THE CONSTRUCTION OF SOME FORESTRY TABLES FOR DAHURIAN LARCH PLANTATIONS

Several growth models were selected to fit data of dahurian larch plantations using nonlinear regression analysis. The best models were used to construct the site index table' the 2-way volume table and the growth process table. The Chapman-Richards equation is the best model used as the guide curve to form the site index table for dahurian larch plantations.

COMPARATIVE ANALYSES ON THE LITTER IN KOREAN PINE MONGOLIAN SCOTS PINE AND DAHURIAN LARCH PLANTATIONS(Ⅱ)CONTENT AND RETURNING AMOUNT OF NUTRIENT ELEMENTS

Comparative analyses were conducted on the nutrient element content and returning amount of main fractional compositions of litter in Korean pine (KP), Mongolian Scots pine(MSP) and Dahurian larch (DL) plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. The results are as follows: (1) The nutrient element content and returning amount in litter varies among different fractional compositions and tree species, the total returning amount of all nutrient elements and the returning amount of K, Ca, Mg, N and P are DL>MSP>KP, the returning amount of Cu is DL>KP>MSP, the returning amount of Fe and Mn are MSP>DL>KP, (2) To KP and DL plantations, the main nutrient element returned is dead needles; dead branches, bark scales and dead cones account for a little proportion; whereas to MSP plantation, besides dead needles,dead branches and bark scales also play an important role in the return of nutrient elements; (3)A little deal of dead leaves can provided a great deal of returning amount of nutrient elements.

THE SEASONAL DYNAMICS OF NUTRIENT CONTENTS IN MANCHURIA ASH-DAHURIAN LARCH MIXED STAND

The yield increasing mechanism of the manchurian ash (Fraxinus mandchurica) and dahurian larch(Larix gmelini) mixed stand was studied on nutrition status of soil and leaves. The results showed that nutrient contents of leaves and contents of the available nutrients of soil in the mixed and pure stands varied with seasons of the year. The available phosphorus contentS of the soil in the larch belt were much higher than those in the manchurian ash belt during growhg season, with the highest value of 3.5 mg/100g, 2~3 times of the latter. The nitrogen contents of leaves of the manchurian ash trees nearest from dahurian larch belt wer 12.7%~80.8% higher than those of its pure stand, and phosphorus 13.4%~140. 8%. The different uptake thythm of the nutrients modified the interspecific competition. The general conclusion is that the high contents of available phosphorus of the soil in dahurian larch belt improved the growing condition of nearby manhurian ash trees.

STUDY ON THE NATURAL REGENERATION EFFECT OF MANCHURIAN ASH BY OPENING UP EFFECT BELT IN DAHURIAN LARCH PLANTATION

Opening up effect belt in dahurian larch (Larix gmelini) plantation can significantly promote the growth and development of manchurian ash (Fraxinus mandshur-ica) natural regcneration seedlings. The quantity, growth and distribution characters of manchurian ash natural regeneration seedling and the seed quantity of manchurian ash on the effect belt are significantly much more than that on remained belt. It provides a theoretical basis for using the management method of - Cutting coniferous to introduce broadleal trees in the coniferous stand, improving the stand structure, increasing the ecological stability and biological productivity.

GROWTH AND YIELD MODELS FOR DAHURIAN LARCH PLANTATIONS

Growth and yield models were developed for individual tress and stands based on 336 temporary plots with 405 stem analysis trees of dahurian larch ( Larix gmelinii( Rupr. )Rupr.) plantations throughout Daxing'anling mountains. Several equations were selected using nonlinear regression analysis. Results showed that the Richards equation was the best model for estimating tree height, stand mean height and stand dominant height from age; The Power equation was the best model for prediction tree volume from DBH and tree height; The logarithmic stand volume equation was good for predicting stand volume from age, mean height, basal area and other stand variables. These models can be used to construct the volume table, the site index table and other forestry tables for dahurian larch plantations.

