共查询到20条相似文献，搜索用时 93 毫秒
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桂东区杉木地径与胸径、树高、材积相关分析 总被引：2，自引：0，他引：2
利用广西昭平县2009年二类调查控制样点的数据中的杉木的地径和胸径、树高为样本数据,并通过SPSS统计分析软件和数理统计知识,对地径与胸径、树高和材积的相关关系进行分析,分别建立地径与胸径、地径与材积的相关关系或曲线回归模型,最后选出最优模型,从而可利用模型由地径推算胸径和材积。结果表明,地径与树高存在显著正相关性,且地径6~20 cm径阶与胸径之间最佳的回归模型为D1.3=-0.199+0.851D地,地径22~40 cm径阶与胸径之间回归模型为D1.3=-1.652+0.913D地,精度是98.7%;同时地径与胸径也存在显著的正线性相关性,地径与材积的回归模型为V=0.000 082D地2.486 79,精度为95.2%。本次所建立的模型精度在允许范围内,可应用到实际中。 相似文献
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榆林市榆阳区杨树地径、胸径、树高、材积相关性研究 总被引：2，自引：0，他引：2
通过对60株榆林市榆阳区内生长的合作杨(Populus simonii×P.pyramidalis cv.‘Opera8177)’生长情况的调查,结果表明:随着树木生长加粗,胸径、地径基本同步增粗,胸径/地径比值变化很小,数值是0.84倍左右,其范围在0.82～0.86;树高的生长量随树木的生长加粗呈现放缓的规律,随着树木生长加粗,树高/地径比值逐渐变小,地径8 cm时,树高/地径比值是58.92倍,地径48 cm时,树高/地径比值是33.38倍。 相似文献
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远足作为最受欢迎的健身休闲活动，实现了居民与郊野的良性互动，许多城市开始关注并尝试建设远足体系。香港通过远足径的建设形成连接郊野公园的网络，并实现郊野公园的功能提升与拓展，提供了可资借鉴的样本。根据其概念和内涵，分析了远足径与绿道在功能定位和管理体制上的差异。以港岛径为例，归纳了选线规划和游径设施设计要点，总结了植被优化修复、安全保障管理、多元社会参与、花事活动组织方面的管理运营经验，并探讨港岛径对其他城市远足径建设与运营的启示。 相似文献
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沙县杉木、马尾松、阔叶树地径一元材积表编制的研究 总被引：1，自引：0，他引：1
地径材积表是林业生产、科研和管理的基础工具。本文结合县级森林资源连续清查样地调查,通过样木地径、胸径成对值测定,建立地径——胸径回归关系,并利用现有省定的一元立木材积表,编制了沙县杉木、马尾松、阔叶树地径一元材积表。 相似文献
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本文根据塞罕坝林场4个树种(樟子松、落叶松、白桦和山杨)的胸径、地径调查材料,利用胸径、地径之间存在的显著直线相关关系,分树种建立经验方程,求算出各径阶的胸径、地径对应值,通过一元立木材积式,导引出一元立木地径材积式(表)。 相似文献
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林木高径比是基本测树因子之一。由于精确树高测定困难（特别是在结构复杂的森林中）,对林木高径比的直接相关研究相对较少。文中从林木高径比的研究对象、影响因素、林木高径比与单一测树因子的关系、林木高径比模型模拟、林木高径比与林木遭受风雪灾害的关系5个方面进行综述,以期为进一步研究林木高径比奠定基础。目前大部分研究是针对结构简单、单层同龄的人工针叶纯林,针对分树种和分林层的研究极少且只有国外报道。林木高径比可能受到树龄、树种、竞争、立地和气候等多种因素的影响。胸径、断面积、材积和地径等单一测树因子与林木高径比关系较为紧密,且呈负相关,而树高、冠长、冠幅、树冠面积、冠径、树冠比和树冠闭合百分比等单一测树因子与林木高径比关系较不紧密。目前的林木高径比模型多以胸径为自变量,然后进行多模型优选,所选的最佳模型多为非线性模型;部分研究则在最佳模型中加入其他的自变量,如竞争、立地、林层和树种等因子。多数研究认为,林木高径比越大,林木越容易遭受风雪灾害。 相似文献
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对浙江主栽的11个油茶Camellia oleifera良种与3个浙江本土油茶品种（种）分别测定果径和籽径及其直径分布,并选取其中6个长林系列品种的油茶果进行混合测验机械脱蒲效果,分析油茶果的脱蒲率、油茶籽破损率和蒲籽分离率,研究果径、籽径对油茶机械化脱蒲的影响,为油茶果机械化脱蒲及加工机械开发提供理论依据与数据支撑。结果表明,果径分布区间在<19 mm、19～31 mm、31～43 mm、>43 mm的油茶果实比例分别为0.67%、35.55%、54.65%、9.13%;不同品种（种）油茶籽径分布有一定的差异,油茶籽径分布区间在<9 mm、9～15 mm、15～21 mm、>21 mm的油茶籽比例分别为1.79%、31.45%、57.80%、8.96%。机械化脱蒲试验结果表明,油茶果的脱蒲率为92.78%,油茶籽的破损率为2.34%,蒲籽分离率为87.20%,油茶籽径大于30mm的油茶籽易受损,果径在19.58～21.22 mm的油茶果不易脱蒲和分离。可依据试验结果对油茶果脱蒲机械的辊子的尺寸、辊子运动的速度、筛选器的间隙等关键零部件进行设计与分析,同时可对不... 相似文献
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樟子松人工林胸径生长规律的研究 总被引：1，自引：0，他引：1
本文以佳木斯市横头山林场樟子松人工林作为研究对象,研究樟子松人工林林木的胸径生长规律,分别用修正指数方程、理查德方程、逻辑斯蒂方程对各等级大小胸径生长数据进行拟合。结果表明,用理查德方程拟合胸径生长较好;胸径连年生长量达到最大的时间在11-14年之间,当时的胸径则差异较大,优势木和劣势木相差将近2cm,范围在5.5-7.5cm之间,年生长最大值的差异较明显,在0.56-0.87cm之间。 相似文献
