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1.
Decay and root rot caused by Heterobasidion annosum (Fr.) Bref. s. lato is the most serious disease of Norway spruce [Picea abies (L.) Karst.]. Mathematical models of disease development have recently been developed for forestry planning purposes. Functions for predicting the probability of decay were developed from two data sets, one comprising trees and another comprising stumps. From the years 1983–2001, 45,587 Norway spruce trees from the Swedish National Forest Inventory (NFI) were analysed for decay incidence at 1.3 m height and correlation with environmental conditions. The decay frequency increased in all studied regions from the first to the second half of the period for trees with comparable tree and environmental attributes. In a stepwise logistic regression, sets of functions were developed showing significance regarding stand age, site index class, temperature sum, height above sea level, diameter at 1.3 m, soil moisture and texture, proportion of spruce and eastern coordinates. The functions were calibrated and validated with a data set from the Swedish NFI from the years 1993–2002 comprising 7,893 stumps. The calibration of decay incidence at breast height to stump height doubled the decay incidence (R 2=0.85). The developed functions could be used to establish initial conditions for dynamic modelling of disease and in strategic planning.  相似文献   

2.
Abstract

The economic outcomes of stump treatment against spore infections of the root rot pathogen Heterobasiodion annosum s. l. were analysed based on simulations in four stands typical of Swedish forestry and forest management: (A) Norway spruce [Picea abies (L.) Karst.] stand on former agricultural soil (SI?=?32), (B) Norway spruce stand (SI?=?26) on forest land; (C) Mixed stand of Norway spruce and Scots pine (Pinus sylvestris L.) (SI?=?24) with only H. parviporum present, i.e. no infection of Scots pine and no possibility of interspecies spread of disease between hosts; and (D) same as C, but H. annosum s. str. (Fr.) Bref and H. parviporum Niemelä & Korhonen present, i.e. interspecies spread of disease possible. Models for disease development, growth and yield and cross-cutting were used in the simulations. The simulated decay frequency in Norway spruce trees ranged between 2 and 90%. Stump treatment at the previous final felling and in all thinning operations was profitable at interest rates 1 and 3% in stands A, B and D, but not in stand C. In stand C, no stump treatment at all or treatment in thinnings only gave the highest net future value. Implications for stump treatment in practical forestry are discussed.  相似文献   

3.
The likelihood of detecting decay present in Norway spruce trees when taking bore core samples at breast height or at stump height was analyzed in two stands. The actual numbers of decayed trees were obtained after the trees were felled. More than 80% of the decay extending to breast height level was detected by taking core samples at that level. However, these core samples revealed only 40–70% of the actual amount of decay present at stump height. At stump height a higher portion of the total amount of decay present was revealed. Heterobasidion annosum was detected in 69 and 77% of the decayed trees in the two stands.

Misjudgements occurred mainly where either (i) decay was present at stump height but not at breast height or (ii) when the decay column had a lateral position. At breast height the probability of finding lateral rot columns was higher than at stump height.  相似文献   

4.
The accuracy of two distant‐independent diameter growth functions for individual trees of Picea abies L. (Karst.) are tested on plots older than 55 years b.h., and with relatively few trees per hectare. Both functions (I1 and I2) have site index, stand basal area, and individual tree basal area as explanatory variables; in addition age at breast height is used in Function I1. Relative to mean measured increment, Functions I1 and I2 underestimate the growth of the test plots by 4.4% and 10.9% respectively; Function I1 shows a root mean squared deviation of 29.2% for single plot predictions, and 5.4% for mean of all plots. Function II predicts the growth as well as some stand functions frequently in use in Norway. Function I2 is unacceptable because age is not an independent variable.  相似文献   

5.

An individual tree basal area increment model was developed for Norway spruce [Picea abies (L.) Karst] in mixed stands of spruce and birch in Estonia. Different regression equations were fitted for different combinations of variables to obtain biologically tractable interactions between growth and factors affecting it. The best fit index of the regression model was pursued in trials with variable combinations. The basal area increment was chosen to describe the tree growth and both the diameter and age of the tree were included as independent variables. The logical growth relationships were obtained. The basal area increment has a culmination introduced by the simultaneous influence of tree size and age explicitly included in the model. The stand level attributes contributed modestly to the explanatory power of the model because of the narrow range of stand conditions sampled. The present model is applicable to Estonian conditions.  相似文献   

6.

