人工落叶松枝下高动态研究

林木枝下高直接影响树木的生长和树干形状,建立林木枝下高动态模型可以了解林木或林分的生长规律．分析了枝下高与林分密度和树高的关系,利用节子剖析数据,结合落叶松高生长数据,建立了落叶松人工林的枝下高动态预测模型．并讨论了其动态预测模型在整枝高度、树冠基部高度和合理间伐时间的确定中的应用．     

毛竹材积主要构件因子关系研究及材积表编制

通过毛竹立竹材积构件因子及立竹胸径与立竹实际材积的关系研究,结果表明:立竹全高、胸高竹壁厚与立竹胸径呈显著的正相关,是立竹胸径的从属因子;竹秆相对高度竹壁厚与秆径呈一致性变化趋势,立竹径级与竹秆相对壁厚无相关;构建了立竹胸径与立竹实际材积的数学模型:V=0.007351-0.001875D+0.000291D2,编制出竹林林分结构易测因子立竹胸径的对应材积表。     

杨树1年生整株苗造林树体控制技术研究

为了论证杨树1年生整株苗造林树体控制技术中最适宜的截干高度以及后期采用何种主干控制技术能使苗木获得较好的生长,本研究采取双因素完全随机试验设计,设置不同截干高度和不同主干控制方式两个因素进行试验.结果表明:1年生整株苗造林树体控制技术的苗木造林平均成活率达97.4％以上,显著高于常规整株苗造林的平均成活率;合理截干高度...     

秃杉树干不同高度处直径生长规律

利用秃杉标准木的解析数据,根据分形理论和R/S分析法,探讨秃杉树干不同高度处直径的相对生长量与树干相对高度之间的生长变化规律。结果表明,树干不同高度处直径相对生长量与绝对高度之间没有相关性,但与树干相对高度之间呈极显著相关;不同高度处直径的增量生长持续强度也不同;并进一步探讨引起树干不同高度处直径生长量不同的原因。秃杉树干相对高度在0.5～0.8之间的直径相对生长量较高,生产中可在树木高生长高峰期来临前,采取各种措施促进树木高生长,从而促进树干材积生长,减小树干的尖削度。     

贵州省平坝县斑苦竹种群结构初探

采用样方法对贵州平坝县十字乡自然生长的斑苦竹种群结构特征进行调查分析,结果表明:斑苦竹种群年龄结构中Ⅱ龄级所占比例最大,达到27.9%,其次为Ⅰ龄级和Ⅲ龄级,占调查总数的比例分别为25.1%、20.0%;胸径主要分布在31～45 mm;高度主要分布在6.0～8.9 m,占总体的57.8%。各龄级植株的径级、高度级存在一定差异。随着龄级的增加,胸径变小,说明斑苦竹种群存在衰退的趋势。     

水曲柳育苗密度对苗木质量的影响

水曲柳(Fraxinus mandshurica Rupr.)是东北地区三大珍贵硬阔叶用材树种之一,也是东北地区的造林树种.垄作时,水曲柳育苗密度决定苗木的产量和质量,试验结果表明,当密度达到50株/m时,是水曲柳的最优育苗密度,其苗高、地径、主根长和侧根数最优,高径比上的比例比较合适,有利于优质壮苗的培育.     

帽儿山地区次生林椴树单木胸高断面积生长模型的研究

应用帽儿山天然次生林区不同林分条件下选设的20块椴树（Tilia amurensis）固定样地的解析木调查资料,分析多个单木竞争指标与对象木胸高断面积定期生长量的相关关系,在椴树单木胸高断面积生长模型中引入林木自身大小、单木竞争指标和立地因子,应用回归分析法建立帽儿山地区天然次生椴树单木胸高断面积生长模型。研究表明：天然次生林下椴树的胸高断面积定期生长量与对象木相对直径（RD）和竞争压力指数（SCI）等指标存在比较明显的相关关系。应用主分量线性组合的方法构造的综合竞争指标（MCI）包含了各竞争指标与胸高断面积生长量之间的绝大部分的相关信息,可以作为竞争指标应用于单木胸高断面积生长模型。     

Potential long-term growth gains from early clump thinning of coppice-regenerated oak stands

A study was established in the Missouri Ozarks to evaluate coppice regeneration of oak. Five years after a 32-year-old stand was clearcut and regenerated naturally through stump sprouts, the dominant sprout on each stump was identified based upon height. Treated plots were thinned to the single dominant sprout on each stump whereas control plots were not thinned. Twenty-five years later the largest 247, 371, 494, and 618 stems per ha were examined and height of the dominant sprout at age 5 was found to be strongly related to dbh at age 30 in both thinned and unthinned plots. However, in the thinned plots, the largest 494 stems per ha were on average 11%, 28%, and 58% greater, respectively, in height, dbh, and volume compared to similar dominant sprouts in unthinned plots. Logistic regression analysis was used to develop curves for the evaluation of potential gains from clump thinning. In this analysis, the average height of a stand at age 5 was used to estimate thinning gains at age 30.     

Development of site index curves for Pinus kesiya in the Philippines

This study was conducted to develop a height–age growth model and site index curves for site quality evaluation of old secondary-growth stands of Pinus kesiya in the northern Philippines. The Chapman-Richards growth function was used in the guide curve method to generate anamorphic site index curves for this species. In order to evaluate the developed model, coefficient of determination (R ² ), root mean square error (RMSE), bias (ē), absolute mean difference (AMD) and mean percent bias (MPB) were used as statistical criteria. The Chapman-Richards model explained about 96.84% of the total variation of the dominant height. The value of ē was ?0.004 m, AMD was 2.566 m, MPB was 3.88% and RMSE was 3.331. The site index curves developed as a result of this study are significant for forest managers in predicting the growth patterns and classification of site productivities for Pinus kesiya stands.     

遗传算法对5种理论生长方程的最优拟合研究

利用北美林肯小区黄杉6个分期的数据,选择Logistic、Richards、Korf、Gompertz和Mitscherlich 5种生长方程建立胸径随年龄变化的生长模型.分别利用遗传算法和传统拟合方法确定参数,并对拟合效果进行对比分析.研究结果显示：遗传算法对于Richards和Korf方程的拟合精度要明显高于传统拟合方法,对于Logistic、Gompertz以及Mitscherlich方程的拟合精度几乎一致.通过将检验数据带入由遗传算法拟合的方程中,除拟合后不符合生物学意义的Korf方程外,发现由剩下4种方程计算得到的预测值与实际值无明显差异（P值均大于0.05）.最终表明遗传算法对生长方程的最优拟合较传统拟合方法更有优势.