滨海盐渍土防护林树种选择的研究

对北方沿海泥质海岸不同类型盐碱地进行造林树种选择试验，并以NaCI溶液处理结合沙培盆栽，测定树木生长指标及生理生化指标。通过综合判定，筛选出柽柳、沙枣、小胡23杨、绒毛白蜡、刺槐、群众杨、抗虫榆、白城杨、中林46号杨、辽宁杨等适合重、中、轻及苏打盐渍土类型的盐碱地造林树种。     

辽宁滨海盐碱地土壤改良及造林技术研究

试验于１９８９年至１９９５年设置在辽宁渤海湾泥质海岸的轻、中、重盐碱土和苏打盐渍土４块试验地上。在盘锦市大洼县拦海防潮堤含盐量为１０ｇ／ｋｇ的重盐土上筛选柽柳为先锋树种，五年后土壤盐分下降到４ｇ／ｋｇ左右。凌海市建业乡苏打盐渍土上沙枣可为抗碱耐涝先锋树种。在中盐碱地，群众杨、１０９柳与紫穗槐混交树高比纯林分别提高３％、１０％；胸径提高１２％、２５％。轻盐碱地可栽种群众杨、绒毛白蜡、１０９柳、刺槐，建立速生丰产林基地。     

滨海苏打盐渍土的改良与造林技术研究

根据土壤分布在河流入海平原处及土壤含盐量０．２％－０．３％，ＰＨ８．５－１０．０、碱化度５０％－６０％，总碱度０．８－１．０，总碱度占阴离子之和的４０％左右等指标，确定滨海苏打盐渍土。改一的苏打盐渍 土选择林树种的顺序：沙枣，小胡杨，群众杨，绒毛白蜡。     

苏打盐碱地杨树品种选育试验

杨树是国内外广泛采用的造林树种,具有生长快,适应性强的特点.在我省西部苏打盐碱地区用来营造用材林、农田防护林、水土保持林及四旁绿化,杨树也是主要造林绿化树种.但是,杨树品种很多,特性各异,什么品种适宜苏打盐碱地生长,是造林中值得注意的问题.为此,我场从一九六七年开始进行苏打盐碱地杨树品种的选育试验.一九七三年又从省内外引进一批杨树品种,在苗圃里观测生育状况和抗性.将少数品种的     

盐碱地造林树种及其特性

盐碱地造林树种及其特性贾福平，贾翠萍盐碱土、盐渍土、盐碱地、盐渍化土壤等是泛指含盐、碱、硝等有害盐类的低产土壤的通称，它包括盐土及盐化土壤、碱土及碱化土壤各种土类。我国有近四亿亩盐碱地，这一巨大的土地资源，有很大的开发利用潜力。因此，利用和改良盐碱地...     

抗盐碱中华红叶杨在天津滨海新区栽植试验

2004-2008年在天津滨海新区低、中、重盐碱地试验种植抗盐碱中华红叶杨。结果表明:抗盐碱中华红叶杨确实是盐碱地绿化好树种。     

盐碱地影响林木生长及抽干的研究

通过多年试验得知,河北省盐碱地区,除有害盐分障碍林木生长以外,土壤粘重、透气性差等,也是影响林木生长的主要原因,有的导致抽干,通过整地等可改善土壤物理性质,加速林木生长,减少抽干;另外,盐碱土脱盐之后土壤产生碱化现象,碱化土对林木破坏性很大,可以选择抗碱性强的树种、地面盖沙和用紫穗槐与乔木混交造林等措施,减轻碱化,促进林木生长。     

盐碱地育苗技术

盐碱地造林是改良利用盐碱地的重要措施之一。在盐碱地上造林 ,选用盐碱地上育出的苗木适应性强 ,对提高造林成活率和苗木生长状况均有良好的作用 ,而且有时由于圃地选择的限制也须在盐碱地育苗。由于土壤含盐量的影响 ,盐碱地育苗有一定的难度 ,因此盐碱地育苗的关键技术就是防盐保苗。1　树种选择不同树种的抗盐能力差异很大 ,同一树种在不同的生长发育期抗盐能力也不同。一般幼苗期抗盐性较差 ,成苗较强 ,随着年龄的增加 ,抗盐性继续增强 ,但到年老阶段又较差。一般情况下 ,土壤含盐量在 0 .1%以下能正常生长的树种有杨、泡桐、女贞子等 …     

绒毛白蜡等树种耐盐力研究

对绒毛白蜡等５个滨海盐碱地引种的树种幼苗舅栽耐盐性试验,选取光合速率、叶绿素含量、细胞膜透性、丙二醛含量、游离脯氨酸含量５个耐盐性生理指标,对树处的耐直是进行了探讨,并结合以往室内与野外工作成果,采用综合打分法比较各树种的相对耐盐力,表明,绒毛白蜡耐力最中,其次为小胡２３号杨、群众杨、白城５号杨、中林４６号杨。     

泥质海岸防护林树种选择及造林工程技术研究

通过造林试验及对树种生理指标的测定，进行滨海盐碱地适地适树及配套工程技术探讨。结果表明：重盐土以柽柳为先锋树种，覆地膜可促进成活；苏打盐渍土以沙枣为优良改土树种，铺山皮土及压乱稻草有利于树木存活、生长；中盐土上，绒毛白蜡为耐盐的珍贵用材树种，掺沙可降低土壤盐分，能有效地提高苗期的造林成活率和保存率。     

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.