抚育间伐技术目标管理新方法     

何玉琦  姚光常 《东北林业大学学报》1990,18(5):105-111

本文利用林层结构划分条件、林分起源、林层年龄、树种组成等因子,将松江河林区的幼、中龄林划分为四个林相组和九个林相类型。在此基础上编制了幼、中龄林林相类型表。用该表能指导幼、中龄林的调查、设计和抚育间伐。该目标管理技术环节易于掌握,并可提高抚育质量。  相似文献   

人工落叶松林优化经营管理系列模型的研究     

陈霖生  孙玉军 《东北林业大学学报》1989,(6)

本文以使得未来林分永续生产周期的净现值最大为准则,应用变分法建立同龄林分木材收获时间问题的优化控制模型。以东北林区的人工落叶松林资料(260块标准地和62株解析木)为例,说明模型中参数的确定及模型的应用,同时,确定人工落叶松林的最优间伐计划和轮伐期。  相似文献   

Polypore diversity in managed and old-growth boreal Picea abies forests in southern Finland     

Reijo Penttilä  Juha Siitonen 《Biological conservation》2004,117(3):271-283

Polypore communities were compared between mature managed, overmature managed, and old-growth spruce-dominated forests in southern Finland. A total of 85 polypore species, with 6000 records, were found in 16 sample plots, each 4 ha in size. Old-growth stands had on average 80% more species than mature stands, and 38% more species than overmature managed stands. Variation in polypore species richness was best explained by diversity of dead wood and the number and volume of dead trees. The best predictor for the number of threatened polypore species was the number of cut stumps. Threatened species were practically confined to old-growth forests and to stands in which the amount of dead wood exceeded 20 m³/ha. This figure appears to represent a stand-level threshold value for the amount of dead wood, below which the persistence of threatened species becomes unlikely. Our results suggest that a significant increase in the amount of dead wood (e.g. by leaving large retention trees and even by killing trees) is needed in managed forests before they become suitable habitats for threatened polypores.  相似文献   

不同林龄兴安落叶松生物量、碳密度及其分布特征     

王亚林 《安徽农业科学》2015,(15)

[目的]探讨不同发育阶段兴安落叶松人工林生物量和碳密度的变化规律。[方法]对辽宁东部山区13、23和32年兴安落叶松人工林生物量和各器官碳密度进行调查。[结果]兴安落叶松乔木层各器官生物量的分配序列均为:树干生物量树根生物量树枝生物量树皮生物量树叶生物量。32年兴安落叶松人工林林木和各器官生物量高于13年和23年的兴安落叶松人工林,32年兴安落叶松人工林仍有增加碳密度的潜力。[结论]该研究为兴安落叶松人工林群落碳汇功能与林分经营分析提供基础资料。  相似文献   

深圳梧桐山风景区林下主要植物群落景观的评价与林分改造对策     

乔红  蔡如  崔少伟  周厚高 《广东园林》2013,(5):68-73

根据研究对象的特性和研究目的,确定植物景观评价因子及其权重,建立城市森林公园林下景观的评价模型。采用AHP法对深圳梧桐山风景区林下典型群落进行了评价,最后得到景观美景度值,就平均得分在6分以下的指标提出相应的改造对策,为森林公园的建设提供依据。  相似文献   

林下观赏型南方红豆杉培育技术研究   总被引：1，自引：0，他引：1  

欧建德  张卫明  刘森勋  潘军  周东雄  罗宁  王金盾 《安徽农业科学》2013,41(4):1585-1587

在福建省明溪进行林下观赏型南方红豆杉培育试验,试验系统研究了立地条件、修枝、林分结构调整、苗木年龄等内容。结果表明:林下观赏型南方红豆杉培育应选择Ⅰ、Ⅱ类立地。在林冠稀疏的林分情况下,应采用多年生南方红豆杉苗木。弱度修枝可显著性促进植株生长,且观赏性状表现理想。林分结构动态调控技术作为一种全新技术,可显著性促进植株生长、保存率,且观赏性状表现理想,在林下观赏型南方红豆杉培育中可以推广。  相似文献   

