Effects of crown-pruning on seed and pollen cone production in two lodgepole pine seed orchards in British Columbia

The effects of top pruning on subsequent seed and pollen cone production in lodgepole pine (Pinus contorta Dougl.) grafted clones in two seed orchards were evaluated. In the older orchard (14 years old), three pruning regimes were applied: an untreated control, a moderate pruning where 25% of the crown was removed and a severe pruning where 40% of the crown was removed. In the younger orchard (ten years old), only a control pruning and a severe pruning (50% of crown removed) were applied. Five-year seed cone production was lower in treated ramets compared to controls in both orchards. However, when cumulative seed cone yields were adjusted for reduced tree heights after pruning, differences were no longer significant in the older orchard. Strong clonal variation was observed in seed cone yields in both orchards. Pollen cone development was less variable among treatments in the older orchard. In the younger orchard, controls consistently produced heavier pollen crops. Pruning recommendations for similar orchards are made and results discussed for reducing the impacts of losses in seed cone yields.Deceased     

The effect of different levels of green pruning on the diameter growth of Pinus sylvestris L.

It was hypothesized that maximum living crown removal can be determined from experimental data using linear statistical models. Pruning experiments were carried out in four Scots pine (Pinus sylvestris L.) stands. Zero to nine living branch whorls were removed in three stands in southern Finland, and 0–4.5 m of the living crown was removed in a stand in northern Finland. Only dead branch whorls were removed from the control trees. A total of 517 trees were analyzed. Diameter increment was measured five years after pruning. The growth reduction was statistically significant when 40% or more of the living crown was removed by pruning. According to the linear models, green pruning decreased diameter growth by 0 to 33% at defoliation levels below 40%. This loss in diameter growth is, from an economical point of view, compensated by the knotfree timber resulting from pruning 2–3 years earlier.     

Effect of pruning Acacia mangium on growth,form and heart rot

Small volumes of timber are now being produced from Acacia mangium plantations in Indonesia. These trees require pruning and thinning to increase the strength and appearance of the wood. However, cut surfaces from pruning are potential infection courts for the entry of decay-causing fungi like heart rot. This study investigated the effects of pruning on stem form and the incidence of heart rot in an 18-month-old plantation of Acacia mangium in South Sumatra. The objectives were to assess whether pruning is associated with an increase in the incidence of heart rot and whether form pruning compared to lift pruning reduced the incidence of heart rot and improved stem form. Form pruning removed 25% of leaf area by removing large branches and those subtending a narrow angle with the stem up to 3 m height, and lift pruning removed 25% of crown length from below. Trees in these treatments were singled before pruning. The third treatment, a control, was not singled and was used to assess base levels of heart rot.No significant difference in diameter increment between the two pruning treatments was found. There was strong evidence that form pruning was associated with better form 18 months after treatment. Trees in this treatment had a reduced number of branches >30 mm diameter and improved stem straightness (reduced kink). Lift pruning reduced average branch size but did not improve stem straightness. No heart rot was detected in any treatment.The results showed that form pruning is likely to have positive benefits on stem straightness and is likely to be effective to any selected pruning height. However a subsequent lift pruning is still considered a requirement. While wounds created from pruning and singling are assumed to have a large impact on the incidence of heart rot, this may not be an issue unless there is a sufficient source of fungi present in the environment to invade the wounds.     

余甘子二龄结果母枝强修剪对一龄结果母枝的影响

采用整体分析和单因子分析相结合的方法,探讨余甘子二龄结果母枝强修剪处理对一龄结果母枝特性的影响。整体分析表明,强修剪处理对选取的五因子在整体上有极显著影响(Λ<Λ_(0.01))。单因子方差分析由Λ统计量转换而成,转换结果表明,二龄结果母枝强修剪处理对一龄结果母枝长、一龄结果母枝粗、一龄结果母枝结果枝数有极显著影响,对结果枝长有显著影响,对结果枝叶数无显著影响。强修剪处理使穗条(一龄结果母枝)在数量上增加,质量提高。这项研究为余甘子优树繁殖,结果、采穗两用果园的建立及树体生长、生殖平衡控制,提供了依据;提出了区间重叠度概念,并探讨了重叠度与处理有效性的关系;同时探讨了单因子显著性与因子组合显著性之间的关系。     

Dynamics of non-structural carbohydrate reserves in pruned <Emphasis Type="Italic">Erythrina poeppigiana</Emphasis> and <Emphasis Type="Italic">Gliricidia sepium</Emphasis> trees

