Paclobutrazol and triadimefon effects on conifer seedling growth and water relations

1990 ◽  
Vol 20 (6) ◽  
pp. 722-729 ◽  
Author(s):  
R. van den Driessche
Keyword(s):  
Stomatal Conductance ◽  
Active Ingredient ◽  
White Spruce ◽  
Height Growth ◽  
Douglas Fir ◽  
Sand Culture ◽  
Growth Responses ◽  
Synthesis Inhibitor ◽  
Xylem Water Potential ◽  
Reduced Height

Growth responses of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings to the gibberellin synthesis inhibitor paclobutrazol were examined in sand culture. Shoot and root dry weights and root lengths were reduced at 5 mg (active ingredient) of paclobutrazol per litre, in the nutrient solution, although the proportion of dry matter allocated to roots was increased by 5 mg (active ingredient) of paclobutrazol per litre. Similar effects were observed with triadimefon, although the reduction in height growth was less in triadimefon-treated seedlings than in paclobutrazol-treated seedlings. Stomatal conductance, transpiration, and needle area:weight ratio were reduced by both paclobutrazol and triadimefon treatments of 13.5-week-old seedlings, although paclobutrazol was more effective than triadimefon in reducing needle arear:weight ratio. Treatment of 1-year-old container seedlings of Douglas-fir and white spruce (Piceaglauca (Moench) Voss) by shoot dipping or plug drenching with paclobutrazol, in December or March, reduced height growth and new needle area:weight ratio after 6 weeks growth in a greenhouse. Xylem water potential of paclobutrazol-drenched seedlings was increased by 0.7 MPa above controls (−1.8 MPa) 11 weeks after planting, and stomatal conductance of drenched white spruce increased with paclobutrazol concentration.

scholarly journals Soil disturbance and 10-year growth response of coast Douglas-fir on nontilled and tilled skid trails in the Oregon Cascades

2002 ◽  
Vol 32 (2) ◽  
pp. 233-246 ◽  
Author(s):  
Ronald Heninger ◽  
William Scott ◽  
Alex Dobkowski ◽  
Richard Miller ◽  
Harry Anderson ◽  
...  
Keyword(s):  
Tree Growth ◽  
Volume Growth ◽  
Soil Surface ◽  
Soil Bulk Density ◽  
Soil Disturbance ◽  
Height Growth ◽  
Douglas Fir ◽  
Negative Effects ◽  
Fine Soil ◽  
Reduced Height

We (i) quantified effects of skidder yarding on soil properties and seedling growth in a portion of western Oregon, (ii) determined if tilling skid trails improved tree growth, and (iii) compared results with those from an earlier investigation in coastal Washington. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were hand planted at eight recent clearcuts in skid ruts in either nontilled or tilled trails, in adjacent soil berms, and in adjacent logged-only portions. Four and 5 years after skidding, rut depths averaged 15 cm below the original soil surface; mean fine-soil bulk density (0–30 cm depth) below ruts of nontilled trails exceeded that on logged-only portions by 14%. Height growth on nontilled trails averaged 24% less than on logged-only portions in year 4 after planting and decreased to 6% less in year 7. For years 8–10, mean height growth was similar for all treatments. Reduced height growth lasted for about 7 years compared with 2 years for coastal Washington. Ten years after planting, trees in skid-trail ruts averaged 10% shorter with 29% less volume than those on logged-only portions. Tillage improved height and volume growth to equal that on logged-only portions. Generalizations about negative effects of skid trails on tree growth have limited geographic scope.

A comparison of growth responses of Douglas fir and Sitka spruce to different nitrogen, phosphorus, and potassium levels in sand culture

1968 ◽  
Vol 46 (5) ◽  
pp. 531-537 ◽  
Author(s):  
R. van den Driessche
Keyword(s):  
Weight Ratio ◽  
Sitka Spruce ◽  
Douglas Fir ◽  
Response To Treatment ◽  
Sand Culture ◽  
Mineral Nutrient ◽  
Growth Responses ◽  
Net Assimilation ◽  
Phosphorus And Potassium ◽  
Nitrogen Phosphorus

Douglas fir and Sitka spruce seedlings were grown in sand culture under controlled mineral nutrient conditions. Nitrogen, phosphorus, and potassium supply levels were varied one nutrient at a time in three separate experiments. The relative growth rate (RGR) of Sitka spruce was found to be higher than that of Douglas fir at high levels of N and K supply, although in all treatments the total dry matter production of Douglas fir was greater than that of Sitka spruce after 95 days. At low levels of P supply the RGR of Douglas fir was greater than that of Sitka spruce.Effects of treatment on RGR were apparently achieved mainly by their effect on net assimilation rate, but leaf weight ratio also showed a small, and significant, response to treatment.