The incidence of butt rot in two consecutive rotations of Norway spruce [Picea abies (L.) Karst.] in 28 permanent sample plots at four different sites in Denmark was evaluated. Incidence of butt rot was estimated by visual examination of stumps at final felling of the previous rotation and by examination of bore cores taken at the butt from a random sample of trees before first thinning of the subsequent rotation. There was no correlation between the incidence of butt rot at final felling of the previous rotation of Norway spruce and the incidence of butt rot at first thinning of the subsequent rotation of Norway spruce. The incidence of butt rot at final felling was between 19 and 100%, and at first thinning between 0 and 20%. The S-form of Heterobasidion annosum (Fr.) Bref. was the most commonly found decay-causing organism at all sites. Root systems of 28 trees without decay at stump height in the present rotation were excavated to estimate the incidence of root rot. Heterobasidion annosum was found in only one root. Resinicium bicolor (Alb. & Schw. ex Fr.) Parm. was found in 25% of the excavated root systems. The result of the study shows that the incidence of butt rot at first thinning of Norway spruce is not necessarily higher on sites where the previous rotation was heavily infected than on sites where infection in the previous rotation was low.  相似文献   

7.
《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   

8.
A material of 1156 observations was used to develop two Norway spruce (P. abies (L.) Karst.) stand volume functions for western Norway. An additive model initially based on a polynomial of second degree was found to be most suitable. The independent variables were stand basal area, Lorey's mean height, the product of basal area and mean height, and the square of the mean height.

In order to roughly reflect the different climatical conditions within western Norway, all municipalities were classified into the categories “inland” and “coast”. The individual observations were assigned the category of the municipality in which they were sited. The type of district was included in the selected additive model by means of a dummy variable approach. Testing showed that two individual regressions should be recommended for prediction purposes in the respective districts. R2 was 0.998 and C.V. was less than 2.5%. The regressions fitted most parts of the material very well, with exception for low densities for inland districts. Testing by means of an independent data set indicated no systematic differences.  相似文献   

9.
Pinus brutia Ten. subspecies brutia, which occurs in the Eastern Mediterranean region, is the main forest species in Syria and important for multi-purpose forestry. In this study, 6,631 10-year past growth diameter increment measurements were taken in 83 temporary sample plots. The current breast height diameter of all trees was measured and a sample of trees was measured for height and age. The plots were placed so as to capture the whole range of variation in site quality, stand age and stand density. The data were used to develop the following models:
•  Dominant height model: the guide curve method was used to fit an anamorphic site index model between stand age and dominant height.  相似文献   

10.
A stand dynamic model was developed to predict the growth response in even-aged forest plantations of different initial planting densities. The model is based on the integration of three subcomponents: height growth, self-thinning, and diameter increment. The integrated model uses the height of dominant trees to simulate stand response to site quality and internal growth potential. An extended self-thinning submodel is used to simulate mortality in stands due to crowding and inter-tree competition. A diameter increment submodel is used to link the height growth and self-thinning submodels. The height growth submodel is based on an application of the “Pipe Model” theory. The three-parameter self-thinning submodel is developed from an extended self-thinning law that captures self-thinning in stands before they attain full stocking. The diameter increment model is based on the assumption that diameter increment is related to height growth and available growing space described by stand density. The integrated model is applied to data collected from a 45-year-old red pine (Pinus resinosa Ait.) plantation subsectioned with different initial planting densities. For the data used, only two parameters were required to capture 99% of measured variation in height growth. Additional data from sites with different planting intensities are required to formulate a more generalized height growth model. The slope of the linear self-thinning limit for red pine is approximately −1.5. Model predictions are consistent with field measurements.  相似文献   

11.
Estimating the height of decay in standing Norway spruce attacked by Fomes annosus (Fr.) Cooke. A method is given for estimating the height of decay due to Fomes annosus in standing Norway spruce. A good correlation is provided by the height of the decay and, at the 1,30m level, the diameter and stage of the decay. The data were obtained using Pressler borings.  相似文献   

12.

There are no instructions on the management of stands of Norway spruce [ Picea abies (L.) Karst.] in which butt rot caused by Heterobasidion annosum coll. (Fr.) Bref. was not discovered until the time of first thinning. A stochastic simulation model describing the spread of butt rot in a stand of Norway spruce was used with a new submodel describing the butt rot of young trees. Non-linear stochastic optimization was used to determine the most profitable management schedule of a young Norway spruce stand with butt rot. If the initial level of butt rot was 5% or 10%, or the stand was thinned in summer with stump treatment, one thinning with a rotation of 55 yrs was optimal. Two winter thinnings with a rotation of 61 yrs was optimal in an initially healthy stand. Optimizations indicated that silvicultural measures that decrease the transfer of H. annosum to next generation at clear-cuttings could be economically fulfilled.  相似文献   

13.
杉木人工林单木断面积生长动态模拟   总被引：2，自引：0，他引：2       下载免费PDF全文
应用面板数据固定效应模型对杉木人工林单木断面积生长规律进行模拟,在模拟过程中,将胸径(DBH)和活冠比例(LCR)作为自变量,又分别加入密度因子和不同类型的竞争指数,同时引入立地条件和林龄效应来解释单木断面积生长过程中的异质性。结果表明:虽然密度因子与竞争指数有较强的相关性,但是在单木断面积生长中都具有不可忽略的重要影响。立地条件与林龄对单木断面积的拟合偏差在不同的林分密度下略有不同,随立地指数或者林龄增加,其对平均单木断面积拟合偏差的影响也增大。  相似文献   