In alley cropping systems, fast growing leguminous trees are pruned to reduce competition with crops for light and to provide organic inputs for crop nutrition. Tree regrowth depends on non-structural carbohydrate reserves in the remaining tree parts. In this study, the dynamics of starch and soluble carbohydrates in roots and stems of completely pruned (all shoots removed), partially pruned (one branch retained on the pruned stump) and unpruned Erythrina poeppigiana (Walp.) O.F. Cook and Gliricidia sepium (Jacq.) Kunth ex Walp. trees were studied under humid tropical conditions in Turrialba, Costa Rica. Measurements on starch and soluble carbohydrates in roots and stems were made at 0, 2, 6 and 12 weeks after pruning during both a “rainy” and a “dry” season. In general, the dynamics of non-structural carbohydrates in roots and stems of pruned E. poeppigiana and G. sepium trees were similar. Starch concentration was highest in unpruned trees and higher in roots than in stems of pruned trees. The effect of pruning intensity was first observed in stems, and starch reserves were more depleted in stems than in roots, an effect more evident during the “dry” season. The critical tree regrowth stage for starch mobilisation was that of vigorous sprout development at six or four weeks after pruning particularly in completely pruned trees. At this time, fine root biomass and length and nodule biomass in pruned trees decreased. Survival of fine roots and nodules was greater in partially pruned than in completely pruned trees. Starch accumulation in roots recommenced at 12 weeks after pruning in G. sepium, and later than 12 weeks after pruning in E. poeppigiana roots. This study showed that E. poeppigiana responded better to pruning regimes than G. sepium. Recovery of trees after pruning is better when trees are partially pruned than when completely pruned.     

Pruning methods to restore Castanea sativa stands attacked by Dryocosmus kuriphilus

Dryocosmus kuriphilus Yasumatsu, an invasive gall wasp originating from Asia, is the latest serious pest attacking Castanea sativa Mill. in Europe; the negative effects on fruit and wood production are considerable. The most effective defense strategy is biological control, but parasitoid effectiveness requires at least 6–10 years to reduce damage to acceptable levels. In Italy, prolonged productivity losses could adversely affect human activity in chestnut orchard stands, resulting in negative socio-economic and hydrogeologic consequences. Thus, it is necessary to quickly reduce the impacts of the infestation to avoid degradation of chestnut stands during the time delay required for parasitoid efficiency. We examined green pruning as a means to reduce negative impacts of gall wasps and stimulate healthy shoots in a young chestnut coppice in Central Italy. Two different pruning cuts (Long- and Short-cut) on growing shoots and four timings of application were tested. The development and phytosanitary status of nodes was observed over 2 years on pruned and control sprouts. Pruning was effective in reducing gall wasp damage though responses varied among pruning techniques and application times. Long-cut pruning made in spring during the full growth phase induced a higher number of new and better-developed shoots. Pruning during the end of the egg-laying period of the gall wasps promoted development of only healthy new shoots. Our results indicate that is possible, by choosing the best combination of time and technique, to identify a pruning method useful to maintain growth and development of C. sativa stands threatened by D. kuriphilus.

     

Effect of pruning intensities of three woody leguminous species grown in alley cropping with maize and cowpea on an alfisol

Field trials were carried out on an Oxic Paleustalf in the humid zone of southwestern Nigeria withLeucaena leucocephala (Lam.) de Wit,Gliricidia sepium (Jacq.) Steud. andSesbania grandiflora (L.) Pers. alley cropped with maize and cowpea. The three leguminous woody species were grown in hedgerows spaced at 2 m. Trials were carried out one year after establishment of the hedgerows using a split-plot design with four replications. TheLeucaena trial had twenty pruning combinations consisting of five pruning heights (25, 50, 75, 100 and 150 cm) and four pruning frequencies (monthly, bi-, tri- and six-monthly). TheGliricidia andSesbania hedgerows were subjected to nine pruning intensities consisting of three pruning heights (25, 50 and 100 cm) and three pruning intensities (monthly, tri- and six-monthly).For the three woody species, biomass, dry wood and nitrogen yield from the hedgerow prunings increased with decreasing pruning frequency and increasing pruning height. Biomass, dry wood and nitrogen yields were in the following orderLeucaena >Gliricidia >Sesbania.The various pruning intensities had no effect on survival ofLeucaena plants. Pruning frequency had a larger effect than pruning height on survival ofGliricidia andSesbania plants. With monthly pruning, about 25 percent of theGliricidia and all of theSesbania plants died within six months of repeated pruning. Even with lower pruning frequencySesbania plants showed lower survival rates thanGliricidia orLeucaena.The various pruning intensities of all the hedgerow species had more pronounced effects on the grain yield of the alley cropped cowpea than on maize grain yield. Higher maize and cowpea yields were obtained with increasing pruning frequency and decreasing pruning height.IITA Journal paper number 335     

