共查询到20条相似文献，搜索用时 969 毫秒
1.
To study the growth and yield of Acacia mangium in the Caribbean region of Colombia, allometric equations of total volume and aboveground plus coarse roots biomass were
fitted as a function of the tree’s diameter at breast height (dbh). The von Bertalanffy’s growth model and 59, 0.1 ha plots
(0.55–9.55 years old) were used to develop site index (SI) curves at 6 years base age. Then, using the state-space approach,
stand growth and yield models were developed for basal area, volume and biomass. The results show that A. mangium is a very promising species for timber production, atmospheric carbon removal and soil restoration because it grows very
fast even in mining degraded soils. On average sites it reaches 15 m in height in 3 years. However, early and reiterated thinning
coupled with initial mortality by cattle invasion of the very young understocked plantations are producing relatively low
yields. 相似文献
2.
《Scandinavian Journal of Forest Research》2012,27(1-4):38-49
Norway spruce (Picea abies (L.) Karst.) is the dominant species in the older forests of central northern Sweden. However, spruce has seldom been planted in the area, partly because existing tools for site classification have indicated a low yield capacity for the species. The aim of this study was to examine the yield capacity of spruce on the basis of existing plantations. In total, 91 operational and experimental plantations in the age interval 27–46 yrs were sampled. Stands were located between 62° and 65° N at altitudes 130–620 m a.s.l. Site index was estimated by height growth and site‐factor equations previously developed from old‐growth stand data. Height developments in the plantations indicate that site index for these stands is on average 4.6 m higher than predicted by site‐factor equations. The differences between the two methods are larger on poor sites than on rich sites. No systematic deviations of top height development from the site index curves could be detected on remeasured sample plots. Existing growth models were applied on measured stand data to predict future growth. Calculated mean annual increments were on average 20% lower when site index was predicted by site factors instead of height and age. The bias means that the yield capacity of planted spruce in northern Sweden has been underestimated by about 35%. 相似文献
3.
R.M. Keogh 《Forest Ecology and Management》1982,4(2):143-153
This paper deals with the height—growth classification of teak in a region that includes the Caribbean, Central America (Belize and Panama), Venezuela and Colombia. Top height, dominant height and dominant-codominant height data from 13 countries have been used as the basis for compiling a provisional regional site classification chart. The latter, although only tentatively valid, should be practically applicable throughout; as more data become available it shall be possible to revise and adjust it. Selected curves from the chart are compared to Asian, Indonesian and Nigerian curves. Recommendations about the application of the chart are given. 相似文献
4.
5.
Accurate estimates of forest productivity are required for sustainable forest management. Height of dominant and codominant trees at a reference age is often used as a measure of site productivity. Eight algebraic difference equations based on the models proposed by Sloboda, Bertalanffy-Richards, Korf, Hossfeld, and McDill-Amateis were tested on the transformed, longitudinal data structure that considers all possible growth intervals. Autocorrelation was modelled by expanding the error term as an autoregressive process according to this data structure. Generalized nonlinear least squares methods were used for model fitting. Several numerical and graphic analyses were used to compare the different candidate models. The relative error in dominant height prediction was used to select 60 years as the best reference age. An algebraic difference equation based on the model proposed by Korf provided the best compromise between biological and statistical aspects and produced the most adequate site index curves. This model is therefore recommended for height growth prediction and site classification of pedunculate oak stands in Galicia. The model is polymorphic and base-age invariant, having only one asymptote. Predictions of height for age intervals between t1 and t2 of more than 15 years should be considered with caution because of the associated critical error. 相似文献
6.
