森林碳固定能力计算方法及长株潭区域碳年固定量估算

根据森林生态系统碳(CO2)平衡原理方程式[Fc=Nc(植物年净C)+Dc(凋落物C)+Mc(微生物C)+Ec(土壤动物及其它有机物C)-Rs(土壤放出C)],建立了森林生态系统碳(CO2)年固定量计算式:Fc=∑m∑nBEFcij·Xcij·11λi·Mkij·113-0.6Rij·Sij式中:Xcij———森林植物年净生产量;3+113Dcij+∑Hk=1j=1i=1Dcij———凋落物碳(CO2)固定量;Mkij———微生物自身碳素量;Rij———土壤呼吸放出CO2量;Sij———面积;i———森林类型序号;j———地域或土类序号。求算出长株潭地区森林生态系统年CO2固定量为3945.3×104t,是长株潭三市2000年工业燃料燃烧排放CO2总量的2.38倍。森林生态系统碳(CO2)固定能力,变幅在6.784～54.163t/(hm2·a-1)之间,大小排序为毛竹林>国外松林>阔叶林>四旁林>柏木林>马尾松林>杉木林>灌丛疏林>经济林。     

林火扑救危险地带自动识别与提取方法研究

安全科学扑火是森林消防的重要工作,影响扑火安全的因素很多,其中地形是最基础的因素.一些特殊的地形对扑火人员的生命安全构成了极大的威胁,如陡坡、窄山谷、窄山脊、单口山谷(葫芦峪)、鞍部、悬崖等,如何高效地识别扑火危险地带,对于科学指挥、安全灭火至关重要.文章以广州市大岭山林场为例,采用GIS(地理信息系统)的栅格分析方法,基于DEM(数字高程模型)分析识别林火扑救危险地带的地形特征,建立ArcGIS可视化分析模型快速提取危险地带,与实际地形对比准确度很高,表明该方法科学有效.     

环洞庭湖防护林的土壤理化性状研究

以环洞庭湖12种主要造林模式防护林为研究对象,对其进行土壤取样和分析,研究环洞庭湖防护林土壤理化性状.结果表明:环洞庭湖区防护林土壤养分处于中高水平,但速效磷比较贫乏;不同造林模式防护林的土壤理化性状存在显著差异,特别是速效氮、速效钾、容重和pH值,其差异性均达到了极显著水平,其中杉木+木荷等针阔混交模式防护林的土壤理...     

Changes in soil properties of Abies holophylla and Quercus-dominated stands 4 years after trenching

Abstract

Few studies tried to isolate the influence of plant roots on the soil characteristics including soil carbon (C) and nitrogen (N) storage. We evaluated the impact of root trenching on soil characteristics of coniferous (Abies holophylla) and deciduous (Quercus spp.) stands 4 years after trenching. Trenching treatment significantly increased the soil water content and nitrate concentration in both stand types. Soil pH, cation exchange capacity, soil C and N pools and isotopic compositions of C and N were significantly different between two stands, but trenching was not found to have significant impact on these soil properties. Our results indicated that root trenching in coniferous and broad-leaved deciduous forests of temperate region could significantly alter soil moisture regime and inorganic N levels, but not C and N stabilization in soils.     

Approach to the estimation of red heart occurrence in Fagus sylvatica based on geometric relationships between branch scar development and knot dimensions

Abstract

The effect of branch scars on the initiation and occurrence of red heart in beech (Fagus sylvatica L.) was studied on 17 trees with red heartwood and 14 trees with no discoloured heartwood, all of which were selected from a 120-year-old high-forest stand in Germany. Logistic regression was used to predict the probability of red heart occurrence for a given tree. The model was based on individual probabilities derived from geometric relationships between scar and knot morphologies, and integrated the diameter at breast height. Using this model, 27 of 31 trees were correctly classified, and the two groups of trees were clearly distinguished by probabilities below 0.25 and above 0.85 (with one exception). Given the constitution of the model, only 17 of 616 scars were found to initiate red heart formation, and the parameters of mechanistic variables were strongly correlated. The results suggest specifying the relationship between scars, knots and red heart, and extending the scope of the model.     

