Height development of shade-tolerant conifer saplings in multiaged Acadian forest standsPublication 2954 of the Maine Agricultural and Forest Experiment Station, University of Maine, Orono, Maine.

2007 ◽  
Vol 37 (12) ◽  
pp. 2715-2723 ◽  
Author(s):  
Andrew R. Moores ◽  
Robert S. Seymour ◽  
Laura S. Kenefic
Keyword(s):  
Abies Balsamea ◽  
Growth Dynamics ◽  
Basal Area ◽  
Height Growth ◽  
Maximum Height ◽  
Conifer Species ◽  
Low Light ◽  
Light Levels ◽  
Time Period ◽  
Forest Experiment Station

Understory growth dynamics of northern conifer species were studied in four stands managed under multiaged silvicultural systems in eastern Maine. Height growth of Picea rubens Sarg., Abies balsamea (L.) Mill., and Tsuga canadensis (L.) Carr. saplings between 0.5 and 6.0 m in height was related to the proportion open sky (POS), using sapling height as a covariate. Height growth of T. canadensis equaled A. balsamea and exceeded P. rubens under very low light levels (POS < 0.1) but is much less responsive to both increasing POS and taller heights, reaching 50% of its maximum height growth at a POS of only 0.09. Abies balsamea outgrew P. rubens under similar dark conditions; at higher light levels (POS > 0.10), both species grew similarly. Evidently, no feasible overstory manipulation of light alone can promote more rapid height development of P. rubens saplings over A. balsamea. A nonlinear light-prediction model using stand basal area is linked with height-growth prediction equations to quantify sapling development from 0.5 to 6 m. Depending on overstory density, P. rubens requires a height advantage of 0.14–0.33 m over a 0.5 m tall A. balsamea to reach a height of 6 m over the same time period.

scholarly journals Mortality Patterns Following Spruce Budworm Infestation in Unprotected Spruce-Fir Forests in Maine

2003 ◽  
Vol 20 (4) ◽  
pp. 148-153 ◽  
Author(s):  
Dale S. Solomon ◽  
Lianjun Zhang ◽  
Thomas B. Brann ◽  
David S. Larrick
Keyword(s):  
Abies Balsamea ◽  
Basal Area ◽  
Growth Function ◽  
Red Spruce ◽  
Balsam Fir ◽  
Stem Density ◽  
Cumulative Mortality ◽  
Time Period ◽  
Composition Classes ◽  
Annual Mortality

Abstract Cumulative and annual mortality of red spruce (Picea rubens Sarg.) and balsam fir [Abies balsamea (L.) Mill.] were examined over a 10 yr period to follow the mortality patterns in unprotected spruce-fir forests in northern Maine. Different mortality patterns were determined based on stand composition classes and merchantability classes. In general, balsam fir was more vulnerable to budworm attack, and reached 92–100% basal area mortality and 84–97% stem density mortality 12 yr after the start of the outbreak. Red spruce, in contrast, had approximately 32–59% basal area mortality and 30–66% stem density mortality during the same time period. Balsam fir mortality started 1 to 2 yr before spruce, while spruce mortality continued 2 to 3 yr after fir mortality was completed. Higher mortality was found in smaller trees than sawtimber-sized trees. Stands with hardwood components (30–70% in basal area) had the lowest mortality rate for both species. Furthermore, Schnute growth function (Schnute 1981) was used to characterize the cumulative mortality trajectories after the defoliation of spruce and fir by stand composition classes. The models estimated the time when annual mortality achieved maximum, the cumulative mortality at that time, and the asymptotic mortality over a long time period after the start of the attack. The information can provide guidelines for predicting protection strategies and scheduling salvage harvests.

Early above- and below-ground responses of subboreal conifer seedlings to various levels of deciduous canopy removal

2006 ◽  
Vol 36 (8) ◽  
pp. 1891-1899 ◽  
Author(s):  
Yves Claveau ◽  
Philip G Comeau ◽  
Christian Messier ◽  
Colin P Kelly
Keyword(s):  
Picea Glauca ◽  
Abies Balsamea ◽  
Root Diameter ◽  
Height Growth ◽  
Stem Diameter ◽  
Abies Lasiocarpa ◽  
Size Dependent ◽  
Light Levels ◽  
Below Ground ◽  
Canopy Removal

