基于冠层分区的辽东山区长白落叶松叶面积模拟研究

文章以辽东山区长白落叶松林(Larix olgensis)为研究对象,通过调查树冠及枝条解析因子、实测叶面积,构建基于最优冠层分区形式的枝条叶面积模型,结果表明:基径(BD)是枝条叶面积(BLA)的最佳解释变量,相对冠层深度(H)0.67是模拟效果最优的冠层分区界限,树冠上层枝条叶面积最优模型为CAR模型:BLA=0.006BD1.746,决定系数(R2)为0.796,预估精度(P)达到90.61%;下层枝条叶面积最优模型为二次曲线:BLA=0.009BD2-0.476BD+7.186,决定系数(R2)为0.709,预估精度(P)达到80.65%。     

楠木人工林树冠体积与叶面积指数预估模型的研究

基于楠木(Phoebe zhennan)人工林5块同定标准地25株枝解析数据,进行楠木人工林树冠体积与叶面积指数预估模型研究,研究结果表明:楠木人工林树冠体积和叶面积指数随着林木胸径、树高、冠幅和冠高的增大而增大;在分析树冠体积和叶面积指数与林木变量的基础上,利用SPSS统计软件建立了树冠体积(V)和叶面积指数(LAI)的预估模型:所建立的楠木人工林树冠体积的预估模型为:V=0.2750L2.253H10.770(L为冠幅,m;H1为冠高,m),叶面积指数的预估模型为:LAI=0.7845+0.5481H1-0.0288H12+0.0007H13;对预估模型进行检验,结果表明,两个模型的预估精度均大于88%,说明所建模型可以较好地预估楠木人工林树冠体积和叶面积指数.     

樟子松人工林生长与收获预估模型的研究

以可变密度全林分预估模型理论为指导,探讨建立了樟子松人工林地位级指数和林分密度指数经验方程,结合林分密度动态预估模型,建立了樟子松人工林断面积预估模型和蓄积量预估模型。经检验模型预测值与实测值误差为3.64%,模型精度96.37%。     

林分直径枯损模型分析与研究

林分株数分布函数和林木生长模型在预估直径生长、径阶株数分布方面已经得到广泛的应用。本文在综合分析各种直径枯损模型的基础上，全面比较和检验了各种模型的适用性和预测精度。结果表明，利用林分株数分布函数或林木生长模型预估林分直径枯损分布，具有结构合理、适用性强及预测精度高等特征，成为预估林分枯损的最佳模型之一。     

基于RS和GIS的林分蓄积预估模型研究

以松溪林业建设投资公司旧县项目林场212个小班为样地资料,从样地对应的遥感和GIS信息中筛选出影响蓄积估测的主要因子信息,构建林分蓄积量预估模型,以达到以少量的地面样地来估测林分蓄积的目的.通过精度验证和可行性分析,结果表明所建立的林分蓄积量预估模型估算结果与小班临时样地调查结果无显著差异,预估结果精度较高,可应用于区域林分蓄积量的估算.     

中国湿地松立木生物量方程的研建

以我国湿地松154株样木的生物量实测数据为基础,综合利用分段建模方法和非线性误差变量联立方程组方法,建立了与立木材积方程相容的地上生物量方程和生物量转换因子模型,以及与地上生物量方程相容的地下生物量方程和根茎比模型。结果表明:所建地上生物量方程的平均预估误差小于5%,地下生物量方程的平均预估误差小于10%,全树生物量估计的平均预估误差小于3%,完全可满足森林生物量计量的精度要求,从而为我国湿地松林的生物量估计及碳汇能力评估提供了计量依据。     

天然林树木材积的一个预估模型

以天然林内的椴木为例,综合考虑胸径和树高的变化情况,使用非线性拟合等方法,给出了一个近似预估树木材积的模型.使用该模型可对树龄在30年以上的天然林树木10年后的材积总量进行预估.如果将同一树种的胸高形数视为常数,按文中的计算,预估所产生的相对误差约为O.06.     

