长宁苦竹种群结构和地上生物量研究

本文研究了长宁苦竹的种群结构和地上部分生物量。结果表明：（1）人工经营和未经营的苦竹种群都为增长型种群，但人工经营苦竹种群落结构简单；（2）人工经营苦竹种群径级结构偏大；地上部分生物量较大；（3）在种群水平，长宁苦竹地上部分生物量为37．58t／hm^2，随径级增大而增大；（4）在构件水平，1a生苦竹的地上生物量为1074．20g／株，2a生的为2041．86g／株；（5）1a生苦竹竿、枝和叶的含水率普遍高于2a生。     

四川省草地生态系统碳储量估算

草地生态系统在全球碳循环中起着极为重要的作用。但是实测数据十分匮乏。利用2008年四川省草原地面调查数据,以及卫星遥感数据,对2008年四川省草地的碳储量进行了估算。主要结论如下:四川省草地总面积约为20.38×104km2,2008年四川省草地总有机碳为2 302.97 Tg,其中地上生物量有机碳为15.54 Tg,地下生物量碳为104.45 Tg,地下根系储存的碳是地上碳储量的6倍多,四川省草地土壤有机碳为2 182.98 Tg。土壤储存的碳是植被的19倍多。     

密度对刺槐幼苗生物量及异速生长模式的影响

刺槐(Robinia pseudoacacia)具有较强的生态适应性和抗逆能力,是黄土高原植被恢复和生态重建的主要优良树种之一(程积民等,2002;陈云明等,2002).     

两种生物量模型的比较(英文)

CAR模型和VAR模型是生物量模型研究与应用中最为常用的基本形式 .该文用再抽样的方法 ,从模型参数的稳定性、模型的预估能力上较全面地分析与比较了两类模型 .通过对CAR和VAR模型比较得出 :CAR模型相对VAR模型 ,不仅参数估计值稳定 ,而且预估能力强 .     

An allometric equation for estimating stem biomass of Acacia auriculiformis in the north-eastern region of Bangladesh

Tree biomass plays an important role in sustainable management and in estimating forest carbon stocks. The objective of this study was to select the best model for measuring stem biomass of Acacia auriculiformis in the study area. Data from five hillocks and 120 individual trees from each hillock were used in this study. Twelve different forms of linear, power and exponential equations were compared in this study to select the best model. Two models (VI and XI) were selected based on R ², adjusted R ², the Akaike information criterion, F-statistics and the five assumptions of linear regression. Model VI was discarded based on the Durbin-Watson value of autocorrelation of the residuals, then the ARIMA (2, 0, 1) model was used to remove the autocorrelation from the model and the final bias-corrected model XI was derived. The model was validated with a test data set having the same range of DBH and stem height of the training data set on the basis of linear regression, Morisita's similarity index, and t-test for mean difference between predicted and expected biomass. A comparison between the best logarithmic and non-linear allometric model shows that the non-linear model produces systematic biases and overestimates stem biomass for larger trees. The overall results showed that the bias-corrected logarithmic model XI can be used efficiently for estimating stem biomass of A. auriculiformis in the northeastern region of Bangladesh.     

Nitrogen and fine root length dynamics in a tropical agroforestry system with periodically pruned Erythrina poeppigiana

The effect of pruning all branches (complete pruning) or retaining one branch (partial pruning) on the dynamics of nitrogen cycling in aboveground biomass, nitrogen supplying power of an amended Eutric Cambisol, and fine root length, was studied in an Erythrina poeppigiana (Walp.) O.F. Cook—tomato (Lycopersicon esculentum Mill.) alley cropping practice in Turrialba, Costa Rica during 1999–2000. Over the 1 year pruning cycle, in which trees were completely or partially pruned four times, respective aboveground biomass production was 4.4 Mg or 7 Mg ha⁻¹ (2-year-old trees) and 5.5 Mg or 9 Mg ha⁻¹ (8-year-old trees); N cycled in aboveground biomass was 123 kg or 187 kg ha⁻¹ (2-year-old trees) and 160 kg or 256 kg N ha⁻¹ (8-year-old trees); mean fine root length was 489 or 821 m (2-year-old-trees), 184 or 364 m per tree (8-year-old-trees). Pruning intensity did not significantly affect net N mineralisation and net nitrification rates during the tomato-cropping season. For the tomato crop, pre-plant mean net N mineralisation rate of 2.5 mg N kg⁻¹ soil day⁻¹ was significantly lower than 16.7 or 11.6 mg N kg⁻¹ soil day⁻¹ at the end of vegetative development and flowering, respectively. Mean net nitrification rates of 3.5, and 4.3 mg N kg⁻¹ soil day⁻¹, at pre-plant and end of vegetative development, respectively, were significantly higher than 0.3 mg N kg⁻¹ soil day⁻¹ at end of flowering. In humid tropical low-input agroforestry practices that depend on organic inputs from trees for crop nutrition, retention of a branch on the pruned tree stump appears to be a good alternative to removal of all branches for reducing N losses through higher N cycling in aboveground biomass, and for conserving fine root length for higher N uptake, although it might enhance competition for associated crops.     

