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利用16-21年生马尾松近熟林间伐密度试验林的观测资料,探讨了不同间伐强度对林分生长与效益的影响。结果表明,不同间伐保存密度(450、600、750、900、1 036株/hm2)对林分生长、林分结构及材种规格均有显著影响。其中林分胸径、单株材积、冠幅随密度增大而减小,密度对树高生长无显著影响;不同间伐密度的林分蓄积量与出材量随着时间推移差异变小;间伐有利于提高大径级林木株数比率从而提高材种规格与效益。根据21年生马尾松人工林生长规律与效益评价,16-21年生近熟林间伐密度保存在600-900株/hm2效益较好。 相似文献
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Ramazan Özçelik Yasin Karatepe Nevzat Gürlevik Isabel Cañellas Felipe Crecente-Campo 《林业研究》2016,27(1):101-117
Estimating individual tree volume is one of the essential building blocks in forest growth and yield models.Ecologically based taper equations provide accurate volume predictions and allow classification by merchantable sizes, assisting in sustainable forest management.In the present study, ecoregion-based compatible volume systems for brutian pine and black pine in the three ecoregions of southern Turkey were developed. Several well-known taper functions were evaluated. A secondorder continuous-time autoregressive error structure was used to correct the inherent autocorrelation in the hierarchical data, allowing the model to be applied to irregularly spaced and unbalanced data. The compatible segmented model of Fang et al.(For Sci 46:1–12, 2000) best described the experimental data. It is therefore recommended for estimating diameter at a specific height, height to a specific diameter, merchantable volume, and total volume for the three ecoregions and two species analyzed. The nonlinearextra sum of squares method indicated differences in ecoregion and tree-specific taper functions. A different taper function should therefore be used for each pine species and ecoregion in southern Turkey. Using ecoregionspecific taper equations allows making more robust estimations and, therefore, will enhance the accuracy of diameter at different heights and volume predictions. 相似文献
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Dilek Yildiz Pascal Nzokou Ayse Deligoz Ismail Koc Musa Genc 《European Journal of Forest Research》2014,133(5):809-818
Determining the adaptability to abiotic conditions and potential establishment success of tree species needs to be conducted before attempting to use a species in large-scale afforestation programs. In this study, the chemical and physiological performance of four Turkish red pine (Pinus brutia Ten.) provenances was investigated after exposure to artificial cold temperature treatments to determine their adaptability to cold environment for potential use in afforestation programs. Seeds were sown and raised for 24, 28, and 32 weeks and exposed to decreasing temperatures in an artificial freezer. Relative electrolyte leakage, chlorophyll fluorescence, and carbohydrate concentrations were measured to determine the variability between provenances. Results showed that diameter and height growth did not vary with origin for each of the three growth stages measured. Root electrolyte leakage values differed between provenances, confirming that cold stress was effectively causing physiological damages when plants were exposed to temperature at ?15 °C and below. The variability observed in the relationship between provenances and cold hardiness responses can be attributed to tree-to-tree variability within provenances and microsites conditions. There was generally no significant difference in chlorophyll fluorescence between provenances, also attributed to low genetic variation between provenances. Carbohydrate concentrations were also very variable and varied significantly among growth stages and provenances. High-altitude provenances had higher soluble carbohydrates concentrations in several cases, suggesting a relationship between altitude, soluble sugars, and cold hardiness. However, these trends were not consistent; therefore, we suggest that such hypotheses be confirmed through more comprehensive further studies. 相似文献
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Hassan Muhamed Sami Youssef Ahmed Mustafa Hishyer Suliman Aree Abdulqader Hishyer Mohammed Richard Michalet 《林业研究》2019,(5):1849-1857
Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest.It was thus essential to assess regeneration before designing optimizing strategies.To this end,we studied the overstory canopy and microhabitat conditions for recruitment of Pinus brutia Ten in 10 plots(20×25 m)on the southern aspects where the Zawita natural forest is still present.In total,1540 regenerating P.brutia were recorded,854 seedlings,597 saplings,and 89 trees.Seedlings and saplings were more frequent beyond the canopy than under the canopy of the parent trees.Regeneration requirements differed between seedlings and saplings.The probability of the occurrence of seedlings was negatively correlated with increasing litter depth and increasing soil compaction.The density of saplings only showed a positive significant correlation with increasing slope.The nearest neighbor index showed a trend toward a positive spatial association between understory shrubs with their neighboring seedlings at a mean distance of 1.6 m.Overall,the study highlighted the requirements for seedling regeneration as a relatively open canopy cover,a light understory litter layer,and noncompacted soils.These results are a step towards designing effective management and restoration programs. 相似文献
