利用Ⅰ—69杨树伐根萌芽更新与植苗造林的效果

对３ａ生Ｉ－６９杨树伐根蓝芽更新与植苗造林的成活率和生长量的连续观测结果表明，在幼龄期，伐根萌芽更新比植苗造林用工少，成活率高，生长量大，而且可以节省大量的造林和抚育管扩经费，经济效益显著。     

浅议杨树伐根萌芽更新造林

近代，由于森林资源日趋枯竭，木材供应紧张，生态平衡失调，为了解决这些问题，杨树在我国及世界各国的林业上，愈来愈占有重要位置。我国北部及中部大面积的防风固沙林和农田防护林其主要树种是杨树，东北原始林区森林采伐后更新的先锋树种也是杨、桦林。近年来兴起的大面积杨树人工用材林，已成为解决木材短缺的重要措施之一。     

采用伐根萌芽法进行杨树更新初报

本文介绍一种新的杨树更新方法一伐根萌芽更新.以往用植苗法、根蘖法成本高、工作量大、休闲时间长、管理困难.水分条件差时成活率低.而采用伐根萌芽法更新克服了上述缺点,并提高了林木生长速度,高生长为根蘖的172%,胸径生长为根蘖的163%.     

短伐桉萌芽更新造林技术

在早期的短伐桉林中进行萌芽更新造林试验 ,采取地块选择、除萌作业、除草与施肥等萌芽促进更新技术措施后 ,取得了较好效果。 4a生以上伐桩萌发率比较稳定 ,达 85 %～ 95 % ,而且萌芽林早期生长优于实生林。该项技术为今后桉树萌芽更新造林提供了参考     

杨树伐根嫁接及萌蘖更新技术

为满足生产中快速成林、减少水土流失等实际需求,解决杨树低产林改造和防护林更新的技术问题,该文详细阐述了伐根嫁接、萌芽更新和根蘖更新的技术细节,介绍了杨树幼林病虫害防治技术,总结出一套行之有效的杨树伐根嫁接及萌蘖更新技术。     

杨树短轮伐期萌芽更新造林与插干造林对比试验

为了探索洞庭湖区杨树不同更新模式的可行性,对XL-90杨萌芽更新造林与插干造林的林分生长及经济效益进行对比研究。萌芽更新造林每个伐桩保留2个萌条,成林后实际密度1 170株·hm^-2;插干造林株行距为4 m×3 m,平均株数840株·hm^-2。结果表明,更新造林4 a,萌芽更新的胸径、树高、单株材积和单位蓄积依次为17.47 cm、14.62 m、0.143 5 m³和167.93 m³·hm^-2,分别比插干造林高6%、2%、14%和59%,单位面积利润高达26 890元·hm^-2,是插干造林的3倍。综上所述,XL-90杨在洞庭湖区适宜短轮伐期萌芽更新造林。     

杨树伐根嫁接更新造林技术

杨树伐根嫁接更新造林技术是北京市林业科技推广站试验研究取得的成果,几年来,在全市应用推广该项技术更新造林面积上千亩。该项技术经有关专家验收,获得了市农业技术推广二等奖。     

L35杨与I-69杨造林胸径生长量对比试验

对泗洪县五里江农场和青阳镇江圩村L35杨与I-69杨对比试验造林地进行生长量测定结果表明,五里江农场7年生的L35杨胸径生长量比I-69杨平均提高33.14%;江圩村9年生的L35杨胸径生长量比I-69杨平均提高32.42%.表明引进的L35杨胸径生长量明显地高于I-69杨.     

