Epicormic Branches Research Articles

Crown structure of old-growth Douglas-fir in the western Cascade Range, Washington

Crown structure of old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) is characterized by low live-branch density, numerous dead branches and epicormic branches, high branch-size variability, and large gaps in the crown. These features define structural complexity of the crown and create variable crown microenvironments. For the 60 m tall, 400-year-old Douglas-fir trees measured in this study, number of live branches decreased and dead branches increased from the upper to lower crown. Dead branches were found below the lowest live branch indicating that crown recession had occurred. Live-branch biomass culminated at 45 m and decreased markedly below 35 m. Numerous vertical gaps between branches occurred below 40 m. Epicormic branches accounted for 14.6–47.5% of the total number of live branches per tree and contributed to increased crown depth. Epicormic branches filled inner regions of the crown, and contributed to increased branch-size variability. A model of crown structure developed for young trees could be fit to the upper crown of the study trees but could not be applied to the middle to lower crown because of increased branch-size variability. Relative levels of photosynthetically active radiation in the crown decreased with decreasing height, but a local peak occurred around 35–40 m, coinciding with the height of marked decrease in live-branch biomass.

複層林スギ上木の後生枝発生の実態 : 発生位置と枝齢,枝径について

複層林スギ上木の後生枝発生の実態 : 発生位置と枝齢,枝径について

Differences in growth and branch production by young plants of two provenances of Quercus robur L.

Summary Growth and branching of Q. robur was studied in young plants grown from acorns collected at two sites in Holland: one, at Ede-de-Klomp, was a registered seed stand having parents with good form; the other was poor phenotype at Wolfheze where parents had crooked trunks and epicormic branches. Observations were made after 6 months growth in the greenhouse and a further eight seasons in the field. In the greenhouse the plants flushed 2‐5 times, with those from Wolfheze generally forming most growth units. Mean length of the growth units produced during the flushes of growth varied between 116 and 242 mm and where there were significant differences between provenances those of Ede-de-Klomp were longer. However, there were no significant differences in height between origins after 6 months growth. Branches were not produced on all trees or on all growth units, their occurrence declining on growth units formed during the later flushes of growth. Between 7 and 64 per cent of buds grew out on those growth units which produced branches, and plants from the Wolfheze origin were generally more branched. After 8 years in the field, the height of the plants varied between 1.3 and 4.2 m, those from Ede-de-Klomp were generally taller with smaller stem diameters than those from Wolfheze. There were significant relationships between shoot length and branch numbers, with the Wolfheze origin generally having more branches per unit length than Ede-de-Klomp. The results are discussed in relation to the phenotype of the parent and early selection of oak provenances.

Effects of residual stand density on growth and volume production in even-aged red maple stands

The effects of five residual stand densities (9.2, 13.8, 16.1, 18.4 m2/ha, and an unthinned control (27.2 m2/ha)) on10-year stand and crop tree growth and bole quality were studied in an even-aged red maple stand in Michigan. A secondary treatment of removing the understory trees (5-10 cm DBH) was applied on half the plots. Diameter growth was significantly greater in all cutting treatments than in the control. Ten-year diameter growth in the heaviest cut treatment was nearly three times that of the control. The interaction between understory removal treatments and density treatments was significant for net basal area growth. Ingrowth in the heavier cut treatments accounted for a significant portion of net basal area growth in the plots without understory removal. Mortality was highest in the control and lowest in the heavier cut treatments. Epicormic branching significantly reduced clear bole length of crop trees in the heavier cut treatments, especially when the understory was removed. For these reasons, a more conservative first entry thinning level of about 17-18 m²/ha without controlling the understory is recommended for even-aged red maple stands.