STUDIES ON OPTIMUM MODELS FOR CULTIVATING DAHURIAN LARCH SEEDLINGS ON FRIGID REGIONS

The optimum models for cultivationg the seedlings of Dahurian Larch (Larix gmelim Rupr. ) were studied in the central nursery of Tahe Forestery Bureau from 1989 to 1993. The resultswerc as follows The optimum models of the main morphological standards of the seedlings were30000 kg /hm2 of' decomposed' ash for improviong soil, 70,000 kg/hm2 of excrement and 1,500 kg/hm2of' calcium superphosphate as basal fertilizer , and 500 kg/hm2 of (NH4)2HPO4 and 220 kg/hm2 of'urea as top dressing. During growth perlod of the seedlings, the growth was greatly checked when thesoil water suction (SWS) was uithin 50 ~ 73. 3 kPa or below 10 kPa but greatest when SWS waswithin 30 ~ 40 kPa in initial growth stage and within 10-20kPa in last growth stage. The method for determining the optimum sowing time is to measure the depth of soil thawing, accumulated temperature abovc 5℃ both at 5 cm of the depth of of soil and in atmosphere. In Tahe region, the optimumsowing trme for Dahurian larch for Dahuria larch is about on May 10 when the depth of soil thawing, the accumulatedtemperature above 5℃ at 5 cm of the depth and the accumulated temperature above 5℃ in atmosphere reaches 40 cm. abovc 46℃ and abovae 56℃ respectively. The optimum seedlings density forthis region is 600-800 individuals/m2.

STUDY ON GEOGRAPHIC VARIATION OF DAHURIAN LARCH IN CHINA

Based on the main characteristics of growth, phenology and resistance at both seedling stage (one year old) and sampling stage (seven years old) of Dahurian larch (Larix gmelinii (Rupr.) Rupr.) from seventeen provenances in China ranging from 47 ° 10' to 52 ° 25' N and 119 ° 57' to 130 ° 25' E, the rules and patterns of infraspecific geographic variation have been studied by using variance analysis, correlation analysis, partial correlation analysis and regression analysis. The best provenance for local site and its neighborhood was selected according to the growth characteristics of seven years provenance test on Liangshui Experimental Forest Farm of Northeast Forestry University.

Growth and yield models for Dahurian larch plantations

Several equations were selected using nonlinear regression analysis for setting up growth and yield modehe of Dahurian larch (Laris gmelinii Rupr.) plantations. Data of 405 stem analysis trees were collected from 336 temporary plots throughout the Daxing’an Mountains. Results showed that the Richards equation was the best model for estimating tree height, stand mean height and stand dominant height by age, the Power equation was the fdiest model for predicting tree volume by DBH and tree height, and the Logarithmic stand vofume equation was good for predicting stand volume from age, mean height. basal area and other stand variables. These models can be used to construct volume tabIes, site index table and other forestry tables for Dahurian ghantations.

COMPARATIVE STUDY OF WOOD PROPERTIES BETWEENWHITE WOOD OF DAHURIAN LARCH AND MONGOLIANSCOTCH PINE

The comparative result shows that the physical and mechanical properties of wood between white wood of Dahurian larch (Larix gmelini (Rupr.) Rupr.) and Mangolian scotch pine (Pinus cylvesthe var. mongolica) are different Some differences are very conspicuous,(e. g. compressivc strength parallel to grain, modulus of elasticity in static bending, toughness and bending strength etc. ),and others are slightly conSPicuous or not conspicuous,(e.g. shrinkage, differential shrinkage and shearing strength parallel to grain etc.). The properties of white wood of Dahurian larch are suitable weight and soft texture, median strength,median shrinkage and good in worability, while which of Mongolian scotch pine are light and soft nearly very soft,weak strength, median shrinkage are good in workability. However, the white wood of Dahuran larch is superior to the Mongolian scotch pine in Strength-to-weight ratio.It is a valuable timber tree.