Allometric relationship for estimating above-ground biomass of Aegialitis rotundifolia Roxb. of Sundarbans mangrove forest, in Bangladesh

Tree biomass plays a key role in sustainable management by providing different aspects of ecosystem. Estimation of above ground biomass by non-destructive means requires the development of allometric equations. Most researchers used DBH (diameter at breast height) and TH (total height) to develop allometric equation for a tree. Very few species-specific allometric equations are currently available for shrubs to estimate of biomass from measured plant attributes. Therefore, we used some of readily measurable variables to develop allometric equations such as girth at collar-height (GCH) and height of girth measuring point (GMH) with total height (TH) for A. rotundifolia, a mangrove species of Sundarbans of Bangladesh, as it is too dwarf to take DBH and too irregular in base to take Girth at a fixed height. Linear, non-linear and logarithmic regression techniques were tried to determine the best regression model to estimate the above-ground biomass of stem, branch and leaf. A total of 186 regression equations were generated from the combination of independent variables. Best fit regression equations were determined by examining co-efficient of determination (R2), co-efficient of variation (CV), mean-square of the error (MSerror), residual mean error (Rsme), and F-value. Multiple linear regression models showed more efficient over other types of regression equation. The performance of regression equations was increased by inclusion of GMH as an independent variable along with total height and GCH.     

Biomass expansion factors for Sitka spruce (<Emphasis Type="Italic">Picea sitchensis</Emphasis> (Bong.) Carr.) in Ireland

The assessment of a forest resource in national inventories provides a firm basis for the calculation of biomass and carbon (C) stocks of forests. Biomass expansion factors (BEFs) and conversion factors provide a robust and simple method of converting from forest tree stem volume to total forest biomass. These factors should be constructed on the basis of nationally specific data in order to take account of regional differences in growth rates, management practices, etc. The objective of this study is to improve the accuracy of biomass estimation by calculating a range of age-dependant BEFs from representative data that more accurately describe the allometry of present forests. The results from this study show that the allocation of biomass to compartments in forest stands and throughout a rotation varies considerably, and that the use of BEFs for the calculation of C stocks in forests of sub-timber dimensions is highly impractical.

不同估算树冠生物量方法的比较——以长白落叶松林为例

以长白落叶松人工林为研究对象,应用平均标准木法及枝解析木法调查树冠生物量,并采用标准枝法与枝条模型估算法对估测的树冠生物量进行了比较研究。分析了枝长与枝基径,枝条生物量与枝基径、枝长等各因子的相关关系,建立一级枝长模型及枝条生物量模型。通过对枝条生物量估测模型的比较,结果表明:枝基径与枝条生物量、叶生物量有很高的相关性,幂函数拟合的精度较高,参数估计较稳定;虽然二次多项式模型拟合的相关系数较大,但因参数变动较大,预测不稳定。在树冠生物量模型研究中,基于胸径建立异速生物量模型,相关系数R2值达0.906以上;通过对估测树冠生物量模型的比较,枝条模型估测法优于标准枝法,同时对模型进行F检验,F值达极显著水平,所选枝条生物量模型对长白落叶松树冠生物量的估测具一定参考价值。     

Forest natural regeneration and biomass production after slash and burn in a seasonally dry forest in the Southern Brazilian Amazon