We examined the growth of understory conifers, following partial or complete deciduous canopy removal, in a field study established in two regions in Canada. In central British Columbia, we studied the responses of three species (Pseudotsuga menziesii var. glauca (Beissn.) Franco, Picea glauca (Moench) Voss × Picea engelmannii Parry ex Engelm., and Abies lasiocarpa (Hook.) Nutt.), and in northwestern Quebec, we studied one species (Abies balsamea (L.) Mill.). Stem and root diameter and height growth were measured 5 years before and 3 years after harvesting. Both root and stem diameter growth increased sharply following release but seedlings showed greater root growth, suggesting that in the short term, improvement in soil resource capture and transport, and presumably stability, may be more important than an increase in stem diameter and height growth. Response was strongly size dependent, which appears to reflect greater demand for soil resources as well as higher light levels and greater tree vigour before release for taller individuals. Growth ratios could not explain the faster response generally attributed to true fir species or the unusual swift response of spruces. Good prerelease vigour of spruces, presumably favoured by deciduous canopies, could explain their rapid response to release.

Early regeneration and growth dynamics of Populus tremuloides suckers in relation to fire severity

2003 ◽  
Vol 33 (10) ◽  
pp. 1998-2006 ◽  
Author(s):  
G. Geoff Wang
Keyword(s):  
Populus Tremuloides ◽  
Fire Severity ◽  
Growth Dynamics ◽  
Basal Area ◽  
Height Growth ◽  
Analysis Of Covariance ◽  
Total Variance ◽  
First Year ◽  
The Third ◽  
Early Regeneration

Four boreal mixedwood stands burned by the 1999 Black River wildfire in southeastern Manitoba were sampled to determine the effect of fire severity on density and diameter and height growth of trembling aspen (Populus tremuloides Michx.) suckers during the first three postfire years. Analysis of covariance, using prefire aspen basal area as the covariate, indicated that fire severity significantly affected postfire aspen sucker density, with significantly lower density found on severely burned plots. Changes in aspen sucker density over the three postfire years depended on fire severity, with significant changes observed only on scorched and lightly burned plots. Sucker mortality was positively related to the initial sucker density, with more than 80% of the total variance being explained. Fire severity significantly affected the growth of dominant aspen suckers in the first, but not the second and the third, postfire years. The first year of growth initially increased and then remained stable with the increase in density, while the second and third years of growth were not affected by density. Since fire severity within and (or) among burned stands is inherently heterogeneous, the effect of fire severity must be taken into account in predicting postfire density and growth of aspen suckers.

Spatially explicit modeling of PAR transmission and growth of Picea glauca and Abies balsamea in the boreal forests of Alberta and Quebec

2005 ◽  
Vol 35 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Kenneth J Stadt ◽  
Victor J Lieffers ◽  
Ronald J Hall ◽  
Christian Messier
Keyword(s):  
Picea Glauca ◽  
Boreal Forests ◽  
Abies Balsamea ◽  
Height Growth ◽  
Growth Potential ◽  
Aerial Photographs ◽  
Spatially Explicit ◽  
Maximum Height ◽  
Eastern Canada ◽  
Functional Relationships

To investigate the feasibility of a spatially explicit, radiation-based regeneration model for the boreal forest, we tested the predictions of a three-dimensional simulator of photosynthetically active radiation transmission (%PAR), MIXLIGHT, and the growth response of understory Abies balsamea (L.) Mill. (balsam fir) and Picea glauca (Moench) Voss (white spruce) to %PAR in two large (>1 ha) mixed-species forest sites, one in eastern Canada at Lac Duparquet, Quebec, and one in western Canada at Calling Lake, Alberta. Overstory tree locations and dimensions were obtained from aerial photographs or ground measurements and allometric relationships. Seasonal %PAR calculated by MIXLIGHT for the Calling Lake site was very similar to seasonal %PAR measured by quantum sensors (n = 5, %PAR range = 15%–33%, r = 0.93). Daily measurements of %PAR were also predicted well by simulations at both sites (n = 34–36, %PAR range = 1%–45%, r ≥ 0.76). Functional relationships, designed to saturate at the maximum height growth potential of these sites, were developed to predict sapling height growth from simulated seasonal %PAR and initial height (R2 ≥ 0.74). These results demonstrate the potential of the MIXLIGHT simulator for estimating PAR at microsites within heterogeneous forests and for modeling understory tree growth.

