林业苗圃化学除草技术

文章介绍了林业苗圃化学除草技术，包括针、阔叶树种苗木及不同苗期除草剂的种类、配方选择，作业时间，施药方法等。特别对带壳出土苗木和不带壳出土苗木对药剂的安全性研究有创新。通过系列应用试验证明，林业苗圃化学除草率可达90％以上，对苗木无不良影响，且有一定的促生作用，与人工除草相比．节省成本93％以上，产效期延长10—15d以上。     

化学除草技术在林业育苗中的应用试验

在马尾松大田育苗中，比较果尔、氟乐灵和除草醚的除草效果。其结果：3种除草剂都能有效杀除杂草，其中果尔和氟乐灵除草率达到85％；3种除草剂对苗木生长没有不良影响。采用化学除草可以节省育苗的除草成本80％。     

广西马尾松低成本造林技术研究

经过对7年生不同造林方式的幼林生长状况分析可知，5种植造林方式幼林生长差异显著，“炼山＋人工铲草”造林方式效果最好，使用除草剂会抑制苗木生长，不炼山同样因杂草繁茂抑制苗木生长，7年生时最佳处理C比最差处理E的胸径、树高、蓄积、保存率分别高37．9％、30．0％、301．5％、82．5％。不同造成林方式对杂灌木生长影响不一样。造林当年除草保苗管理至关重要。     

除草剂在油松育苗中的应用试验

在油松育苗中应用除草剂灭草效果明显,当苗木出土6～8周以后,用除草醚（1．1g·m^-2）、拿捕净（0．05mL·m^-2）＋果尔（0．05mL·m^-2）、除草醚（0．55g·m^-2）＋果尔（0．05mL·m^-2）分别进行土壤喷施处理,除草率达到96．8％、98％、99％。一定剂量的除草剂混用可增加有效期和除草率。施用除草剂对苗木不同时期生长无影响,且较为经济,每年可节约除草费用900～1200元·hm^-2。     

杉松育苗应用果尔化学除草试验研究

通过应用不同剂量的果尔（ＧＯＡＬ）在杉苗于播后苗前、苗期，松苗（芽苗切根移栽）苗期的除草试验，认为杉木育苗于播后出苗前商品用量为７５０ｍｌ／ｈｍ２，除草效果可达９８％，苗木出土不受影响。苗期商品用量为６００～７５０ｍｌ／ｈｍ２，除草效果可达９５％以上。松类育苗苗期商品用量为９００ｍｌ／ｈｍ２，除草效果可达９５％以上。杉松苗期施用果尔对苗木生长无不良影响，与人工除草相比，降低费用８９．３％。     

杨树育苗地化学除草技术

为了在苗圃普及使用除草剂进行化学除草，进行了小面积的化学除草试验，试验结果表明：处理5（果尔＋高效盖草能）、处理6（果尔＋精禾草克）除草效果好，除草率分别达到93．7％和91．4％．可以在生产中使用，如果结合土壤处理，可防除苗木整个生育期的杂草，从而降低生产成本。     

乙草胺除草剂圃地使用技术

苗圃杂草生长快、种类多、数量大,人工除草不仅劳动强度大、成本高,而且还易使幼苗根系松动,妨碍苗木正常生长。苗圃地化学除草,油茶、板栗等苗圃地试验,每亩施乙草胺60～75毫升,对苗木安全,除草效果达95％以上,持效期30～60天。比人工除草,省工85％以上,节约费用87％以上,而且施药操作简单,不污染环境。     

优良品种油茶栽培技术

对优良品种油荼杂优闽1进行引种栽培，林地套种大豆、木薯、地瓜等农作物，能促进油茶幼林生长。结果表明，油茶苗木栽培之后，苗木成活率可达98．6％。油茶林木经过3年的经营管理，抚育除草、施肥、病虫害防治，树木生长迅速，林木生长良好。3年的油茶树木平均树高1．05m，冠幅1．22m。     

化学除草剂在苗圃中的应用研究

选用正确的化学除草剂在苗圃播后芽前和苗期使用除草效果显著．除草率达90％以上．同时对种子发芽、出苗、苗生长安全。采用化学除草比人工除草减少除草用工59．1％～66．7％．降低除草成本46．8％～62．9％。     

除草醚与阿特拉津混用除草试验

通过本试验表明：除草醚和阿特拉津混合使用，不但对苗木生长无害，而且还能提高除草效果，降低除草成本２０％，克服了长期使用除草醚造成的弊端。     

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.