Dynamics of soil C,N and Ca in four Swedish forests after removal of tops,branches and stumps as predicted by the Q model

Abstract

We used the Q model to examine the dynamics of carbon (C), nitrogen (N) and calcium (Ca) in the litter/soil system in different scenarios of harvesting intensities, S (stems only), SSl (stems and slash, i.e. tops, and branches including needles) and SSlSt (stems, slash and stumps including coarse roots). Empirical data from long-term field experiments in Sweden, two sites with Norway spruce and two with Scots pine with different levels of productivity, were used to calibrate the model against the stem-only treatment. The highest initial reduction in soil C, N and Ca stores was predicted for SSlSt, and the reduction was more pronounced at low productive sites than at the high productive ones. Most of the decline in soil C and Ca stocks was offset by the litter production in the following forest stand. N showed an initial phase of immobilisation in stumps and coarse roots, while N was immediately released from tops and branches, which contained N-rich needles. Removal of stumps and coarse roots in combination with slash resulted in a similar load of inorganic soil N as for the S treatment, whereas the SSl treatment with stumps left in the soil initially reduced the inorganic soil N pool.     

地面三维激光扫描技术在林业中的应用与展望

以地面三维激光扫描技术的测量原理、技术特征为切入点, 重点论述了该技术在国内外林业领域的应用现状、不足及前景。与传统研究手段相比, 地面三维激光扫描技术在测树效率、三维建模、模型化精度等方面具有较大的优势, 显示出更广阔的应用前景。     

桉树择伐后套种3种阔叶树的生长及土壤理化性状效应分析

为探讨桉树择伐后套种阔叶树的可行性和适生性,摸索适宜的桉树套种混交模式,对闽南山地桉树人工林择伐后分别套种米老排、卷荚相思、灰木莲所形成的复层异龄混交林分的生长量及土壤理化性状进行调查分析。结果表明:1)桉树择伐后,采用3桉∶3阔的行带状方式套种米老排、卷荚相思、灰木莲的不同混交林中,3个阔叶树种的保存率均较高且生长良好,均可达到速丰林的年均生长量标准;桉树—米老排、桉树—卷荚相思、桉树—灰木莲混交均可以有效促进桉树的生长,并在一定程度上改善土壤理化性状。2)套种后混交林中的桉树树高、胸径、材积分别比纯林提高3.35%～11.24%、4.05%～12.32%和11.85%～40.59%。3)米老排、卷荚相思和灰木莲与桉树的套种方式可作为桉树纯林择伐后套种混交的推荐模式。     

Derivation of stumpage value and logging costs for individual forest stands using aerial photographs and cartographic modelling

A procedure for calculation of stumpage value and logging costs of individual mature forest stands using aerial photo‐interpretation and a grid‐based geographical information system (GIS) is presented. The stumpage value may be computed from characteristics related to the trees, i.e. site index, stand mean height, crown closure, and tree species distribution, using price equations. By means of cost equations, the logging costs may be calculated from the tree characteristics and the terrain characteristics of slope gradient and skidding distance. The practical application of the procedure was demonstrated by a case study in a 710 ha forest area in southern Norway. The tree characteristics were determined by photo‐interpretation of individual stands. Skid paths for wood transportation from the stands to landings along the forest roads were delineated by photo‐interpretation of the ground conditions. Slope and skidding distances were derived by a digital elevation model and cartographic modelling. Finally, the photo‐interpreted tree characteristics and the computed slope and skidding distances were used for calculation of the stumpage value and the logging costs of each stand. According to previous tests, the accuracy of the procedure corresponded to the accuracy that could be achieved by the field‐survey methods used most frequently.     

Fire models and methods to map fuel types: The role of remote sensing

Understanding fire is essential to improving forest management strategies. More specifically, an accurate knowledge of the spatial distribution of fuels is critical when analyzing, modelling and predicting fire behaviour. First, we review the main concepts and terminology associated with forest fuels and a number of fuel type classifications. Second, we summarize the main techniques employed to map fuel types starting with the most traditional approaches, such as field work, aerial photo interpretation or ecological modelling. We pay special attention to more contemporary techniques, which involve the use of remote sensing systems. In general, remote sensing systems are low-priced, can be regularly updated and are less time-consuming than traditional methods, but they are still facing important limitations. Recent work has shown that the integration of different sources of information and methods in a complementary way helps to overcome most of these limitations. Further research is encouraged to develop novel and enhanced remote sensing techniques.