Effect of pruning intensities of three woody leguminous species grown in alley cropping with maize and cowpea on an alfisol

Field trials were carried out on an Oxic Paleustalf in the humid zone of southwestern Nigeria withLeucaena leucocephala (Lam.) de Wit,Gliricidia sepium (Jacq.) Steud. andSesbania grandiflora (L.) Pers. alley cropped with maize and cowpea. The three leguminous woody species were grown in hedgerows spaced at 2 m. Trials were carried out one year after establishment of the hedgerows using a split-plot design with four replications. TheLeucaena trial had twenty pruning combinations consisting of five pruning heights (25, 50, 75, 100 and 150 cm) and four pruning frequencies (monthly, bi-, tri- and six-monthly). TheGliricidia andSesbania hedgerows were subjected to nine pruning intensities consisting of three pruning heights (25, 50 and 100 cm) and three pruning intensities (monthly, tri- and six-monthly). For the three woody species, biomass, dry wood and nitrogen yield from the hedgerow prunings increased with decreasing pruning frequency and increasing pruning height. Biomass, dry wood and nitrogen yields were in the following orderLeucaena >Gliricidia >Sesbania. The various pruning intensities had no effect on survival ofLeucaena plants. Pruning frequency had a larger effect than pruning height on survival ofGliricidia andSesbania plants. With monthly pruning, about 25 percent of theGliricidia and all of theSesbania plants died within six months of repeated pruning. Even with lower pruning frequencySesbania plants showed lower survival rates thanGliricidia orLeucaena. The various pruning intensities of all the hedgerow species had more pronounced effects on the grain yield of the alley cropped cowpea than on maize grain yield. Higher maize and cowpea yields were obtained with increasing pruning frequency and decreasing pruning height. IITA Journal paper number 335     

The effects of early and intense pruning on light penetration,tree growth,and epicormic shoot dynamics in a young hybrid larch stand

We examined the effect of early and intense pruning on light intensity under the canopy, individual growth, diameter–height relationships, and epicormic shoot dynamics in young hybrid larch (Larix gmelinii var. japonica × L. kaempferi) to establish a new effective management method for hybrid larch plantations. The objective is to produce high-quality wood while reducing silviculture costs using a combination of low-density planting and early and intense pruning. In a young hybrid larch plantation, we pruned branches to two different heights (2 and 4 m above ground level) using a no-pruning treatment as a control. Although the growth rates were lower in the heavy pruning treatment (4 m above the ground level) than in other treatments in the year following pruning, when measured 4 years later, growth did not differ between treatments. The number of epicormic shoots increased in the year following pruning, as did the relative photosynthetic photon flux density (rPPFD). The number of epicormic shoots was also dependent on the size of individual trees. However, survival of epicormic shoots was not sufficiently high to be problematic for high-quality timber production. If branches are pruned carefully such that the rPPFD does not rise above 20%, the emergence of epicormic shoots can also be controlled. Our results indicate that early and intense pruning is an effective component of a new management system for hybrid larch plantations.     

修枝间伐对松突圆蚧抑制作用的研究

严重危害广东省沿海地区马尾松的松突圆蚧(Hemiberlesia pitysophila Takagi),自1982年在深圳、珠海等地发现后，至今危害面积约43万ha，其中枯萎或涉死的约8万ha。     

缺苞箭竹地上部分生长的研究

不同森林郁闭度条件下,对缺苞箭竹花期、衰老期竹林各年龄植株数、开花数和花期、未花期、幼苗期不同年龄植株颜色老化特征、自然整枝、高、径、枝、叶生长、生物量等测定结果表明:竹林和植株的生长、老化和开花,不但与植株年龄、发育阶段有关,也与森林郁闭度密切相关。     

苹果改良纺锤形树形整形修剪技术研究

对当年定植的苹果幼树刻芽定干，提高了整形带内的萌芽率和发枝率，以刻3芽和刻4芽效果最好。作小主枝缓放处理的1a生枝在基部刻枝条的侧芽、背下芽，在刻芽数占总芽数的1／5、1／3、2／3等3个处理中，随刻芽数增加萌芽率提高，以刻2／3芽的处理萌芽率最高，达91.1%；作小主枝的1m以下的1a生枝极重短截，可极明显地促发壮枝，年生长量可达145.7cm;小主枝基产重环剥可控制旺梢生长,利于花芽分化,提高成花率;对基部小主枝的侧生分枝拉枝、刻芽，可提高萌芽率和中、短枝比例。采用改良纺锤形整形的乔砧矮化密植2001苹果，栽后第2年见花，第3年就有一定产量，第4年进入初结果期，单株产量可达32.8kg。     