Provenance Variation in Phenotypic Traits in Quercus robur and Quercus petraea in Danish Provenance Trials

A study of 33 provenances in Danish field trials with Quercus robur and Q. petraea was made between 1993 and 1998. The trials include Danish, Dutch, German, Norwegian and Swedish provenances, and were established between 1900 and 1988. Growth, flushing, stem form and epicormic shoot formation were studied. There were strong geographical clines for growth; however, the variation within regions was considerable. Time of flushing followed a more complex clinal pattern and was related to both latitude and distance from the ocean. Stem form was highly variable within different geographical regions and it is suggested that this could be caused by different management regimes in the past. Oaks from some locations in Sweden and Norway seemed especially straight. Stem form is one of the most important parameters for commercial oak management and could be seriously improved through breeding, as it was under considerable genetic control. Epicormic shoot production was in part under genetic control, but no geographical patterns were found. Danish provenances of Q. petraea were growing more rapidly than similar Q. robur on sandy locations. Quercus petraea produced fewer epicormic branches and stem form was equal to or better than Q. robur. Quercus petraea should be recommended for landscape use on windy locations in Denmark.

Effects of residual stand density on growth and volume production in even-aged red maple stands

The effects of five residual stand densities (9.2, 13.8, 16.1, 18.4 m 2 /ha, and an unthinned control (27.2 m 2 /ha)) on10-year stand and crop tree growth and bole quality were studied in an even-aged red maple stand in Michigan. A secondary treatment of removing the understory trees (5-10 cm DBH) was applied on half the plots. Di- ameter growth was significantly greater in all cutting treatments than in the control. Ten-year diameter growth in the heaviest cut treatment was nearly three times that of the control. The interaction between understory removal treat - ments and density treatments was significant for net basal area growth. Ingrowth in the heavier cut treatments ac - counted for a significant portion of net basal area growth in the plots without understory removal. Mortality was highest in the control and lowest in the heavier cut treatments. Epicormic branching significantly reduced clear bole length of crop trees in the heavier cut treatments, especially when the understory was removed. For these reasons, a more conservative first entry thinning level of about 17-18 m≤/ha without controlling the understory is recommended for even-aged red maple stands.

Assessment of Residual Stand Quality and Regeneration Following Shelterwood Cutting in Central Appalachian Hardwoods

Abstract Partial cutting to develop two-age stands is a relatively new practice in the central Appalachian region, and forest managers need quantitative information in order to evaluate how well it meets management objectives. Typically, this practice leaves a residual overstory of 10 to 40 ft² per ac of basal area and leads to regeneration of desirable shade-intolerant species which comprise the second age class. In this study we evaluated residual tree quality and regeneration 2 to 5 yr after cutting in 20 stands on the Monongahela National Forest in West Virginia. Tree grades were not significantly affected by the cutting. The largest grade reductions, due primarily to epicormic branching and logging wounds, occurred with large white oak sawtimber (11%) and white ash small sawtimber (10%). Epicormic branching following the cut was greatest for white oaks in the suppressed and intermediate crown classes. Across all species, the trees in the lower crown classes produced the greatest number of epicormic branches. Overall, epicormic branching on the 16 ft butt logs of dominant and codominant trees was low. For white oak (Quercus alba), 64% of these trees produced no epicormic branches. But 75% of yellow-poplars (Liriodendron tulipifera), 82% of black cherries (Prunus serotina), 78% of northern red oaks (Quercus rubra), and 89% of white ashes (Fraxinus americana) produced no epicormic branches on butt logs. Logging wounds occurred on 45% of the residual trees across the 20 stands, but 21% had large wounds over 100 in². Regeneration of both shade-intolerant and tolerant species was prolific following the cutting. Total numbers of tree seedlings and sprouts ranged from 8,217 stems/ac in the mixed oak stands of the Ridge and Valley Province to 30,845 stems/ac in the beech-cherry-maple stands in the Allegheny Mountains. The birches, primarily sweet birch (Betula lenta), comprised the most abundant species across the study area, but species composition varied depending on forest cover type. Regeneration numbers were lowest in the mixed oak stands in the Ridge and Valley Province. North. J. Appl. For. 15(4):203-210.