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Ulvcrona Kristina Ahnlund; Claesson Svante; Sahlen Kenneth; Lundmark Tomas 《Forestry》2007,80(3):323-335
The effects of pre-commercial thinning on tree and branch characteristicswere analysed at two experimental sites in northern Sweden,where pre-thinning of Scots pine stands to 600, 1000 and 1800stems per hectares at heights of 1.5, 3, 5 and 7 m had beencombined in a factorial design. A total of 90 trees were cutand branches were measured in whorls sampled at 1-m intervals,starting with the whorl closest to 0.5 m above ground. Effectsof the treatments on tree and branch characteristics were analysedby a fixed-effect analysis of variance model, which was appliedseparately for each experimental site and whorl height. Diameterat breast height (d.b.h.) and living crown to height ratio decreased,while the height/d.b.h. ratio (stem form) increased with increasingstand density, and generally with increased height at thinning.No treatment effect was found on the number of branches perwhorl or branch angle, but branch diameter (BD) was significantlyinfluenced by both stand density after thinning and height atthinning. BD decreased with increases in stand density and decreasedwith increases in height at pre-commercial thinning. Relativebranch size (RBS), defined as the ratio between the sum of thediameters of branches in a whorl and stem perimeter under barkat the location of that whorl, was significantly influencedonly by stand height at the time of treatment. RBS decreasedby 46 per cent in whorls located below the current baseof the living crown with each step increase in stand heightat pre-commercial thinning. The results indicate that the numberof stems after pre-commercial thinning has a greater impacton tree size and shape than timing of pre-commercial thinning.Stand density after thinning also has a greater impact on branchsize, in the sense that it will affect branch size further upthe tree than the timing of pre-commercial thinning. However,by delaying the time for pre-commercial thinning it is possibleto reduce the RBS in the lower part of the stem. This mightbe an important measure to improve timber quality later in therotation period, which cannot be done solely by regulating standdensity. 相似文献
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Herbaceous weeds present amajor obstacle to foresters in the earlyestablishment and growth of Turkish red pine (Pinus brutia Ten.), an important coniferof the semi-arid Mediterranean region. Greatgenetic variability of this pine species indrought resistance has already beenwell-studied. The existence of such variationwithin this species in relation to herbaceousweed competition is unknown. This studyinvestigated the effect of herbaceous weedcompetition on the growth of the seedlings ofTurkish red pine seed sources with differentmoisture regimes in their native sites, usingthe rapid screening technique. Two-month-oldTurkish red pine seedlings were grown inindividual pots in a glasshouse either with orwithout joint goose goat grass (Aegilopscylindrica L.). After two simulatedgrowing seasons, grass competitionsignificantly and progressively reduced pinegrowth. Although mean total pine biomass wasreduced by 71% due to weed competition,seedlings of different pine seed sourcesdisplayed significant differences in growthresponses to the weed treatments: dry site seedsource seedlings generally exhibitedsignificantly greater growth than moist siteseed source seedlings under weed competition. These results suggest that competition fromherbaceous weeds is an important factor inreducing the early growth of Turkish red pineseedlings, and that selection ofcompetition-tolerant seed sources can result insubstantial enhancement of the competitivestatus of this pine species against itsherbaceous competitors in early years. 相似文献
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W. J. Cousins 《Wood Science and Technology》1974,8(4):307-321
Summary The effects of strain-rate, moisture content, and bulk density on the transverse fracture properties of Pinus radiata wood are described. As the strain-rate is increased from 2×10-6 sec-1 to 102 sec-1, the strengths of both wet and airdry woods increase, with the greater increase occuring in wet wood. At the same time, the failure strain tends to decrease. The energy absorbed by airdry wood decreases, and that absorbed by wet wood increases. An explanation of the variation of strength with strain-rate is developed. Initially the measured strength of latewood is related to the strength of the compound middle lamella matrix connecting adjacent tracheids, and then by making the assumption that wood failure occurs when a certain proportion of the load bearing hydrogen bonds in the matrix have failed, and by applying reaction rate theory to the formation and rupture of the stressed hydrogen bonds, a strength versus time to failure relationship that is in good agreement with the experimental data is derived.The work described below was carried out at the Physics and Engineering Laboratory as part of a PhD research program at the Victoria University of Wellington. 相似文献