Long term cone production and growth responses to crown management and gibberellin A4/7 treatment in a young western hemlock seed orchard

At age 5–6 years, rooted cuttings in a western hemlock (Tsuga heterophylla) clonal seed orchard received either a severe (ST) or moderate (MT) top pruning (upper 50 and 25% of live crown removed, respectively), or were left untopped (UT). Over the following 6 years, UT trees increased in height from 1.5 to 3.9 m, whereas through annual and biennial top and side pruning, MT trees grew to 2.2 m and ST trees were maintained at 2.0 m. Crown pruning had no effect on the subsequent annual production of seed or pollen cones. Spray applications of gibberellin A_4/7 in years 2 and 4 of the study increased 5-fold and 2-fold the percentage of trees producing a medium and greater crop, respectively, of seed and pollen cones in each year 3 and 5.     

Effects of thinning and pruning on knots and lumber recovery of Taiwania (<Emphasis Type="Italic">Taiwania cryptomerioides</Emphasis>) planted in the Lu-Kuei area

This study investigated the effects of various thinning and pruning methods on the knots (number and size) and lumber recovery from Taiwania (Taiwania cryptomerioides Hay.) plantation trees. The results showed that heavy thinning caused more knots and larger-diameter knots than medium or no thinning; moreover, pruning caused fewer numbers of knots and smaller-diameter knots than no pruning. Better-quality Taiwania trees occurred with the no-thinning/no-pruning treatments, as shown by analyzing the knots, although the results also showed that the healing process seemed to have produced not completely clear wood during the 9 years after the pruning treatment. The thinning intensity slightly enhanced the lumber recovery of logs. Pruning did not affect lumber recovery from taiwania trees and logs. Thinning increased the lumber recovery per tree due to an increase in the diameter at breast height.     

Effect of pruning on branch production and water relations in widely spaced ponderosa pines

This study dealt with the effects of pruning on branch and leaf area (F _a) production of ponderosa pines growing in silvopastoral systems in Patagonia. We hypothesized that pruning positively influences the number of branches per whorl and their basal area growth rate, changing F _a production. In addition, we studied some water relations in order to explain potential differences in branch growth rates between treatments. Two mathematical models were developed to estimate branch and total F _a. The averaged diameter at the third year of pruning was, for high-pruned trees 3.1 and 3.6 cm at the bottom and middle of the crown, against 4 and 4.4 cm for low-pruned trees. Pruning did not produce changes in the number of branches per whorl (approximately 7.6 branches per whorl). Water stress may be responsible of this lower branch growth in pruned trees. Water potential, stomatal conductance and transpiration were lower in high- than in low-pruned trees.     

Changes in arboreal ant populations following pruning of coffee shade-treesin Chiapas,Mexico

Reducing or eliminating shade cover in coffee (Coffea arabica L.) agroforestry systems affects fungal disease and pest outbreaks, coffee yields, and can result in biodiversity loss of important predators, such as ants. Less dramatic changes in shade structure or composition may also affect ants. Shade tree pruning, a common management practice in shaded coffee systems, has unknown consequences for ant communities. The effects of pruning on arboreal ant communities were investigated by measuring ant abundance, distribution, and species richness in the short (1 week) and long-term (6 months) after shade tree pruning in one 25×50 m plot. Shade tree pruning significantly affected the distribution and abundance of two of the most common ant species (Azteca instabilis F. Smith and Camponotus senex textor Forel), and in general did not affect other ants. After pruning, C. senex textor ants were 80% more abundant on coffee plants and shade trees, whereas A. instabilis abundance dropped by 40% on coffee plants and 73% on shade trees after pruning. Additionally, C. senex textor were significantly more widespread, whereas A. instabilis distributions were more restricted. The effects of pruning were strong over the short-term, but were not evident over the long-term. Shade tree pruning did not affect ant diversity. Thus shade tree pruning largely affected certain aspects of arboreal ant communities in one coffee agroforestry system, with important implications for biological control.     