Silvicultural methods of oak regeneration with special respect to shade tolerant mixed species

An overview is presented of the silviculture of pedunculate oak ( Quercus robur L.) and sessile oak ( Q. petraea Liebl.) in Germany. This presentation is confined to less dry to moist and stagnic gleysol sites, where the intention is to produce primary timbers in long rotation periods. Incorporation of a shade tolerant species as an admixture species is indispensable to the suppression of epicormic branches. The most frequent and recommended admixture species for this purpose is beech ( Fagus sylvatica L.). Because beech is competitively stronger than the oaks on these sites, silvicultural measures must be taken to keep it in check. According to the classic silviculture which has taken shape in the Spessart and Pfälzer forests, the desired goal of a two-storeyed stand with oak in the overstorey and beech in the understorey is achieved by means of heavy seeding beneath an open and rapidly cleared canopy. Because this procedure resembles clear cutting and entails its recognized disadvantages, trials have recently been undertaken to regenerate oaks in a silviculture with permanent canopy cover. Trials with young oaks show that they still achieve satisfactory growth at 15–20% of full light. Accordingly, successful regeneration is possible in beech stands under an open canopy or in gaps, and under an approximately closed canopy cover in pine stands due to their more penetrable crowns. The problematic aspect of this, especially in beech stands, is that young beeches become competitively stronger than oaks as canopy cover increases. This requires great effort in restraining the beech during cleanings and thinnings. Furthermore, browsing by wild animals must be minimized as it exclusively affects oak. As a result, however, there will be significantly fewer oaks and more beeches in the dominant layer than when using classic methods.

Tissue culture responses of explants taken from branch sources with different degrees of juvenility in mature black locust (Robinia pseudoacacia) trees.

We studied the in vitro responses of cambial tissue and dormant vegetative buds obtained from top and epicormic branches of three mature black locust (Robinia pseudoacacia L.) trees. Cambial tissues isolated from epicormic branches produced more callus than cambial tissues isolated from top branches, whereas in vitro shoot cultures derived from buds excised from top branches grew faster than those derived from buds excised from epicormic branches. There were no significant differences between the two branch sources in in vitro bud break or shoot multiplication from bud explants or cambial-derived callus tissue, respectively. Furthermore, the top branches, generally considered to be the most mature in a tree, were not recalcitrant in terms of morphogenic capacity compared to epicormic branches.

Epicormic branch dynamics in a secondary hardwood forest in Hokkaido

Epicormic branch dynamics in a secondary hardwood forest in Hokkaido

Effects of Cutting Time, Stump Height, Parent Tree Characteristics, and Harvest Variables on Development of Bigleaf Maple Sprout Clumps

Abstract In order to determine the effects of stump height, year of cutting, parent-tree size, logging damage, and deer browsing on bigleaf maple (Acer macrophyllum) sprout clump development, maple trees were cut to two stump heights at three different times. Stump height had the greatest impact on sprout clump size. Two years after clearcutting, the sprout clump volume for short stumps was significantly less than that for tall stumps. The sprout clump volume, area, and number of sprouts were significantly less for trees cut 1 and 2 yr before harvest than for trees cut at harvest. Sprout clump size was positively correlated with parent tree stem diameter and stump volume, and negatively correlated with the percentage of bark removed during logging. Browsing had no significant impact on average clump size. Uncut trees produced sprout clumps at their base and epicormic branches along the length of their stems; thus their crown volume averaged four to five times that of cut trees. Cutting maple in clearcuts to low stumps may reduce maple competition with Douglas-fir regeneration and still maintain maple in the next stand. West. J. Appl. For. 11(4):120-124.