Coppicing is an alternative reforestation tool for teak in the tropics, substantially reducing regeneration time/costs and associated demands for labor and seed when available. Growth rates of coppiced material are rapid in most situations, but stem/wood quality is a frequent concern. We compared coppiced teak plantations to paired seed-origin plantations, at ages 3, 8, and 13 years, on Forest State Corporation managed land located in Java, Indonesia. Teak trees were evaluated for height, diameter, lower-bole straightness, and presence of disease in both plantation types and at three ages. Mean height and diameter of trees in coppiced plantations were both significantly greater than that in their paired seed-origin plantations at all three ages. Furthermore, heights and diameters in coppiced plantations were higher than expected based on established growth tables for Java. Coppiced plantations were less symptomatic of disease than seed-origin plantations, which promises better wood production and quality. Lower-bole stems in coppiced plantations developed less straight than those in seed-origin plantations, but these deviations faded with time and will likely become insignificant within a 60-year rotation. Based on these results from existing coppiced plantations in Java, coppiced plantations can make a major contribution to teak production in Indonesia. 相似文献
7.
杉木人工林优势高生长模拟及多形地位指数方程 总被引：6，自引：1，他引：6
采用差分法构建以Korf等 6种理论生长方程为基础的多种多形地位指数方程 ,探讨它们的多形表达涵义 ,并对其模拟性能进行了较为全面的分析 ,得到结论 :(1)基于理论生长方程 ,通过差分法可以构建具有良好生物学基础的多形优势高方程 ;(2 )理论生长方程的拐点取值情形对其模拟优势高生长的精度具有至关重要的影响作用 ;(3)差分方程较方程原型更适合于大范围数据的拟合 ,如数据基础为地区或产区层次时 ,其拟合效果明显要好 ;(4 )多形优势高方程展现出了较高的模拟精度 ,其中以Korf、Richards、Weibull方程的 2参数多形表达式及Sloboda方程的 3参数多形表达式为佳 ,采用优良的多形优势高生长模型可以构建说理性完备的多形地位指数方程。 相似文献
8.
9.
Teak (Tectona grandis Linn F.) is a popular exotic species in Ghana, widely grown in industrial plantations and small scale community woodlots. In spite of its importance, local information on the growth and yield of this species is lacking. Presented here are the results of a preliminary investigation into the growth and yield of teak in northern Ghana. Data were collected from 100 temporary sample plots from plantations ranging in age from 3 to 40 years. A standard volume equation, site index curves and provisional empirical yield tables were developed and presented. Site index curves were used to classify plantations into site classes of I, II and III, in order of decreasing productivity. Yield functions indicate that teak can be grown on biologically optimum rotations of 31, 38 and 48 years on site classes I, II and III, respectively. At extended rotations with the adoptions of suitable thinning schedules, trees of sawlog sizes could be obtained on site class I. 相似文献
10.
《Southern Forests》2013,75(2):115-120
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. 相似文献
11.
12.
油松人工林单木树高生长模型研究 总被引：9，自引：5，他引：4
使用Richard,Logistic,Korf,Mitscherlich,Schumacher,weibull等6种理论生长方程拟合了不同立地条件下油松人工林单木树高生长过程,从中选出模拟效果最优的生长方程。研究结果显示:三参数理论生长方程Lo—gistic、weibull、Richard、Korf对油松树高生长拟合的精度基本相近,明显高于二参数的Mitscherlich、Schumach—er方程;立地指数显著影响各方程渐进线参数和形状参数,将立地指数引入各理论生长方程中,构建了模拟油松人工林单木树高生长精度最优的预测方程为Logistic式;使用未参加建模的油松解析木数据对构建的预测方程进行T检验,发现预测值与实测值之间无显著差异(P=0.6213>0.05)。可见,本文构建的预测方程可以准确预测油松人工林单木树高生长过程,为油松人工林科学经营提供重要参考。 相似文献
13.
Tectona grandis (teak) is one of the most important tropical timber species occurring naturally in India. In India, teak is the single most important commercial timber species. Scientifically sound growth models, based on advanced modelling techniques, are often not available, although they are necessary for the successful management of teak stands in the country. Long-term forest planning requires mathematical models. In this paper, an attempt is made to develop a dynamic growth model based on the limited data, consisting of three annual measurements, collected from 15 teak sample plots in Gujarat state of India. A biologically consistent whole-stand growth model is presented, which uses the state-space approach for modelling rates of change of dominant height, stand density and stand basal area. A simple model containing few free parameters performed well and is particularly well suited to situations where available data are scarce. 相似文献
14.