毛竹密度效应新模型的研究   总被引：2，自引：0，他引：2  

万绍平 《经济林研究》1999,(4)

本文应用人工神经网络理论,对毛竹密度效应进行定量研究,建立了毛竹密度效应的三层前馈反向传播神经网络ＢＰ模型,仿真结果表明,人工神经网络模型能表征毛竹林分平均胸径、平均高度、密度对林分杆产量的映射效应,从而为毛竹密度效应研究提供了新方法。  相似文献   

闽北杉木人工林生物量及其分配的动态变化     

丁洪峰 《安徽农业科学》2016,44(30):136-138

[目的]研究杉木生物量及其分配的动态变化。[方法]以闽北杉木林为研究对象,在典型区域设置46块样地,采用收获法测定46株标准木的生物量,林龄为5~33年。[结果]建立了闽北杉木器官及整株生物量与测树指标(胸径和树高)的回归模型;除树枝和树叶外,其他器官(树干、地上和树根)及整株的回归效果良好;随着林龄的增加,器官及整株生物量逐渐增加,在林龄为40年左右时达到稳定,同时构建了林木生物量与林龄的回归模型;随着林龄的增加,树干生物量的比例逐渐增加,其他器官生物量的比例逐渐减小,并在林龄为25年左右达到稳定。[结论]随着林龄的增加,杉木生物量及其分配呈现可预测的动态变化。  相似文献   

Forest stand dynamics and sudden oak death: Mortality in mixed-evergreen forests dominated by coast live oak     

L.B. Brown  B. Allen-Diaz 《Forest Ecology and Management》2009

Sudden oak death (SOD), caused by the recently discovered non-native invasive pathogen, Phytophthora ramorum, has already killed tens of thousands of native coast live oak and tanoak trees in California. Little is known of potential short and long term impacts of this novel plant–pathogen interaction on forest structure and composition. Coast live oak (Quercus agrifolia) and bay laurel (Umbellularia californica) form mixed-evergreen forests along the northern California coast. This study measured tree mortality over a gradient of disease in three time periods. Direct measurements of current mortality were taken during 2004, representing a point-in-time estimate of present and ongoing mortality. Past stand conditions, c. 1994, were estimated using a stand reconstruction technique. Future stand conditions, c. 2014, were calculated by assuming that, given a lack of host resistance, live trees showing signs of the disease in 2004 would die. Results indicate that coast live oaks died at a rate of 4.4–5.5% year⁻¹ between 1994 and 2004 in highly impacted sites, compared with a background rate of 0.49% year⁻¹, a ten-fold increase in mortality. From 2004 to 2014, mortality rates in the same sites were 0.8–2.6% year⁻¹. Over the entire period, in highly impacted sites, a 59–70% loss of coast live oak basal area was predicted, and coast live oak decreased from 60% to 40% of total stand basal area, while bay laurel increased from 22% to 37%. Future stand structures will likely have greater proportions of bay laurel relative to coast live oak.  相似文献   

Calibrating the self-thinning frontier     

Jerome K. Vanclay  Peter J. Sands 《Forest Ecology and Management》2009

Calibration of the self-thinning frontier in even-aged monocultures is hampered by scarce data and by subjective decisions about the proximity of data to the frontier. We present a simple model that applies to observations of the full trajectory of stand mean diameter across a range of densities not necessarily close to the frontier. Development of the model is based on a consideration of the slope s = ln(N_t/N_t−1)/ln(D_t/D_t−1) of a log-transformed plot of stocking N_t and mean stem diameter D_t at time t. This avoids the need for subjective decisions about limiting density and allows the use of abundant data further from the self-thinning frontier. The model can be solved analytically and yields equations for the stocking and the stand basal area as an explicit function of stem diameter. It predicts that self-thinning may be regulated by the maximum basal area with a slope of −2. The significance of other predictor variables offers an effective test of competing self-thinning theories such Yoda's −3/2 power rule and Reineke's stand density index.  相似文献