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1.
The effects of species mixture on the growth and yield of mid-rotation mixed stands of Scots pine and silver birch 总被引：1，自引：0，他引：1
The effect of tree species mixture on stand volume yield and on tree-species-specific diameter and height growth rates were analysed in managed mixed stands of Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Ehrn.).Data were obtained from 14 repeatedly measured stands located in Southern Finland on mineral soil sites with varying admixture of Scots pine and silver birch. Statistical analysis was carried out for studying the effect of species mixture on the development of stand characteristics. For the analysis, the plots were categorised into three groups (plot types) according to the species dominance. In order to analyse species-specific growth rates, individual-tree mixed linear growth models for tree diameter and height growth were developed for both tree species.The results clearly show that the yield of the managed mid-rotation, mixed stands was greater for stands dominated by Scots pine than for stands dominated by birch, and the stand volume increment decreased with an increasing proportion of silver birch. Analysis of diameter and height growth by tree species revealed that the main reason for this pattern is the negative impact of birch competition on the growth of pine trees. The increase in diameter of pine was clearly hampered if the proportion of birch was high. An abundance of birch also slightly decreased the growth in height of Scots pine, although the effect was less than on diameter growth. Species mixture did not affect the diameter growth of birch but did have a significant effect on height development. Height growth of birch was considerably greater in pine-dominated stands than in birch-dominated stands. In pine-dominated mixed stands, the height growth of birch was quite close to that of dominant pine trees, and birches can endure in competition with pines for light.The results apply for even-aged and single-storey managed stands, where stocking density and structure are controlled with pre-commercial and commercial thinnings. The results are not applicable to unmanaged mixed stands undergoing self-thinning. This study provides new information on mixed stands from a silvicultural perspective, which can be applied in decisions involving the management of mixed stands. 相似文献
2.
Shouzheng Tang Chao Ho Meng Fan-Rui Meng Yong He Wang 《Forest Ecology and Management》1994,70(1-3):67-73
A self-thinning model is developed for fully stocked and under stocked pure even-aged stands. The self-thinning power law for fully stocked stands can be considered as a special case of this model. A stand growth model is developed by combining the self-thinning model with a basal-area increment model. This stand growth model can be used to estimate the average diameter and stand density at any given stand age with any initial stand conditions. The model was tested with yield table data. The model predictions were found to be agree with independent developed yield table data. 相似文献
3.
This study developed growth models for Eucalyptus saligna Sm., E. camaldulensis Dehnh., E. macarthurii H.Deane & Maiden, E. resinifera Sm., E. siderophloia Benth. and E. grandis Hill ex. Maiden, for the central highlands of Angola, and used these models to simulate the development of stand characteristics. The obtained model set included dominant height, diameter increment, tree height and self-thinning models. The study was based on 10 499 radial increment observations measured on cores taken from about 700 trees growing in 22 plots located in seven sites in the Angolan highlands. The model set makes it possible to simulate stand development on an individual tree basis. Comparison of simulated stand development and measurements indicated good performance of the models. A non-linear fixed-effects diameter increment model performed best for most species, but a non-calibrated linear mixed-effects model used with the Snowdon correction was better for E. saligna and E. macarthurii. This study showed a similar dominant height development of young stands as found in most previous studies done for southern Africa. Some differences emerged at older ages. 相似文献
4.
Stand Density Control Diagrams for Scots pine and Austrian black pine plantations in Bulgaria 总被引：1，自引：0，他引：1
Stand Density Control Diagram (SDCD) is a stand-level mathematical model, which describes the relationships between yield,
density and mortality throughout all stages of stand development. The SDCD is primarily used to derive density control schedules
by management objectives. The main objectives of the present study are to define a modified model of SDCD for application
to Scots pine (Pinus sylvestris L.) and Austrian black pine (Pinus nigra Arn.) plantations in Bulgaria, to examine the fitness of the model with representative experimental data sets from plantations
of both species and to present a way of direct application of the SDCDs for practical purposes. The constructed SDCDs characterize
the spatial-temporal dynamics of the pine plantations in a broad range of densities, forest sites and growth stages from 4
to 26 (28) m of dominant height class. The full density lines were fixed with self-thinning exponents α = 1.69 and α = 1.75
for Scots pine and Austrian black pine, respectively, and the trajectories of natural thinning for 23 initial densities (444-40000/ha)
were determined. A direct way for application of the SDCDs to the plantation management was designed to estimate the optimal
initial densities for the maximum attainable final yield and large-size wood production by self-thinning stands. 相似文献
5.