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Dimitris Zianis Gavriil Xanthopoulos Kostas Kalabokidis George Kazakis Dany Ghosn Olga Roussou 《European Journal of Forest Research》2011,130(2):145-160
Empirical allometric equations relating biomass of aboveground components to dendrometric variables for Pinus brutia Ten. trees are derived in this paper. They are based on data collected from Lesvos (North Aegean Sea) and Crete (South Aegean Sea) Islands. Comparisons to published equations for the same species growing in northwestern and southeastern Turkey, for Pinus nigra A. growing in Turkey and Pinus halepensis Mill. found in Western Aegean (island of Evia), are also presented. The biomass of branches from destructively sampled trees (twelve in Crete and six in Lesvos) was divided into four size classes (0?C0.63 cm, 0.64?C2.5 cm, 2.51?C7.61 cm, and 7.62?C22.8 cm). Tree crown biomass was calculated as the sum of the biomass in the four classes plus the fraction of stem above crown base. Over bark stem biomass was estimated through bole volume conversion based on wood density. The results showed clearly that, for a given diameter, the Cretan trees had more crown biomass and a higher share of small branches than trees on Lesvos, probably due to differences in environment and stand structure. Comparisons to published diameter versus crown biomass equations reveal a lower crown biomass for Turkish sites of Calabrian pine and Aleppo pine on Evia Island, while only Turkish Black pine seems to be comparable to the Calabrian pine on Crete. The derived allometries can be used for landscape fire behavior modeling, for ecophysiological studies and for the Kyoto protocol requirements of carbon changes in Pinus brutia Ten. forests located in northern and southern Greek sites. 相似文献
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A. Gutiérrez Oliva V. Baonza Merino J. I. Fernández-Golfín Seco M. Conde García E. Hermoso Prieto 《Wood Science and Technology》2006,40(3):190-204
The natural forests of Laricio Pine (Pinus nigra Subsp. salzmannii) cover in Spain an area of 353,000 ha, producing annually 310,000 m3 of roundwood. This species is considered as the fourth, most important Spanish conifer, being its timber frequently used
in construction. The natural area of distribution of Laricio pine in Spain is officially divided into ten different regions
of provenance, being only four of them considered as productive. The present study on the influence of growth conditions on
extracted wood basic density (EBD) is carried out on 89 P. nigra trees, sampled from the two most productive Spanish regions of provenance (R.7 and R.8) in seven different sites. Cross-sectional
disks were cut at 3 m (in 89 trees) and every 3 m height (in 18 trees) from the butt up to 15 m. For assessing the pattern
of radial variation of the properties, 20×20×20 mm3 wood samples were taken radially from every cross-sectional disk. In every 20×20×20 mm3 wood sample, age and distance to the pith of the central annual ring was recorded, together with the average growth rate.
Extractive content and EBD were measured in every sample. The results lead to the conclusion that there is not a significant
relationship between EBD and provenance or growth rate. On the contrary, a significant relationship has been found between
EBD and site quality or cambial age. The results also demonstrate that in a tree EBD tends to diminish from the base to the
top and from the pith outwards. The main result of the present study is related with the observation that for the same cambial
age, annual ring width has no significant influence on EBD, confirming that its utility as a predictor of the quality of timber
is highly questionable, at least if the ring curvature is not considered. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):528-539
The interaction between stand density and dominant height and the development of volume, mean diameter, mortality and distribution of volume during a period from precommercial thinning to first commercial thinning was studied on permanent plots in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands in Sweden. The reciprocal equation of the yield density effect was used to level the volume yield. Higher density after precommercial thinning resulted in higher yield and smaller mean diameter. The mortality up to first thinning was low, but is also dependent on density after precommercial thinning. The positive skewness of the volume distribution was higher in denser stands. 相似文献