14.
Stem and root rot of Douglas fir, Pseudotsuga menziesii (Mirb.) Franco. In 20 year old Douglas fir most of the butt rot was caused by Fomes annosus. Stem decay was central as well as eccentric reaching the sap wood in either case. The side roots of 20 year old Douglas fir were compared with those of a 40 year old stand with butt rot. In individual trees with decay there were less roots with Fomes annosus decay in the younger stand. Calocera viscosa was more abundant in the older stand. Soil conditions which might have favoured root rot in the young stand are discussed.  相似文献   

15.
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   

16.
Abstract

Natural root and butt rot infection with Heterobasidion spp. was recorded on three occasions in trees from a 20-year-old Norway spruce [Picea abies (L.) Karst.] clone trial. In the first assessment, carried out when the trial had been running for 15 years, 29.5% of the trees felled were infected with Heterobasidion spp., but no statistically significant differences were found between the different clones. In the second assessment, also at 15 years, bore cores were taken from 595 trees. Of these cores, 16.5% were infected, but again no statistically significant differences were found between the different clones. Combining the two first assessments also revealed no significant differences. The discrepancy in rot incidence between the two assessments was explained by the inaccuracy of the bore core method. The third assessment was carried out after the trial had been running for 20 years. At that time, 424 trees of 50 clones were felled and sampled. Visible infection was recorded in 46.5% of the trees. The differences between clones were statistically significant and the broad-sense heritability estimate was 0.18. There were no significant genotypic correlations between tree size and rot infection; this is important for the Norway spruce breeding strategy. Calculations show that economic viability would increase by 0.28 SEK per plant for every 10% decrease in root rot frequency at final felling.  相似文献   

17.
《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   

18.
In the absence of reliable and representative data on the frequency of seed years, seed amounts, germination and survival of seeds, the data of the observation period 1992–1996 of the permanent national forest inventory of Austria are used to develop a model describing the probability for the occurrence, density and height of Norway spruce (Picea abies (L.) Karst) natural regeneration in the forests of Austria. The forest inventory provided data on natural regeneration (saplings between 10 and 130 cm height) on clusters within a 3.89 km square sampling grid. A logistic equation is used to predict the probability for natural regeneration occurrence. Input parameters for this equation are the variables that describe the site, with slope and azimuth as continuous variables, and growth districts and vegetation types as discrete variables; the crown competition factor describes density and the quadratic mean diameter describes the stage of development of the stand. The same equation type is used to predict the probability for the occurrence of Norway spruce, conditional on the occurrence of some regeneration. An additional variable in this species specific model is a dummy variable which is set to 1 if Norway spruce occurs in the overstory and otherwise zero. Additional site variables entering this model are elevation and vegetation types characterizing soil fertility and moisture. Because the density and height of spruce regeneration depends on the stand's susceptibility to browsing, the probability for browsing is also modelled as a logistic equation depending on elevation, vegetation type, and stand density. Finally the probability distribution for height and density of the regeneration is described by two bivariate Weibull-distributions, each one describing browsed and unbrowsed Norway spruce regeneration respectively.  相似文献   

19.
Fomes annosus (Fr.) Cke. and other decay fungi in a Douglas fir stand, Pseudotsuga menziesii (Mirb.) Franco. 40% of the trees in a 40 years old Pseudotsuga menziesii stand showed butt rot. 85 trees were analysed for decay fungi. Fomes annosus, the most frequent fungus, also invaded the sap wood. Factors of the soil favourable to the rot and the possibility of transmission of the most frequent decay fungus, Fomes annosus, from (a) neighbouring spruce stands, (b) from the roots of Scots pine from the previous crop arc discussed. Caniophora puteana was isolated from about 10% of the butt rots. The importance of Calocera viscosa which grew out of the central decay of twelve trees as a decay fungus is still under investigation.  相似文献   

20.
Mean diameter by basal area (dg) is an important stand variable for long‐term economic forecasts of forest holdings. In order to use stand‐by‐stand surveys based on aerial photo interpretation as the data basis for forecasts, dg has to be determined. The objective was to develop and test a regression function for dg in mature stands of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) applicable in southeastern Norway. A study of 700 plots was used to estimate a function for dg . An additive model was found to be most suitable. The independent variables were potential yield capacity, Lorey's mean tree height, crown closure determined by ocular estimation by means of aerial photographs, and the product of potential yield capacity and crown closure. The R2 value was 0.604 and the coefficient of variation was 10.8%. The regression fitted most parts of the calibration data quite well, but it may overestimate the mean diameter in pure spruce stands by 1–2%, and underestimate the diameter in pure pine stands by 3%. For mixed coniferous stands the regression seems satisfactory. Testing by means of an independent data set showed systematic errors of 3–23%. The systematic errors were due partly to calibration problems in connection with the ocular crown closure estimation.  相似文献   

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