Dependence of runout distance on the number of rock blocks in large-scale rock-mass failure experiments

To examine how the number of rock blocks affects the rock-mass runout distance, large-scale outdoor rockfall experiments were physically performed using cubiform granite rock blocks on a slope prepared with granite slabs under both dry and water-saturated conditions. To learn more about the runout mechanism, numerical simulations were also conducted using three-dimensional DEM to reproduce the physical experiments under dry conditions. Longitudinal rock-mass runout distance between the gravity centre in the initial rock block assembly before failure and the apparent gravity centre at final deposition was 10 % larger for experiments under water-saturated conditions than those under dry conditions, with identical numbers of rock blocks in the physical experiments. The physical and numerical experiments revealed that rock blocks at the front and top surfaces had a longer runout distance than those at the rear and bottom surfaces. A rock block scarcely surpassed the rock blocks in front longitudinally and the rock blocks next to it laterally. The equivalent coefficient of friction between gravity centres was positively correlated with the number of rock blocks, which contradicts the findings of a negative correlation between the volume of sturzstroms (rockfall avalanches) and the equivalent coefficient of friction in classic studies on the long runout mechanisms. Our results were likely attributable to the fact that more kinetic energy was dissipated due to repeated inelastic intercollisions with other surrounding rock blocks and granite slabs when the initial rock-mass volume (number of rock blocks) was larger.     

Influence of volcanic activity on vegetation succession and growth environment on the hillslope of Sakurajima Volcano in southern Kyushu,Japan

This study was conducted in order to examine the influence of long-term volcanic activity on vegetative succession and growth on the slope of Sakurajima in southern Kyushu, Japan. We investigated the vegetation,depth of the volcanic ash layer, and dry density and p H of the surface soil at six places on the north-northwestern slope, 2.3–3.4 km from the Minami-dake crater, where a layer of pumice stone was deposited by the Taisho eruption in 1914. The height and diameter at breast height(DBH) of the trees increased with increasing distance from the Minami-dake crater, as did the number of individuals and species, and basal area. The Shannon–Wiener diversity index(H') demonstrates that vegetative succession is significantly affected by distance from the Minami-dake crater, as areas farther from the crater exhibited later seral stages. Comparison of the diversity index and species number of the crater region with that of the climax forest in Kagoshima indicates that vegetative growth alone cannot advance succession in the study area, as the local vegetative community is heavily influenced by the harsh environmental conditions associated with continual exposure to long-term volcanic activity. Seral stage, ash layer depth,dry density, and p H of the soil surface layer are governed by distance from the Minami-dake crater. The results of this study indicate that conditions for vegetative growth and succession improve with increasing distance from the source of constant volcanic activity. Thus, soil development is promoted by the acidification of the soil, which decreases the dry density and p H of the soil surface layer.The introduction of plant species resistant to volcanic ash and gas is recommended to promote soil development and improve the infiltration capacity of the soil.     

湿地水文功能研究进展

湿地是流域水资源和水循环的重要组成部分,是自然界最富生物多样性的生态系统和人类最重要的生存环境之一,它不仅为人类的生产、生活提供多种资源,而且具有巨大的生态环境功能和效益。湿地的水文功能主要包括调蓄洪水、补充地下水、提供水源、保持或改善水质、调节气候、保护海岸带等功能,其独特的水文功能对维持流域生态系统的健康和改善区域生态环境具有十分重要的意义。因此,湿地水文功能的研究已引起国内外学者的关注。本文从湿地水文、水文功能两个方面综述了国内外研究的现状,并指出了目前研究中存在的主要问题及未来研究的发展趋势。     

森林生态旅游对林业经济的促进作用

本文通过对森林生态旅游在林业中的地位和作用的分析 ,得出森林生态旅游是摆脱资源危机和经济围困、促进林业经济发展的有效手段之一。     

魔芋甘露聚糖免疫作用的研究

研究了魔芋甘露聚糖免疫作用,通过给昆明系小鼠灌胃,持续25d,观察魔芋甘露聚糖对其免疫功能影响。结果表明,魔芋甘露聚糖组半数溶血值(HC50)、淋巴细胞刺激指数(SI)及细胞毒百分率明显上升,提示魔芋甘露聚糖可明显提高小鼠细胞免疫和体液免疫,并增强TNF产生。     