NUTRIENT CYCLING IN THE DAHURIAN LARCH PLANTATION ECOSYSTEM

Based on the determinations of the nutrient elements including N,P,K,Ca, and Mg of Dahurian larch plantation ecosystem in the eastern part of northern China,the analysis of contents.distribution,accumulation of plant and soil nutrient elements,and the properties of the nutrient cycling throuth the larch plantation ecosystem were conducted,The results were as follows:the nutrient content of various ecosystem varied with plant organs,ages and distributive layer.The totan amount of nutrinet elements accumulated in the larch ecosystem was 27098kg/hm2,in which soil accumulation and plant accumulation were 268946 kg/hm2 and 2040.602kg/hm2,respectively;the annual absorption of nutrient elements was 197.394kg/hm2,in which the annual relention and annual return of nutrientelements were 76.183 and 121.211kg/hm2,respectively,Compare to other forest communities,the cycling rates of various nutrient elements through larch plantation ecosystem was relatively higher.

GROWTH EFFECT OF DAHURIAN LARCH-MANCHURIAN ASH MIXED FORESTS

With the method of stem analyses by the microscope, the xylem’s accumulations atdifferent ages were quantitatively studied using the data of typical plant association for Dahurianlarch (Larix gmelini Rupr) and Manchurian ash (Fraxinus mandshurica Rupr) mixed forests. Thedeveloping process for this important mixed forest type in the study area was systematically established. The result showed that in the artificial stand of Dahurian larch mixed with naturalManchurian ash. only those which have the same origin as Dahurian larch can grow up before theclosing of stand and form the components of the main layers. After 24 years seif-thinning, when theywere 29 years old, Dahurian larch would be at the stage of no self-thinning. At last the stand woulddevelop to the broad-leaved forests dominating with the Manchurian ash.

STUDIES ON PHYSICAL AND MECHANICAL PROPERTIES OF DAHURIAN LARCH-WOOD OF TWO WOOD COLOURS

Dahurian larch growing in Daxing’an Mountains can be divided into two types according to the wood colour: one is red, the other is white. Based on the national standard of the "Testing methods for physical &mechanical properties of wood", the parameters of wood colour and physico-mechanical properties of the above two different woods were tested and analyzed.The result showed that the colour rational phenetic parameters, physico-mechanical properties and work abilities of thc two woods were quite different, combincd with the other morphological characteristics, they belong to intraspccific two different types of Dahurian larch. The white wood is superior to the red one as a valuable timber tree. Because the cocfficients of shrinkage, hardness and colour of both are different, they were mixed working in the past, inevitably there have been various defects in working. In order to overcome these defects, we propose that the departments of wood production, salesmen and consumers should use them differently according to their individual character.

COMPARATIVE ANALYSIS ON THE LITTER IN KOREAN PINE MONGOLIAN SCOTS PINE AND DAHURIAN LARCH PLANTATIONS(Ⅰ) AMOUNT AND FLUCTUATION OF LITTER FALL

Investigations were made in korean pine, mongolian scots pine and dahurian larch plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. Data are tabulated on the amount and seasonal and annual nuctuations of fractional composition of the litter (conifer needles, branches, cones, bark scales, broad leaves) in the three plantations. The accounts of conifer needle branch and bark scale litter are as follows: korean pine: 71- 16%, 6. 23% and 7. 32%; mongolian scots pine: 43. 65%, 18. 52 % and 32. 12%; dahurian larch:90. 30%, 7. 83% and 1. 85%. There are certain broadleaf litter in dahurian larch and mongolian scots pine plantations (account for 7. 61% and 8. 92%respectively). The litter wither and fall concent ratively in autumn in dahurian larch plantation and scattered all year long in korean pine and mongolian scots pine plantations. Along with the increase of stand age, the absolute amount of litter tend to increase, the relative amount of main fractional compositions (conifer needle, branch and bark scale) in korean pine and mongolian Scots pine plantations maintain stead, whereas in dahurian larch plantation, the relative amount of conifer needle is decreased gradually and the relative amount of other fractional compositions are increased gradually.

EVALUATION OF SITE QUALITY FOR DAHURIAN LARCH FORESTS

The site index table, site class table and quantizing model ofdahurian larch forests were formed based on 418 temporary plots and 179 dominant stem analysis trees. By testing raw data which were not used to form the site index table, the site index table of plantations was validated. The site index table or site class table can be used in timber stands according to the intensive degrees of forest management. The quantizing model can be used in cutover, deforested and nonforested areas.