海南省主要人工林树种树高一元材积模型构建

以海南省5个主要人工林树种为研究对象,分别采用直接建立树高一元材积模型和二阶回归估计的方法,同时与胸径一元材积模型进行比较,结果表明:在立木材积与单一因子的相关性中,胸径最为紧密,树高次之;由于树高受立地质量影响较大,树高一元材积模型很难满足现行的立木材积表编制技术规程的要求;受树高―胸径模型的精度限制,利用二阶回归估计方法建立的树高一元材积模型难以提高模型预估精度;从模型自变量的选择和样本组织角度,提出了提高模型预估精度的方向。     

用于干形描述的2个少参数削度函数

以修正的Brink函数和Pain函数拟合尾巨桉干形曲线.材料来源于南非暖温带花岗岩低地草原地区桉树工业用材林53块标准地的153株尾巨桉干形测定数据.2个削度方程均能对调查数据进行很好地拟合,只是在不同的相对高度时有小的偏差.参数少的方程具有十分好的应用前景,因为从理论上来说,可以用参数预估的方法建立一个广义的干形模型.参数预估不能运用于修正的Brink函数,但在Pain函数的基础上建立参数预估模型是可能的甚至是必要的,因为Pain函数是把绝对树干直径描述为相对树干高度的函数.为此,对参数预估模型是否能描述的树形差异或者仅仅是大小的差异作了测度评价.应用结果表明,参数预估模型未必能用于描述树形的差异.     

用分段建模方法建立东北落叶松立木材积和生物量方程

以东北落叶松(Larix spp.)立木材积和地上生物量数据为例,通过采用误差变量联立方程组和分段建模方法,研究建立了相容的立木材积方程、地上生物量方程及生物量转换函数.结果表明:采用误差变量联立方程组能确保立木材积与地上生物量之间估计结果的相容性,而分段建模方法能有效解决常用模型在小径阶存在的系统偏估问题;本文所建立的分段一元模型,地上生物量和立木材积的总体预估误差均不超过5％;分段二元模型,地上生物量的预估误差基本在4％以内,立木材积的预估误差则小于3％.     

异速模型评估森林植被生物量有机碳储量

在孟加拉的吉大港南部森林地区,利用异速模型评估森林植被的有机碳的储量.异速模型被分别应用测试树木(被划分两个胸高直径级)、灌木和草本植物.采用基部面积估算胸高直径级为从> 5 cm 到 ≤ 15 cm 和> 15 cm树木的生物量有机碳储量模型最好,分别有很高的决定系数(胸高直径级> 5 cm 到 ≤ 15 cm 的r2 为0.73697,胸高直径级> 15 cm 的r2为0.87703),且回归系数(P = 0.000)显著.其它模型(包括采用树高,胸高直径,树高和胸高直径,以及综合树高、胸高直径和木材密度)的线性和对数关系都表现出很低的决定系数.分别建立了20种优势树种的异速模型,采用树木基部面积的模型都得到很高的决定系数值.单独采用灌木和草本植物总生物量的异速模型有较高的决定系数(灌木的r2 为0.87948,草本植物的r2 为0.87325),且回归(系数)性显著(P = 0.000).生物量有机碳的评估是复杂的和耗时的研究,本研究所建立的异速模型可以应用于孟加拉和其它热带(地区)国家的森林植被的有机碳储量的测算.     

Allometric equations from a non-destructive approach for biomass prediction in natural forest and plantation in West Africa

Allometric equations are required for a rapid estimation of commercial timber volume and forest biomass stocks. In order to preserve the forest ecosystem, this study applied a non-destructive sampling approach to measure biophysical properties of living trees. From these measurements, volume and biomass models were developed for 11 dominant tree species in a semi-deciduous natural forest and for Acacia auriculiformis in a plantation located in southern Benin. The observations were combined to develop also generic models applicable to non-dominant tree species. Wood samples of the tree species were collected with an increment borer and analysed in the laboratory to determine species-specific wood densities. The sample size was composed of 243 trees in natural forest and 21 trees in plantation. The measurements were conducted in 30 plots of 50 m × 50 m. The graphical assessment of correlation between model outputs (biomass and volume) and variables (diameter and height) and the statistical analysis confirmed that the logarithmic model with two variables had the best predictions. The assessment also confirmed that the model using diameter only as a variable had good predictions when observations on height were unavailable. The comparative analysis of model predictions showed that the generic model in this study over-estimated biomass by up to 74.80% for certain species and under-estimated biomass by 21.18% for other species. The study shows that there are no statistically significant differences between the wood densities in this research and that published in previous studies.     

