燕山山地白桦林的空间结构研究

为了解燕山山地白桦天然次生林的空间结构,以河北省孟滦林场和黑龙山林场的白桦天然次生林为研究对象,对其角尺度和混交度等空间结构特征参数进行了研究。结果表明:孟滦林场和黑龙山林场的白桦天然次生幼龄林均呈聚集分布,平均角尺度分别为0.58和0.55,孟滦林场的白桦天然次生幼龄林的聚集程度高于黑龙山林场;2个地区的白桦天然次生中龄林也呈明显的聚集分布。孟滦林场白桦天然次生林平均混交度为0.32,混交树种只有2个;黑龙山林场平均混交度为0.47,混交树种达到5个。     

我省白桦次生林的分布及生长特性

白桦(Betula platyphylla Suks)次生林在我省分布为数不少。据统计,其蓄积约占我省森林总蓄积的16.8％。可见其在森林经营中所应占的地位。我们综合以往调查资料,研究分析其生长特性,试图对我省桦木生产的合理布局和经营管理等方面提出一些看法。一、分布状况白桦是喜光、喜酸性土壤的树种,耐瘠薄严寒,适应性强,分布广,易在针叶林采伐迹地上更新,常见与山杨伴生,堪称北方次生林区的“姐妹”树种,白桦是其中的先锋树种之一。按我省植被分区分类系统看,白桦次生林的分布范围主要属于暖温带落叶     

东北天然次生林阔叶树种枝条基径模型

树冠是树木的重要组成部分,研究树冠结构是定向培育森林的技术手段,目前树冠模型常采用枝解析的方法。该研究用帽儿山地区天然次生林10个阔叶树种的枝条解析数据建立树冠结构相关的模型,提出了一种模拟阔叶树种枝条基径的模型,用逐步回归拟合枝条基径与总着枝深度、胸径、树高、冠幅、冠长之间的多项式回归关系,相关指数在0.9以上。模型检验结果表明冠长与着枝深度的组合对模型贡献率较小,白桦和椴树的相关指数较小。该研究对抚育整枝提供理论指导,为森林经营措施的优化提供技术支撑。     

天然杨桦林林分密度的研究

山杨、白桦是黑龙江省次生林主要组成树种。由于森林面积的长期大量采伐、火烧及各种人为破坏的作用,以山杨、白桦为主的天然更新的次生林面积也在不断增加,其中尤以幼中龄林为多,已占全省杨桦林总面积的72.3％。为提高次生林经营管理的水平,1980年以来,我们对杨桦林的林木生长、林分生长过程中的群体结构规律,树冠生长发育与林分群体生长的关系、林分密度     

小兴安岭4种森林类型细根生物量的时空格局

【目的】对原生林及其皆伐后自然演替形成的次生林和造林形成的人工林的细根生物量及土壤特性进行研究,分析不同更新方式对细根动态分布的影响、了解细根与土壤特性之间的互动效应,为阐明森林生态系统中碳和养分循环以及为该地区森林恢复和森林经营提供理论依据。【方法】以小兴安岭南坡典型阔叶红松林、皆伐后天然更新的白桦次生林、皆伐后栽植的红松人工林和兴安落叶松人工林为研究对象,于2013年5—9月用连续钻取土芯法采集细根(直径≤2 mm)和土壤,测定细根生物量的垂直分布与季节动态,分析生物量与土壤特性的相关性。【结果】典型阔叶红松林、红松人工林细根生物量均显著高于白桦次生林和兴安落叶松人工林(P0.05);各森林类型细根生物量的垂直分布存在显著差异(P0.05),细根主要集中在0～20 cm土层中,其中白桦次生林0～20 cm土层中细根生物量占其细根总生物量的比例最高(75.81%),典型阔叶红松林最低(62.73%);各森林类型细根生物量存在季节性波动,各森林类型活、死细根生物量均有2个峰值;4种森林类型的细根生物量与土壤温度的相关性不显著,除典型阔叶红松林外,其他3种森林类型的细根生物量与土壤含水率极显著正相关(P0.01),4种森林类型的细根生物量与土壤水解氮含量极显著正相关(P0.01),白桦次生林的细根生物量与土壤有效磷含量显著负相关(P0.05)。【结论】本地区的顶极群落——典型阔叶红松林和以典型阔叶红松林的建群种为主要组成树种的红松人工林细根生物量显著高于以先锋树种白桦和兴安落叶松为主要组成树种的白桦次生林和兴安落叶松人工林;细根生物量在土壤中的分布具有明显的不均匀性,主要集中在养分含量较高的土壤表层,处于演替顶极阶段的森林较处于演替早期的森林采取更精细的获取资源的策略,土壤下层细根占细根总生物量比例较高;细根生物量的季节变化与物候节律一致,细根生物量的高峰期出现在春末和初秋。     