Study on the cutting propagation technique ofPicea koraiensis

The cutting propagation technique ofPicea koraiensis was carried under automatic spraying of total sunlight by adopting the same year epicormic branches from different trees with different age treated by different hormones in different concentration and time and the orthogonal and randomized block was designed. The results were as follows: (l)The rooting rate of the cutting reached at least 87 percent, when the cuttings were from the seed tree with the age below 25 years old and the cuts of the cuttings base were in vertical angle and on the fine sand medium. (2) The sequence of effective factors affecting the rooting rate were the style of cut, the age of seed tree and the type of medium. (3) There are significant differences of rooting rate among different clones.

Artificial Pruning of Immature Oak Stands is Not Profitable

Abstract Artificial pruning is one way in which an increase in end product quality can be achieved. Secondary data as well as a field study were used to evaluate the cost efficiency of pruning in immature oak stands in southeastern Missouri. A pruning time prediction model was developed from data collected during a field study of pruning. Number and size of limbs as well as height of log segment were found to be important factors affecting pruning time. The TWIGS growth and yield model was used to project tree growth from which the volume of clear wood produced as a result of pruning was estimated. When labor costs were included, all present net worths (PNWs) of the pruning investment were found to be negative due to the small amount of clear wood produced and a small price difference between clear and knotty wood. Excluding labor cost, assuming that it will be absorbed by the landowner, PNW was positive for 60, 70, and 80 yr rotations at only the 3.0% discount rate. The knot-free stumpage price necessary to earn a 5.0% discount rate was estimated and found to be substantially higher than present prices in the region. Because of low return and potential risk of epicormic branching, artificial pruning of immature oak stands is not an economical management option. South. J. Appl. For. 19(1):14-17.

Use and abuse of wildlife models for determining habitat requirements of forest fauna

The extent of stem damage and rate of crown recovery were studied following a high intensity fire in a 16-year-old planted stand of Eucalyptus diversicolor and Eucalyptus muellerana in Western Australia. Trees defoliated by fire were killed back substantially further than trees which were fully crown scorched, with E. diversicolor being killed back further than E. muellerana in each of the fire intensity classes. The greater resistance of E. muellerana to fire damage was attributed to the fact that it had thicker bark than E. diversicolor over much of the length of the stem. Five years after fire all E. muellerana had apically dominant crowns, whereas up to 40% of E. diversicolor still had crowns dominated by lateral epicormic branches originating from the stem. Fire-caused wounds on the lower stem were uncommon, probably because most woody debris had been removed during site preparation prior to establishment. Overall, E. muellerana exhibited greater tolerance to fire than E. diversicolor, being more resistant to stem damage and having a greater capacity to re-establish an apically dominant crown from epicormic buds following crown damage. © 1994 Taylor & Francis Ltd.

Stem damage and crown recovery following high intensity fire in a 16-year-old stand ofEucalyptus diversicolorandEucalyptus muellerana

Summary The extent of stem damage and rate of crown recovery were studied following a high intensity fire in a 16-year-old planted stand of Eucalyptus diversicolor and Eucalyptus muellerana in Western Australia. Trees defoliated by fire were killed back substantially further than trees which were fully crown scorched, with E. diversicolor being killed back further than E. muellerana in each of the fire intensity classes. The greater resistance of E. muellerana to fire damage was attributed to the fact that it had thicker bark than E. diversicolor over much of the length of the stem. Five years after fire all E. muellerana had apically dominant crowns, whereas up to 40% of E. diversicolorstill had crowns dominated by lateral epicormic branches originating from the stem. Fire-caused wounds on the lower stem were uncommon, probably because most woody debris had been removed during site preparation prior to establishment. Overall, E. muellerana exhibited greater tolerance to fire than E. diversicolor, being m...