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黄龙山林区主要树种的树高与胸径关系的分析 总被引：6，自引：0，他引：6
利用森林资源“二类调查”的1087个角规样点的角规控制胸径检尺调查资料，分别对油松林、栎类林、白桦林、山杨林及硬阔林、软阔林的平均树高和平均胸径的关系进行回归分析。结果表明，各树种林分平均高与胸径之间存在着显著的相关关系，即：H＝a b lnD、H＝a bD且相关紧密。在黄龙山林区用胸径估测平均树高，对于森林资源清查和育林作业设计具有十分重要的意义。 相似文献
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基于多项生长指标的楠木胸径估测模型研究 总被引：2，自引：0，他引：2
收集了楠木胸径、树高、枝下高、冠幅等生长指标,分别参照常规的线性、乘幂、指数、对数及双曲线等单因素变量模型,构建了基于多项生长指标的胸径估测方程.结果表明,基于树高、枝下高、冠幅等多项生长指标的胸径估测较单因素变量估测模型效果更优;楠木胸径估测的首选模型为:D=205.6074e-74.0621/H+0.0027e12... 相似文献
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现在有关树冠冠径（K）和干直径（D）之关系的研究相对较少。胸径在15～35cm之间并且相关系数（R2）高于0.6的关系近似于一条直线。本研究主要论述了帽儿山10种主要阔叶树的树冠冠径（K）和干直径（D）之间的关系。 相似文献
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对海涂哺鸡竹笋产量分布和竿径变化规律初步研究结果表明，哺鸡竹出笋不均勾，盛笋期在整个笋期的中前期；笋期从造林后开始逐年推迟，最后稳定在５月上旬左右。竹竿胸径逐年增粗，到成林时基本稳定，受土壤条件影响较深。 相似文献
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通过采集山西省天然油松林的根径、胸径样本数据，依据《根径立木材积表编制技术规程》的技术要求，利用数理统计和回归关系建立天然油松林根径-胸径数学模型，同时进行数学模型检验，最后建立根径材积表，以达到支持生产的目的。 相似文献
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We investigated the impacts of elevated temperature and carbon dioxide concentration ([CO2]) on diameter growth of Scots pine (Pinus sylvestris L.), aged about 20 years, grown with a low nitrogen supply in closed chambers at (i) ambient temperature and [CO2] (AT+AC), (ii) ambient temperature and elevated [CO2] (AT+EC), (iii) elevated temperature and ambient [CO2] (ET+AC), and (iv). elevated temperature and [CO2] (ET+EC). Each treatment was replicated four times. Diameter growth was monitored with a band dendrograph at 15-min intervals throughout the growing seasons of 1997, 1998 and 1999. Over the monitoring period, diameter growth began 2-3 weeks earlier in trees in the ET+EC and ET+AC chambers than in trees in the AT+AC and AT+EC chambers. However, the cessation of growth occurred about a week later in trees in the ET+EC, ET+AC and AT+EC chambers compared with the AT+AC chambers. The duration of the growing season was 115 and 108 days in the ET+EC and ET+AC chambers, respectively, and 95 and 84 days in the AT+EC and AT+AC chambers, respectively. The ET+AC and ET+EC treatments enhanced diameter growth most early in the growing season, whereas in trees in the AT+AC and AT+EC treatments diameter growth rate was highest in the middle of the growing season. Diameter growth rate leveled off more slowly in trees in the ET+EC and AT+EC treatments than in the other treatments. The growth response to elevated T, elevated [CO2] or both decreased with time and it was less than the maximum observed in other studies for small seedlings and under optimal growth conditions. Nevertheless, cumulative diameter growth for the 3-year period was 67% greater in trees in the ET+EC treatment, and 57 and 26% greater in trees in the AT+EC and ET+AC treatments, respectively, compared with trees in the AT+AC treatment. Over the 3 years, [CO2] had a statistically significant (P < 0.10) effect on both absolute and relative diameter growth, but the interaction between [CO2] and temperature was not significant. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):226-232
