Response of <Emphasis Type="Italic">Pinus pseudostrobus</Emphasis> Lindl. to fertile growing medium and tephra-layer depth under greenhouse conditions

Major disturbances that remove vegetation cover create conditions that differ greatly from those in adjacent forests. In volcanic areas, tephra deposition can be a major disturbance that eliminates vegetation cover and creates a barrier for plant establishment. The eruption of the Paricutín volcano, in Michoacán, México, from 1943 to 1952, created large tephra deposits adjacent to forest stands. Many of these deposits still lack native vegetation and understanding of the limiting factors for establishment of native tree species is necessary to restore these areas. Pinus pseudostrobus early growth in response to the amount of fertile growing medium on top of a variable-depth tephra layer was evaluated in a greenhouse experiment. Increasing amounts of fertile growing medium increased height of 28-week-old plants (no growing medium = 5.5 cm tall ±1.8 cm, 3 cm of growing medium = 21.2 ± 4.6 cm and 6 cm of growing medium 24.8 ± 4.4 cm). Other variables showed the same trend (diameter, number of fascicles, belowground biomass and aboveground biomass). Our results suggest that P. pseudostrobus establishment in tephra covered areas will depend on the accumulation of a fertile layer of more than 3 cm in thickness.     

永春县马尾松摘梢造林试验效果分析

通过对马尾松摘梢与无摘梢造林成活率、胸径生长、高生长情况进行调查分析,结果表明:摘梢造林平均成活率比无摘梢高出28%,摘梢造林与无摘梢造林对马尾松的胸径、树高生长影响均无显著差异,坡位对马尾松的胸径、树高生长影响极显著差异。     

FT-IR study of the changes in carbohydrate chemistry of three New Jersey pine barrens leaf litters during simulated control burning

Low intensity control burns are a standard fuel reduction management tool used in pine barrens ecosystems. Periodic disturbances through fire can be an important influence on the cycling of nutrients within the ecosystem. Previous studies have shown that the inorganic chemistry of leaf litter residues differs with increasing temperature. Our study compared chemical changes in white oak (Quercus alba), pitch pine (Pinus rigida) and black huckleberry (Gaylussacia baccata), characteristic of the New Jersey pine barrens, during thermal decomposition using FT-IR spectroscopy. Three replicates of senescent leaf material were ground and separately heated for 2 h at: 100, 200, 300, 400 and 550 °C. These temperatures are representative of the range seen in fuel reducing prescribed burns in the pine barrens. Unburned litter of each species was used as a control. An optimization process using varying amounts of KBr and oak litter was performed to develop favorable FT-IR spectral conditions for a sample to KBr ratio of 0.75%. Chemometric analysis of the FT-IR spectra using principal component analysis (PCA) was used to analyze the changes in carbohydrate chemistry of each litter plant species (leaf litter species) at each temperature. In general, it appears that there is clear separation of leaf litter species at the different combustion temperatures. Infrared spectroscopy illustrated that all three species shared wavenumbers characteristic of the primary components of leaves such as cellulose, lignin and hemicellulose. Results from the PCA indicated separation of litter species and species by combustion temperature. PC axis 1 corresponds to the effects of temperature on leaf litter species and PC axis 2 separates the leaf litter species. At the low temperatures (control-200 °C), oak, pine and huckleberry litter species separated from each other. Wavenumbers that contributed to the separation of species at low temperatures belonged to functional group stretching frequencies of outer surface waxes, basic sugars, fatty acids and aldehydes. It appears that oak had more IR bands specific to suberin content. Convergence of these species occurs at 300 °C. Complexity of chemical composition decreases at this particular temperature as is shown by the decrease in wavenumber richness when compared to litters at low and high temperatures. Oak, pine and huckleberry had similar IR spectra showing bands belonging to outer surface wax content, pectin, lignin and hemicellulose. With increasing temperatures (400-550 °C), differences between litter species increased slightly. Plant material was reduced to similar composition due to thermal decomposition, which consisted of inorganic materials such as carbonate, phosphate and sulfate ions and possible fused aromatics.     

阔叶红松林及其次生杨桦林优势树种间氮素营养关系的研究

为了探讨阔叶红松林演替与原始阔叶红松林稳定性中存在的Ｎ素机制作用,１９９１年７月,在长白山（北坡）自然保护区（海拔７４０ｍ）,应用近几年建立的化学和生物化学分析方法,通过分析土壤Ｎ素及有效形态ＮＯ３－Ｎ、ＮＨ４－Ｎ的供应和林木的Ｎ素吸收利用状况,对原始阔叶红松林及破坏后形成的两个不同龄级的杨桦林中优热树种林木的Ｎ素营养状况及树种间Ｎ素营养关系进行了研究。结果表明：１．各样地土壤中Ｎ素营养状况及树种     

国外引种松树松脂化学组成的特征

Ｗ．Ｂ．Ｃｒｉｔｃｈｆｉｅｌｄ和Ｅ．Ｌ．Ｌｉｔｔｌｅ,Ｊｒ．将油松组松树分成６个亚组。本文采用ＧＣ、ＧＣ－ＭＳ方法对分属４个亚组的１６种国外引种松树松脂化学组成的特征进行研究,发现每一个亚组的松脂各有其特点。马尾松、黄山松等国内松树树种与黑松、琉球松、同属一个亚组,其松脂的化学特征比较相似;而与湿地松、火炬松等另一亚组松脂则有较大区别,说明亚组的划分有利于松树的化学分类。不同地理变种的加勒比松松脂     

A Screening Trial of 28 Species Conducted on Non-Saline and Saline Soils in Dry Tropical Northeast Australia

Abstract

A trial to examine the suitabilities of 28 tree species for both non-saline and saline soils was carried out in a dry tropical area of northern Australia. The trial consisted of two experiments, Experiment 1 on a non-saline site and Experiment 2 on a saline site. In each experiment, trees of all the species were grown in a randomised complete block design with 6 blocks (replicates) and were measured for survival; height and diameter at breast height (DBH) at age 24 months. These parameters were found to differ significantly between species in both experiments. Of all species tested, Azadi-rachta indica, Eucalyptus camaldulensis, E. citriodora, E. maculata, E. pellita, E. raveretiana, Khaya senegalensisand Paulowniafortue-niihad high survival and fast growth in height and DBH on the non-saline site while E. camaldulensis, E. drepanophylla, E. moluc-cartaand E. raveretianaperformed better on the saline site. Salinity greatly affected survival for some species and reduced tree growth in both height and DBH for most species tested. E. camaldulensisis suggested to be one of themost important species for land rehabilitationin theregion.     

原生态黄山松的保护性开发

黄山御墅天筑山地别墅内原生态资源丰富,尤其是原生态黄山松保护性开发成为项目的重点,从现状调查、原因分析、解决实施三个阶段入手,通过规划设计、建造施工和养护管理,合理避让和利用,基地现场的黄山松90%保留,将项目不露痕迹的融合在自然景观里,成为尊重原生态,可持续发展的景观项目。