【目的】研究了江南油杉人工林生长规律,以期为江南油杉人工林合理经营提供科学依据。【方法】在全面调查广西林科院老虎岭实验林场27年生江南油杉人工林基础上,在不同的3个标准样地内选择了12株平均木进行树干解析,深入分析其树高、胸径、单株材积生长规律及形数变化规律。并采用6种林木生长经验模型进行回归分析和比较,选出合适的生长模型。【结果】27年生江南油杉树高、胸径、材积的总生长量随着年龄的增加而增加,其中,树高生长总量为16.9 m,胸径生长总量为20.3 cm,材积生长总量为0.283 685 m^3。江南油杉胸高形数是随着年龄的增加先急剧增加,然后再缓慢下降,形数曲线呈反"J"型变化,胸高形数在第7年后小于1,第24年后曲线变化趋于平稳状态,保持在0.52左右。【结论】1)树高在6~14 a和18~24 a处于较高的增长水平,是江南油杉树高生长的速生期。胸径生长的速生期在6~16 a和18~27 a出现。树高和胸径的连年生长量随年龄的增加而增高增粗,树高的高生长期比胸径高生长期早2 a,树高与胸径的低生长期出现在同年。材积的第1个生长高峰期在1~14 a,在第26年后是材积的第2个生长高峰期。各龄阶胸高形数表明江南油杉的胸高形数大,树高尖削度小。2)通过比较分析6种生长模型对江南油杉胸径、树高和材积的实测值的拟合情况,苏玛克(Schumacher)模型可作为江南油杉树高和胸径生长模型,韦布尔(Weibull)模型可作为材积生长模型。经检验,预测值和实测值的残差及相对总误差均较小,模型精度较高,证明所选择的数学模型预测值与实际生长规律基本吻合。3)27年生江南油杉材积的连年生长量和平均生长量曲线经27 a生长仍未相交,说明江南油杉在27 a内尚未达到数量成熟。通过材积生长模型的推算结果,江南油杉材积年平均生长量与连年生长量相交于48~49 a间,即江南油杉数量成熟年龄为49 a,此时的江南油杉材积生长量为0.942 460 m^3。 相似文献
15.
16.
利用湿地松人工林标准地材料,选择Korf方程并用免疫进化算法求解参数,分别立地质量建立林分蓄积量、平均胸径、平均高和株数等因子模型,按照变量间的函数关系及生长量、生长率的定义,编制了具有主林木的湿地松人工林经验收获表,为生长收获预估提供了定量依据。 相似文献
17.
Diego Prezand Markku Kanninen 《Forest Ecology and Management》2005,210(1-3):425-441
Management scenarios with rotation lengths of 20 and 30 years were developed for different site qualities (high, medium and low) under two different management options (high individual tree growth versus high stand growth) for teak (Tectona grandis L.f.) in Costa Rica. The scenarios are based on data collected in different regions in Costa Rica, representing different site conditions, offering a variety of possible management options for high-quality teak yield.
Three competition indices were used for modeling the competition and for the definition of intensities and the plantation age at thinning. The maximum site occupation (MSO) and the Reineke density index (RDI) provide conservative stand density management limits, resulting in the need to execute several thinning frequently. The competition factor (CF) matches the field observations and seems to be more appropriate for the growth characteristics of the species.
Final stand densities varied between 120 and 447 trees ha−1, with mean diameter at breast height (dbh) of 24.9–47.8 cm, and mean total heights between 23.0 and 32.4 m, depending on rotation length and site quality. The mean annual increment of total volume (MAIVol) at the end of the rotation varied from 11.3 to 24.9 m3 ha−1 year−1, accumulating a total volume over rotation of 268–524 m3 ha−1.