Allometric equations based on a fractal branching model for estimating aboveground biomass of four native tree species in the Philippines

Fractal branching models can provide a non-destructive and generic tool for estimating tree shoot and root length and biomass, but field validation is rarely described in the literature. We compared estimates of above ground tree biomass for four indigenous tree used on farm in the Philippines based on the WanFBA model tree architecture with data from destructive sampling. Allometric equations for the four species varied in the constant (biomass at virtual stem diameter 1) and power of the scaling rule (b in Y = aD ^b ), deviating from the value of 8/3 that is claimed to be universal. Allometric equations for aboveground biomass were 0.035 D ^2.87 for Shorea contorta, 0.133 D ^2.36 for Vitex parviflora, 0.063 D ^2.54 for Pterocarpus indicus and 0.065 D ^2.28 for Artocarpus heterophyllus, respectively. Allometric equations for branch biomass had a higher b factor than those for total biomass (except in Artocarpus); allometric equations for the leave + twig fraction a lower b. The performance of the WanFBA model was significantly improved by introduction of a tapering factor “τ“ for decrease of branch diameter within a single link. All statistical tests performed on measured biomass versus biomass predicted from the WanFBA results confirm the viability of the WanFBA model as a non-destructive tool for predicting above-ground biomass equations for total biomass, branch biomass and the leaf + twig fraction.     

Evapotranspiration estimation of <Emphasis Type="Italic">Platycladus orientalis</Emphasis> in Northern China based on various models

Platycladus orientalis is one of the most popular afforestation species and greening species for water management in arid and semi-arid regions of northern China. We applied various models to estimate and validate artificial P. orientalis forest evapotranspiration features with the goal of accurately estimating the water use of a P.orientalis plantation. The American Society of Civil Engineers Evapotranspiration–Penman–Monteith model(APM) and FAO56–Penman–Monteith model(FPM) are extensively applied for vegetation evapotranspiration estimation because their reliability has been validated by many scholars. The Priestley–Taylor model(PT) and Hargreaves model(HS) require only the daily maximum temperature,daily minimum temperature and solar radiation to estimate evapotranspiration and are thus widely applied to grasslands but not to forests. We used the Energy Balance Bowen Ratio(EBBR) system to validate the accuracy of the four models. The results indicated that:(1) Compared to the EBBR measurement annual value, APM was the most accurate, followed by FPM, and PT;(2) During the year, the accuracies of the four models varied. APM and FPM underestimated evapotranspiration during June, July and August, whereas PT and HS overestimated evapotranspiration during this period. In the rest of the year, the estimation accuracies were reversed;(3) An analysis of the possible reasons indicated that wind speed, air temperature and precipitation were the most important contributors.High temperatures were measured in June, July and August, which led to an overestimation by PT and HS because these two models only calculated the temperature and radiation without vegetation information. Underestimation also occurred when a low temperature was recorded. Though APM and FPM addressed both meteorological and vegetation factors, slight deviations still existed; and(4) The two models were modified based on EBBR-measured data. Relative humidity was introduced into PT, and parameter ‘‘A’’ in the HS estimation model was amended to1.41. The accuracy of the modified models significantly increased. The study highlighted the application, comparison and improvement of four models in estimating evapotranspiration and offers more approaches to assess forest hydrological functions.     

