油松林木枯损率模型研究

林木枯损率模型是树木生长与收获模拟系统中的一个重要组成部分。本文在充分研究国内外林木枯损率模型的基础上,根据北京市油松复位样地的数据,应用Logistic模型预测油松枯损率,模型自变量选择树木大小、竞争因子和林分密度等指标。研究结果显示:油松林木枯损率随径阶增加而呈U型分布,在5~15cm径阶时林木枯损率逐渐降低,之后枯损率又逐渐增加;枯损率随竞争激烈程度和林分密度的增加而增加。使用油松检验数据对建立的枯损率模型进行检验,发现该模型预测的油松枯损率与观测值之间没有显著差异。因此该模型可用于油松径阶和单木枯损率的预测。     

基于Cox比例风险函数及混合效应的落叶松云冷杉混交林林木枯损模型研究

[目的]将生存分析方法和混合效应模型方法相结合,构建林木枯损模型,提高模型的模拟精度。[方法]以吉林省汪清林业局20块落叶松云冷杉林样地数据为材料,基于生存分析方法中的Cox比例风险函数模型方法,把林分因子和立地因子作为协变量加入到模型中去,构建林木的枯损及生存模型,并在此基础上考虑样地水平的随机效应,最后与不考虑样地水平随机效应的模拟效果进行比较分析。[结果]表明,Cox比例风险函数模型在描述林木枯损时,具有很好的适应性。单木初始胸径与林木的风险函数呈反比,与生存率呈正比;大于对象木断面积与风险函数呈正比,与生存率呈反比;初始林分公顷株数与风险函数呈正比,与生存率呈反比;立地因子对林木的枯损及生存没有显著影响。与固定效应模型相比,Cox比例风险函数模型在考虑了样地水平的随机效应后,模型的模拟精度获得明显的提高,并且达到极显著程度。由于大于对象木断面积和初始林分公顷株数两个变量在考虑了样地水平的随机效应后影响不显著,最后只考虑了单木初始胸径一个变量对枯损的影响,与不考虑随机效应相比,差异也达到显著水平。[结论]林木本身的大小对自身的枯损具有明显的影响,胸径小的林木较胸径大的林木更易枯损...     

林木枯损木径级结构的初步探讨

与开发利用我省林区枯损木资源提供依据,指导森林经营活动以一九八○年全省连续清查资料为依据对枯损木的径级结构及其规律进行了初步探讨。1 资料来源选择森林状况具有一定代表性的露水河、白河、天桥岭、临江、大兴沟、敦化等6个林业局和东丰、延吉、和龙、桦甸辉南、浑江、集安、汪清等8个县市的一九八○年全省固定样地复查资料共计220份。其中幼中令林140份,成过熟林80份。     

兴安落叶松人工林单木枯损模型的研究

本研究以大兴安岭农林科学院基地施业区兴安落叶松人工林为研究对象,采用2001-2005年的12块复测样地数据,通过分析单株林木的枯损率与单木各调查因子之间的关系,应用Logistic方程建立了兴安落叶松人工林单木枯损模型。结果表明,胸径是影响林木枯损最重要的因子,直径越小,单木枯损概率越大。     

我国林木枯损量分析及森林经营措施建议

利用第八次全国森林资源清查数据,对全国林木枯损量现状及其变化趋势进行了专题分析。结果表明,全国林木蓄积年均枯损量约1.18亿m3,由各种灾害引起的林木枯损量占近40％。与第七次清查相比,林木年均枯损消耗量增加18％,枯损量增加主要来自集体林,人工林和幼龄林的枯损量增加幅度较大。白桦、冷杉林的枯损率较高,平均郁闭度0.75以上的林分枯损率高,特用林的年均枯损率也较高。因此,加强森林经营管理、推进森林抚育工作十分迫切。     

林分枯损模型的研究

线性回归模型和分布函数在预估直径生长、径阶株数分布方面已经得到了广泛的应用。本文利用回归模型和分布函数构成叠加模型预估辽宁资源连续清查数据的林分株数枯损分布,结果表明其具有结构合理、实用性强及预测精度高等特征。     

白河林业局单木枯损模型研究

利用白河林业局1990年、2000年10年间二类调查数据,整理出复位样地7个主要树种(组)的单木枯损数据,通过逐步回归和变量筛选的方法,用Logistic模型形式拟合7个树种(组)的单木枯损模型,结果表明,林木的直径大小是影响枯损概率的最重要因子,它们之间呈递减的关系.     