白桦育苗技术

白桦（Betula platyphylla）适应能力强,在采伐迹地和火烧迹地上常成纯林或与其它树种组成混交林,在分布区,蓄积量丰富。在河北省现有用材林中蓄积量占首位,林地面积居第二位。是河北省天然次生林的主要树种,同时木材用途广泛,树皮可入药^[1]。白桦是高海拔山地云杉、落叶松等的伴生树种,也是构成针阔混交林唯一生长比较稳定的阔叶树种,对防止森林火灾及病虫害的蔓延、保持森林景观的多层次性,有着不可替代的作用,即使是有一定面积的白桦纯林也给人们带来良好的视觉享受。     

帽儿山典型森林群落优势种空间分布格局及其关联性

选取帽儿山地区阔叶红松林、红松人工林和水曲柳天然次生林3种典型群落,基于方差均值比、L函数和角尺度方法比较研究各群落乔灌层优势种的空间分布格局与空间关系。结果表明,帽儿山典型森林群落优势种的空间分布格局主要呈聚集分布或随机分布。阔叶红松林乔木优势种呈随机分布或不显著聚集分布;红松人工林中红松呈随机分布;水曲柳次生林乔木优势种主要呈随机分布。各群落灌木优势种均呈聚集分布。帽儿山典型森林群落中各乔木优势种间主要呈空间正关联或无空间关联,红松与阔叶树小尺度无关联,大尺度正关联,阔叶树种间主要呈正关联。红松人工林与水曲柳天然次生林乔木优势种间均呈正关联。帽儿山典型森林群落优势种空间关系良好,空间结构稳定。     

银柴采种与育苗

<正> 银柴(Aporusa dioica(Roxb.)Muell.-Arg.),大戟科银柴属,又名大沙叶、甜糖木,小乔木,高可达8～10m,是南方地区常见的一种乡土阔叶树种。分布于广东、海南、广西、云南等地,国外,越南、缅甸、印度和马来西亚也有分布,多见于海拔1000m以下丘陵山地次生林内、林缘、灌丛中。在自然分布的森林群落中常为伴生树种。树冠浓荫,四季常绿,枝叶茂密。银柴对大气污染的抗逆性较强,可作为营造景     

对天然次生林抚育强度的一点意见

牡丹江林区分布着大面积的天然次生林,以东京城林业局为例,天然次生林的面积占全局有林地总面积的59％,其中柞树次生林占49％,杨桦次生林占10％(1971年)。天然次生林在森林经营中占有重要地位,是重要的后     

穆棱主要树种叶量分布的研究

基于黑龙江省穆棱市5个主要树种,对所有样木进行枝条解析从而获得树叶的生物量数据.把树冠分为上层、中层和下层,分别研究探索三层的树叶的生物量与林龄的关系,旨在为进一步分析和探索穆棱市5个主要树种的叶量分布奠定基础条件.结果表明:椴树和红松的三个层次叶量与年龄的相关性都比较显著,对于椴树和红松而言,上层的叶量与年龄的相关性最大,而中层的叶量与年龄的相关性最小,而白桦、云杉、冷杉三个层次的叶量与年龄的相关性则比较低.     

Within crown variation in the relationship between foliage biomass and sapwood area in jack pine

The relationship between sapwood area and foliage biomass is the basis for a lot of research on eco-phyisology. In this paper, foliage biomass change between two consecutive whorls is studied, using different variations in the pipe model theory. Linear and non-linear mixed-effect models relating foliage differences to sapwood area increments were tested to take into account whorl location, with the best fit statistics supporting the non-linear formulation. The estimated value of the exponent is 0.5130, which is significantly different from 1, the expected value given by the pipe model theory. When applied to crown stem sapwood taper, the model indicates that foliage biomass distribution influences the foliage biomass to sapwood area at crown base ratio. This result is interpreted as being the consequence of differences in the turnover rates of sapwood and foliage. More importantly, the model explains previously reported trends in jack pine sapwood area at crown base to tree foliage biomass ratio.     