Influence of container nursery regimes on drought resistance of seedlings following planting. I. Survival and growth

1991 ◽  
Vol 21 (5) ◽  
pp. 555-565 ◽  
Author(s):  
R. van den Driessche
Keyword(s):  
Drought Stress ◽  
Lodgepole Pine ◽  
Weight Ratio ◽  
Dry Weight ◽  
White Spruce ◽  
Douglas Fir ◽  
Reduced Height ◽  
Growth Increase ◽  
Sand Beds ◽  
Container Nursery

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) seedlings were grown in Styroblock containers in a container nursery from February to July 1988 and then exposed to three temperatures and three levels of drought stress applied factorially during 18 July to 29 September 1988. Mean temperatures of 13, 16, and 20 °C were imposed in growth chambers, in a cooled plastic house, and in an ambient plastic house, respectively. Control, medium, and severe levels of drought stress were imposed in a series of eight cycles, resulting in mean xylem pressure potentials of −0.32, −0.50, and −0.99 MPa, respectively. Seedlings were kept in the ambient plastic house until January, when they were lifted and cold-stored until planting. Between 11 and 18 April 1989, seedlings were planted in 0.5 m deep sand beds, which provided hygric, mesic, and xeric conditions for testing all species and treatments. At the end of nursery growth, increase in nursery temperature increased height and height:diameter ratio in all species and shoot:root dry weight ratio in Douglas-fir and lodgepole pine. Increase in temperature also increased the number of seedlings with large well-formed buds in white spruce, but reduced the number in Douglas-fir. Drought stress reduced height and dry weight in all species and bud length in lodgepole pine. After 9 weeks in sand beds, low nursery temperature increased survival (19% for lodgepole pine and white spruce grown in the xeric bed), except for Douglas-fir grown in the xeric bed. Nursery drought stress also increased survival (16% for Douglas-fir and lodgepole pine in the xeric bed), but had little effect on white spruce. Low temperature and drought stress treatments that increased survival also reduced height and dry weight of lodgepole pine and white spruce after one growing season in sand beds. Survival showed significant negative correlations with height, dry weight, and height:diameter and shoot:root weight ratios. Low nursery temperature continued to affect growth after planting, increasing relative growth rate and allometric ratio (K) of Douglas-fir and decreasing K of white spruce.

Soil properties, aspen, and white spruce responses 5 years after organic matter removal and compaction treatments

2005 ◽  
Vol 35 (8) ◽  
pp. 2045-2055 ◽  
Author(s):  
Richard Kabzems ◽  
Sybille Haeussler
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Soil Compaction ◽  
Forest Floor ◽  
White Spruce ◽  
Post Treatment ◽  
Ecosystem Dynamics ◽  
Growth Responses ◽  
Organic Matter Removal ◽  
Reduced Height

Retaining organic matter and preventing soil compaction are important factors affecting the sustainability of managed forests. To assess how these factors affect short-term ecosystem dynamics, pre-treatment and 1 year and 5 year post-treatment soil properties and post-treatment tree growth responses were examined in a boreal trembling aspen (Populus tremuloides Michx.) dominated ecosystem in northeastern British Columbia, Canada. The experiment used a completely randomized design with three levels of organic matter removal (tree stems only; stems and slash; stems, slash, and forest floor) and three levels of soil compaction (none, intermediate (2-cm impression), heavy (5-cm impression)). Removal of the forest floor initially stimulated aspen regeneration and significantly reduced height growth of aspen and white spruce (Picea glauca (Moench) Voss). The compaction treatments had no effect on aspen regeneration density. At year 5, heights of both aspen and white spruce were negatively correlated (r2 > 0.31, p < 0.0001) with upper mineral soil bulk density and were lowest on forest floor removal treatments, where minimal recovery from compaction was observed. There was some evidence for recovery of soil properties to preharvest conditions where expansion of herbaceous vegetation increased soil organic matter.

scholarly journals Effect of Leader Clipping on Height Growth of Young Coastal Douglas-Fir (Pseudotsuga menziesii var. menziesii)

2002 ◽  
Vol 17 (2) ◽  
pp. 75-77 ◽  
Author(s):  
Frank C. Sorensen
Keyword(s):  
Pseudotsuga Menziesii ◽  
Height Growth ◽  
Douglas Fir ◽  
Height Increment ◽  
Depressing Effect ◽  
Linear Fashion ◽  
Diameter Increment ◽  
Reduced Height

Abstract Leaders of 3- through 7-yr-old Douglas-fir seedlings were left unclipped or were clipped for 1 to 4 consecutive years. Terminal removal reduced height increment in a significantly linear fashion and was about 19 cm for each year clipped. All treatments had comparable height increment in the 4 yr after clipping, and the initial depressing effect on height was still present at age 23. Diameter increment was reduced but not significantly. West. J. Appl. For. 17(2):75–77

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.