This study estimates the aboveground biomass accumulation after forest clearing and slash burning and describes the structure and successional development of the secondary forest in the seasonally dry southern Amazon. The original burn study was conducted in four land clearings in 1997, 1998, and 1999. The size of the clearings varied from 1 to 9 ha. The native forest was felled, allowed to dry for approximately three months and then burned by the end of the dry season. A census was conducted in the central 1-ha forest on each site prior to the area's felling and burn. The aboveground biomass (AGB) and structure were similar to other primary tropical forests. However, the high density of Cecropia spp. before the forest felling and burn treatment indicates past low intensity disturbances. Seven and eight years after the fire, the fallow forests were still in an early successional stage dominated by Cecropia spp. The four areas had a high biomass accumulation during the studied period, varying from 7.5 to 15.0 Mg ha⁻¹ year⁻¹. The lower biomass accumulation in one plot was an effect of a higher fire severity, produced by the one-year difference in time between slash and burn of the forest, slowing the natural regeneration of Cecropia spp. The time needed for this forest to recover to the pre-fire AGB levels ranged from 20 to 30 years, assuming the current AGB accumulation rates are maintained. Considering these results, the maintenance of regenerating secondary forests in the Amazon would be a significant contribution to soil and watershed protection, minimizing biodiversity losses and perhaps mitigating climatic changes effects in the region.     

Topographic and biotic regulation of aboveground carbon storage in subtropical broad-leaved forests of Taiwan

There is a growing need to understand, and ultimately manage, carbon storage by forest ecosystems. Broad-leaved evergreen forests of Taiwan provide an outstanding opportunity to examine factors that regulate ecosystem carbon storage. We utilized data from three Taiwan Forest Dynamics Plots (FS, LHC, and PTY) in which every tree is identified, measured, tagged and mapped, to examine factors regulating carbon storage as estimated from aboveground biomass. Allometric equations were used to estimate the aboveground biomass of each tree, and a model building procedure was used to examine relationships between plot-level aboveground biomass (AGB; Mg/ha) and a suite of topographic and biotic factors. We found that our study sites have AGB values comparable to some of the most carbon dense forests in the world. Across all three sites, maximum biomass was contained in the taxonomic families Fagaceae, Lauraceae and Theaceae. In the FS site, we identified slope convexity (P = 0.03) and elevation (P < 0.001) as topographic predictors of AGB and found that maximum AGB was found in topographically flat areas. In FS, stem density (P < 0.001) was a significant biotic predictor of AGB and the maxima occurred at intermediate densities. In LHC, we found that convexity (P < 0.001) and slope (P < 0.001) were significantly related to AGB which was maximized along a topographic ridge in the plot. Species richness (P < 0.001) was a significant biotic predictor of AGB in LHC, and the relationship indicated slightly higher AGB at higher levels of species richness. The only significant factor related to AGB in PTY was species richness (P = 0.02). Further work is needed to seek a mechanistic understanding of topographic factors and species richness as drivers of carbon storage in forests.     

东北天然次生林下木树种生物量的相对生长

以东北天然次生林下木层主要树种为研究对象,将各树种按照植株形态分为乔木型植物和典型灌木2类,利用不同函数和自变量构建单物种及混合物种2类器官生物量方程,挑选出标准误较小、拟合性较好的方程作为最佳生物量模型,比较基于不同自变量的生物量模型的优劣,分析植物生物量与个体大小的相对生长关系。结果表明:1） 筛选出的各树种器官最佳生物量模型大多显著（P<0.05）,且R²值大多超过0.800,方程形式以幂函数为主,少数为二次多项式、线性方程和指数方程,乔木型植物生物量均以离地面10 cm处树干直径（D₁₀）解释较理想,典型灌木的最佳生物量模型多以冠幅（CA）和冠幅乘以高度（CAH）为自变量; 单物种模型与混合物种模型相比,并非所有的单物种模型都优于混合物种模型。2） 引入高度变量H和主干长变量L对各树种器官生物量模型的R²值的贡献相似,但包含主干长变量的生物量模型的R²值增加较小。与单变量生物量模型相比,大多典型灌木生物量模型的R²值增加,多数乔木型植物生物量模型的R²值减小; 与H相比,L并不是一个较好的预测变量。3） 下木树种器官生物量与植物大小的相对生长研究再次表明相对生长关系并不唯一,乔木型植物器官生物量与D₁₀的相对生长关系的变化范围是1.712～2.555,其中多年枝、总枝、地上部分、粗根、地下部分和个体生物量与D₁₀的幂指数接近理论值8/3。典型灌木各器官生物量与CA和CAH的相对生长关系的范围分别是0.688～1.293和0.436～1.017,其中叶、新枝、粗根、地下部分和个体的生物量与CA接近等速生长,多年枝、总枝和地上部分与CAH接近等速生长。     

Biomass equations for selected drought-tolerant eucalypts in South Africa

In the water-scarce environment of South Africa, drought-tolerant eucalypt species have the potential to contribute to the timber and biomass resource. Biomass functions are a necessary prerequisite to predict yield and carbon sequestration. In this study preliminary biomass models for Eucalyptus cladocalyx, E. gomphocephala and E. grandis · E. camaldulensis from the dry West Coast of South Africa were developed. The study was based on 33 trees, which were destructively sampled for biomass components (branchwood, stems, bark and foliage). Simultaneous regression equations based on seemingly unrelated regression were fitted to estimate biomass while ensuring additivity. Models were of the classical allometric form, ln(Y) = a+x₁ln(dbh)+x₂ln(h), of which the best models explained between 70% and 98% of the variation of the predicted biomass quantities. A general model for the pooled data of all species showed a good fit as well as robust model behaviour. The average biomass proportions of the stemwood, bark, branches and foliage were 60%, 6%, 29% and 5%, respectively.     