鄂西南天然马尾松林枯损模型的研究

本文通过对马尾松林固定样地重复观测 ,取得了各径级的枯损数并构造出经阶分布模型 y =a e-D b) 。经检验该模型拟合效果良好。     

关于建立林分枯损模型的探讨

本文对林木的枯损与适宜度、健壮度、竞争度的关系,影响林木枯损的因素及林木枯损的分布进行了论述,为建立枯损模型提出了理论依据,对建立枯损模型的方法作了叙述。     

长白落叶松苗木施肥效应函数模型

通过对长白落叶松S1-1苗木的正交施肥试验,建立了苗高与N肥,新梢与N肥,新梢干重与N、P和全苗干重与N、P的施肥效应函数模型。通过该模型可以计算出不同施肥量下的长白落叶松苗木生物量。最后确定长白落叶松S1-1苗木的最适的施肥量:N为0.16～0.22g/株,P为0.01～0.04g/株。     

STUDY ON PREDICTION MODEL OF SEED CROP OF LARIX OLGENSIS SEED ORCHARD

Blossomandfruitingarethebasicoftreeregeneration.butitisusuallycon-strainedbyenvironmentalfactorsandtreephysiologicalfactors,whichleantoseed-bearingcyclicityphenomenon,andbedseedlingnursingandafforestation,andaffecttheseedlingquantityandquality.Soitisthebasicofscientificforestmanage-menttomastertheblossomandbearfluitruleandpredicatetheseedcrop.MATERIALSANDMETHODSTheGeneralSituationofExperimentalSitesTheexperimentwerecarriedoutatQingshanLarixolgenslYseedorchard,Heilongiiangprovince,an…     

Spatial estimation of the density and carbon content of host populations for Phytophthora ramorum in California and Oregon

Outbreak of the emerging infectious disease sudden oak death continues to threaten California and Oregon forests following introduction of the exotic plant pathogen Phytophthora ramorum. Identifying areas at risk and forecasting changes in forest carbon following disease outbreak requires an understanding of the geographical distribution of host populations, which is unknown. In this study, we quantify and map the population density and carbon contents of five key host species for P. ramorum in California and Oregon, including four hosts killed by the pathogen (Notholithocarpus densiflorus, Quercus agrifolia, Quercus kelloggii and Quercus chrysolepis) and the foliar host Umbellularia californica which supports high sporulation rates. We integrate multiple sources of vegetation data, assembled from sparsely distributed (regional-scale) forest inventory and analysis (FIA) plots and more densely distributed (landscape-scale) plots for monitoring sudden oak death, and develop spatial prediction models based on correlation with environmental variables and spatial dependencies in host abundance. We estimate that 1.8 billion N. densiflorus trees (68 Tg C) and 2.6 billion Quercus host trees (227 Tg C) occur across 3.9 and 17.7 million ha of their respective habitat. A total of 436 million U.californica trees (14 Tg C) occur across 4.2 million ha which frequently overlap with Quercus and N. densiflorus host populations. Combination of landscape-scale data with FIA data resulted in more accurate estimation of host populations and their carbon contents. Forests of northern California and southwest Oregon have the highest concentration of the most susceptible hosts along with climatic conditions that favor pathogen spread. This study represents the first spatially-explicit estimate of P. ramorum host populations and their carbon contents which exceed previously published estimates. Our results will inform landscape- to regional-scale models of disease dynamics and guide management decisions regarding ecosystem impacts including risk of C release following widespread tree mortality.     

兴安落叶松天然林枯立木年龄结构的研究

本文用兴安落叶松天然林19块标准地资料,分析了林分枯立木年龄结构;并用三参数Weibull函数拟合了林分枯立木的龄阶分布,经X~2-检验,结果表明拟合效果良好。同时研究了林分活立木年龄与枯立木年龄之间的关系以及天然林的抚育问题。     

可变参数相对树高曲线模型及其应用研究

用我国现行一元立木材积表估计林分或样地的立木材积偏差很大，而直接利用二元立木材积表，则野外实测树高的工作量又太大。本研究针对这一实际问题，提出了通过建立可变参数相对树高曲线模型，将二元立木材积表直接用于林分或样地立木材积估计的方法，其估计精度可达到接近实测树高曲线法的水平。研究提出的可变参数相对树高曲线模型结构通式为：ＲＨｉ＝。     

