Effect of the amount of lignin on tensile properties of single wood fibers

Chemical components are the main factors affecting the mechanical properties of wood fibers. Lignin is one of the main components of wood cell walls and has a critical effect on the mechanical properties of paper pulp and wood fiber based composites. In this study, we carried out tensile tests on single mature latewood tracheids of Chinese fir (Cunninghamia lanciolata (Lamb.) Hook.), using three different delignified treatment methods to obtain different amounts of lignin. We applied single fiber tests to study the effect of the amount of lignin on mechanical tensile properties of single wood fibers at the cellular level. The results show that in their dry state, the modulus of elasticity of single fibers decreased with the reduction in the amount of lignin; even their absolute values were not high. The amount of lignin affects the tensile strength and elongation of single fibers considerably. Tensile strength and elongation of single fibers increase with a reduction in the amount of lignin.     

Seed viability of selected tree,shrub, and vine species stored in the field

Seeds from 10 species were collected, sealed in fiberglass screen pouches, and stored under hardware-cloth cages on both a forest and cleared site for up to five years. At each site, half of the pouches were placed under leaf litter and the other half were planted in mineral soil. Liquidambar styraciflua and Callicarpa americana seeds had high germination rates under all conditions. Quercus falcata, Sassafras albidum, Rhus copallina, and Vaccinium arboreum required planting in mineral soil to ensure germination. Planted Myrica cerifera and Vitis aestivalis seeds germinated well on both sites. Myrica cerifera also germinated well if placed under litter on the forest floor and Vitis aestivalis if placed under litter on the cleared site. Germination of Crataegus uniflora seeds was erratic. Most Lonicera japonica were unsound when collected. Germination rates generally decreased over time, but some Sassafras albidum, Myrica cerifera, and Vaccinium arboreum seed germinated after four years, and Rhus coppalina, Callicarpa americana, Crataegus uniflora, and Vitis aestivalis seeds germinated after five years in the field.     

Sorption of Cr(VI) on the wood of Japanese larch treated with concentrated sulfuric acid

A carbonaceous sorbent was prepared from the wood of Japanese larch (Larix leptolepis) by dehydration with concentrated sulfuric acid in a 69% yield. The abilities of the sorbent to remove Cr(VI) from aqueous solutions were investigated. Research parameters included the initial solution pH, temperature, and initial concentration of Cr(VI) in solution. The removal of Cr(VI) was highly solution pH dependent and was mainly governed by physicochemical sorption under weak acidic conditions. The equilibrium data fit well in the Langmuir isotherm model. The Langmuir constants were calculated at different temperatures, and the sorption capacity increased with rising temperature, indicating the endothermic nature of the Cr(VI) sorption onto the sorbent. The desorption experiments suggest that the Cr(VI) sorption is generally irreversible, owing to strong interaction of HCrO ₄ ⁻ with the active sites of the sorbent.     

世界单竹属栽培品种研究

竹亚科(Bambusoideae)单竹属(Lingnania McClure)是竹类植物中的一个特殊类群,由于其节间较长,特别适于劈蔑编制生产和生活用品,历史上一直都是其分布区居民不可或缺的生产和生活资料,被广泛栽培和应用。单竹属植物种类较少,全世界近20种,中国产14种,主要分布于华中及华南部分省区。越南有少量分布。为适应国际竹类栽培品种登录工作的需要,依据《国际栽培植物命名法规(ICNCP)》的规则和要求,经系统整理,已确认单竹属传统栽培品种4个,新登录栽培品种1个,再加上2个原栽培品种,共计7个栽培品种,分属于2个不同竹种。现将这些栽培品种及其相关信息整理,以便查阅和参考。     

世界方竹属栽培品种整理

全世界竹亚科(Bambusoideae)方竹属(Chimonobambusa Makino)植物约有30余种及种下分类群,主要分布于中国(秦岭以南各地区及西藏东南部)、日本和越南,缅甸、美国、欧洲也有少量引栽。根据《国际栽培植物命名法规(ICNCP)》的相关规则和要求,国际竹类栽培品种登录中心(ICRCB)组织有关专家,对竹亚科方竹属的栽培品种进行了系统整理。到目前为止,已经确认全世界有17个栽培品种,涉及4个不同的方竹属竹种。现将这些栽培品种及其相关信息整理报道,以便查阅和参考。     

南方集体林区林业经济增长的产业结构演变及其差异分析*--基于13个省（区）1995-2011年的统计数据

以13个省(区)1995-2011年林业产值数据为基础,利用动态偏离-份额分析法,分析我国南方集体林区林业经济增长、产业结构演变及其差异。结果表明：与全国整体水平相比,南方集体林区林业经济有着较快的增长速度和较好的林业产业结构素质,具有一定的区域竞争力优势,但林业第一产业增长速度和产业结构素质均低于全国平均水平,不具有区域竞争力优势,林业第二和第三产业增长速度和产业结构素质高于全国平均水平,具有区域竞争力优势;与南方集体林区整体水平相比,江苏、广东、安徽和广西4个省(区)的林业经济增长速度较高,江苏、浙江、福建、湖南和广东5省的林业产业结构素质较高,其中,又以前3个省(区)的林业产业结构素质优势最为明显,江苏、安徽、广东和广西4个省(区)的林业产业具有一定的区域整体竞争优势;进一步采用聚类分析方法,将南方集体林区13个省(区)林业产业发展类型区分为4类,即优势类型区、后发优势类型区、优势待提升类型区和优势滞后类型区,针对不同类型区的特点,提出相应对策建议。     

Analysis of the change in the original Metasequoia glyptostroboides population and its environment in Lichuan, Hubei from 1948 to 2003

Lichuan, located at the foot of the Wuling Mountain in southwest Hubei Province of central China, is well known in the world for the discovery of the living fossil Metasequoia glyptostroboides Hu & Cheng in the 1940s. Its natural habitat has been well protected by the Chinese government. In order to provide a scientific foundation for the protection of the Metasequoia resource, it has become necessary to analyze the changes in the original, natural Metasequoia mother trees (ONMMT) and their environment from 1948 to 2003. The results and countermeasures are as follows: First, the distribution areas have little changed, involving four towns/farmland, 45 villages, 5,746 individual trees in 1983 and 5,388 trees in 2003, covering nearly 600 km², with an average density of less than 0.1 tree/hm². The Metasequoia distribution consists of two main types: a scattered distribution type found mainly at the foothills or near houses, roads, villages and rivers while the population distribution type is found mainly at the mountains and valleys with a minority at low elevations in the mountains and basins. The largest Metasequoia populations have 105 and 123 trees. Second, in the past, attention was only paid to the protection of individual trees while the protection of the Metasequoia population and environment was neglected. This led to a shift from the past mixed forests to pure Metasequoia forests, with a simpler structure, reduced biodiversity and conditions non-conducive for natural renewal. From 1983 to 2003, 386 original Metasequoia mother trees died. So it is vital to enhance the protection of the only original Metasequoia population in the world and its habitat. Third, modern ecological means should be taken to protect the original Metasequoia population and its habitat. Research on the restoration and rehabilitation of Metasequoia vegetation should be carried out. Restoration and rehabilitation should be put into practice in the Xiaohe Valley, where the highest concentration of Metasequoia is found. Fourth, efficient measures should be taken to stop human activities that are harmful to Metasequoia and to improve the environment of ONMMT in order to promote the protection of the ONMMT population and its ecosystem. Eco-emigration and the return of marginal agricultural land to forestry can be practiced. __________ Translated from Acta Ecologica Sinica, 2005, 25(5): 972–977 [译自: 生态学报, 2005, 25(5): 972–977]