Forestry between land use intensification and sustainable development: Improving landscape functions with forests and trees     

Jørgen Bo Larsen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):191-195

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Research Note—Vegetation Effects on Suburban Air Conditioning     

《Urban geography》2013,34(6):558-564

Conventional wisdom indicates that shade trees reduce air-conditioning energy demands in U.S. southern-tier states. Existing studies of shade effects on dwellings generally do not consider that contemporary home structures are inhabited and well insulated. Through a statistical analysis of weather, vegetative, and energy consumption data for 38 inhabited, modern homes in the eastern suburbs of Atlanta, we establish that existing tree plantings play only a small role in energy conservation for individual homes vis-à-vis insulation and heat gain from external walls and windows.  相似文献   

Topsoil morphology indicates bio-effective redox conditions in Venice salt marshes     

Friederike Lang  Moritz von der Lippe  Susanne Schimpel  Tiberio Scozzafava-Jaeger  Wolfgang Straub 《Estuarine, Coastal and Shelf Science》2010

Visual traces of iron reduction and oxidation are linked to the redox status of soils and have been used to characterise the quality of agricultural soils. We tested whether this feature could also be used to explain the spatial pattern of the natural vegetation of tidal habitats. If so, an easy assessment of the effect of rising sea level on tidal ecosystems would be possible. Our study was conducted at the salt marshes of the northern lagoon of Venice, which are strongly threatened by erosion and rising sea level and are part of the world heritage “Venice and its lagoon”. We analysed the abundance of plant species at 255 sampling points along a land–sea gradient. In addition, we surveyed the redox morphology (presence/absence of red iron oxide mottles in the greyish topsoil horizons) of the soils and the presence of disturbances. We used indicator species analysis, correlation trees and multivariate regression trees to analyse relations between soil properties and plant species distribution. Plant species with known sensitivity to anaerobic conditions (e.g. Halimione portulacoides) were identified as indicators for oxic soils (showing iron oxide mottles within a greyish soil matrix). Plant species that tolerate a low redox potential (e.g. Spartina maritima) were identified as indicators for anoxic soils (greyish matrix without oxide mottles). Correlation trees and multivariate regression trees indicate the dominant role of the redox morphology of the soils in plant species distribution. In addition, the distance from the mainland and the presence of disturbances were identified as tree-splitting variables. The small-scale variation of oxygen availability plays a key role for the biodiversity of salt marsh ecosystems. Our results suggest that the redox morphology of salt marsh soils indicates the plant availability of oxygen. Thus, the consideration of this indicator may enable an understanding of the heterogeneity of biological processes in oxygen-limited systems and may be a sensitive and easy-to-use tool to assess human impacts on salt marsh ecosystems.  相似文献   

关于一类时变大系统的平稳振荡     

彭晓林  吴晓非 《成都信息工程学院学报》1992,(4)

本文应用大系统的分解方法以及一个推广的不等式,研究了一类线性时变大系统的平稳振荡问题,得到了一个新的、简洁的结果,并给出了应用实例。  相似文献   

Reviews     

《The Geographical journal》2001,167(4):379-384

Books reviewed:
J. Ludwick, D. Tongway, D. Freud-Enberger, J. Nobel and K. Hodgkinson, (eds.) Landscaping Ecology: Function and Management
John Keay, The Great Arc: the dramatic tale of how India was mapped and Everest was named
Massimo Craglia and Harlan Onsrud, (eds.) Geographic Information Research: Trans-Atlantic Perspectives
Martin Dodge and Rob Kitchin, Mapping Cyberspace
David M. Smith, Moral Geographics: Ethics in a World of Difference
Denis Cosgrove, (ed.) Mappings
J. C. Iliffe, Datums and Map Projections for Remote Sensing, GIS and Surveying  相似文献   

青岛沿海冬季观果木本植物     

李宝华  陈沪宁 《海岸工程》1996,15(4):41-45

主要介绍了青岛沿海地区栽培和野生冬观果树木的种类，开花结果日期，分布状况，生长习性及用途。对栽培种在青岛市沿海新建城镇园林绿化中宜积极应用，野生种宜在沿海苗圃先进行引种驯化再加以推广使用。  相似文献   