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.

Changes in mitotic index during onset of dormancy in Douglas-fir seedlings

1980 ◽  
Vol 10 (3) ◽  
pp. 371-378 ◽  
Author(s):  
W. C. Carlson ◽  
W. D. Binder ◽  
C. O. Feenan ◽  
C. L. Preisig
Keyword(s):  
Mitotic Index ◽  
Cold Storage ◽  
Rapid Determination ◽  
Moisture Stress ◽  
Height Growth ◽  
Douglas Fir ◽  
Seed Source ◽  
Reduced Height ◽  
Terminal Buds

A method is presented for rapid determination of the mitotic index in terminal buds of Douglas-fir, Pseudotsugamenziesii (Mirb.) Franco. Fertilization at planting increased mitotic index but fertilized seedlings entered dormancy at the same time as unfertilized seedlings. Cold storage, prior to dormancy, reduced mitotic index rapidly and was related to reduced height growth the following year. The effects of moderate moisture stress and seed source on mitotic index were slight.

Light-growth responses of coastal Douglas-fir and western redcedar saplings under different regimes of soil moisture and nutrients

2001 ◽  
Vol 31 (12) ◽  
pp. 2124-2133 ◽  
Author(s):  
C Ronnie Drever ◽  
Kenneth P Lertzman
Keyword(s):  
Soil Moisture ◽  
Growth Rates ◽  
Growth Response ◽  
Height Growth ◽  
Douglas Fir ◽  
Site Quality ◽  
Thuja Plicata ◽  
Growth Responses ◽  
Western Redcedar ◽  
Light Levels

We characterized the radial and height growth response to light for coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) and western redcedar (Thuja plicata Donn ex D. Don) saplings growing in sites of different regimes of soil moisture and nutrients on the east coast of Vancouver Island, British Columbia. We determined that at low light levels, site quality has little effect on the growth response of Douglas-fir saplings. At light levels above approximately 40 and 60% full sun, Douglas-fir saplings show statistically significant differences in height and radial growth, respectively, that reflect the differences in soil moisture and nutrient regimes of the sites we examined. Western redcedar approaches its maximum radial and height growth rates at about 30% full sun. Our data suggest that partial-cutting treatments need to create light environments greater than about 40% full sun to achieve growth that represents a high proportion of the site growing potential for Douglas-fir at full sun, while the high shade tolerance of western redcedar allows silvicultural treatments that retain a high amount of forest structure without compromising growth rates of young trees.

Effects of mechanical stimulus, shade, and nitrogen fertilization on morphology and bending resistance in Douglas-fir seedlings

2003 ◽  
Vol 33 (9) ◽  
pp. 1602-1609 ◽  
Author(s):  
Stephen J Mitchell
Keyword(s):  
Nitrogen Fertilization ◽  
Mechanical Stimulus ◽  
Douglas Fir ◽  
Height Increment ◽  
Stem Form ◽  
Diameter Increment ◽  
Reduced Height ◽  
Bending Resistance ◽  
Volume Increment ◽  
Bending Stresses

Three-year-old coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were planted in a factorial experiment with three levels of shading (0, 30, and 60%), three levels of mechanical stimulus (staked, freestanding, and bent), and two levels of nitrogen fertilization (0 and 200 kg/ha) to investigate the separate and combined effects of these factors on morphology and bending resistance. Fertilization increased branch angle and increased the sensitivity of branch and leader extension to bending stresses but did not affect volume increment, stem form, or bending resistance. The effects of shading and mechanical treatments on morphology were independent and additive. Shading reduced stem diameter and volume increment, but did not affect height increment, producing more slender trees. Bending produced less slender trees through a combination of reduced height increment and increased diameter increment. Staking did not affect tree morphology. Trees under heavy shade were responsive to bending but were more slender and had lower bending resistance than unshaded trees with the same mechanical stimulus. These results point towards the biological basis for the development of tree instability in high density stands.

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