Derivation of locally valid estimators of the aboveground biomass of Norway spruce

The carbon (C) stocks of forests are usually calculated from inventory-based estimates of the stem volume, tree-species-specific wood densities, biomass expansion factors (BEF) and functions for the mass of branches and needles/leaves, and the C concentration. However, reported BEFs in the literature are inconsistent, and especially the reliability of the C stock estimates for young stands is unknown. We describe an efficient method for deriving locally valid functions in order to estimate the aboveground biomass of young Norway spruce (Picea abies Karst.) stands. Data were collected from two adjacent stands, representing the treatment Control and Fertilized of an amelioration experiment. The stem volume was derived from Mass Tables as a function of diameter and height and was converted to stem mass with a species-specific conversion factor. Subsamples of branches from different positions within the canopy were selected by probability proportional to size (PPS) sampling. Needles and branches were weighed separately. The obtained expansion functions for branch and needle biomass have dbh as the only input variable and are accurate (0.88<R²<0.96). Earlier published allometric functions carried a considerable bias, especially when applied for young stands. We found that differences in soil fertility do not alter the ratio between the masses of stems, branches, and needles. Regionally derived biomass expansion functions can be used for sites with different soil fertility, can greatly improve the estimate of the aboveground biomass, and can be generated with a modest effort of field and laboratory work.     

Estimating biomass of white spruce seedlings with vertical photo imagery

Estimation of individual tree seedling biomass isrequired in a variety of forest management andresearch applications such as assessment of netprimary productivity and carbon sequestrationpotential of forest stands, understory forest fuelinventories, and development of silviculturalguidelines to promote the growth of desired treespecies. Photo imagery is a promising non-destructivemethod for estimating the aboveground biomass of treeseedlings. This method was tested using naturallyregenerated white spruce (Picea glauca (Moench)Voss) seedlings growing in the understory of a mixedconifer shelterwood in central Ontario. In the fall of1997, 45 seedlings were sampled from plots exposed toone of three mechanical release treatments (earlyspring release, mid summer release, and no release(control)) in 1994. Each seedling was photographed inthe field to measure the vertical projected area(silhouette area) of the aboveground portion of theseedling. Seedlings were harvested, basal diameter andtotal height measured, and biomass (dry mass) offoliage, branches, main stem and total abovegroundplant tissue determined. Regression analysis revealeda strong relationship between both silhouette area andbasal diameter, and seedling biomass. Coefficients ofdetermination for regression equations usingsilhouette area were equal to 0.892, 0.918, 0.926, and0.937 for the main stem, branches, foliage, and totalaboveground biomass, respectively. Respectivecoefficients of determination for regression equationsusing basal diameter were 0.960, 0.945, 0.953, and0.977. Silhouette area-based equations for totalaboveground and foliar biomass differed significantly(P < 0.005) among release treatments. Nosignificant differences among treatments were observedbetween silhouette area-based equations for biomass ofbranches and main stem (P > 0.05), or betweenbasal diameter-biomass (allometric) equations for allcomponents (P > 0.1). The method was thentested by validating the biomass equations using anindependent data set from 35 white spruce seedlingsfrom the same site and cohort, but exposed todifferent treatments and microenvironmentalconditions. For each seedling, biomass components werepredicted using silhouette area-based and allometricequations, and a relative error of predictioncalculated. The mean relative error for silhouettearea-based predictions varied among biomass componentsfrom –20.25% to –3.21%, with standard deviation ofthe error ranging from 23.04% to 33.44%. The meanrelative error for allometric equations ranged from–2.46% to –21.75%, with standard deviations of23.34% to 32.61%. These results suggest that: (1)photo imagery can be used as an alternative to moretraditional allometric methods of biomass estimation,and (2) general (developed for a broad range ofgrowing conditions) equations derived by either methodare preferable to those specifically calibrated for agiven growing environment.