Thinning alters crown dynamics and biomass increment within aboveground tissues in young stands of Chamaecyparis obtusa

The stand density of a forest affects the vertical distribution of foliage. Understanding the dynamics of this response is important for the study of crown structure and function, carbon-budget estimation, and forest management. We investigated the effect of tree density on the vertical distribution of foliage, branch, and stem growth, and ratio of biomass increment in aboveground tissues; by monitoring all first-order branches of five trees each from thinned and unthinned control stands of 10-year-old Chamaecyparis obtusa for four consecutive years. In the control stand, the foliage crown shifted upward with height growth but the foliage quantity of the whole crown did not increase. In addition, the vertical distribution of leaf mass shifted from lower-crown skewed to upper-crown skewed. In the thinned stand in contrast, the foliage quantity of individual crowns increased two-fold within 4 years, while the vertical distribution of leaf mass remained lower-crown skewed. The two stands had similar production rates, numbers of first-order branches per unit of tree height, and total lengths of first-order branches. However, the mortality rate of first-order branches and self-pruning within a first-order branch were significantly higher in the control stand than in the thinned stand, which resulted in a higher ratio of biomass increment in branch. Thinning induced a higher ratio of biomass increment in foliage and lower in branch. The increased foliage quantity and variation in ratio of biomass increment after thinning stimulated stem growth of residual trees. These results provide information that will be useful when considering thinning regimes and stand management.     

Canopy development in young sugi (Cryptomeria japonica) stands in relation to changes with age in crown morphology and structure

In young sugi (Cryptomeria japonica D. Don) stands, crown shape (crown length/crown diameter) ratio, average branch inclination, and spatial density of foliage in the crown increased with stand age. Within crowns, foliage distribution increased from the apex downward and, until crown closure, reached a maximum near the crown base. After crown closure, the maximum occurred near the middle of the crown. In each stand, foliage distribution in the canopy showed almost the same vertical change over time as it did in individual crowns. The vertical distribution of foliage in the canopy moved upward with stand age, accompanied by an increase in canopy depth and leaf mass. The shape of the vertical distribution was almost symmetrical between the upper and lower halves in the closed stands, although slightly skewed downward. The logarithm of average spatial density decreased linearly as cumulative leaf mass increased with distance from the top of the canopy. The total cross-sectional area of the crowns exceeded the stand area from the middle of the canopy downward in the closed stands because of crown overlap. However, partly because of changes in crown morphology and structure, the increase in leaf mass with stand age did not always cause more severe crown competition.     

Estimating foliage biomass in Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) plots

Dynamic decomposition models are needed to estimate changes in the carbon stock of boreal soil because these changes are difficult to measure directly. An important aboveground carbon flux to the soil is foliage litterfall. To estimate this flux, both the amount and the turnover rate of the foliage biomass component must be known. Several methods for estimating foliage biomass of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.), including biomass equations and biomass expansion factors (BEFs), were compared with predicted foliage biomass based on forest inventory plot-level measurements. Measured foliage biomass was up-scaled from the branch-level to the plot-level by combining forest inventory variables (diameter, height, height at the crown base and crown base diameter) based on the assumptions of pipe model theory. Combining the foliage biomass: cross-sectional area ratio with the forest inventory variables provided accurate estimates of foliage biomass at the plot-level for plots in southern Finland. The results emphasize the need to test biomass equations with independent data, especially when the equations applied are based on neighboring regions.     

Spatial partitioning of biomass and diversity in a lowland Bolivian forest: Linking field and remote sensing measurements

Large-scale inventories of forest biomass and structure are necessary for both understanding carbon dynamics and conserving biodiversity. High-resolution satellite imagery is starting to enable structural analysis of tropical forests over large areas, but we lack an understanding of how tropical forest biomass links to remote sensing. We quantified the spatial distribution of biomass and tree species diversity over 4 ha in a Bolivian lowland moist tropical forest, and then linked our field measurements to high-resolution Quickbird satellite imagery. Our field measurements showed that emergent and canopy dominant trees, being those directly visible from nadir remote sensors, comprised the highest diversity of tree species, represented 86% of all tree species found in our study plots, and contained the majority of forest biomass. Emergent trees obscured 1–15 trees with trunk diameters (at 1.3 m, diameter at breast height (DBH)) ≥20 cm, thus hiding 30–50% of forest biomass from nadir viewing. Allometric equations were developed to link remotely visible crown features to stand parameters, showing that the maximum tree crown length explains 50–70% of the individual tree biomass. We then developed correction equations to derive aboveground forest biomass, basal area, and tree density from tree crowns visible to nadir satellites. We applied an automated tree crown delineation procedure to a high-resolution panchromatic Quickbird image of our study area, which showed promise for identification of forest biomass at community scales, but which also highlighted the difficulties of remotely sensing forest structure at the individual tree level.     