Effects of Crown Thinning on Baldcypress Height, Diameter, and Volume Growth

1988 ◽  
Vol 12 (4) ◽  
pp. 252-256 ◽  
Author(s):  
Stephen G. Dicke ◽  
John R. Toliver
Keyword(s):  
Volume Growth ◽  
Basal Area ◽  
Height Growth ◽  
Taxodium Distichum ◽  
Volume Increment ◽  
Crown Thinning ◽  
Epicormic Branching

Abstract Crown thinning a 63-year-old stand of baldcypress (Taxodium distichum [L.] Rich.) averaging 220 ft²/ac of basal area to 180, 140, and 100 ft²/ac resulted in 5-year diameter growths of 0.44, 0.51, and 0.77 in., respectively. The unthinned control was significantly less at 0.31 in. Six-year height growth averaged 3.1 ft and was not influenced by treatment. Thinning to 140 and 100 ft²/ac stimulated epicormic branching on many trees, which may lower log quality. All crown thinning treatments appeared to increase sawtimber volume increment and sawtimber volume/ac over the control 5 years after thinning. South. J. Appl. For. 12(4):252-256.

Growth ofPseudotsuga menziesiiandTsuga heterophyllaseedlings along a light gradient: resource allocation and morphological acclimation

1997 ◽  
Vol 75 (9) ◽  
pp. 1424-1435 ◽  
Author(s):  
D. Mailly ◽  
J. P. Kimmins
Keyword(s):  
Leaf Morphology ◽  
Biomass Accumulation ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Low Light ◽  
Growing Seasons ◽  
Light Levels ◽  
Light Gradient ◽  
Relative Light Intensity

Silvicultural alternatives that differ in the degree of overstory removal may create shady environments that will be problematic for the regeneration of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Gradients of light in the field were used to compare mortality, growth, and leaf morphological acclimation of two conifer species of contrasting shade tolerances: Douglas-fir and western hemlock (Tsuga heterophylla (Raf.) Sarg.). Results after two growing seasons indicated that Douglas-fir mortality occurred mainly at relative light intensity (RLI) below 20%, while western hemlock mortality was evenly distributed along the light gradient. Height, diameter, and biomass of the planted seedlings increased with increasing light for both species but at different rates, and maximum biomass accumulation always occurred in the open. Douglas-fir allocated more resources to stem biomass than western hemlock, which accumulated more foliage biomass. Increases in specific leaf area for Douglas-fir seedlings occurred at RLI ≤ 0.4 and red/far red (R/FR) ratio ≤ 0.6, which appear to be the minimal optimum light levels for growth. Conversely, western hemlock seedlings adjusted their leaf morphology in a more regular pattern, and changes were less pronounced at low light levels. These results, along with early mortality results for Douglas-fir, suggest that the most successful way to artificially regenerate this species may be by allowing at least 20% of RLI for ensuring survival and at least 40% RLI for optimum growth. Key words: light, light quality, leaf morphology, acclimation.

Photoinhibition of DCMU-Enhanced Fluorescence in Lake Ontario Phytoplankton

1987 ◽  
Vol 44 (12) ◽  
pp. 2144-2154 ◽  
Author(s):  
M. Putt ◽  
G. P. Harris ◽  
R. L. Cuhel
Keyword(s):  
Vertical Mixing ◽  
Natural Populations ◽  
Bright Light ◽  
Euphotic Zone ◽  
Lake Ontario ◽  
Enhanced Fluorescence ◽  
Low Light ◽  
Light Levels ◽  
Phosphorus Status

Measurement of 1-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) enhanced fluorescence (FDCMU) suggested that photoinhibition of photosynthesis was frequently an artifact of in situ bottle incubations in Lake Ontario phytoplankton. In a seasonal study, FDCMU of all populations was depressed by bright light in an incubator. However, when the euphotic zone did not exceed the depth of the mixed layer, vertical transport of phytoplankton into either low-light or dark regions apparently allowed reversal of photoinhibition of FDCMU. Advantages of FDCMU as a bioassay of vertical mixing include rapidity of response time, ease of measurement in the field, and insensitivity of this parameter to changes in phosphorus status of the population. Because of seasonal changes in the photoadaptive response of natural populations, the rate constants and threshold light levels required to cause the response must be determined at each use if the method is to be quantitative.

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