基于回归分析的辽西北沙地赤松地径与胸径建模研究

本文对505株辽西北沙地赤松地径(D_(0.1))与胸径(D_(1.3))数据进行回归分析,结果表明:辽西北沙地赤松地径与胸径之间存在明显相关性,采用6种数学模型,进行赤松地径与胸径相关分析,其中三次曲线方程D_(1.3)=-1.068+0.602 D_(0.1)+0.011 8 D_(0.1)~2-0.000 2 D_(0.1)~3为最佳模型。     

杉木人工林可变密度收获表、密度标准表编制的研究

为反映Rieneke所定义的林分充分密集条件下直径与株数间的量变关系,以杉木人工林标准地为材料.通过L=[(N/N_m)~2+(D/D_m)~2]~(0.5)式解出各标准地L值,并由大至小排序。根据统计学原理.选取30块大样本标准地求解N=D~(-h)的b值.得出标准直径与密度指数的变化规律:随着标准直径的降低,密度指数及其范围增大;反之.减小。以拓广Richard式为密度指数、地位指数、树高与断面积数学模型。检验表明.断面积、蓄积精度很高.达99％或以上.证明这些数学模型准确反映了它们之间的量变关系。根据这些数学模型及杉木人工林地位指数表或模型参数编制可变密度收获表;以最大密度指数代入模型编制密度标准表。     

“适用于小型电子计算机的”等截面无铰拱力素分析的简化数学模型及其精度估计

数学模型要适应相应的计算工具的功能,这是个非常现实的问题。小型电子计算机(如:DJS—130电子计算机)由于功能的限制,用它来作等截面无绞拱力素分析时,使用有限元法的数学模型虽然精度高,但并非是一个简洁有效的手段。相反,如果按一般的结构解析数学模型(如:交通部公路设计手册“拱桥”中的一系列公式),由于要做很多积分的数值解,则要列出相当繁杂而冗长的计算程序,     

落叶松树皮单宁组分的研究(凝缩类单宁组分研究之一)

从兴安落叶松(Larix gmelini)树皮提取物中分离出来的水溶性单宁,通过花色素反应、硫解反应、间苯三酚反应、~(13)C-核磁共振、旋光、紫外光谱和红外光谱等方法研究,判定为原花青定。落叶松树皮原花青定的终端单元由(+)—儿茶素及(—)—表儿茶素组成,二者的比例为8:2,延伸单元由(+)—儿茶素及(—)—表儿茶素组成,二者的比例约为3:7,水溶性单宁分子的平均聚合度约为8。     

马尾松毛虫质型多角体病毒的研究——Ⅰ.病毒的毒力测定

本文对马尾松毛虫质型多角体病毒(D.CPV)防治技术进行研究。室内个体、群体毒力测定表明:病毒包含体为2×10~5—2×10~8CPB/ml,校正死亡率均达82%以上,其浓度间致毒死亡率差异不显著。林间防治试验表明:林间致毒浓度为2×10~6CPB/ml时,校正死亡率70.7%,低于病毒加20%速灭杀丁(1∶2.5万倍液)死亡率88.5%的17.8%。温度平均低于18.4℃,幼虫总死亡率(73.5%—77.2%),温度平均在19—29℃之间的死亡率(82.7%—89.9%),病毒致死率相差不大。     

朝鲜循环式采伐法简介(二)

(十)循环周期期间的伐木计划1、采伐区域别的伐木量(1)按平均指数计算的方法①根据伐木林地的蓄积、周期间平均生长量、平均伐木率计算年平均伐木量。R_年=U_o(〔1+(P/100)〕~(n-1)·(D/100))/(〔1+(P/100)〕~(n-1))·C/100式中:R_年—年平均可采伐量规模;U_o—循环区被伐林地的总蓄积(m~3);P—伐木林地周期间平均生长率(%);n—循环周期;C—平均伐木率。     

山东省临沂地区杨树人工林林分密度管理图的编制

山东省临沂地区杨树人工林林分密度管理图,于1986年冬至1987年春在该地区设置69杨等临时标地356块资料基础上编制而成。密度为278—5952株/ha(其中500—1894株/ha者占89.1％);优势高为5.9—28.6m;平均胸径为3.8—28.6cm;蓄积量为3.9—339.7m~3/ha。管理图编制方法:等树高线选用M~(-1)=A_1+B_1N~(-1)式,等直径线选用D~(-1)=A_2+B_2N式;最大密度线采用M_(Rf)=K_2·N_(Rf)~(K_1~′)式;密度管理线采用M_(Ry)=K_3·N_(Ry)~(K_1~′)式。本密度管理图的精度,等树高线为97.6％;等直径线为98.9％,符合生产要求。     

攀西地区云南松林燃烧性的研究

本文定量的研究四川省攀枝花——西昌地区不同林型的云南松林地上部分生物量及云南松林各层次可燃物的数量、类型及热值分布规律等。研究结果表明:云南松林地上部分可燃物总量为95.043t/ha,其中乔木层77.914t/ha,灌木层4.164t/ha,草本层0.104t/ha,凋落层12.860t/ha。测定了12种可燃物的发热量。计算出不同林型的云南松林燃烧时潜在能量为:草类——云南松林177.57×10~(10)J/ha,灌木——云南松林154.56×10~(10)J/ha,常绿栎类——云南松林167.63×10~(10)J/ha,落叶栎类——云南松林158.74×10~(10)J/ha,旱冬瓜——云南松林170.57×10~(10)J/ha。     

文山松毛虫质型多角体病毒生物活性测定

测定病毒制剂的毒力,常用已知含量的病毒对敏感昆虫进行毒力的生物测定。我们用4℃保存一年的文山松毛虫质型多角体病毒,对6—7龄文山松毛虫进行生物活性测定的结果,LC_(50)为601.5×10~3PIB/ml,其95％置信限为354.1×10~3—102.2×10~4PIB/ml;1×10~8、1×10~7、1×10~6PIB/ml的LT_(50)分别为13.73,15.65,23.85天,其95％置信限分别为12.80—14.72,14.55—16.84,22.02—25.85天。     

山鹡鸰繁殖生态及雏鸟生长发育观察初报

于1999—2001年、2006—2008年的4—9月,对吉林省左家自然保护区内的山鹡鸰的繁殖生态及雏鸟生长发育进行观察和分析。结果表明,仅由雌鸟筑巢,筑巢期5~6 d,每窝产卵4~5枚,孵化期9~10 d,雏巢期10 d。体重呈"S"型增长,其逻辑斯谛方程为:m=10.83/〔1+e-0.8355(t-2.4689)〕。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.