2种离子固化剂改善黄土抗剪强度和抗渗性的研究

为了探讨CONAID和LUKANG 2种离子固化剂的固土性能及其影响因素,对不同固化剂掺量、养护龄期、压实度和含水率的固化黄土进行了直剪试验和渗透试验.研究结果表明:随着固化荆掺量、养护龄期和压实度增大,2种固化土的内摩擦角和黏聚力呈上升趋势,渗透系数呈下降趋势,且规律比较接近.其中LUKANG固化剂对黄土抗剪强度和抗渗性的改善效果优于CONAID固化荆.建议在施工过程中选用LUKANG固化剂,掺量宜取0.01%.为了达到更好的抗剪和抗渗效果,应尽量延长固化土的养护龄期,增加压实度.     

砒砂岩区沙棘定植株与萌蘖株生长指标间的关联分析

砒砂岩区为中国自然生态环境最为恶劣的地区之一。多年来的科学研究和生产实践均证明，沙棘为适应这一地区的最佳先锋植物。2～8a沙棘定植株的平均高、地径分别与萌蘖株高、冠幅间存在着较好的正相关关系；中等盖度（40％～70％）的沙棘人工林分，其萌蘖能力最高。生产实践中可充分利用沙棘萌蘖性能强的优势，有效降低种植密度，减少种植成本，实现砒砂岩区快速、经济、高效恢复植被的目的。     

Organic nitrogen mineralisation in two contrasting agro-ecosystems is unchanged by biochar addition

Biochar additions to soil have been reported to enhance soil fertility whilst simultaneously storing carbon (C). We tested whether either fresh or field-conditioned (aged) biochar amendment to two contrasting agricultural soils would alter the mineralisation of organic N compounds. The mineralisation of ¹⁴C-labelled amino acids and peptides were determined over 20 days within each soil. An exponential kinetic decay model was subsequently fitted to the mineralisation data. Overall, statistical analysis revealed significant but small differences between the two biochar treatments and the unamended control treatment. We conclude that biochar has very limited impact on the mineralisation rate of low molecular weight dissolved organic N compounds in these agro-ecosystems.     

井冈山自然保护区森林资源变化分析

以井冈山林相图为基础图形资料,根据1999年的二类清查资料建立数据库,建立森林资源地理信息系统,论述了森林资源的分布特征;统计了各种森林类型的面积;实现了资源现状的可视化以及森林类型自动查询和检索;并输出专题图.关于森林资源变化动态分析得出:从1988年至1999年井冈山自然保护区的森林覆盖率从73.1%增长到85%:有林地比例从77.80%增加到88.38%,1988年、1995年、1999年单位面积的蓄积量分别为65.25m3/hm2、96.15m3/hm2、105.50m3/hm2,蓄积显著增加后趋于稳定.1995年和1999年保护区总生物量分别为6 160 986.70t和6 245 181.834t,碳储量密度分别为86.82t/hm2和90.93t/bm2,平均增长1.83t/hm2·a,碳汇作用明显.     

河北植物新增补属、种与入侵物种新分布

报道了《河北植物志》与《河北高等植物名录》未记录的植物1属3种1变种。其中拔毒散(Sida szechuen-sis Matsuda)、偃狗尾草[Setaria viridis(L.)Beauv. var. depressa(Honda)Kitag.]在河北省首次记录。     

祁连山南麓退耕地人工植物群落的枯落物容水性能

对位于祁连山南麓的青海省大通县退耕地人工植物群落的枯落物容水性能进行了研究。该地区从20世纪80年代初期陆续退耕还林的人工植物群落年龄虽只有10~27 a,但其枯落物层厚度已达2.9 cm,相当于天然植物群落(30~200 a)的56.9%;其枯落物容水量平均达4 mm,相当于天然植物群落的35.7%。研究表明退耕地植物群落的林龄越大,植物垂直层数越丰富,则枯落物干物蓄积量和容水率越大,枯落物容水量也越大。在人为去除枯落物层后,其地表径流速度较去除前增加了33%~35%,枯落物层的缓流、滞流作用十分明显。经逐步回归分析,影响植物群落枯落物容水量的因素99.8%的为枯落物干物的蓄积量、林龄、植物层数和枯落物容水率。     

