相对冠长在杉木人工林立木材积测定中的应用

形数随相对冠长增大而减小,两者之间存在紧密的相关关系,把相对冠长作为辅助因子,配合树高建立形数预测模型,按立木材积三要素测定材积,可在不测上部直径的情况下,有效地提高立木材积的测定精度。     

三种阔叶树枝桠材应拉木和对应木的解剖特征及材性的研究

通过对３ 种阔叶树 （米槠、木荷、拟赤杨） 枝桠材的应拉木和对应木的解剖特征及材性的观察和试验,并与正常干材比较, 结果表明： 它们在纤维、导管的长度、宽度、纤维次生壁 Ｓ２ 层纤丝角、化学成分、纤维素相对结晶度、密度、吸水性、涨缩性以及顺纹抗压强度、抗弯强度及其弹性模量等都存在显著差异。     

Friction velocity u* and roughness length Z_o of atmospheric surface boundary layer in sparse-tree land

lntroductionProtectionforestisoneofthemostfrequentlyusedrneasurestoprotectcropsfromstrangewindandtoreducesoiIevaporationandsoiIerosion.ProtectionforestinfarmIandcanbeclassifiedinthreekinds(Cao1983)tonekindissheIterbeIts.SecondissparsetreeinfarmIand,generaIlycaIIedagroforestinChina.ThiskindincludesreguIarlyandrandomIyplantedorn8turalIygrowingtreesinfarmingarea.ThethirdiscIusteroftrees.Thesethreekindsofforestexisttogetherinf8rmIandarea.ThesheIter-beltsaregeneralandtheprotectiveeffectanda…     

Effects of perennial fodder crops on soil structure in agricultural headlands

In agricultural headlands, rooting and yield of crops may be limited because of soil‐structure changes as a consequence of multiple passes of turning machinery. We hypothesized that perennial forage crops can substantially alter soil structure in agricultural headlands. On one experimental field and two commercial farms on Haplic Luvisols from respectively loess and sandy loess in the Lower Rhine Bay (Germany), we investigated how 4 y of continuously grown grass/clover or alfalfa affected soil structure and the performance of subsequent spring wheat. Compared with a crop rotation with annual plowing to 30 cm soil depth, perennial forage crops led to increased soil C content (+1.3% to +22.8%) and N content (+4.2% to +15.1%), higher densities of medium and coarse biopores at a depth of 35 cm, more large water‐stable soil macroaggregates, higher biomass and abundance of anecic earthworms, and higher grain yield and grain protein content of spring wheat grown as the following crop. Root‐length density of spring wheat in the subsoil was not affected by the preceding perennial fodder crops in two of the three field trials. We concluded that besides increasing N input to the soil, perennial cropping of grass/clover or alfalfa has effects on soil structure that may substantially reduce yield losses in agricultural headlands.     

Effect of mulching on soil and plant water status, and the growth and yield of wheat (Triticum aestivum L.) in a semi-arid environment

Mulching is one of the important agronomic practices in conserving the soil moisture and modifying the soil physical environment. Wheat, the second most important cereal crop in India, is sensitive to soil moisture stress. Field experiments were conducted during winter seasons of 2004-2005 and 2005-2006 in a sandy loam soil to evaluate the soil and plant water status in wheat under synthetic (transparent and black polyethylene) and organic (rice husk) mulches with limited irrigation and compared with adequate irrigation with no mulch (conventional practices by the farmers). Though all the mulch treatments improved the soil moisture status, rice husk was found to be superior in maintaining optimum soil moisture condition for crop use. The residual soil moisture was also minimum, indicating effective utilization of moisture by the crop under RH. The plant water status, as evaluated by relative water content and leaf water potential were favourable under RH. Specific leaf weight, root length density and dry biomass were also greater in this treatment. Optimum soil and canopy thermal environment of wheat with limited fluctuations were observed under RH, even during dry periods. This produced comparable yield with less water use, enhancing the water use efficiency. Therefore, it may be concluded that under limited irrigation condition, RH mulching will be beneficial for wheat as it is able to maintain better soil and plant water status, leading to higher grain yield and enhanced water use efficiency.     

无锡森林文化的继承与发展

从社会文明发展史角度,揭示了无锡森林文化优良传统,并根据新时期创建生态文明社会要求,提出森林文化如何继续与发展。       

城市森林建设优良景观树种——耐寒细柄阿丁枫的培育

细柄阿丁枫树形高大,侧枝发达;枝繁叶茂,观赏价值高,不仅具有较高森林水源涵养功能、改良林地土壤、提高肥力作用,改善林分景观结构及防火功能,而且具有潜在抗寒适应性。经北亚热带南京地区自然极端低温-7℃~8℃下选出的耐寒植株,3年生幼树未见受冻,显示出较强的抗寒力。经无性杆插繁殖培育,3年生绿化苗木可达3.5m,胸径4,并开花结实;可在城市园林绿化建设和城市森林建设构建景观防火型模式中应用。       

漳州市居住区植物景观设计

根据漳州市居住区现状,强调居住区植物景观设计应重视植物景观的生态、保健和文化功能等,并提出对策。       

屋顶花园的建造与养护——以北京嘉里中心商务区为例

屋顶花园可以节约能源;延长建筑物寿命;减少雨水流失量;减轻热岛效应等。文章通过嘉里中心屋顶花园的建植以及养护,探讨了适宜屋顶花园栽植的植物种。       

张家港市园林绿地遥感调查

文章探讨了利用遥感技术对张家港市城市绿地遥感调查的应用方法,并为规划提供了科学依据。