《Forest Ecology and Management》1997,98(1):49-60
A red alder planting spacing study was used to compare three modeling approaches that have been successfully used for other tree species. These three approaches predict stand structure and dynamics in plantations that are 7 to 16 years old, with planting densities of 976 to 13 899 trees/ha. The diameter-distribution-prediction approach tended to over-predict the diameter at breast height (dbh) for larger trees in stands planted at low density and to under-predict dbh for smaller trees in stands planted at high density. This approach may be useful for comparing planting densities when a tree list is not available. The stand-table-projection approach tended to under-predict dbh for smaller trees in young stands planted at low density and to over-predict dbh for smaller trees in young stands planted at high density. This approach, however, provided consistency between stand- and tree-level growth projections, and should be useful for comparing planting densities when a tree list is available. The individual-tree-growth approach provided the best representations of observed diameter distributions at all planting densities, stand ages, and growth intervals. This approach may be best suited for stands that have been thinned, stands with mixtures of species, and stands with heterogeneous size classes. 相似文献
6.
《Southern Forests》2013,75(3-4):153-161
This study developed growth models for Pinus patula Schiede ex Schltdl. et Cham. for the Central Highlands of Angola for simulating the development of stand characteristics. The model set included dominant height, individual-tree diameter increment, individual-tree height and self-thinning models. The study was based on 7 656 radial increment observations obtained from increment cores from eight plots located in five sites in the Angolan Highlands. The model set enables the simulation of stand development on an individual tree basis. Despite the fact that site variation among the plots was small, a traditional site category index based on slope catena correlated logically with the observed diameter growth rate of the plots. The developed models showed a high level of accuracy when the simulated stand development was compared to observed development. The shape of the dominant height model is similar to earlier models developed in southern Africa. 相似文献
7.
Prince Rupprecht's larch (Larix principis-rupprechtii Mayr) stands growing at three different densities were investigated to determine characteristics of self-thinning. Tree density
decreased with increasing stand age, and the higher density stand had higher mortality than the lower one. Mean stem volume
increased with increasing stand age, and the higher density stand had higher relative growth rate of mean stem volume than
the lower one. Mean stem volume (ν) increased with decreasing tree density (ρ), resulting in self-thinning line being expressed
as ln ν=lnK-α ln ρ, whereK and α are coefficients. The slope of self-thinning line, —α, over the whole study period for all sites was similar with a
mean value of —2.13. The ν-ρ trajectories before reaching the self-thinning slope of—3/2 could be described by Tadaki's model.
The phase self-thinning line tended to decrease toward a slope of—3/2 with increasing stand age, which trends agreed with
those of the published data of aPinus strobus stand andP. densiflora stands. 相似文献
8.
Susumu Kurinobu Daryono Prehatin Naiem Mohanmad Kenji Matsune Osamu Chigira 《Journal of Forest Research》2007,12(3):230-236
A growth model for a plantation of Paraserianthes falcataria was provisionally derived from measurements of 32 permanent plots taken over a period of 2 years in Pare, Indonesia. This
model first predicts height growth with the polymorphic site index equation. Then density-related growth and mortality, that
is, diameter and stand density, are calculated to satisfy the mathematical relationship for the reciprocal and self-thinning
equations, both of which were based on the maximum size–density line with the slope of −1.759 identified in this study. Cumulative
predictions on diameter and stand density, starting with each of three age classes, 3, 4, and 5 years after planting, and
continuing for the next 2 years, agreed well with the observations of age-class mean. An exception was for stands that were
7 years old, which were marginal, but closest to the rotation age of 8 years. Contrasting height/diameter relationships among
the three age classes were described reasonably well with this model, and the predicted basal growth area was found to agree
fairly well with observations. These results suggest that the growth model presented here has good potential for applying
size–density control for plantations of P. falcataria. However, measurements for an additional few years might be necessary to derive a model that will more accurately predict
diameter size at the rotation age. 相似文献
9.