Comparative analysis of multi-criteria probabilistic FR and AHP models for forest fire risk(FFR) mapping in Melghat Tiger Reserve(MTR) forest

A comparative study of Frequency Ratio(FR)and Analytic Hierarchy Process(AHP)models are performed for forest fire risk(FFR)mapping in Melghat Tiger Reserve forest,central India.Identification of FFR depends on various hydrometeorological parameters altitude,slope,aspect,topographic position index,normalized differential vegetation index,rainfall,air temperature,land surface temperature,wind speed,distance to settlements,and distance by road are integrated using a GIS platform.The results from FR and AHP show similar trends.The FR model was significantly higher accurate(overall accuracy of 81.3%,kappa statistic 0.78)than the AHP model(overall accuracy 79.3%,kappa statistic 0.75).The FR model total forest fire risk areas were classified into five classes:very low(7.1%),low(22.2%),moderate(32.3%),high(26.9%),and very high(11.5%).The AHP fire risk classes were very low(6.7%),low(21.7%),moderate(34.0%),high(26.7%),and very high(10.9%).Sensitivity analyses were performed for AHP and FR models.The results of the two different models are compared and justified concerning the forest fire sample points(Forest Survey of India)and burn images(2010-2016).These results help in designing more effective fire management plans to improve the allocation of resources across a landscape framework.     

Allometric models to estimate foliage biomass of Tamarindus indica in Burkina Faso

Tamarindus indica L. is a multi-purpose tropical species. In West Africa the local people use its leaves daily as a source of food, medicine and income. To prevent the over-exploitation of this species for its use for non-timber forest products, the estimation of foliage production needs to be adressed. This study aimed to (1) assess the effects of distribution zone and tree size on foliage production of T. indica in Burkina Faso, and (2) develop allometric equations to estimate foliage biomass of this species. A semi-destructive method was used to assess foliage biomass of 120 trees over six stem-diameter size classes within two distribution zones (Sub-Sahelian and North-Sudanian). A two-way ANOVA was perfomed to test the effect of distribution zone and tree size class on foliage production. Allometric equations were fitted with 80% of the sample trees randomly selected and 20% were used for model validation. The results showed that between the two factors, tree size class exhibited a significant effect on foliage production of T. indica both in the Sub-Sahelian and North-Sudanian zones. Allometric equations to predict the foliage biomass of T. indica were similar for its distribution zones in Burkina Faso. Therefore, a general model is adequate for the prediction of foliage biomass of T. indica at a larger scale including a variety of ecological conditions. Stem diameter at 1.3 m aboveground was the most accurate predictor variable (adjusted R² = 0.81) with a prediction error of ?2.76%. This study opens up new potentials to develop and use allometric equations for West African trees of high socio-economic value in their effective and sustainable use for non-timber forest products.     

Allometric differences between current-year shoots and large branches of deciduous broad-leaved tree species

Current-year shoots are mostly made of primary tissues, whereas first-order branches comprise mainly secondary tissues. Differences in tissue composition of these units reflect differences in functional design. We compared the allometry of current-year shoots and first-order branches in eight deciduous broad-leaved tree species and examined the functional differences underlying the design of current-year shoots and first-order branches. Allometric relationships of first-order branches tended to be compatible with predictions of the pipe model and elastic similarity model. That is, allometric constants of the relationships between leaf mass and stem diameter at the branch base and between stem diameter and stem mass were 2.0 and 0.33-0.38, respectively, indicating that the functional regulation of stem form of first-order branches can be predicted by the two models. However, allometric relationships of current-year shoots were not compatible with the predictions of the pipe and elastic similarity models. Thus, the allometric constant of the relationship between leaf mass and stem diameter at the base of current-year shoots was larger than 2.0, and the allometric constant of the relationship between stem length and stem diameter of shoots was larger than 1.0 in all species examined. However, current-year shoots had an allometric constant of leaf mass against stem length that was less than 1.0, suggesting a functional demand on shoot design to reduce self-shading. Also, allometric constants of stem length against stem diameter at the shoot base were larger in monopodial species than in sympodial species, whereas allometric constants of leaf mass per shoot against stem length were smaller in monopodial species than in sympodial species. We propose that the allometries of current-year shoots reflect their function as disposable units for temporary leaf arrangement.     