巨尾桉萌芽更新最佳伐根高度的确定

不同伐根高度对巨尾桉萌芽更新的影响研究表明：伐根高度在-5～20cm范围内，对萌芽能力、萌芽林生长及林分生物量的影响差异不显著；但降低伐根高度，能促进新根系形成，有利于继代经营。综合考虑各种因素，伐根高度以5cm为宜。巨尾桉萌芽林长势与一人林分相当，但营林成本明显下降。     

I－69杨胶合板用材林密度及立地效应研究

以胶合板材为培育目标，研究了Ｉ－６９杨胶合板用材林平均单株材积与造林密度和优势高的关系。分别不同林龄（６～１１ａ）建立了平均单株材积与造林密度及优势高的模型Ｖ＝ａ０Ｎａ１Ｈａ２０，通过生产弹性分析、边际产量分析，研究了密度效应及优势高效应，计算出了不同林龄林分的生产弹性值和边际产量，并且根据立地及密度效应模型研究了造林密度、林龄、立地指数对林分蓄积的影响。认为在长江中、下游地区营造Ｉ－６９杨胶合板用材林密度应适当减小，选择造林地时以立地指数大于等于２０ｍ林地为佳。     

I-69杨胶合板用材林产量及生物量结构

采用 2 90块标准地调查资料 ,分析了 I- 6 9杨胶合板用材林的产量和生物量结构随立地指数和造林密度的变化规律。胶合板材产量随立地指数的增大而增大 ,且占总产量的百分比在立地指数为 14、16、18m时 ,随造林密度的增大而减小 ;当立地指数为 2 0 m和 2 2 m时 ,保持稳定在 50 %左右。磨木浆材和化学浆材产量随立地指数和密度的增大而增加。在立地指数为 14、16、18m时磨木浆材产量占总蓄积量的百分比和化学浆材产量占总蓄积的百分比均随造林密度的增大而增大 ;在立地指数为 2 0、2 2 m时则受造林密度的影响不大 ,分别保持在 30 %和 2 0 %左右。林分和单株的树干、树枝、树皮生物量组成比例均随立地指数、造林密度的变化无明显的差异。营造 I- 6 9杨胶合板用材林时选择立地指数 2 0、2 2 m的地段以及用造林密度 156 (8m× 8m)、2 0 4 (7m× 7m )株·hm-2 为最佳。     

I－69杨胶合板用材林密度及立地效应研究

以胶合板材为培育目标,研究了I-69杨胶合板用材林平均单株材积与造林密度和优势高的关系。分别不同林龄(6～11a)建立了平均单株材积与造林密度及优势高的模型V=a₀N^a₁ H₀^a₂,通过生产弹性分析、边际产量分析,研究了密度效应及优势高效应,计算出了不同林龄林分的生产弹性值和边际产量,并且根据立地及密度效应模型研究了造林密度、林龄、立地指数对林分蓄积的影响。认为在长江中、下游地区营造I-69杨胶合板用材林密度应适当减小,选择造林地时以立地指数大于等于20m林地为佳。     

Recovery of canopy trees and root collar sprout growth in response to changes in the condition of the parent tree after a fire in a cool-temperate forest

The relationship between the recovery of canopy trees after fire and root collar sprout dynamics was investigated during 1998–2000 in a secondary cool-temperate broad-leaved forest consisting of Quercus mongolica var. grosseserrata and Betula platyphylla var. japonica trees, in northern Hokkaido, Japan, which burned in April 1998. All of the Betula trees that were severely damaged, two-thirds of those slightly damaged, and half of those intact in 1998, died within three growing seasons after the fire. By contrast, half of the Quercus trees that were slightly damaged and half of those severely damaged recovered their foliage, and no slightly damaged or intact trees died during the three growing seasons after the fire. Many Betula trees developed several fruiting bodies of wood-destroying fungi on their stems, irrespective of damage severity. Fungi also infected some of the surviving Quercus, although the crowns tended to recover. Although many sprouting Betula were observed in 1998, the number of sprouts declined rapidly over the study period. Multiple regression analyses showed that the survival and growth of Betula sprouts were positively influenced by the number of sprouts in 1998, damage severity in 1998, and the degree of recover or decline during the study period, and were negatively influenced by parent tree size. On the other hand, a few sprouts of Quercus remained alive. Quercus remained dominant and the dominance of Betula was rapidly reduced after the fire. However, many Betula sprouts remained alive. Stand structure will change drastically for the time being.     