西林吉林业局天然兴安落叶松立地条件的调查研究

西林吉林业局位于漠河县境内,东经121°29′-123°11′,北纬52°47′-53°20′;属中低山山地地貌,母岩以酸性侵入岩和中性火成岩为主,常见花岗岩;地带性植被为兴安落叶松(Larix gmelinii)林;年均气温-4.9℃,极端最低气温-52.3℃,极端最高气温达36.8℃≥10℃积温为1650.4℃,年均雨量约为403.4mm,集中在7-8月,无霜期约92d,属寒温带气候。     

豫西伏牛山区日本落叶松林水文效应研究

测定了豫西伏牛山区日本落叶松林的林冠截流降雨、土壤渗透速度和地表径流。结果表明,生长期林冠截流降雨１８５１ｍｍ,截流率为２４４％,饱和截流量５ｍｍ,截流量随降雨量增加而增加,截流率随降雨量的增加而减少;土壤渗透速度在１０ｍｍ．ｍｉｎ－１左右;地表径流系数在１１％～２０％之间;泥沙流失量７５×１０３ｋｇ·ｈｍ－２～１２×１０３ｋｇ·ｈｍ－２;土壤渗透速度、地表径流量随造林整地方式不同而变化。     

Calibrating and testing a gap model for simulating forest management in the Oregon Coast Range

The complex mix of economic and ecological objectives facing today's forest managers necessitates the development of growth models with a capacity for simulating a wide range of forest conditions while producing outputs useful for economic analyses. We calibrated the gap model ZELIG to simulate stand-level forest development in the Oregon Coast Range as part of a landscape-scale assessment of different forest management strategies. Our goal was to incorporate the predictive ability of an empirical model with the flexibility of a forest succession model. We emphasized the development of commercial-aged stands of Douglas-fir, the dominant tree species in the study area and primary source of timber. In addition, we judged that the ecological approach of ZELIG would be robust to the variety of other forest conditions and practices encountered in the Coast Range, including mixed-species stands, small-scale gap formation, innovative silvicultural methods, and reserve areas where forests grow unmanaged for long periods of time. We parameterized the model to distinguish forest development among two ecoregions, three forest types and two site productivity classes using three data sources: chronosequences of forest inventory data, long-term research data, and simulations from an empirical growth-and-yield model. The calibrated model was tested with independent, long-term measurements from 11 Douglas-fir plots (6 unthinned, 5 thinned), 3 spruce-hemlock plots, and 1 red alder plot. ZELIG closely approximated developmental trajectories of basal area and large trees in the Douglas-fir plots. Differences between simulated and observed conifer basal area for these plots ranged from −2.6 to 2.4 m²/ha; differences in the number of trees/ha ≥50 cm dbh ranged from −8.8 to 7.3 tph. Achieving these results required the use of a diameter-growth multiplier, suggesting some underlying constraints on tree growth such as the temperature response function. ZELIG also tended to overestimate regeneration of shade-tolerant trees and underestimate total tree density (i.e., higher rates of tree mortality). However, comparisons with the chronosequences of forest inventory data indicated that the simulated data are within the range of variability observed in the Coast Range. Further exploration and improvement of ZELIG is warranted in three key areas: (1) modeling rapid rates of conifer tree growth without the need for a diameter-growth multiplier; (2) understanding and remedying rates of tree mortality that were higher than those observed in the independent data; and (3) improving the tree regeneration module to account for competition with understory vegetation.     

华北落叶松抚育间伐技术的研究

本文论述了如何以效应生长量分析为基础,通过对华北落叶松人工林间伐林分的研究,建立与间伐有关的系列断面积收获预估模型。以此为基础,提出了一套确定抚育间伐强度和预测目标径级收获量的具体方法.通过对伐前密度为5550株·hm~(-2),地位指数级为10的华北落叶松人工林的研究,提出了间伐起始期15a,间隔期5a,采取4次间伐,间伐株强分别为30.3％,17.1％.22.4％,7.8％的间伐体制。     

EFFECT OF LOW TEMPERATURE ON POLLEN VITALITY OF LARIX OLGENSIS

After the treatment of pollen of larix olgensis at the different low temperature,the pollen vitality was observed by using fluorescent staining method.several concluuons were ob-tained:1)0℃一3℃ is the best temperature range for storing pollen of Larix olgensis.2)At the same temperature,humidity is the key factor influencing the pollen vitality,3)Different clones shows different resistance to low temperature.Among the ten clones 2# clone shows the highest resistance.