Effects of closing mountain for forest restoration in the watershed of Miyun reservoir,Beijing

The paper provides a systematical analysis of ecological restoration effects of natural secondary forest of closurearea in Chao Guanxi Gou, Miyun County, Beijing. The results indicate that through more than twenty years of hillclosing afforestation since 1983, canopy closure has improved almost by 0.2; forest cover rate has raised from 7.2% to 93.8%; biodiversity, tree biomass and vegetation community have increased to a great extent. Compared with the average canopy closure before hillclosing afforestation in this area, it has improved to over 0.4 in average and increased by 0.1-0.2. The forest coverage degree has reached more than 90%. Consequently, the forest plays more important roles in intercepting precipitation, improving water storage capacity of soil, decreasing the surface runoff, and preventing soil and water loss.     

不同海拔高度对周公山柳杉人工林植物多样性及土壤养分的影响

【目的】研究海拔高度对周公山柳杉人工林林下植物多样性及土壤养分的影响,对人工林的抚育及合理经营有着重要意义,旨在为人工林近自然改造以及利用山地造林、恢复森林生态提供科学依据。【方法】采用代表性样地法和随机取样法相结合的方法,在800、1 000和1 200 m 3个海拔高度对周公山柳杉人工林林下的物种组成、物种重要值、物种多样性和土壤养分进行了初步研究和对比分析。【结果】1)林下草本层共发现植物33种,属于19科32属;林下灌木层共发现植物49种,隶属于39属26科。2)草本群落Shannon-Wiener多样性指数(H)、Simpson优势度指数(H’)和Pielou均匀度指数(JSW)均随着海拔的升高表现为先升高后降低的趋势,符合"中度膨胀"理论,而草本层物种丰富度指数(D)以及灌木层群落各多样性指数则符合负相关关系理论。3)林下植被0~40 cm深度土壤养分随土层深度增加,全氮、全磷、有效磷、速效钾、有机碳、有机质含量均降低。4)物种多样性指数与有机质、全氮(TN)、全磷(TP)、有效磷(AP)的含量呈显著负相关。【结论】应控制人为干扰的强度,保持合理的林分密度,改善柳杉人工林的物种组成和群落结构,使人工林处于一种天然更新状态。     

Evaluation of potential land productivity in Wulushan,West China

The general situation of the total land resources in Wulushan, West China was studied by field investigations with the aid of a GIS software, called Region Manager. The current status of land use in Wulushan is described. The potential land productivity was evaluated by a fuzzy comprehensive method, We take each plot as a basic unit of evaluation on the basis of an index system of land resources in Wulushan which was developed from the investigation data. Evaluation of potential land productivity is the key part of land management. A guideline is presented in this paper for a proper utilization of the land resources and to develop the productive capacity of the land.     

Impacts of fractal features of soil on moisture infiltration capacity of typical stands in Jinyun mountain of Chongqing city

The soil structure was expressed with fractal dimensions of particle size distribution (PSD), aggregate size distribution (ASD), and soil pore size distribution (SPD). The effect of soil fractal features on soil infiltration velocity and process was studied. The result of the fractal feature shows that fractal dimensions of PSD are obviously greater than those of ASD and SPD, and in different soil genetic horizons, the fractal dimension of ASD has the greatest variability, and shows a downtrend on the top-to-bottom genetic horizon. According to the soil infiltration process curve, the infiltration process was divided into three phases: (1) the initial phase (0–5 min), (2) the transition phase (5–30 min), and (3) the stable phase (30–180 min). In the initial phase of infiltration, the soil structure of soil genetic horizon A was the major influencing factor; in the transition phase of infiltration, the pore distribution of soil horizon AB and soil structure of horizon B were the major influencing factors; in the stable phase of infiltration, the soil structure of horizon C was the major influencing factor to the infiltration velocity. Soil infiltration process is influenced comprehensively by soil PSD, ASD, and SPD. In the overall soil water infiltration, the infiltration in shrub forest land was much faster than that in other land uses, and in the initial infiltration phase, arable land soil infiltration was much faster than that in forest land, and in the stable infiltration phase, the infiltration velocity in forest land was faster than that in arable land. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 73–78 [译自: 北京林业大学学报]