Allometric model of the Reineke equation for Japanese cypress (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>) and red pine (<Emphasis Type="Italic">Pinus densiflora</Emphasis>) stands

An allometric model that explains the mechanism of the difference in the slope of the Reineke equation (A) among species was proposed based on the allometric relationships of mean tree height (H) to quadratic mean diameter D (H ∝ D ^θ ) and stand density N (H ∝ N ^δ ), i.e., A = θ/δ. The proposed model was fitted to Japanese cypress (Chamaecyparis obtusa Endl.) and red pine (Pinus densiflora) stands. The allometric exponents θ and δ were, respectively, 0.8995 and −0.5000 for cypress and 0.8612 and −0.6619 for pine. The difference between cypress and pine was significant for δ but not for θ. Inserting the exponents into the model resulted in predicted slopes of −1.7991 for cypress and −1.3011 for pine. The difference in the slope of the Reineke equation between the two species was produced by characteristics related to the tree crown, rather than characteristics related to stem slenderness. The proposed model enables us to estimate the slope of the Reineke equation from commonly measured stand attributes, such as mean tree height and quadratic mean diameter. Therefore, the proposed model is expected to be practical and convenient for estimating the slope of the Reineke equation and for explaining the mechanism of its variation among species. The model should be also accepted as a generalized model of the stand density versus quadratic mean diameter relationship, whereas the original Reineke equation should be seen as a specific case of this model.     

麻疯树人工林单木生物量与生产力模型研究

回归分析法是构建单木生物量模型进而估算群体生物量的基本方法。本文研究了攀枝花市马店河一个麻疯树4年人工林生物量与生产力模型的构建过程,运用相关生长定律分析参数合理性,并筛选了适宜的模型构建参数。首先,用地径、高度、D2H、树冠直径、冠幅、枝下高、树冠垂直投影体积这些灌木生物量测定中经常采用的外部形态指标构建麻疯树单木生物量模型,得到拟合性最好的幂函数、抛物线、对数函数模型。其次,采用树体构型指标,如枝条数量（不同年龄枝级）与分支率（总体分支率、）参数构建单木生物量模型,得到相关性不等的幂函数、抛物线模型。用年龄平均法与直径增量法同时估算了麻疯树单木生产力,分别为Pa=4.93±3.92 kg.a-1,Pd=4.59±3.82 kg.a-1,方差分析差异不明显。经回归,获得单木生产力模型。通过排序,获得对生产力贡献较大的因子,并对筛选的因子进行多元回归,得到Y=∑AiXi（其中Ai为第i个常数,Xi为第i个变量,i为测定变量总个体）,提高了估算的精确度。分析表明,地径、冠幅直径、冠幅、冠幅垂直体积都能较为准确的估算单木生物量、生产力,但生殖生物量估算相关系数在0.8以下（0.607〈r2〈0.753）,精确度不高,表明生殖自身特性的独特性。     

Production losses due to a summer frost in a Salix viminalis short‐rotation forest in southern Sweden

The effect of a single night frost during late spring on the current year production of two clones of Salix viminalis was determined in two monoclonal stands that displayed a gradient from virtually undamaged plants, shielded from outgoing radiation by a neighbouring spruce forest, to heavily damaged plants in the unshielded parts. Compared with the undamaged stand parts, frost caused production losses of 47% and 60% in the two clones during the first year of the second cutting cycle. The clone‐specific allometric relationship between shoot dry weight and diameter was changed by the frost in one clone, showing lower shoot weights in damaged shoots compared with undamaged shoots of the same diameter. In the other clone, allometric relations were not affected by the frost. The relative variation in weight between the stools did not differ systematically with frost damage intensity, and therefore it could not be concluded that frost in monoclonal stands would enforce a competitive hierarchy. It was inferred that the single night frost indirectly can have a negative effect on the production of the stands during the years to come.     

长江中下游平原地区3种木犀属植物叶片的生长规律

[目的]分析3种木犀属植物金桂（Osmanthus fragrans vat．thunbergii）、银桂（0．fragrans vat．如latifolius）和四季桂（0．fragransCV．Semperfl0）叶片的生长规律。[方法]采用大样本、随机取样方法测定成株叶片的长度、宽度、面积和生物量。[结果]四季桂的叶长显著高于金桂和银桂,银桂和四季桂的叶宽和生物量显著高于金桂,3种桂树叶面积间差异显著。3种小乔木叶片的生长规律均可由多种函数形式较好地表达,在最佳的拟合方程中,叶长和叶宽间呈同速或异速生长,叶面积和生物量则均为异速生长;在植物种水平上,银桂和四季桂叶片均呈异速生长。[结论]随着叶面积增长,金桂的物质增长速率最快。     

基于异速生长关系的棉籽蛋白质含量模拟模型

基于不同熟性棉花品种的异地分期播种和施氮量试验,运用异速生长模型分析棉籽氮浓度与棉籽生物量间的关系,建立氮素的潜在增长模型,进而综合品种特性、主要气象条件(温度、太阳辐射)和栽培措施(施氮量)等因子,建立基于异速生长关系的棉籽蛋白质含量模拟模型。利用不同生态点品种、播期和施氮量的田间试验资料的检验结果表明:安阳、淮安和徐州试点模拟值与实测值的根均方差(RMSE)分别为2.2%、4.1%和2.3%。说明依据棉籽蛋白质含量与生物量间的异速生长关系模拟棉籽蛋白质形成切实可行,模型预测性好,广适性强。模型的不足在于其精确度受棉籽干物质累积模型和棉铃对位叶N浓度模型的影响较大。     

