Biogeography of mangrove and saltmarsh vegetation: implications for conservation and management in Australia

Despite an undeserved reputation for being dull and homogenous systems, mangal and saltmarsh in Australia have highly complex patterns and processes. Their role as key edge systems between land and sea has implications for many species which have larval stages in mangal and saltmarsh, but spend adult life as benthic, pelagic or demersal species. Many such species are also important commercially. Mangal and saltmarsh are both highly dynamic systems, reacting rapidly to changes in hydrological condition and sedimentation. In many areas of the world mangal and saltmarsh are threatened systems, especially near human habitation. Appropriate management strategies for mangal and saltmarsh are therefore critical for both conservation and sustainable use, the two key objectives of the Convention on Biological Diversity. Clearing and associated development, invasion of alien species, pollution effects and poor management are the key threats to these systems. Management at a bioregional level, including the development of a comprehensive system of protected areas, is identified as the key management strategy which will ensure an adequate future for these dynamic systems.     

内燃机故障声响信号时间序列模型诊断方法

本文运用统计模式识别原理,提出了一种以内燃机声响信号的时间序列自回归系数及自回归倒谱系数作为模式的特征参数,对参考模式和待检模式用灰色系统的关联测度、Mahalanobis距离测度和Kullback-leiber信息量距离测度同时进行识别,并用层次分析法对识别结果进行综合,从而达到诊断故障目的的方法。通过实验验证,表明其是有效而可行的方法。     

武夷山风景名胜区景观空间格局研究

景观结构又称景观空间格局 ,是大小和形状不一的景观嵌块体在景观空间上的排列 (伍业钢等 ,1992 )。景观结构决定着景观功能 ,而功能的改变最终将从结构的变化中反映出来 ,因此 ,景观空间格局研究是景观生态学三大核心问题的核心 (贾宝全等 ,2 0 0 1)。景观异质性是景观最重要的属性之一 (Formanetal .,1986 ;Risseretal.,1984 ;Turner,1987) ,而景观空间格局既是景观异质性的具体体现者 ,同时又是多种生态过程在不同尺度上作用的最终结果 (贾宝全等 ,2 0 0 1)。景观空间格局及其变化和发展是自然、生物和社会要素相互作用的结果 ,影响着…     

三明市森林资源景观格局分析研究

运用景观格局指数，依靠GIS技术支撑，对三明市森林资源景观格局进行研究。结果表明，本地区森林资源景观多样性指数、均匀度指数、破碎化指数较低，优势度指数较高，某些单个森林资源景观的破碎化指数增长快，这说明区域内存在有占优势的景观类型，整体森林资源景观较完整，但随着人类干扰强度的增大，系统的开放性越强，斑块越变越小，并呈直线化和直角化趋势。     

Landscape Patterns and Dynamics in Shanhaiguan Forest Farm,Hebei Province

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Root architecture in relation to tree-soil-crop interactions and shoot pruning in agroforestry

Desirable root architecture for trees differs between sequential and simultaneous agroforestry systems. In sequential systems extensive tree root development may enhance nutrient capture and transfer to subsequent crops via organic pools. In simultaneous systems tree root development in the crop root zone leads to competition for resources.Fractal branching models provide relationships between proximal root diameter, close to the tree stem, and total root length or surface area. The main assumption is that a root branching proportionality factor is independent of root diameter. This was tested in a survey of 18 multipurpose trees growing on an acid soil in Lampung (Indonesia). The assumption appeared valid for all trees tested, for stems as well as roots. The proportionality factor showed a larger variability in roots than in stems and the effects of this variabilily should be further investigated. A simple index of tree root shallowness is proposed as indicator of tree root competitiveness, based on superficial roots and stem diameter.Pruning trees is a major way to benefit from tree products and at the same time reduce above-ground competition between trees and crops. It may have negative effects, however, on root distribution and enhance below-ground competition. In an experiment with five tree species, a lower height of stem pruning led to a larger number of superficial roots of smaller diameter, but had no effect on shoot:root ratios or the relative importance of the tap root.     

Cutting technic forPinus elliottii plantation of the multi-benefit management pattern

The cutting technic for thePinus elliottii plantation of the multi-benefit management pattern in the hilly region of Jiangxi Province was studied by establishing the model of growth progress according to Richards function and simulating the tending cutting on computer by use of dynamic programming. The results showed that the best time for the initial thinning was at tree age of 8–10 and final cutting was at tree age of 25. The optimal thinning project was 3 times of thinning cutting including the first thinning, and the thinning time was at tree ages of 8, 12 and 16, respectively. Their thinning intensities were separately 950, 700 and 300 trunks per hectare, and the preserved density was 550 trunks per hectare until the final cutting Foundation item: This study was supported by Natural Science Foundation of Jiangxi Province (A grant 0330023) Biography: WANG Qing-chun (1970-), male, Ph. Doctor, Senior Engineer in Academy of Forest Inventory & Planning, Jiangxi, Nanchang 330046, P.R. China. Responsible editor: Song Funan     

Simultaneous flowering of umbrella bamboo （Fargesia murieliae） at its native home in Central China

Introduction The life history of many bamboo species is characterized by an unusual flowering habit. They often flower and die simultaneously over wide areas at long intervals (3–120 years), and then regenerate from seed or rhizome (Janzen 1976; Liese 19…     

甜槠群落主要种群空间分布格局对人为干扰的响应

研究了不同人为干扰强度对甜槠天然群落中主要种群甜槠和赤楠的分布格局的变化动态.结果表明,人为干扰会使甜槠种群的聚集性加强,而赤楠种群的聚集性降低.干扰强度对甜槠聚集性的影响随树龄的增大而逐渐减小,而对赤楠聚集性的影响则是随林龄增大呈现由小→大→小的规律.     

杭州次生湿地中早园竹林的种子库特征

实验通过野外调查和萌发试验对杭州西溪湿地经济竹林的种子库特征进行研究。结果,经济竹林种子库中共出现14科26种植物,其中以十字花科、大戟科、玄参科、菊科和禾本科为主。种子库密度的垂直分布呈下降趋势。其种子库中有劣性杂草如一年蓬和蒲公英,并占有优势。竹林地10~15 cm土壤的板结和贫瘠是种子量稀少的主要原因,竹林大部分是在干扰和干旱生境下萌发的草本和灌木种子库,亦有永久种子库的贡献。