Modeling Branch Length and Branch Angle with Linear Mixed Effects for Dahurian Larch

In this study,the sample data was based on 2 190 branch length and angle samples of 30 trees from dahurian larch（Larix gmeiinii） plantations located in Wuying Forest Bureau in Heilongjiang Province.The stepwise regression techniques were used to develop branch length and branch angle models:BL= b1 + b2 DINC + b3 DINC2 + b4 DBH·DINC2,BA = b1 + b2 DINC + b3 DINC2 + b4 DBH·DINC.Then,the developed models were fitted using linear mixed-effects modeling approach based on LME procedure of S-PLUS software.Evaluation statistics,such as AIC,BIC, Log Likelihood and Likelihood ratio test were used for model comparisons.The results showed that the branch length and branch angle models with parameters b1,b2,b3 as mixed effects showed the best performance.Exponential and power functions were incorporated into mixed branch length and branch angle model.The addition of the exponential and power functions significantly improved the mixed-effects model.The plots of standardized residuals indicated that the mixed-effect model with exponential and power functions showed more homogeneous residual variance than the mixed-effects model.Validation confirmed that the mixed model with calibration of random parameters could provide more accurate and precise prediction.Therefore,the application of mixed model not only showed the mean trends of branch length and branch angle,but also showed the individual difference based on variance-covariance structure.

Modeling Microibril Angle with Mixed Models for Dahurian Larch

In this study,the sample data was based on 2 790 samples of 9 trees from dahurian larch （Larix gmelinii） plantations located in Qitaihe Forest Bureau in Heilongjiang Province.The modified Logistic model y = b1 /[1 + exp（b2 x）]+ b3 was selected to modeling microfibril angle from six models based on nonlinear regression.Then,the logistic model was fitted using nonlinear mixed-effect modeling approach based on NLME of S-PLUS software.Evaluation statistics,such as AIC,BIC, Log Likelihood and Likelihood ratio test were used for model comparisons.The results showed that the Logistic model with parameters b1,b2,b3 as mixed effects showed the best performance.Correlation structures included compound-symmetry structure （CS）,first-order autoregressive correlation structure AR（1）,moving average correlation structure MA（1） and autoregressive-moving average correlation structure[ARMA（1,1）]were incorprated into the best microfibril angle mixed model.[ARMA（1,1）]significantly improved the precision of mixed model.Validation confirmed that the mixed model with calibration of random parameters could provide more accurate and precise prediction.Therefore,the application of mixed model not only showed the mean trends of microfibril angle,but also showed the individual difference based on variance-covariance structure and correlation structure.

DYNAMIC THINNING SYSTEM FOR LARCH PLANTATION

Systematic researches were carried out in dahurian larch (Larixgmelini) plantation in the spring of 1958 at Maoershan Forest Farm attached to Northeast Forestry University. First of all, a new tree classificdtion method. relat11'e classification in small group, was presented. Each small group was composed of one tree in the center and six adjacent trees, which formed a hexagon in space. All these seven trees. then, can be divided into five classes such as class A class B,class C. class D and class E respectiveiy. For the conxenience of comparison. the stand used for the trial was duvided into five experimental plots in which the thinning intensity for each plot was controllca as follows: 10% for the first plot; 20% for the second plot- 30% for the third plot; 40% for the fourth plot and the fifth plot without thinning for comparison. Thinning operation was carried out according to the principle of reserving A-class trees, cutting B- class trees in the intensity as required, releasing C-class trees and removing D and E class trees.Through 14 years study- the result shows that if the stand volume of contrast plot is considered as 100% after the first thinning' the volume of other plots are 114. 9% for the first plot, 128. 4% for the second plot, 133. 1% fOr the third plot and 118. 5% for The fourth plot respectively. Meanwhile, biomass and increment of diameter can also be increased significantly after thinning by this method.