Many boreal tree stands are neither clearly even-aged nor clearly uneven-aged. The stands may undergo a series of stages, during which an even-aged stand is transformed into two-storied mixed stand, and finally to multistoried or uneven-aged stand structure. The species composition often changes during the succession of stand stages. This study developed models for stand dynamics that can be used in different stand structures and species compositions. The model set consists of species-specific individual-tree diameter increment and survival models, and models for ingrowth. Separate models were developed for Scots pine, Norway spruce, and hardwood species. The models were used in a growth simulator, to give illustrative examples on species influences and stand dynamics. Methods to simulate residual variation around diameter increment and ingrowth models are also presented. The results suggest that mixed stands are more productive than one-species stands. Spruce in particular benefits from an admixture of other species. Mixed species improve diameter increment, decrease mortality, and increase ingrowth. Pine is a more beneficial admixture than birch. Simulations showed that uneven-aged management of spruce forests is sustainable and productive, and even-aged conifer stands growing on medium sites can be converted into uneven-aged mixed stands by a series of strong high thinnings. 相似文献
10.
《Scandinavian Journal of Forest Research》2012,27(5):416-426
The effects of a birch admixture on the height and diameter growth and maximum branch diameter in planted Scots pine stands was studied using models constructed with a data set from 13 stands of 9–16 yrs of age and 2–8 m dominant height on average sites on mineral soils in southern Finland. The density and height of the birch varied highly between and within stands. Simulated results indicated that the pines were capable of keeping up in height growth with birches that had originated from seed. Even a very high number of birches (10?000 stems ha?1) had virtually no effect on the height growth of the pines. The number of birches had a pronounced effect on the diameter growth and the maximum branch diameter in pine. Retention of a temporary birch component in young pine stands seems a feasible way of mitigating the adverse effects of low planting densities on the external quality of pine. 相似文献
11.
12.
The allometric relationships between mean weights of components, such as stems, branches and leaves and tree weight as well
as their time-trajectories, were studied with data of self-thinning Pinus densiflora stands with different densities. The allometric relationships existed between the weights of stems, branches and leaves and
the tree weight during the course of self-thinning. The stem weight ratio increased with increasing tree weight because the
allometric coefficient in stem was higher than unity, whereas the branch weight ratio and the leaf weight ratio decreased
because the allometric coefficients in branches and leaves were less than unity. An allometric power relationship existed
between mean component weight and mean tree weight during the course of self-thinning. The time-trajectory of mean component
weight (w
o) and density (ρ) in the early growth stage was expressed as a mathematical model which incorporates the allometric power
relationship into the Tadaki’s model, whereas the model for describing w
o-ρ trajectory in the later growth stage was derived by combining the allometric power relationship with 3/2 power law. The
two models, Tadaki’s model and 3/2 power law, showed a good fit to data from P. densiflora stands. The time-trajectories of mean tree weight (w)-density (ρ) or w
o-ρ initially almost moves nearly vertically in the low-density stand, moves along a steep curve and an inclined curve in the
medium- and high-density stands, respectively, and gradually approaches self-thinning line in the early stage of stand development,
whereas they reached and moved along the self-thinning line in the later stage of stand development. The self-thinning exponents
were determined to be 1.71, 1.19 and 1.13 for the trees, 2.38, 1.33 and 1.20 for the stem, 3.16, 1.55 and 1.46 for the branches,
2.66, 1.39 and 1.35 for the leaves in the low-, medium- and high-density stands, respectively. The 3/2 power law of self-thinning
is derived on the basis of simple geometric model of space occupation by growing trees, but allometric growth of tree and
components can make the slope of the self-thinning line being different from −3/2. The reasons that the self-thinning exponents
of components in the low-density stand were greater than those in the medium- and high-density stands were discussed. 相似文献
13.
Kazuharu Ogawa 《European Journal of Forest Research》2009,128(5):447-453
Interrelationships between self-thinning, biomass density, and plant form were mathematically modeled in relation to stand
development in which self-thinning is either not occurring or is occurring. The relationship between biomass density and mean
shoot mass is derived as a simple power function at the stage when self-thinning does not occur. When self-thinning occurs,
constant biomass density is attained when the 3/2 power law of self-thinning applies and the allometric coefficient is assumed
to be 1/3 in the allometry between mean plant height and aboveground mass. The applicability of this mathematical model and
the allometric reformulations of the self-thinning exponent were tested using experimental data for dense populations of Chamaecyparis obtusa seedlings during the first 2 years of growth. On the basis of the results of the present model and experimental data, the
dependence on competition of the mean height:diameter ratio, mean stem diameter, and leaf biomass density are discussed. As
a result, the mean height:diameter ratio was almost asymptotically constant at the latter growth stage in the second-year
seedlings, so that the 3/2 power law of self-thinning was held in the present analysis. However, the value of height:diameter
ratio will become smaller in older stands, because tree height is considered to be asymptotic with respect to tree age due
to hydraulic and other limits. Therefore, the present modeling implies that one of the reasons why the 3/2 power law from
a geometric basis has been recently rejected depends on whether or not the height:diamter ratio is constant in older trees. 相似文献
14.