Transgenic poplar with enhanced growth by introduction of the ugt and acb genes

The transgenic poplar (Populus tremula L.) was obtained by transfer of the ugt and acb genes via triparental mating, which was employed to deliver large fragments of TDNA as a cluster. Freshly harvested seeds of local poplar were placed on MS agar medium and plantlets were obtained. After 1 year of subcultivation, plantlets were infected with a transconjugant of triparental mating with target ugt and acb genes into axillary buds. The transformed sprouts so obtained were cut and subcultivated on agar medium with an addition of 0.6 mg/l indole-3-butyric acid as an auxin source. The transformed sprouts showed GUS activity and resistance to gentamycin and kanamycin. The integrity of the target ugt and acb genes into poplar genome was demonstrated via PCR and Southern blot hybridisation. The transgenic poplar plants revealed a higher growth energy, corresponding to a higher content of IAA as opposed to control plants. Both transgenic and non-transformed plants were potted into soil for outdoor acclimatisation and subsequently transferred to earth in beds. Growing outside during 3 years, the transgenic poplar demonstrated a higher growth rate with fast bud and branch development.     

贵州息烽林场森林火险的数量生态学分析及区划

对贵州息烽林场６７个森林火险调查样方进行ＰＣＡ、ＣＯＡ排序和模糊综合评判表明：海拔影响林场森林可燃物分布状况和土壤含水量;林场森林火险以危险和较危险两级为主,影响的主要因素是海拔、森林可燃物类型和火源状况;森林可燃物分为非林分型可燃物,林相整齐的中幼林型可燃物和近成过熟林型可燃物、林相不整齐林分型可燃物;林场森林型可燃物和近成熟林型可燃物、林相不整齐林分型可燃;林场森林火险区划为４级区域,即很危险区（Ⅰ）、危险区（Ⅱ）、较危险区（Ⅲ）和略危险区（Ⅳ）。     

The effect of release cutting on the growth and external quality of the dominant trees in a Pinus sylvestris stand established by spot sowing

The effect of the number of Pinus sylvestris trees in seed spots on the growth and external quality of the dominant trees was studied. The trees were monitored during the period between release cutting and the first commercial thinning. The treatments were one, two and four of the tallest seedlings retained per seed spot, and a control. The mean height of the dominant trees was highest in the one‐tree and two‐tree treatments. Diameter at breast height (DBH) increased with increasing spacing. On average, the stump diameter was 1.5–4.7 cm greater in the one‐tree treatment than in the control. Slenderness (height/DBH) was highest in the control treatments. The average living crown limit of the dominant trees was 4.6 m, and was at its highest in the two‐tree treatment. The results indicate that the competition in seed spots decreases the height growth of the dominant trees.     

生态立省与生态文明建设

新世纪初,贵州省作出“生态立省”的重大战略举措,这是一项复杂的系统工程,是以可持续发展为核心,以人与自然和谐为主线,以发展生态经济、保护生态环境、培育生态文化为主要内容,全面促进经济社会与人口、资源和环境的协调发展。在“生态立省”建设中要注重和培养新发展意识的文明观——生态文明观,建立文明健康的生态文化体系,包括生态环境、生态意识和生态制度。生态文明是人类社会文明史上的一种新的文明形式,是当代环境与发展形势下物质文明和精神文明建设的生态化形式。     

发展沼气在我省实施“生态立省”战略中的地位、作用以及问题思考

本文介绍了我省农村沼气建设的基本情况,阐明了沼气建设在我省农村小康社会建设中发挥的作用及战略地位,对目前存在的问题进行了论述并提出了相应的对策。     

地震滑坡区覆盖生态毯对土壤湿度和养分的影响

为了研究生态毯覆盖对土壤湿度和养分的影响,首次将生态毯应用于地震滑坡区砾石泥沙堆积区和泥沙堆积区。结果表明:铺设生态毯的土壤含水量均高于裸地的;各层的土壤水分含量随干旱日数的增加呈下降的趋势,生态毯的下降趋势较为平稳;保水效果为椰纤维生态毯秸秆+椰纤维生态毯秸秆生态毯裸地。覆盖生态毯可以提高土壤有机质含量和p H值;土壤速效N、P、K和全N、全P、全K的含量也有一定程度的提高。铺设生态毯能有效固定地震滑坡区的砾石泥沙,改善土壤的水热条件,进而增加根系、微生物的活动和植被有机体的积累,促进枯落物的分解,逐步提高土壤中的养分含量。