STUDIES ON BIOMASS AND PRODUCTIVITY FOR DAHUIAN LARCH PLANTATIONS

The biornass and productivity for dahurian larch (Larix gmelini) plantations of four structure types were measured. The biomass of trees, understory' herb and litter was surveyed using methods of average standard tree and subsample yield respectively.The estimated total mean biomass for dahurian larch plantation communities of four structure types was 159. 445 t/hm2 and the net productivity was 12. 237 t/hm2. a.

QUANTITATIVE ANALYSIS FOR INTERSPECIFIC RELATIONSHIP OF LARCH STAND MIXED WITH ASH

Permanent sample plots were set up for researching interspecific relationship of the artificia1 larch stand mixed with natural ash in the slash site in Maoershan Experiment Forestry Farm of Northeast Forestry University. All trees in the plots were taken as objective trees and tree number,DBH, distance between trees and that of crown diameter were measured in range of 1-6m from every objective tree. Then study by Alemdag competition index, variance analysis and quantitation method were made. The result showed that the intraspecific competition was more intensive than the interspecific competition. Especially the competition between larch and ash was least relatively. For these kinds of site, the suitable mixture at 20-30 ages should be 2800 Ind/hm2 in density and 2 larch;1 ash in mixed ratio, which might improve site condition to promote stand produetivity.

兴安落叶松林火烧迹地土壤理化性质驱动因子

探索火烧迹地土壤理化性质的驱动因子是解释生态系统响应火干扰机制的重要组成部分。旨在分析兴安落叶松林火烧迹地土壤理化性质的决定因子,深入认识火干扰在北方森林生态系统所扮演的角色,为北方森林火烧迹地火后恢复、林业可持续发展提供科学支持和理论依据。以过火后1 a的兴安落叶松林火烧迹地为研究对象,设置了不同火烈度和立地条件的火烧迹地及对照研究样地共计35块。在每个研究样地记录了树种、胸径、存活状态等乔木数据,测量了坡向、坡位、坡度、海拔等地形数据,利用植被变化情况量化了火烈度。分别采集了0—5 cm和5—10 cm的土壤样品并测定其9种理化指标,对比了过火与未过火样地这些土壤理化指标的差异。然后,分析了各土壤理化指标与火烈度量化结果的关联趋势,比较了火烈度、地形和乔木因子对火烧迹地土壤理化性质的影响程度。与对照样地相比,火干扰提升了土壤理化指标观测值的离散程度,显著提高了0—5 cm土壤含水率(MC)(P<0.05)和5—10 cm土壤MC、总氮(TN)、总有机碳(TOC)含量(P<0.05)。土壤理化性质与火烈度有明显关联趋势的并不多,观察到0—5 cm土壤MC随火烈度指数的增加而减少,0—5 cm土壤无机氮与5—10 cm土层土壤pH、速效钾(AK)、铵态氮(NH_(4)^(+)-N)随火烈度指数的增大而增大。相关分析表明,地形因子与火烧迹地土壤理化性质关联程度较高,坡位、坡度、坡向与土壤吸湿含水率(HMC)、MC、硝态氮(NO_(3)^(-)-N)和5—10 cm土壤总氮(TN)、总有机碳(TOC)均呈显著负相关(P<0.05),而与土壤AK、pH、NH_(4)^(+)-N和有效磷(AP)则以正相关为主,其中坡度与0—5 cm土壤AK、pH、NH_(4)^(+)-N和AP均呈极显著的正相关(P<0.01)。方差分解分析结果表明,对照样地土壤理化指标的变异主要由乔木因子和地形因子共同解释,但在火烧迹地,乔木因子总解释比例降低了,而地形因子单独解释的比例增加了,两者对于土壤理化指标变异的共同解释比例大幅降低了。火干扰能够提升地形对土壤理化性质的影响程度。地形是火烧迹地土壤理化性质差异的主导因子,其影响较火烈度更为深刻,因此,当火烈度相同但地形不同时,火干扰引发的生态系统响应可能不同。所以,地形的主导作用可能是导致在不同区域研究火烈度与土壤理化性质的关系得出不同结果与结论的重要原因之一。