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. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):493-502
The three‐parameter Weibull function met specified statistical standards for goodness of fit as a model for the diameter distribution of moderately thinned Norway spruce stands in Denmark. Weibull distributions estimated by percentile estimators fit the majority of 522 observed diameter distributions (material made available by the Danish Forest Experiment Station) at the 10% level of significance in the Chi‐square and Kolmogoroff‐Smirnow tests. The Weibull distribution was less suited to describe the diameter distribution in unthinned stands and heavily thinned stands. Weibull parameter predictions were developed and used in connection with a Danish yield table for Norway spruce on clay‐rich coastal soils. The use of the Weibull distribution to predict stem frequencies in different diameter classes before and after a specified thinning of stands is demonstrated. 相似文献
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Diameter distribution of trees in natural stands managed on polycyclic cutting system 总被引：1，自引：0，他引：1
Diameter frequency distribution in a specific stand provides basic information for forest resources management.In this study,four probability models were applied to analyze diameter distribution of natural forests after selective cutting with different intensities (low intensity of 13.0% in volume,medium intensity of 29.1%,high intensity of 45.8%,and extra-high intensity of 67.1%).The results show that the skewness and kurtosis of the four models are positive except that of low intensity selective cutting,which suggest that the number of small-size trees dominate the stand.The more intensity of selective cutting,the wider range of diameter distributions.The diameter structure of selective cutting with low intensity met Weibull and Beta distributions;that of medium intensity met Weibull,negative exponential as well as Gamma distributions;that of high intensity cutting met Weibull and negative exponential distributions,but that of extra-high intensity could not meet any above model.Weibull distribution model fits better than others regarding the structure of diameter distribution in natural forests managed on polycyclic cutting system.The results will provide basic information for sustainable management for mixed natural stands managed on a polycyclic cutting system. 相似文献