Comparison of branch biomass relationships for North Carolina and Oklahoma/Arkansas loblolly pine seed sources growing in southeastern Oklahoma

Comparison of branch-level foliage and branch (wood+bark) biomass relationships for North Carolina Coastal (NCC) and Oklahoma/Arkansas (O/A) loblolly pine (Pinus taeda L.) seed sources provided an indication of biomass partitioning differences between these two seed sources. The objective of this study was to quantify and compare the branch-level foliage and branch biomass of NCC and O/A provenances on an excessively drained site in southeastern Oklahoma to assess their branch-level biomass partitioning patterns; a modeling process was developed to accomplish this objective. It was found that seed source significantly influenced the amount of foliage per branch. If tree and branch dimensions were held constant, NCC branches would carry approximately 30% more foliage per branch than O/A branches. The relationship between tree and branch dimensions and branch production did not differ for the two seed sources. Vertical distributions of branch and foliage biomass were found to be similar for the two seed sources as well. Thus, on the droughty site observed in this study: (1) the NCC seed source tended to partition more biomass into the foliage component at the individual branch level than did the O/A seed source; (2) the two seed sources were similar in their propensity to partition biomass into the branch component at the branch level, and (3) the two seed sources were similar in the vertical distribution of branch and foliage biomass within the crown.     

Analysis of the morphology and structure of crowns in a young sugi (Cryptomeria japonica) stand

Crown form, vertical changes in branch inclination and vertical distribution of foliage density in a young sugi (Crytomeria japonica D. Don) stand were analyzed using allometric equations. Tall trees had deeper crowns than short trees, whereas the crown diameters of both tall and short trees were similar. Apical roundness was more pronounced in the lower-story trees, which were characterized by umbrella-shaped crowns. The vertical distribution of foliage density was approximated by a nearly symmetrical curve. Tall trees had higher spatial densities of foliage than short trees. Branch inclination also varied significantly with tree height. The middle-story trees had the largest branch inclinations and the lower-story trees had the smallest branch inclinations. Even in young uniform stands, crown morphology and structure were modified in response to the light environment.     

Crown projection area of young Pinus sylvestris: A model and its test

In this study we applied a theoretical model for determining the projection area of a Scots pine (Pinus sylvestris L.) crown in different directions. The model is based on the assumption that the foliage elements (shoots) are randomly distributed within a symmetrical crown envelope. The model was tested using photographically measured data for three young Scots pine crowns. The compatibility between calculated and measured values was satisfactory.     

城市绿化红皮云杉树冠形状研究

红皮云杉是东北地区重要的造林和城市绿化的优秀树种,在城市环境的红皮云杉树形优美,树冠浓密圆润。本文对吉林省7个城市绿化的红皮云杉进行了调查研究,结果表明,红皮云杉的冠高比接近黄金数0.618 0,而森林中的红皮云杉冠高比0.402 2。     

Within-crown structural variability of dwarfed mature Abies mariesii in snowy subalpine parkland in central Japan

We investigated mature dwarf Abies mariesii trees growing in conifer thicket–meadow parklands on a snowy subalpine plateau, where these dwarf trees are buried in the accumulated snow in winter. We focused on structural variation in the needles, shoots, and branchlets within different crown positions (leader crown vs lower crown) of the dwarf trees. In the leader crown, which appears above the snow surface earlier than the lower crown, current-year shoots and branchlets had greater total biomass, and foliage was more closely packed along the stem axis than in the lower crown, whereas current-year shoots in the leader crown had a lower needle mass ratio than in the lower crown. These results suggest that current-year shoots and branchlets in the leader crown have a specific structure that allows them to harvest more light, although construction and maintenance costs would be higher. In contrast, the structural characteristics of current-year shoots and branchlets in the lower crown efficiently concentrate incoming light by avoiding mutual shading within foliage, thus leading to increased biomass of photosynthetic needles within shoot and branchlet biomass. Such within-crown variability at various hierarchical levels from needles to branches in mature, but very dwarf, A. mariesii trees maintains the crown and allows survival within conifer clumps in areas of subalpine parklands that receive heavy snowfall.