The most suitable scenario for teak plantations for high-quality sites is the 30-year-rotation scenario with five thinnings of intensities between 20 and 50% (of the standing trees) at the ages of 4, 8, 12, 18 and 24 years. After the sectioning of the merchantable stem in 4-m length logs, the merchantable volume varied between 145 and 386 m3 ha−1, with an estimated heartwood volume of 45–195 m3 ha−1, both depending on rotation length and site quality. 相似文献
18.
On alluvial sandy loams in the western Llanos of Venezuela, biomass and inventories of macronutrients were determined for ten teak plantations (0.5–9 years old) and a mature forest stand which preceded them. Mean tree and stratified random sampling methods of estimating biomass are compared with regression estimates.Aboveground biomass of the mature forest averages 398 t ha?1. The average yearly productivity of biomass per ha of the teak plantations is greater on sites with soils having higher clay contents; It was measured as 23 t (9-year-old plantation), 16 t (7 years), 10–14 t (6 years) and 7–14 t (4 years).The original ecosystem stores per ha for these sites range between 8380 and 8840 kg N (total), 4550 and 4890 kg P, 2290 and 2540 kg K, 6720 and 6850 kg Ca and 960 and 1760 kg Mg.In the mature forest most N, P and Mg is stored in the soil, whereas 70% of the K and 40–50% of the Ca is stored in the vegetation. The ecosystem K stores of the teak plantations are an average of 40% lower than in the original forest. This difference is interpreted as being due to leaching loss caused by replacement of the original forest.Using data from the literature and from this study, a nutrient budget has been calculated for the first rotation period of teak. It is predicted that substantial amounts of Ca will be removed from the site by the teak harvest. These exports may not be replenished by atmospheric inputs and soil mineral weathering, especially on the highly productive sites. 相似文献
19.
《Forest Ecology and Management》2005,204(1):11-21
Eucalyptus is the most valuable cultivated forest genus in Brazil nowadays. Modeling eucalypts growth has been a challenge for foresters in recent years due to the strong site and genetic variations, management regimes and multiple products generated from those plantations. Because the forest height growth is directly related with the site characteristics and with forest productivity, the improvement on the height growth representation implies in better productivity estimation. A nonlinear mixed-effects model was developed to represent the height growth pattern of eucalypts clonal stands from the Brazilian coastal region. Likewise in other scientific fields, this type of modeling methodology showed to be flexible, precise and accurate, generating multimorphic growth curves for different sites and clones. 相似文献
20.
Aaron R. Weiskittel David W. Hann David E. Hibbs Tzeng Yih Lam Andrew A. Bluhm 《Forest Ecology and Management》2009
Height growth equations for dominant trees are needed for growth and yield projections, to determine appropriate silvicultural regimes, and to estimate site index. Red alder [Alnus rubra Bong.] is a fast-growing hardwood species that is widely planted in the Pacific Northwest, USA. However, red alder dominant height growth equations used currently have been determined using stem analysis trees from natural stands rather than repeated measurements of stand-level top height from plantations, which may cause them to be biased. A regional dataset of red alder plantations was complied and used to construct a dynamic base-age invariant top height growth equation. Ten anamorphic and polymorphic Generalized Algebraic Difference Approach (GADA) forms were fit using the forward difference approach. The Chapman–Richards anamorphic and Schumacher anamorphic model forms were the only ones with statistically significant parameters that yielded biologically reasonable predictions across a full range of the available data. The Schumacher model form performed better on three independent datasets and, therefore, was selected as the final model. The resulting top height growth equations differed appreciably from tree-level dominant height growth equations developed using data from natural stands, particularly at the younger ages and on lower site indices. Both the rate and shape parameters of the Schumacher function were not influenced by initial planting density. However, this analysis indicates that the asymptote, which is related to site index, may be reduced for plantations with initial planting density below 500 trees ha−1. The final equation can be used for predictions of top height (and thus) site index for red alder plantations across a range of different growing conditions. 相似文献