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森林生态系统中林分胸径和树高的Granger因果关系研究 总被引:3,自引:0,他引:3
滞后阶数为1时,胸径和树高互为Granger原因,这从理论上证明,建立胸径和树高模型是合理的.当滞后阶数为2时,胸径不再是树高的Granger原因,但树高仍是胸径的Granger原因,两者相比,树高的影响更深远.所以在森林培养时,应更加注重树高,以维持树高对胸径的影响. 相似文献
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采用随机抽样法抽取马尾松成熟林分50个小班为调查样本,调查胸径、树高、单位蓄积量及密度等测树因子,并运用回归分析法进行测树因子相关性分析。结果表明,林分蓄积量与密度、胸径、树高之间存在显著线性关系,其相关性数学模型可用三元线性回归方程表示。在各项因子中,密度是影响林分蓄积量的主导因素。相关性变化趋势分析表明,在兼顾林分产量和林木径级的情况下,合理保留密度为105株。 相似文献
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厚朴林分结构与产量关系的研究 总被引:3,自引:0,他引:3
通过对影响厚朴树皮产量的因子分析,提出了对单株厚朴树皮产量有直接贡献的因子是密度、树高、胸径和树干干重。在厚朴林分形成过程中,密度是影响林分厚朴树皮产量的主导因子;及时地进行合理间伐,改善林木生长环境,是提高单位面积树皮产量和整个林分质量的重要措施。 相似文献
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大强度抚育对油松人工林天然更新的影响 总被引:1,自引:0,他引:1
以油松人工林为研究对象,在大强度抚育条件下,通过林分层次结构、各层次林木胸径结构、树高结构及其林木分布格局等指标研究林下天然更新状况,结果表明:油松人工林在22a、32a时分别进行株数强度50%和40%的下层抚育,后经20a天然更新(林分年龄52a),林分形成明显层次结构,分为主林层、演替层及更新层,整个林分林木胸径、树高结构均呈多峰分布,其中主林层、演替层林木胸径和树高结构均呈单峰山状分布,更新层林木胸径和树高结构呈多峰分布,各林层平均胸径分别为23.2cm、12.6cm和3.1cm,平均树高分别为18.4m、14.5m和2.8m,而对照标准地胸径、树高结构均呈单峰分布,平均胸径、树高分别为18.6cm及17.9m;主林层、演替层各层林木空间分布呈均匀分布,密度分别为840株/hm~2和1 125株/hm~2,更新层林木空间分布呈聚集分布,密度为675株/hm~2,对照样地林木空间分布偏向均匀分布,密度为1 605株/hm~2。 相似文献
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运用随机抽样法抽取马尾松成熟林分50个小班,调查胸径、树高、单位蓄积量及密度等测树因子,运用回归分析法进行测树因子相关性分析,结果表明,林分蓄积量对于密度、胸径、树高之间存在显著线性关系,其相关性数学模型可用三元线性回归方程y=b0+b1x1+b2x2+b3x3表示,其中,密度是影响林分蓄积量的主导因素。相关性变化趋势分析表明,在兼顾林分产量和林木径级的情况下,合理保留密度每667 m2为105株。 相似文献
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林分密度对油松中龄林生长特征的影响 总被引:1,自引:0,他引:1
《山西林业科技》2015,(1)
以平顺县和太原东山25年生的油松人工林为调查对象,通过样地调查,研究林分密度对树高、胸径、枝下高和冠幅等生长特征的影响,以及生长特征指标之间的相互影响。结果表明,林分密度对树高无显著影响,枝下高随林分密度的增大而增大,冠幅、胸径均与林分密度呈显著负相关关系;林分密度为950株/hm2时,树高、胸径、枝下高和冠幅之间相关性均不显著;林分密度为3 050株/hm2时,胸径与树高、胸径与冠幅、冠幅与枝下高显著相关;林分密度为5 600株/hm2时,胸径与树高、冠幅、枝下高,树高与冠幅、枝下高及冠幅与枝下高间均显著相关。 相似文献
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雷州刚果12号桉W5无性系林分蓄积量与胸径树高密度及其之间关系的探讨 总被引:2,自引:0,他引:2
采用雷州林业局2002年森林二类调查的刚果12号桉W5无性系林分1071块样地中279块样地材料,进行蓄积量与胸径、树高、密度及其之间关系的探讨分析。分析结果表明:胸径是影响林分蓄积量的主要因素,其次是树高与密度;树高与胸径关系密切,呈正相关,但两者的生长随着造林密度的加大而显著下降。因此,进行W5无性系林分密度试验,提出合理的造林密度,是提高其单位面积蓄积量的关键。 相似文献
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对福建省连江县境内不同造林密度6年生的湿地松人工林的调查数据,采用数学方法对树高、胸径进行方差分析,结果表明:4种密度(1352、1605、1890和2500株/hm2)对6年生湿地松树高生长影响不明显,但胸径的差异性显著,且随着密度的增大而呈递减趋势。同时,对冠幅、生物量和生长曲线的比较分析结果也说明:福建省引种湿地松宜适当稀植。最后,通过胸径和冠幅线性关系的回归分析,计算出湿地松各径级林分的保留株数。 相似文献
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Stand density management diagrams are average stand-level models that graphically display the relationship between stand yield, density, height and diameter throughout the various stages of forest development in even-aged stands. These are useful tools for designing, displaying and evaluating alternative density regimes in even-aged forest ecosystems to achieve a desired future condition. In this paper, we present a stand density management diagram constructed for sandalwood stands in Karnataka state of India. The relationship between stand