同龄纯林自然稀疏规律的研究 总被引：29，自引：9，他引：29
本文提出同龄纯林自(然)稀硫的理论方程式。这个方程式概括了各种不同立木度林分的自稀疏规律,由此方程式结合断面积生长模型可以导出不同初始密度林分的自然生长过程。熟知的完满立木度林分的自稀疏规律是本文所述方程式的特例。一个实例说明不同初始密度林分自然生长过程的计算方法及例证不同密度林分自稀疏规律的不同。 相似文献
15.
16.
对福建省连江县境内不同造林密度6年生的湿地松人工林的调查数据,采用数学方法对树高、胸径进行方差分析,结果表明：4种密度（1352、1605、1890和2500株/hm2）对6年生湿地松树高生长影响不明显,但胸径的差异性显著,且随着密度的增大而呈递减趋势。同时,对冠幅、生物量和生长曲线的比较分析结果也说明：福建省引种湿地松宜适当稀植。最后,通过胸径和冠幅线性关系的回归分析,计算出湿地松各径级林分的保留株数。 相似文献
17.
18.
《林业研究》2021,32(1)
In this study,a geometric model of a growing forest stand has been explored.The basic relationships considered link stand volume and stand density,diameter at breast height(DBH),mean DBH and mean height.The model provides simple formulas connecting the exponents of all the relationships.Application of the formulas to real forestry data provided a high level of predictions of an exponent from two others measured through regressions from empirical data.The Pinus sylvestris L.data were of a static nature,a collection of individual stands,while the Pseudotsuga menziesii(Mirb.) Franco data were dynamic,representing forest stand development over time.The ability of the model to predict exponents in the empirical data implies,on the one hand,a substantial level of similarity between the model and the forestry data.And,on the other hand,the model gives an example in which parameters of one relationship may be linked to parameters of another.Supposedly this kind of 'relationship between relationships' may be observed in forest stands undergoing active growth and competition-induced self-thinning. 相似文献
19.
Growth responses to planting density and management intensity in loblolly pine plantations in the southeastern USA Lower Coastal Plain 总被引：1，自引：0，他引：1
? Background
A culture/density study was established in 1995 in the Lower Coastal Plain of the southeastern USA to evaluate the effects of intensive silviculture and current operational practices on the growth and yield of loblolly pine plantations across a wide range of planting densities (741–4,448 trees/ha). The operational regime consisted of bedding and herbicide application in site preparation and fertilizer applications at planting and in the eighth and 12th growing seasons. The intensive management regime had additional complete competition control, tip moths control, and more repeated fertilization treatments.? Methods
The data from 14 locations from this split-plot experiment design with repeated measurements were analyzed with a mixed-effects model approach in terms of average DBH, average height, average dominant height, survival, stand basal area, and stand volume.? Results
In the first few years after planting, there were no significant effects of management intensity and planting density. In later years, both management intensity and planting density significantly impacted response variables, and their interaction was only significant for average diameter at breast height (DBH). Responses to intensive management in DBH were greatest at the lowest planting densities. Intensive management resulted in larger average DBH, average height, dominant height, stand basal area, and volume. Intensively managed plots had more mortality at age 12. There were negative average DBH, average height, dominant height, and survival responses but positive stand basal area and volume responses to increasing planting density. However, there were no significant differences for planting densities above 2,224 trees/ha.? Conclusions
The results demonstrate that both management intensity and planting density significantly affect loblolly pine productivity in the Lower Coastal Plain, and their effects are additive in nature due to the general lack of interactions. 相似文献20.
To support forest management decisions on converting stands from even-aged to uneven-aged management, tree models are needed
that can simulate both options. Therefore, an individual tree model for Pinus halepensis Mill. is compared with the respective yield table. The individual tree model is built from data of two Spanish forest inventories
in this province and evaluated with published yield tables, which have been built from permanent observational plots. The
individual tree model consists of a basal area increment model and a height increment model, both based on two measurements
of about 4,000 trees from single species stands of Aleppo pine. The R2 values of 0.362 and 0.107 for the basal area increment model and the height increment model, respectively, are within the
range of other published models of this type. Comparing the model with the yield tables for different site indices, we find
that our model matches the yield table well. Only in higher ages where the database for the yield table was poor, our model
indicates higher basal area growth rates than the yield table. 相似文献