Allometric models for estimating aboveground biomass of shade trees and coffee bushes grown together

Allometric models for dominant shade tree species and coffee plants (Coffea arabica) were developed for coffee agroforestry systems in Matagalpa, Nicaragua. The studied shade tree species were Cordia alliodora, Juglans olanchana, Inga tonduzzi and I. punctata. The models predict aboveground biomass based on diameter at breast height (for trees), and the stem diameter at a height of 15 cm and plant height (for coffee plants). In addition, the specific gravity of the studied species was determined.The total aboveground biomass of the shade trees varied between 3.5 and 386 kg per tree, and between 0.005 and 2.8 kg per plant for coffee. The aboveground biomass components (foliage, branch, and stem) are closely related with diameter at breast height (r > 0.75). The best-fit models for aboveground biomass of the shade trees were logarithmic, with adjusted R ² between 0.71 and 0.97. In coffee plants, a high correlation was found (r = 0.84) with the stem diameter at 15 cm height, and the best-fit model was logarithmic, as well. The mean specific gravity was 0.52 (± 0.11) for trees and 0.82 (± 0.06) for coffee plants.     

Application of site-specific biomass models to quantify spatial distribution of stocks and historical emissions from deforestation in a tropical forest ecosystem

Allometric equations developed for the Lama forest, located in southern Benin, West Africa, were applied to estimate carbon stocks of three vegetation types:undisturbed forest, degraded forest, and fallow. Carbon stock of the undisturbed forest was 2.7 times higher than that in the degraded forest and 3.4 times higher than that in fallow. The structure of the forest suggests that the individual species were generally concentrated in lower diameter classes. Carbon stock was positively correlated to basal area and negatively related to tree density, suggesting that trees in higher diameter classes contributed significantly to the total carbon stock. The study demonstrated that large trees constitute an important component to include in the sampling approach to achieve accurate carbon quantification in forestry. Historical emissions from deforestation that converted more than 30% of the Lama forest into cropland between the years 1946 and 1987 amounted to 260,563.17 tons of carbon per year(t CO2/year) for the biomass pool only. The study explained the application of biomass models and ground truth data to estimate reference carbon stock of forests.     

Effects of phenology,water availability and seed source on loblolly pine biomass partitioning and transpiration

One-year-old loblolly pine (Pinus taeda L.) seedlings from four seed sources (Arkansas, Georgia, Texas and Virginia) grown in 1-m-deep sand-filled pits in two water regimes (well-watered and drought) were studied, to gain insight into the process of seedling establishment. Whole-plant transpiration was measured biweekly from July to December. Whole-plant harvests were conducted at 6-week intervals from April to December. Whole-plant transpiration and transpiration per unit leaf and root area were affected by treatment, seedlot and phenology. Seedlings of the Arkansas seedlot maintained significantly higher transpiration rates per unit leaf and root area during drought than seedlings of the Virginia, Georgia or Texas seedlots, but did not accumulate greater biomass. The high transpiration rates of the Arkansas seedlings were attributed to their deep root systems. Allometric relationships indicated that, relative to the whole plant, biomass allocation to needles of drought-treated seedlings was enhanced during the summer (allometric ratio 1.09), whereas allocation to roots was enhanced in the spring and fall (allometric ratios of 1.13 and 1.09, respectively). Relative to the whole plant, biomass allocation to needles of well-watered seedlings was enhanced throughout the experiment (allometric ratio of 1.16 declining to 1.05), whereas the allometric ratio of root to total biomass was 0.89 or less throughout. Allometric relationships also indicated variation in biomass partitioning to roots in three soil layers (0-30, 30-60 and 60-100 cm), which differed among harvests in each soil layer. Root growth in both well-watered and drought-treated seedlings was concentrated in the top soil layer in the spring, shifted to the middle and bottom soil layers in the summer, and then increased in the top soil layer in the fall. Compared with well-watered seedlings, drought-treated seedlings had higher rates of root growth in the bottom soil layer in the fall, a characteristic that would confer tolerance to future periods of limited soil water availability.