density, dominant height, quadratic mean diameter, relative spacing and stand volume is exhibited in one graph. The relative spacing index was used to characterise the growing stock level. Two equations were fitted to the data collected from 19 sample plots measured annually for three years: one relates quadratic mean diameter with stand density and dominant height, whereas the other relates total stand volume with quadratic mean diameter, stand density and dominant height. 相似文献
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为研究厚朴树高、胸径和树皮厚度对其产量的影响,从而为厚朴品种选优及丰产栽培提供理论指导。采用系统抽样方法抽取了10~14 a的90个厚朴单株样本,测量其单株树高、胸径、树皮厚和树皮产量,通过建立和分析厚朴产量回归方程可知,胸径、树高和树皮厚与产量均成正相关关系;胸径、树高、树皮厚对产量的直接影响从大到小依次为胸径、树高、树皮厚,其中胸径对产量的影响以直接影响为主,树高对产量的间接影响稍高于直接影响,其间接影响主要是通过胸径对产量产生影响,树皮厚主要通过胸径和树高对产量产生间接影响,直接影响较小。 相似文献
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The influences of cambial age and ring width on density of Sitkaspruce (Picea sitchensis (Bong.) Carr) were analysed in relationto within-tree trends in tracheid diameter and cell wall thickness.Discs were sampled at breast height from a total of 24 trees,from seven stands at three contrasting sites in Wales, and atbreast height, 30 per cent and 60 per cent total tree heightfrom one of the stands. Across the juvenile wood, ring density decreased with ring numberfrom the pith while radial tracheid diameter increased. Theseoverall trends were considered to be inherent to tree growth,presumably associated with cambial ageing, since they occurredin all trees on all sites. In juvenile wood, density also variedwith site growth rate (as indicated by ring width) at similarcambial age, wider rings being associated with more rapidrateof change in tracheid diameter with ring number and with decreasein tracheid wall thickness. Consequently, on a site having treeswith high growth rate density decreased more rapidly acrossthe juvenile wood, down to a lower minimum value, than on siteswith a slower growth rate. In mature wood, the decrease in densitywith increase in ring width was associated with differencesin both tracheid diameter and wall thickness. Density was slightly(though not significantly) higher at breast height than in comparablerings at 30 per cent total height, associated with significantlythicker tracheid walls at breast height. Changes in radial tracheid diameter (with ring number, or withring width) were associated with greater differences in theearlywood than towards the latewood end of each growth ring,while variations in wall thickness with ring width were associatedwith rate of increase in wall thickness towards the latewoodend. This may account for some previously conflicting reportson influence of silvicultural management on density, for densityis likely to vary with influence of environment on the seasonalcycle of cambial activity. The extent of the juvenile wood as delimited by the inner coreof wide growth rings does not necessarily correspond to theregion of varying tracheid dimensions in Sitka spruce. 相似文献