雷竹笋“一早两高”栽培技术研究

对雷竹林分进行调整立竹密度与竹龄结构、除草松土、分期施肥、人工灌溉及冬季林地覆盖共５项技术措施，使雷竹笋获得高产、早产和高效益；８种不同覆盖物试验结果表明，比对照均提早始笋期４１ｄ，延长产笋期２４～９７ｄ，增加竹林笋平均产量３３．６ｔ／ｈｍ２，产值３４．２３万元／ｈｍ２；经综合评定，砻糠覆盖为最佳处理，与对照相比，笋产量、笋产值和纯收益分别增长２９．４％、２７０．３％和３１０．２％，投入与产出比为１：８。     

毛竹笋材两用林丰产结构的初步研究

对宜溧山区和宁镇丘陵区毛竹笋材两用林定点观测研究表明；（１）廊的林分结构是竹林丰产的关键。以产笋为主、产竹为辅的毛竹笋材两用林丰产结构为每公顷立竹２７００～３３０支，胸径〉９．０ｃｍ，年龄组成应保护１～３度竹，各龄级比例为１：１：１，笔直林产量（竹材、竹笋）高。以产竹为主、产笋为辅的毛竹材笋两用林丰产结构为每公立竹２７００～３６００支，胸径９．０ｃｍ，年龄组成应保留１～４度竹，各龄级比例为３：３：     

要重视解决毛竹山经营中的存在问题

溧阳市是江苏省传统的毛竹重点产区。现有毛竹３６００公顷，产竹量９５０．４万株（平均眉围２５．７厘米，平均枝下高３．９米），其中９２．８％分布在南部低山丘陵区；２．２％、５％分别分布在西南部丘陵区和北部低山丘陵区。毛竹是溧阳市的重要森林资源，占全市有林地的１４．２％，基本上位于大、中、小型水库及河流的上游，对于涵养水源，减少水土流失，保护生态环境起着举足轻重的作用。全市的毛竹林大部分形成大小年经营（大年留笋养竹，小年挖笋不养竹），其中逢双大年面积为２１３３公顷；逢单大年面积１０６６．７公顷；花年面…     

龙脑樟矮林基地施肥试验研究

龙脑樟矮林基地施肥试验表明：在适生的林地头几年施进口尿素的效果优于施进口复合肥；施肥后可明显提高基地鲜枝叶产量，从而提高龙脑产量和经济效益。每ｈｍ＾２施尿素３００ｋｇ，龙脑产量比对照增加１．５倍，需增加投资４０９０．５元，净增效益２０５９９．５元，净增投资与效益比为１：５；每公顷施尿素６００ｋｇ，龙脑产量比对照增加２．３倍，需增加投入６４９９．５元，净增３０４７５．５元，净增投资与效益比为１：４．     

广东省毛竹低产林改造技术与推广成效

广东省现有毛竹林１０ｈｍ＾２，８５％的为低产林，１９９２～１９９６年，通过办占示范，推广采用护笋养竹，合理砍伐，劈山除杂，松土施肥，竹林保护等技术措施，对５．５万ｈｍ＾２低产竹林成功地进行了改造，经测定验收，平均每年立竹增５５５株／ｈｍ＾２，胸径比增１．８ｃｍ，新增林价总值１．６９亿元，取得了明显的“三大效益”。     

吊丝单竹、云南甜竹、大头典竹出笋规律研究

对吊丝单竹、云南甜竹、大头典竹在相同抚育措施下出笋规律进行调查，结果表明：吊丝单竹出笋早、数量多，平均达37．05支／丛，但出笋总重量低，平均仅25．25／丛，云南甜竹、大头典竹出笋迟，但云南甜竹的笋总产量最高，达42．2／丛，大头典竹出笋产量次之，达40．1／丛。方差分析表明，吊丝单竹与云南甜竹、大头典竹间存在1％极显著水平。从出笋的月规律变化上看，7月下旬和8月中旬均是3种竹子出笋高峰期，而7月中旬和8月上旬均出现出笋低谷期，8月中旬过后均出现出笋逐渐减少趋势，吊丝单竹、大头典竹9月下旬产笋仅零星出现，云南甜竹出笋则在9月下旬仍达到一个小高潮，而后出笋逐渐停止。     

花岗岩立地杉木幼林施肥效应

两年试验得出，磷肥对花岗岩发育的黄红壤上杉木幼林生长有明显促进作用，钾肥作用次之，氮肥无明显生长效应；磷肥和氮、钾肥之间存在交互作用；施入氮或钾肥能导致幼林对磷肥需求的提高。２５ｋｇＰ２Ｏ５／ｈｍ２作基肥，２年后树高与地径增加２４％和３０％；每公顷施５０ｋｇＰ２Ｏ５与５０ｋｇＫ２Ｏ，２年树高与地径分别提高２３％和２４％。     

毛竹大径材培育的效益分析

本试验历时１０年，根据大径竹的生长特点，除从选地、养笋、择伐、密度、治虫等方面进行林分管理外，主要采取撩壕、深挖、施肥、清鞭、除蔸等技术措施，由表及里全面细致改良其深层次土壤的理化性质，充分提高肥力，为发大笋、长大竹创造优良的生长环境，取得显著成效。平均每度每ｈｍ２产新竹杆重５５ｔ，净产值２８８２５．５元，比对照增加２．５９倍和２．０２倍，１２ｃｍ以上的大径竹产量占增产总数的９３％；产量最高的林分，每度每ｈｍ２产新竹杆重７８ｔ，净产值４０５２５．５元，比对照增加４．０９倍和３．２５倍，创国内目前材用竹单产较高水平。     

花岗岩立地杉木幼林施肥效应

两年试验得出，磷肥对花岗岩发育的黄红壤上杉木幼林生长有明显促进作用，钾肥作用次之，氮肥无明显生长效应；磷肥和氮，钾肥之间存在在交互作用；施入氮或钾肥能导致幼林对磷肥需求的提高，２５ｋｇＰ２Ｏ５／ｈｍ＾２作基肥，２年后树高与地径增加２４％和３０％；每公顷施５０ｋｇＰ２Ｏ５与５０ｋｇＫ２Ｏ，２年树高与地径分别提高２３％和２４％。     

杉、松、桉幼林两年施肥效应研究*

杉木幼林Ｐ肥效应极显著，每公顷施２５ｋｇＰ２Ｏ５效应最好，树高增２４％，地径增３０％，ＰＫ、ＮＰ和ＮＰＫ效应也显著；湿地松幼林Ｐ肥效应也极显著，ＰＮ、ＰＫ效应更好，每公顷施５０ｋｇＮ、５０ｋｇＰ２Ｏ５树高增７４％，地径增６９％，施５０ｋｇＰ２Ｏ５、５０ｋｇＫ２Ｏ树高增７２％，地径增６５％；尾叶桉幼林·ＮＰＫ效应最显著，ＰＮ、ＰＫ效应也显著，ＮＫ增幅不大，每公顷施１００ｋｇＮ、１００ｋｇＰ２Ｏ５、５０ｋｇＫ２Ｏ，树高增２４５％，地径增２７９％，胸径增１１５６％。造林时应施足ＮＰＫ基肥。     

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.