Effects of pruning on the concentration of secondary metabolites in Colophospermum mopane leaves

Colophospermum mopane, commonly known as mopane, produces secondary metabolites during the growing season. However, there is still insufficient knowledge on the quantity of secondary metabolites and the effect of browsers on the concentration of secondary metabolites. A pruning experiment was conducted in the Musina Nature Reserve, Limpopo province, South Africa, to simulate the effect of browsers on the concentration of secondary metabolites in mopane leaves. The twigs from 40 selected experimental mopane trees were pruned back 50 mm from their tips using a hand shear. The total amount of leaf and shoot biomass removed from branches of selected experimental trees was less than 10%. Three independent samples composed of seven mopane leaves per 40 mopane trees were randomly collected from the canopies of experimental and control trees per sampling event. The dried leaves from each three independent samples were then mixed separately and a pooled sample of 10 g per treatment per sample cycle (55 d) was used for determination of total phenols (TP), condensed tannins (CT) and protein-precipitating tannins (PPT). Results showed that <10% pruning does not have an effect on the amount of secondary metabolites in the mopane leaves. The concentration of TP, CT and PPT increased during leaf flush in October and then declined as the leaves matured and aged. It is concluded that the amount of secondary metabolites in mopane leaves is not dependent on <10% pruning, but appeared to be associated with leaf growth stages. The ability of mopane to produce secondary metabolites has implications on the seasonal diet composition and distribution of browsers in mopane woodland.     

Pruning quality affects infection of Acacia mangium and A. crassicarpa by Ceratocystis acaciivora and Lasiodiplodia theobromae

Pruning (singling) is a common silvicultural practice in commercial Acacia plantations because these trees tend to have multiple stems. The wounds resulting from pruning are susceptible to infection by pathogens. Ceratocystis acaciivora and Lasiodiplodia theobromae have been shown recently to be important pathogens of A. mangium in Indonesia, where they are commonly associated with wounds on trees. The aim of this study was to determine the impact of different wound types on infection of A. mangium and A. crassicarpa by these two pathogens. Isolates of C. acaciivora and L. theobromae, found to be the most pathogenic in a prior study, were used to inoculate pruning wounds. Results showed that pruning conducted in a manner to reduce stem damage, resulted in lower levels of fungal infection. Where pruning resulted in tearing of the bark, there were higher levels of infection and disease occurred even without artificial inoculation. Inoculation of pruning wounds with C. acaciivora and L. theobromae showed that both fungi have the potential to cause disease. However, C. acaciivora was most virulent. Results of this study showed conclusively that careful pruning will result in lower levels of disease in young A. mangium and A. crassicarpa plantations.     

Influence of root pruning and cutting interval ofLeucaena hedgerows on performance of alley croppedrabi sorghum

The influence of root pruning and cutting interval ofLeucaena hedgerows on alley croppedrabi sorghum was investigated. Paired (60 cm)Leucaena hedgerows spaced 6.6 m wide were subject to either root pruning, using a country plough during mid-kharif season, or no root pruning. The cutting frequency ofLeucaena hedgerows ranged from one month to six months during therabi cropping period. The effect on soil moisture, crop growth, yield and yield components ofrabi sorghum was examined.Root pruning ofLeucaena hedgerows increased grain and stover yields of the alley croppedrabi sorghum by 33 and 17%, respectively, over root not pruned hedgerows. Similarly, shorter cutting intervals (one and two months) increased crop yields as compared with longer cutting intervals (three and six months). The growth (height and dry matter) of the crop was similarly influenced. Soil moisture studies indicated that the competition between crop and hedgerows was considerably reduced by the root pruning. The results clearly showed that the competition between hedgerows and arable crop can be reduced considerably by root pruning and frequent cutting (at one to two months interval) of the hedgerows.     

Early root morphology of jack pine seedlings grown in different types of container

Abstract

This study compared the effects of container type on early root system morphology of jack pine (Pinus banksiana Lamb.) seedlings to determine impacts of container type on root characteristics that may be important for tree stability. Seedlings were grown for one season in Multipots®, Ventblocks®, Copperblocks®, Starpots® and Jiffy® pellets, and for a second season in sand culture in pots. After the first growing season, roots that had grown between Jiffy plugs were cut using a knife, either “early”, in September, or “late”, in November. Seedlings produced in non-pruning containers, Multipots and Ventblocks, had more vertical structural roots, less even root distribution and high shoot:root mass after a second season. Seedlings grown in pruning containers, Copperblocks, Starpots and Jiffy pellets, had more horizontal structural roots and more evenly distributed roots. Jiffy seedlings had high shoot:root mass after pruning, but ratios decreased to low levels similar to Starpots and Copperblocks after a second season in pots. Early pruning of Jiffy seedlings removed less root mass than late pruning, but total live root mass of early and late pruned seedlings was similar after the potting trial. Pruning containers thus produced structural root forms with more desirable characteristics for tree stability. These characteristics were evident after the first season and persisted after the second season in the potting trial.