石榴保健功能的研究进展

石榴果实富含对人体有益的抗氧化剂和营养成分,具有极高的保健作用。作者综述了石榴对人体有益的抗氧化剂和功能成分,以及近几年来国内外对石榴及其加工产品在抗癌、抗心血管疾病、抗胃病、抗糖尿病等方面的研究进展,最后在石榴研究领域提出了建议,以期为我国石榴研究与产业化开发提供了理论依据,为进一步开发石榴种质资源提供参考。     

Vibrational and acoustical experiments on logs of spruce

Summary This paper presents the results of some vibro-acoustical experiments conducted on logs of spruce. The aim from this study was in the beginning to study the possibilities of investigating acoustically the presence of decay in the stems of standing trees, and for assessing the strength of wood in the shape of logs. First, a brief review is made for the different experimental techniques used in studying the response of mechanical systems in general with emphasis on an efficient technique used for evaluating the impulse response of vibrating systems. Then a literature survey on the effects of decay on the strength and on the damping properties of wood are presented with some practical general implications regarding decay inspection of wood composites. Lastly some experiments using vibrations and sound which were conducted on two specimens of wood logs, one sound and one decayed, are presented with some discussions regarding the implementations of these methods for the quality grading and defect detection in wood logs and standing trees. Received 16 July 1997     

湛江市林地景观演变及其功能评价研究

利用RS和G IS技术分析了湛江市1996—2007年林地数量和其景观格局的变化,定量评价了其对区域生态系统服务功能的影响。结果表明:在12年中,湛江市林地景观总面积显著增加;斑块破碎程度增大,空间格局变得更为复杂;湛江林地景观的格局演变主要受人类活动的干扰影响,林地生态系统服务功能显著增强的结果与其景观空间格局的变化有密切相关性。最后提出了湛江今后的林地保护和发展策略的建议。     

18个杨树品系湖区对比试验初报

全国各地的杨树良种在洞庭湖区蜂拥而至的情况下,选择6个南方型黑杨、7个北方型黑杨、3个三倍体毛白杨以及由湖南省林业科学院等单位培育的2个湘林美洲黑杨新无性系,在洞庭湖垸内进行不同杨树品系的对比试验。根据5年生杨树的生长量分析,初步显示湘林-77、湘林-90两个新无性系最具生长优势,可在湖区推广应用;南林-1388、南林-895、转抗杨、南林-351、鲁山杨（辽宁杨）、南林-95杨6个黑杨派南方型无性系可作一般性生产用种在湖区应用;欧美杨108等7个黑杨派北方型无性系、白杨派3个三倍体毛白杨无性系5年生的材积仅为南林-95杨的54．7％-12．9％,不宜在湖区推广应用。     

浅析竹类植物的城市生态环境效应

竹子具有显著的生态效应，在生态建设中发挥着巨大的作用。在总结有关竹类植物生态效应研究成果的基础上，针对现代城市环境特点，着重分析竹类植物对城市环境的生态作用，指出在城市生态环境建设中应重视竹类植物的运用及其生态功能的持续有效发挥。     

风沙干旱区葡萄引种与优选试验初报

辽宁省章古台果树示范场，经过5a的葡萄引种与优选试验，对5个葡萄新品种的适应性、生长效果等指标进行了综合测试。从中选出了适合风沙干旱区生长的两个葡萄新品种——火星无核、藤稔。     

大尺度小样本情况下的数据预测方法对比研究

采用反距离加权法(IDW)、协同克里格法(Cokriging)、回归模型法,利用云南省134个县(市)气象站观测数据对全省≥10°积温区域进行预测.结果表明,由于气象站点稀少,用不同的方法结合不同的辅助信息得到的预测结果不同.反距离加权法强调了空间距离尺度的影响,但未能较好地体现云南省局部积温的分布规律;协同克里格法则优于反距离加权法,但在样本数偏少的情况下预测结果会出现明显的凹凸现象;回归模型法预测结果能很好地体现云南省北低南高、西高东低的气温总体变化规律,又能体现峡谷地带中局部干热河谷的特点,是3种方法中效果最好的预测方法.     

Discussion on Status and Functions of China’s Forestry

In recent years, the quantity and quality of global forest resources are declining continually. Contrarily, the both in China are increasing, which is deeply related to the sustainable forest management and eco-system management in China. With the trend that world community knows more about the important role of forest, more and more functions of forest are recognized. The impact and functions of China’s forestry deserve more concern. Based on some experiences in the field of forestry research, the authors introduced and analyzed the key role of China’s forestry for the sustainable development, and explained the functions of China’s forestry, such as ensuring ecological safety, addressing climate change, improving economic development, promoting social harmony and prospering ecological culture.     