Self-thinning lines and allometric relation in Chinese fir (Cunninghamia lanceolata) stands

We calculated a self-thinning exponent of 1.05 for tree mass using the 3/2 power equation in 93 Cunninghamia lanceolata plots.According to Weller’s allometric model,the self-thinning exponent for tree mass was calculated as 1.28 from the allometric exponents h and d.The both self-thinning exponents were significantly lower than 3/2.The self-thinning exponent of organs was estimated to be 1.42 for stems,0.93 for branches,0.96 for leaves,1.35 for roots and 1.28 for shoots,respectively.The self-thinning exponent of stem mass was not significantly different from 3/2,whereas thinning exponents of trees,branches,leaves and roots were significantly lower than 3/2.The stand leaf mass and stand branch mass were constant regardless of the stand density.The scaling relations among branch,leaf,stem,root and shoot mass(MB,ML,MS,MR and MA,respectively) showed that MB and ML scaled as the3/4 power of MS,whereas MS or MA scaled isometrically with respect to MR.     

Allometric equations for urban ash trees (Fraxinus spp.) in Oakville,Southern Ontario,Canada

Tree growth equations are an important and common tool used to effectively assess the yield and determine management practices in forest plantations. Increasingly, they are being developed for urban forests, providing tools to assist urban forest managers with species selection, placement, and estimation of management costs and ecosystem services. This study describes the development of allometric equations for Fraxinus americana and F. pennsylvanica growing in Oakville, Canada. With data collected from 103 ash trees, five allometric models were tested to develop equations estimating diameter-at-breast-height (dbh), tree height, crown width and crown height, using age and dbh as explanatory variables. Mean annual growth rates are presented to demonstrate species growth performance and were not significantly different over the first 40 years of growth for the two species. Of all the tested random coefficient models for both species, the cubic with weight 1/x provided the best fit for estimating dbh from age. The best models for other parameters were the loglog for crown height from dbh, the quadratic for crown diameter from dbh, and the linear for tree height from dbh for F. americana. Model types showed more consistency for F. pennsylvanica with linear providing the best fit for crown diameter, crown height and tree height from dbh. The number of model types suggests the difficulty of fitting any single model to the vast array of conditions affecting plant growth in urban areas where management practices and environment can significantly influence tree size and growth. These models may be used to estimate the growth of ash tree populations in Oakville and communities with similar climate, soil, planting, and management environments.     

昆明市3种木兰属园林乔木叶片的表型可塑性与生长规律

[目的]为木兰属植物资源的合理开发及利用提供科学参考。[方法]以玉兰、紫玉兰和荷花玉兰3种常见木兰属园林乔木为研究对象,通过测定其成株叶片的长、宽、面积及生物量,分析其叶片的表型可塑性和生长规律。[结果]3种植物均具有较大的表型可塑性。叶生物量的变异系数最大,为35．45％～57．50％。叶面积变异系数次之,为34．72％～48．44％。叶长、叶宽的变异系数均较小,为18．77％～28．28％。玉兰与荷花玉兰的叶宽与叶长呈幂函数异速生长规律,而紫玉兰呈直线同速生长;玉兰、紫玉兰的叶生物量与叶面积呈直线同速生长规律,而荷花玉兰呈幂函数异速生长。[结论]玉兰、紫玉兰和荷花玉兰3种成株叶片在叶长、叶宽、叶面积以及叶生物量等数量性状均具有较大的表型可塑性。     

Predicting mean aboveground forest biomass and its associated variance

An approach to simplify the prediction of average aboveground forest biomass values and their associated variability is presented in this study. The advantage of the proposed approach is based on the fact that it can be applied to any form of equation describing tree size–shape relationships and to any tree species. The proposed approach was tested against a tree-level dataset comprising of 1211 pairs of aboveground tree biomass (M) and tree diameter (D) values. The compiled trees were grouped into several D classes and average M estimates (μ_M) with their associated variances (σ_M) were predicted for each class based on second-order Taylor expansion formulas. Nineteen beech (Fagus moesiaca Cz.) plots were also used to derive μ_M and σ_M estimates on an area basis in order to test the applicability of the approach on forest scale. The only assumption made was that the simple allometric model M = aD^b can accurately describe the M–D relationship. The results indicated that the mere recording of D distribution and appropriate selection of a and b values may provide very good estimates for μ_M and σ_M both at global and forest level. It is therefore concluded that biomass studies related to carbon sequestration, biofuel potential, ecophysiological processes and management practices are considerably simplified.     

松嫩平原赖草无性系构件生长的可塑性及其规律

赖草（Leymus secalinus）是长根茎型无性系优良禾草,研究建植初期无性系构件生长的可塑性及其规律具有重要理论与实践意义。本试验采用整个无性系完整挖掘的方法,定量分析了其无性系构件生长的数量特征和可塑性。结果表明,经过一个生长季,赖草无性系构件的生长均具有较大的变异系数,其中,分蘖节芽的最大,为107.9%,可塑性最大。间隔子长度的最小,为29.4%,可塑性最小;分株和根茎均以生物量的可塑性高于其数量。随着根茎长度的增加,根茎和分株的生物量均呈极显著（P<0.01）线性函数同速生长,分株数量、总芽数和根茎芽数均呈极显著（P<0.01）幂函数异速生长。赖草无性系具有分株数量优先于根茎伸长的构件生长原则。