青岛两次极端高温天气成因分析   总被引：1，自引：0，他引：1  

颜梅  郭敬天  傅刚  张晓慧 《海洋湖沼通报》2004,(2):10-15

本文从天气学角度分析青岛历史上两次极端高温过程的特点。发现青岛出现极端温度两次过程有共同的特性：都发生在厄尔尼诺当年，都是大陆深厚暖高压控制；低空有强而持久的暖中心；高空为较强的下沉运动，有利于下沉增温；高低层相对湿度小，天气晴好，有利于太阳辐射地面增温；地面北风场。有利于大陆高温热风南袭。这些是促成高温过程的重要原因。  相似文献   

The use of plant water relations to characterize tree species and sites in the drylands of northern Ethiopia     

K. Gebrehiwot  B. Muys  M. Haile  R. Mitloehner 《Journal of Arid Environments》2005,60(4):581-592

Water relations of four tree species were studied in four sites in the drylands of northern Ethiopia. Predawn water potentials were significantly higher at all sites as compared to midday measurements for Acacia etbaica and Boswellia papyrifera. In contrast, Lannea fruticosa revealed this significant difference only once, while Terminalia brownii at only two of the four sites. An analysis of variance showed that A. etbaica has a wider tolerance range as compared to the other species. There was no significant difference among the four sites in terms of predawn, midday and diurnal ranges of water potential. The study revealed that A. etbaica and B. papyrifera are performing better as compared to T. brownii and L. fruticosa under the current climatic conditions. Understanding the physiological basis of survival, productivity, ability to cope with low moisture availability, and growth potential of indigenous species in the drylands is essential for the utilization and promotion of these and other species.  相似文献   

Financial appraisal of date-frond mat fence systems for wind erosion control and sand dune stabilization in the arid region of the United Arab Emirates     

Y.T. Gumaa  I. Haffar  M.A. Al-Afifi 《Journal of Arid Environments》1998,39(4):549-557

A discounted cash flow model was employed to assess the viability of four wind barrier systems. The systems were utilized for wind erosion control and sand dune stabilization in the Al-Ain region of the United Arab Emirates. These systems consisted of four densities of date-frond mat fences erected in the form of checker board grids between rows of two local tree species:Prosopis spicigeraandAcacia tortilis. Analysis of cost estimated was based on the annual equivalent value of costs for each system. The economic life of the systems varied as a function of the time needed for the different trees in the different systems to reach the self-support stage. Results indicated that the systems’ ranking according to the minimal costs varied among the different tree types and the number of fences; but there was a general decrease in cost with increased fence density using the same tree, and this was due mainly to the effect of the fence on reducing the cost of tree development and maintenance as a result of reducing accumulated eroded sand. The minimal cost was recorded in D-10 treatment (seven fences) usingProsopis spicigera.  相似文献   

The relationship between sap flow of intercropped young poplar trees (Populus×euramericana cv. N3016) and environmental factors in a semiarid region of northeastern China     

De‐Xin Guan  Xiao‐Jing Zhang  Feng‐Hui Yuan  Ni‐Na Chen  An‐Zhi Wang  Jia‐Bing Wu  Chang‐Jie Jin 《水文研究》2012,26(19):2925-2937

Estimating transpiration of the trees in agroforestry system is important in water management of the site. Sap flow of intercropped fast‐growing young poplar trees and microclimate factors in semiarid northeastern China was measured in two growing seasons (2008 and 2009). Sapwood growth and water storage of wood and leaf increment during the growing season were involved in the calculation of sap flow. The results showed that diurnal variation of sap flow followed to that of short wave solar radiation. Sap flows both in 10 min mean and daily gross values mainly depended on solar radiation and vapor pressure deficit, and the relations well fit hyperbolic function. The regression coefficients of monthly window data indicated that the seasonal variation of sap flow capacities decreased gradually from June to September. Moderate soil water stress of upper soil layer (0–50 cm) did not constrain the sap flow because the trees could use the water at deeper soil layer. The daily sap flow per tree ranged 0.8 to 18.1 and 3.7 to 23.8 kg d^?1 tree^?1, with averages of 8.7 and 14.3 kg d^?1 tree^?1 in 2008 and 2009 respectively. An empirical model was established to estimate the sap flow of the poplar trees by solar radiation, vapor pressure deficit, leaf area index and Julian days. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献