Uncertainty assessment of large-scale forest growth predictions based on a transition-matrix model in Catalonia

Key message

When predicting forest growth at a regional or national level, uncertainty arises from the sampling and the prediction model. Using a transition-matrix model, we made predictions for the whole Catalonian forest over an 11-year interval. It turned out that the sampling was the major source of uncertainty and accounted for at least 60 % of the total uncertainty.

Context

With the development of new policies to mitigate global warming and to protect biodiversity, there is a growing interest in large-scale forest growth models. Their predictions are affected by many sources of uncertainty such as the sampling error, errors in the estimates of the model parameters, and residual errors. Quantifying the total uncertainty of those predictions helps to evaluate the risk of making a wrong decision.

Aims

In this paper, we quantified the contribution of the sampling error and the model-related errors to the total uncertainty of predictions from a large-scale growth model in Catalonia.

Methods

The model was based on a transition-matrix approach and predicted tree frequencies by species group and 5-cm diameter class over an 11-year time step. Using Monte Carlo techniques, we propagated the sampling error and the model-related errors to quantify their contribution to the total uncertainty.

Results

The sampling variance accounted for at least 60 % of the total variance in smaller diameter classes, with this percentage increasing up to 90 % in larger diameter classes.

Conclusion

Among the few possible options to reduce sampling uncertainty, we suggest improving the variance–covariance estimator of the predictions in order to better account for the multivariate framework and the changing plot size.

     

河岸带植被对河流生态功能影响研究进展

综述了河岸带植被的遮荫作用,廊道效应,截污效应,及外来生物入侵等对河流生态功能影响的相关研究成果。结果表明,河岸带植被的遮荫可以影响河水的化学过程和生物过程;河岸带植被在地域景观中还起着重要的廊道功能,对生物多样性保护有重要意义;河岸带植被对于控制面源污染,过滤污染物,保护水质起着缓冲作用。外来生物入侵对河岸带植被生态功能造成了较大的负面影响,消除河岸带中入侵生物的不利影响,恢复河岸带植被是一项刻不容缓的任务。     

华北落叶松幼林抚育试验的调查研究

华北落叶松实行幼抚,不仅可大大促进林木生长发育,而且是提高造林保存率不可缺少的措施,十分重要。     

上虞丘陵山区杜英-蚯蚓-家禽立体生态功能的研究

根据上虞丘陵山地土地利用的特点，研究畜禽粪有机废弃物的无害化、资源化良性循环利用，建立杜英—蚯蚓—家禽立体生态模式。通过分析系统的经济效益和生态功能，表明各环节是互利互补、相互促进的良性循环。     

章古台引种欧洲针叶树育苗试验初报

在辽宁省章古台经多年引种育苗试验表明，引种苗木特别是1年生苗能否正常越冬，成为引种成败的首要限制因子。就欧洲赤松而言，波兰、爱沙尼亚种源1年生苗的越冬保存率在80％以上，2年生苗生长量与樟子松相仿且均能安全越冬，为适宜种源；在试验过的4个欧洲黑松变种中，Pinus nigra var.austriaca较抗寒，1年生苗木越冬保存率可达96％，2年生苗木全部能安全越冬，是最有希望的变种。挪威云杉苗木不能露地越冬，不宜作造林树种引种，可作为绿化树种试栽。     

扬州城市森林的文化承载功能初探

以城市森林为骨架建立起来的城市绿化空间,与城市建筑、文化相互补充和制约,是突出城市文化特色的重要载体之一。本文以历史文化名城扬州为例,分析了城市绿化空间的外貌特征及其文化承载的方式,在此基础上,对扬州城市森林建设中实现文化表达的途径进行了探讨。为建设扬州城市森林、实现生态城市目标、再现扬州历史文化名城特色提供了借鉴。       

湖南省青石冈国有林场生态系统服务功能价值评价

笔者构建了适合湖南省青石冈国有林场森林生态系统服务功能的评价指标体系,采用2009年森林资源调查资料及社会公共数据评估了青石冈4种主要森林类型的生态服务功能总价值.结果表明:生态系统服务功能价值每年为20.622亿元.其中涵养水源13.388亿元,保育土壤1.098亿元,固碳释氧2.788亿元,积累营养物质0.818亿...