Hurricane Damage to a Flood Plain Forest in the Luquillo Mountains of Puerto Rico

Hurricane Hugo caused low to moderate damage to a flood plain forest that was partially protected by its topographic position. Treefalls and the location of damage suggested N to NW wind direction during the storm. Thirty percent of the trees, or 693 trees/ha, had some damage and 84 percent of the damage was to the canopy. Most of the damage to trees was caused by direct wind impact (83%) as opposed to secondary effects (16%). Over 80 percent of the snapped, leaning, and uprooted trees were dicotyledonous. Tree mortality was only 1 percent, and most of the damage to the sierra palm Prestoea montana (R. Grah.) Nichols was loss of leaves. Rapid refoliation, epicormic branching, adventitious root production, resprouting, and regeneration from seed in open areas were observed nine months after the event. Ten percent of the aboveground biomass and 12-16 percent of the nutrient stocks (N, P, K, Ca, Mg) were transferred to the forest floor, mostly in the form of woody biomass and nutrient-rich leaves. Palm leaves were the dominant leaf component of necromass. Instantaneous in situ fine and coarse necromass production was 10 and 9.2 Mg/ha, respectively. Net changes in aboveground mass, N, P, K, Ca, and Mg (in percent of prehurricane value) were 8, 3, 0, 3, 12, and 1, respectively, in spite of a high rate of loss by export. The source of additional mass and nutrients were boles from upland forests that fell into and remained inside the flood plain.

Growth Response of Upland Oak Sawtimber Stands to Thinning in Connecticut

Abstract Thirty pairs of thinned and unthinned plots in roadside fuelwood areas, and 12 plots in each of 2 commercial cordwood thinnings were located in Connecticut oak sawtimber stands. Thinning during 1969-82 reduced stocking on plots an average of 30%. Subsequent stand basal area growth, cubic-foot growth, and board-foot growth were similar among all treatments. There was no decrease in stem quality nor increase in epicormic branching associated with thinning. Thinning mature oak sawtimber stands provides forest managers an opportunity to capture volume of declining trees while increasing growth on residual oak sawtimber. North. J. Appl. For. 8(3):104-107.

Thinning Red Alder: Effects of Method and Spacing

Abstract A 14-year-old fully stocked red alder (Alnus rubra Bong.) stand on a site index 30 m (50 yr) site in northwest Oregon was precommercially thinned and growth measured for 5 years. Treatments were (1) 4.3 x 4.3 m spacing (541 trees/ha), chemically thinned, (2) 6.1 x 6.1 m spacing (269 trees/ha), chemically thinned, (3) 6.1 x 6.1 m spacing, chain-saw thinned, and (4) control (1754 trees/ha). Chemical thinning was done by trunk injection of 2,4-D and caused some damage (flashback) to neighboring crop trees. Thinning increased individual-tree radial growth 49% to 100% and decreased tree height growth by as much as 56%. In combination, this resulted in no significant change in tree volume growth with thinning. The lack of tree volume growth increase combined with the decrease in stem density with thinning produced a net decrease in stand volume growth with thinning. A review of the literature showed height growth reductions to be common among other alder studies. Tree basal area growth on the chemically thinned plots did not increase as much as on the chain-saw thinned plots, suggesting a prolonged growth reduction effect from the herbicide treatment. Diameter growth decreased with increasing degree of herbicide-induced crown damage. Thinning increased the size but not the numbers of epicormic branches. The longevity or effects on wood quality of these branches is not known. For. Sci. 35(1):16-29.

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

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.

Cause and Control of Dogwood Anthracnose in Northeastern United States

Native flowering dogwood (Cornus florida) in parts of northeastern United States have shown increasing dieback and mortality since the late 1970's. Symptoms consist of necrotic spots, scorch, and blight of the leaves, nondehiscence of some blighted leaves, cankers, epicormic branches, and dieback beginning in the lower branches. The anthracnose fungus Discula sp. was identified as the primary cause. Post-infection stresses may have intensified tree decline. The fungicides chlorothalonil (Daconil 2787) or mancozeb (Manzate 200) applied at 10-day intervals during leaf expansion reduced foliar symptoms. Additional recommendations are pruning, fertilization, and watering to promote tree vigor.