提高材积表精度的一种有效方法

本文用多项式方程Ｖ＝ｍΣｉ＝０ａｉＤｉ的图形拟合材积Ｖ关于胸径Ｄ的回归方程Ｖ＝ｆ（Ｄ）的图形，并通过加大次数ｍ的方法不断减小拟合误差，从而使得用Ｖ＝ｍΣｉ＝０ａｉＤｉ编制的材积表的度比目前通常采用的一些方程编制的材积表的精度高出许多。当多项式方程的次数ｍ＝Ｂ时，材积表的精度就已经由过去的０．９５４１提高到了０．９８７３。     

都江堰杉木,柳杉,水杉地径一元材积表的编制

在都江堰市收集的杉木、柳杉、水杉地径测定样木共２３１９株，采用６个数学模型，分别研究了三树种树干基部三个不同部位直径（Ｄ０．００、Ｄ０．０５、Ｄ０．１０）与胸径（Ｄ１．３）的关系。研究结果表明：杉木、柳杉，水杉地径──胸径最佳相关方程分别为Ｄ１．３＝－０．１９７２２６２＋０．８６６４８６７Ｄ０．１０＋０．００００７０６Ｄ、Ｄ１．３＝－０．２８８０３６＋０．７８８７７２０Ｄ０．１０＋０．００２４９５４Ｄ．１０、Ｄ１．３＝－１．０７７２３２３＋０．８７１７２１４Ｄ０．１０；－０．０００３３００Ｄ．１０。并通过建立三树种胸径与材积相关方程，编制了都江堰市杉木、柳杉、水杉地径一元材积表。     

南方型杨树二元材积方程的拟合

该文通过５３０林杨树立木调查资料，分别采用８种模型进行回归拟合，经过误差比较与精度分析，选出Ｖ＋Ｃ１＋Ｃ２Ｄ＋Ｃ３Ｄ２＋Ｃ４ＤＨ＋Ｃ５Ｄ３Ｈ＋Ｃ６Ｈ作为杨树二元立木材积方程模型，供编制立木材积表与科研生产中使用。     

杉木人工林二元立木材积动态模型的研究

通过对多种二元立木材积方程的拟合和比较，以动态模型Ｖ＝ａＤｂ＋ｃ（Ｄ＋２．３Ｈ）Ｈｄ＋ｅ（Ｄ＋２．３Ｈ）拟合杉木人工林二元立木材积效果最佳。     

大叶相思材积和生物量表的编制*

为探索大叶相思生物量和材积表编制方法，本文根据薪材林研究中收集的一些样木资料，选用Ｗ（Ｖ）１＝ａＤｂ（下称１式）和Ｗ（Ｖ）２＝ａ（Ｄ２Ｈ）ｂ（下称２式）两种模型，经回归分析推导出两组干、枝、叶和总生物量及材积的回归方程。对两组回归方程分析比较结果，１式自变量Ｄ容易测定且精度高，故以１式作为编表模式，编制成材积表和各组分的生物量表。     

柳杉单株木材种出材率表编制的研究

在闽东地区收集柳杉人工林样木材料，选择一致性削度方程ｄ＾２＝４／πＶＬ＾Ｂ－１．Ｂ／Ｈ＾Ｂ和一致性材积比方程Ｖ／Ｖ＝１－（１－ｈ／ｎ）＾Ｂ作为基础模型，结合累积商品材长度比和树皮率的回归方程，编制了柳杉人工林单株木二元材种出材率表，检验证明，该表精度符合要求，可在生产中应用 。     

思茅松人工林二元材积模型的编制

现地收集思茅，西双版纳等两个地区１２个县的思茅松人工林标准地１４６块，标准木５８０株。采用线性，非线性模型求出解山本式Ｖ＝αＤ＾ｂＨ＾ｃ中的三参数ａ，ｂ，ｃ，通过精度检验，选取各模型中最佳模型Ｖ＝０．００００６４０５３Ｄ＾１．９５７１６１８３Ｈ＾０．８７１６３５６６）作为思茅松人工林的二元材积模型，其系统偏差为－０．００２２％，剩余标准差为０．０２４，剩余方差和０．３２３，复相关系数为０．９９２。     

柳杉单株木材种出材率表编制的研究

在闽东地区收集柳杉人工林样木材料，选择一致性削度方程ｄ２＝４πＶＬＢ－１·Ｂ／ＨＢ和一致性材积比方程ＶＶ＝１－（１－ｈп）Ｂ作为基础模型，结合累积商品材长度比和树皮率的回归方程，编制了柳杉人工林单株木二元材种出材率表，检验证明，该表精度符合要求，可在生产中应用。     

马尾松采脂林胸径破坏致材积测量误差的修正

经进行调查和试验表明，用马尾松采脂林被割胸径的测量值和树高，查符合精度要求的二元材积表，所得材积相对误差高达３０％以上．为此，在分析修正误差可能途径的基础上，研究了干基不同高度直径与胸径的相关关系，并建立了相关模型．结果表明，距地面１０ｃｍ，１５ｃｍ和２０ｃｍ处的干基直径与胸径的关系极为紧密．根据Ｄ１．３—Ｄ０．１０，Ｄ１．３—Ｄ０．１５和Ｄ１．３—Ｄ０．２０相关模型修正的胸径测量材积，在可靠性为９５％时，精度均可达到９７％以上．     

乔木树种望高比的研究

望高比（Ｂ）是胸有率（ｑ２）和树干形状指数（ｒ）的函数，是一个比望调理我为的千形指标。绝大多数乔木树种的望高比在０．６４－０．７４之间。由望高比导出的普雷勒材积式为Ｖ－２Ｂ／３ｇ（Ｈ＋１）＝ｆｐｇ（Ｈ＋１），而绝大多数树种的普雷斯勒形数ｆｐ在０．４３－０４９之间，经７０株马尾松的木验证，其材积平均误差仅＋０．１％。普雷斯勒形数与树种之间的关系，有待进一步探讨。     

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.