth after overstory removal, but regression equations left much variability in growth unexplained. Discriminant analysis was used to develop functions that identified trees meeting or exceeding specified levels of average annual height growth 5, 10, or 20 years after release; the classifications were generally successful at least 70% of the time.

scholarly journals Thirteen-Year Height and Diameter Growth of Douglas-Fir Seedlings under Alternative Regeneration Cuts in Pacific Northwest

2011 ◽  
Vol 26 (2) ◽  
pp. 57-63 ◽  
Author(s):  
Tzeng Yih Lam ◽  
Douglas A. Maguire
Keyword(s):  
Pacific Northwest ◽  
Treatment Effects ◽  
Basal Area ◽  
Height Growth ◽  
Douglas Fir ◽  
Diameter Growth ◽  
Treatment Level ◽  
Growth Responses ◽  
Significant Treatment ◽  
Ecosystem Responses

Abstract Interest in managing Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) forests in the Pacific Northwest under silvicultural systems other than traditional clearcutting has prompted research on the efficacy of alternative systems for successful regeneration and sustained timber productivity of Douglas-fir. The College of Forestry Integrated Research Project, implemented by Oregon State University, was established to compare various ecosystem responses and public perceptions among treatments implemented under clearcutting, shelterwood-with-reserves, and group selection silvicultural systems. The objective of this analysis was to quantify the following three responses of planted Douglas-fir seedlings to initial regeneration cuts: cumulative 13-year height growth (H13yr; 1992–2004), cumulative 13-year diameter growth (D13yr; 1992–2004), and most recent 5-year height growth (ΔH5yr; 2000–2004). Differences in variability of overstory density at the treatment level led to significant differences in the variance of understory growth responses. After accounting for heterogeneous variance, analysis of variance indicated significant treatment effects for all three responses. Treatment effects were explained by the decline in H13yr, D13yr, and ΔH5yr with increasing overstory competition as represented by basal area of residual trees immediately after harvesting (initial basal area). Predicted height:diameter ratio of Douglas-fir seedlings increased as IBA increased. Under regeneration methods that retain a portion of the overstory, a residual overstory with basal area <80 ft2/ac allows establishment, growth, and continued survival of Douglas-fir regeneration during the 13 years following harvest.

Effects of soil organic layer removal on regeneration after clear-cutting a northern hardwood stand in New Brunswick

1993 ◽  
Vol 23 (10) ◽  
pp. 2093-2100 ◽  
Author(s):  
Mark R. Roberts ◽  
Hongyun Dong
Keyword(s):  
Seedling Survival ◽  
Woody Species ◽  
Height Growth ◽  
Organic Layer ◽  
Northern Hardwood ◽  
Clear Cutting ◽  
Seed Availability ◽  
Soil Organic Layer ◽  
Advance Regeneration ◽  
Over Time

Our objective was to determine the effects of clear-cutting and removal of the soil organic layer and residual vegetation on regeneration of woody species from seed. Germination, survival, and height growth of woody seedlings were followed over a 4-year period after clear-cutting in plots with and without the organic layer and vegetation removed. After 4 years, Betulaalleghaniensis Britton and Rubusidaeus L. predominated on the disturbed plots. On the undisturbed plots, Rubus, Acersaccharum Marsh. (mostly advance regeneration), and Acerpensylvanicum L. (new germinants and advance regeneration) were most abundant. Germination (all species combined) was 1.2–1.5 times higher on the disturbed plots in the first 2 years. Seedling survival was 19–33% higher on the disturbed plots in years 1 and 2 because of the lower occurrence of lethal surface temperatures (>42 °C). Little recruitment of most species occurred after year 2 except for A. saccharum, which increased in density over time on both treatments. Acerpensylvanicum occurred only on the undisturbed plots and decreased steadily in density over time. Differences among species in regeneration patterns were related to seed availability, seedbed characteristics, and regeneration strategies. Betula was the tallest species on 40% of the disturbed plots in spite of higher Rubus densities. Advance regeneration dominated 57% of the undisturbed plots. The relative heights, densities, and growth rates of species indicate that Rubus provides less competition than advance regeneration for Betula crop trees.

Recovery of Douglas-fir seedlings and saplings wounded during overstory removal

1993 ◽  
Vol 23 (8) ◽  
pp. 1684-1694 ◽  
Author(s):  
Steven D. Tesch ◽  
Kathryn Baker-Katz ◽  
Ed J. Korpela ◽  
John W. Mann
Keyword(s):  
Discriminant Analysis ◽  
Height Growth ◽  
Douglas Fir ◽  
Upright Position ◽  
Size Classes ◽  
Lateral Branches

Damaged and undamaged Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings and saplings, ranging in height from 15 to 450 cm, were monitored for 6 years after overstory removal to evaluate recovery from an assortment of logging wounds. Mortality (26%) was concentrated in seedlings less than 75 cm tall and was not related to damage. Surviving trees recovered from most wounds within the 6-year period. In most cases, lateral branches turned up to replace broken terminal leaders or stems; bole wounds healed over; and trees that had been pushed over returned to an upright position. A combination of a bole wound and being pushed to the ground resulted in the poorest recovery, especially for larger trees. With discriminant analysis, initial crown ratio alone enabled correct reclassification of sample trees as crop trees from 64 to 71% of the time; small trees were the most difficult to classify correctly. The addition of preharvest height growth and percentage of bole girdled variables improved the reclassification slightly. Across all three size classes analyzed, damaged trees with initial crown ratios of at least 0.66 were classified as crop trees a minimum of 75% of the time after 6 years. Significant height growth reductions were found only for damaged trees taller than 150 cm.

Root system response of naturally regenerated Douglas-fir (Pseudotsuga menziesii) after complete overstory removal

2012 ◽  
Vol 42 (10) ◽  
pp. 1858-1864 ◽  
Author(s):  
Nathan A. Briggs ◽  
Christian Kuehne ◽  
Ulrich Kohnle ◽  
Jürgen Bauhus
Keyword(s):  
Pseudotsuga Menziesii ◽  
Root Elongation ◽  
Small Sample Size ◽  
Root Systems ◽  
Douglas Fir ◽  
Small Sample ◽  
System Response ◽  
Radial Increment ◽  
Advance Regeneration ◽  
Closed Canopy

Long regeneration periods, which result in two-layered or multilayered forest stands, are an important element of the close-to-nature forest management paradigm in central Europe. Such extended regeneration periods, however, may lead to undesirable development of advance regeneration, specifically in species such as Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) where root growth is strongly curtailed under competition. We hypothesized that root systems of naturally regenerated Douglas-fir that had grown under closed canopy for prolonged periods would be inhibited in their capacity to develop adequate structural root systems following release through removal of the canopy. Complete root systems of six approximately 25-year-old Douglas-fir that had grown for at least 12 years underneath a closed canopy before overstory removal were excavated using subterranean explosives. Root elongation, radial increment of primary lateral and vertical roots, and aboveground stem growth were investigated using retrospective analysis of growth rings. Structural roots of the previously suppressed Douglas-fir were capable of strongly responding to release from competition relative to growth prior to removal, but this response, particularly in the form of root elongation, was delayed. However, since the growth response of roots was not stronger than that above ground, an imbalanced root to shoot ratio, likely developed in trees when grown under the canopy, was not reverted. Generalizing interpretation of the derived findings of this study is limited because of the small sample size and the lack of freely grown control trees. Whether or not previously suppressed trees can develop the same physical stability as open-grown individuals therefore deserves further investigation.

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