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Wood density, a gross measure of wood mass relative to wood volume, is important in our understanding of stem volume growth, carbon sequestration and leaf water supply. Disproportionate changes in the ratio of wood mass to volume may occur at the level of the whole stem or the individual cell. In general, there is a positive relationship between temperature and wood density of eucalypts, although this relationship has broken down in recent years with wood density decreasing as global temperatures have risen. To determine the anatomical causes of the effects of temperature on wood density, Eucalyptus grandis W. Hill ex Maiden seedlings were grown in controlled-environment cabinets at constant temperatures from 10 to 35 degrees C. The 20% increase in wood density of E. grandis seedlings grown at the higher temperatures was variously related to a 40% reduction in lumen area of xylem vessels, a 10% reduction in the lumen area of fiber cells and a 10% increase in fiber cell wall thickness. The changes in cell wall characteristics could be considered analogous to changes in carbon supply. Lumen area of fiber cells declined because of reduced fiber cell expansion and increased fiber cell wall thickening. Fiber cell wall thickness was positively related to canopy CO2 assimilation rate (Ac), which increased 26-fold because of a 24-fold increase in leaf area and a doubling in leaf CO2 assimilation rate from minima at 10 and 35 degrees C to maxima at 25 and 30 degrees C. Increased Ac increased seedling volume, biomass and wood density; but increased wood density was also related to a shift in partitioning of seedling biomass from roots to stems as temperature increased. 相似文献
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间伐对杉木和马尾松人工林生长及植物多样性的影响 总被引:2,自引:0,他引:2
以秦淮河流域溧水林场间伐10年的杉木和马尾松人工林为研究对象,分析了间伐对林分生长及林下植物多样性的影响.结果表明:间伐促进了杉木和马尾松林分胸径、树高和冠幅的生长,间伐后杉木胸径、树高、冠幅比未间伐的增长率分别为11%、23.4%和26.7%;马尾松分别为23.5%、6.4%和39.2%.间伐10年的杉木林和马尾松林单株材积均明显增大,增长量分别为0.009 6 m3和0.031 1 m3,两个林分总蓄积量表现出不同的变化规律:杉木林的蓄积量减少了0.5 m3,而马尾松林分则增加了8.3 m3.杉木和马尾松间伐样地的枯损蓄积和株数枯损率明显降低.杉木和马尾松间伐后枯损蓄积分别降低了0.331 m2和0.098 m2;株数枯损率分别降低了21.8%和4.1%. 两种林分间伐后林下灌木和草本植物多样性都明显增加,杉木林下植物种类由16种增加至23种,马尾松林下植物种类由20种增加至23种. 相似文献
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施肥与抚育间伐对马尾松天然次生林土壤肥力的影响 总被引:6,自引:0,他引:6
经对地位指数为12~14的低山丘陵红壤区马尾松天然林进行施肥与抚育、间伐试验,4a后进行土壤肥力测定,结果表明:①氮、磷、钾肥无论是单施,还是任意二种或全营养配合施用,土壤全效及速效养分含量都有不同程度的提高,肥力状况均有明显改善。其中以全氮和速效磷的增幅为最大,全磷和速效氮的增幅次之,而以全钾和速效钾的增幅为最小;②施肥对土壤pH值具有一定的调节作用,并能显著提高土壤有机碳和有机质含量,因而明显改善土壤肥力状况,提高土壤保水保肥能力;③抚育与间伐对土壤速效氮、速效磷、速效钾含量以及土壤含水率、有机碳、有机质含量都有明显提高。其效果为抚育大于间伐,而间伐则以密度为110~120株/667m^2时效果为最佳。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):483-492
Altogether 82 plots (261 estimations) of Picea abies (L.) Karst, and 193 plots (360 estimations) of Pinus sylvestris (L.) stands were estimated by a vertical tube. The “crown free projection”, CFP, of stands thinned in three methods with different thinning grades was measured: unthinned, heavily and very heavily thinned, heavily thinned delayed first thinning, extra heavily thinned and thinned from the top. Basal area (m2ha?1) density (stems ha?1) and diameter sum (m ha?1) were plotted against CFP. Basal area was the best practical measure of stand in this study. Generally Scots pine stands have higher CFP and the curves are steeper than in Norway spruce stands. Depending on the grade of thinning, heavily and very heavily thinned spruce stands, delayed first thinning included, have CFP values of 10–15% and stands thinned from the top, 20–40%, compared with 30–80% and 30–60% respectively in pine stands. Extra heavily thinned stands have the highest CFP, 20–80% in spruce and 50–90% in pine stands. The CFP levels after thinning are too high in pine stands for avoidance of sucker and sprout production of aspen and birch. In dense Norway spruce stands thinned from the top or heavily and very heavily thinned, the CFP values are low enough (≤30%) to diminish the production of suckers. 相似文献
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Four populations representing the entire natural distribution range of Pinus brutia (Ten.) in Crete (Greece) were sampled to determine: (1) Altitudinal variation within populations of Lassithi, Vorizia, Koustagerako, and Samaria, and; (2) Longitudinal variation among the four populations, based on morphological and anatomical differences in cone, needle and seed characteristics. Samples were collected from 10 trees per altitude, at three altitudes in each population. A total of 12 morphological and anatomical traits from needles, cones and seeds were analyzed to assess the altitudinal and longitudinal variations of the species in the island. The number of teeth per cm showed significant (P<0.01) differences between altitudes in Samaria, Vorizia and Lassithi, while needle length, width and the number of resin canals showed significant differences (P<0.01) between altitudes in Koustagerako. Cone width showed patterns of variation along the altitudinal gradient in Koustagerako, Samaria and Vorizia. Most traits had their highest means at the middle altitudes (650masl) in all the four populations. Overall, no clear altitudinal differentiation was detected, probably due to high rate of gene flow. Longitudinal variability showed a clear pattern of differentiation along the east–west climatic gradient. Needle length, width, sheath length, number of teeth per cm and the number of resin canals were the most useful traits for determining the climatic gradient clines. 相似文献