浙江林学院东湖校区空气负离子浓度变化特征     

洪丹琴  章锦河 《福建地理》2009,(1):71-77

选择浙江林学院东湖校区作为监测点,通过测定空气正、负离子浓度,空气温、湿度,风速,光量子等项目对空气负离子浓度变化特征进行研究．结果表明：白天空气负离子浓度有一个高峰期,出现在8：00-9：00;8月空气负离子浓度最高;空气负离子浓度随相对湿度的升高而增大,随温度、风速和光量子的增大而降低．  相似文献   

林业高等教育在云南边疆少数民族地区的成效研究—以西南林学院为例     

王宏虬  刘兴东 《云南地理环境研究》2009,21(5):27-29,35

以西南林学院在云南边境少数民族地区工作的毕业生为研究对象,运用田野调查,采取访谈法、选择个案进行调查研究,从而得出高等林业教育对云南边境少数民族社会、经济的实际成效。从用人单位对毕业生的评价以及毕业生的自我评价中,找准高等林业教育在教育、教学、管理和服务等方面存在的不足,提出高等林业教育当前需要改进的工作：一是进一步加大课程体系和教学内容改革力度;二是要创新培养模式,提高学生综合素质;三是加强实验实习基地建设,培养实践能力。  相似文献   

内蒙古东北部阿龙山地区早白垩世A型花岗岩特征及其意义   总被引：1，自引：0，他引：1  

韩振哲  王洪杰  李中会  李娟娟  李文龙  刘旭光 《华南地质与矿产》2009,(4):1-9

内蒙古东北部阿龙山地区的早白垩世花岗岩岩体就位于火山喷发形成的塌陷破火山口中央或火山断裂中,岩石类型有石英二长（斑）岩、晶洞正长花岗岩、文象碱长石英正长岩等。岩石普遍具文象结构、晶洞构造,但未见碱性暗色矿物;岩石化学上具高硅、富碱和富铝、低钛镁等特征,且岩石中富集高场强元素（HFSE）,在微量元素蛛网图中出现Sr、Ba相对亏损,稀土配分曲线呈轻稀土富集的不对称右倾“海鸥”型,δEu亏损中等,岩石具较低的εNd（t）值（-3．00）和低的86Sr／87Sr初始值（0．708734）。以上岩体的岩石学、主微量元素及同位素特征表明,岩体具有铝质A1型花岗岩的特征,其成因与陆内巨量火山喷发造成的伸展、崩塌机制有关,反映了非造山板内拉张的构造环境。  相似文献   

深圳市公安地理信息系统数据库建设     

肖昶  邱儒琼  王波  李丹 《地理空间信息》2006,4(2):33-34

根据深圳市公安局警用地理信息系统数据库建设的实际经验,阐述了系统后台的数据组织和库体设计,并就数据库的安全与维护进行探讨。  相似文献   

Soil erosion and conservation on land cultivated and drained for afforestation     

P. A. Carling  M. S. Glaister  T. P. Flintham 《水文研究》1993,7(3):317-333

Erosion of soil from pre-afforestation plough furrows has been measured on four soil types in Scotland for 12 to 18 month periods between 1987 and 1990. Rainfall-run-off was also measured at one site. Run-off is directly proportional to furrow length and rainfall intensity, and for a wide range of intensities (typically > 6 mm hr^?1) small amount of soil is flushed out of the furrows. However, for furrow spacings of 3.8 m, a critical downslope run-off increment associated with significant soil loss is of the order of 25 cm³ s^?1 m^?1, which is in accord with a storm of five years return period and a maximum intensity of 25 mm hr^?1. The total run-off volume for any hydrograph is commensurate with the total rainfall in the rainstorm — typically 40–80% by the hydrograph peak and approaching 100% by the end of the hydrograph; i.e. long term storage is negligible. A positive relationship was recorded between furrow length, slope angle and sediment yield, with deposition predominating in furrows less than 30 m in length on slopes less than a few degrees. Soil loss is proportional to the excess streampower expended by the run-off with an exponent in the range 1–1.5. For the soils examined, significant differences in soil loss when comparing sites for low power expenditure become undifferentiated at high power expenditures. For the rainfall regimes monitored, maximum soil losses were in the region of 40 kg per meter run-length of furrow, when soil peds were ripped from the bed. Laboratory data concerning the critical erosion threshold power and shear stress to erode soil peds are in general accord with the threshold furrow run-lengths defined using the field data for a five year storm and the soil losses observed.  相似文献   

Hydrologic characteristics of Appalachian loose‐dumped spoil in the Cumberland Plateau of eastern Kentucky     

Timothy J. Taylor  Carmen T. Agouridis  Richard C. Warner  Christopher D. Barton  Patrick N. Angel 《水文研究》2009,23(23):3372-3381

Heavily compacted lands, typical of traditional surface mine reclamation techniques, have been shown to hinder tree growth, increase levels of flooding, and produce suboptimal water quality. Utilizing loose‐dumped spoil, in accordance with the Forestry Reclamation Approach (FRA), has demonstrated success with regards to promoting tree growth and survival; however, additional information is needed to assess the potential of FRA to ameliorate other environmental concerns related to water quantity. To better understand the hydrologic characteristics of loose‐dumped spoil, key hydrograph parameters (discharge volume, peak discharge, discharge duration, lag time, and response time) were monitored for three common spoil types: (1) predominately brown weathered sandstone, (2) predominately gray weathered sandstone, and (3) a mixture of both sandstones and shale. Although spoil types were found to differ hydrologically, these differences were relatively minor. Measured discharge volumes were low (averaging 12% of rainfall for all events and treatments), peak discharge rates were small (between 2·5 × 10^?5 and 3 × 10^?3 m³/s), and the duration of discharge was long (6 days on average). From a hydrologic perspective, the results of this study indicate that mine spoils need not be segregated for reclamation as long as the spoil is placed in accordance with the loose‐dumped techniques as outlined in the FRA. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Predicting individual tree attributes from airborne laser point clouds based on the random forests technique   总被引：2，自引：0，他引：2  

Xiaowei Yu  Juha Hyyppä 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(1):28-37

This paper depicts an approach for predicting individual tree attributes, i.e., tree height, diameter at breast height (DBH) and stem volume, based on both physical and statistical features derived from airborne laser-scanning data utilizing a new detection method for finding individual trees together with random forests as an estimation method. The random forests (also called regression forests) technique is a nonparametric regression method consisting of a set of individual regression trees. Tests of the method were performed, using 1476 trees in a boreal forest area in southern Finland and laser data with a density of 2.6 points per m². Correlation coefficients (R) between the observed and predicted values of 0.93, 0.79 and 0.87 for individual tree height, DBH and stem volume, respectively, were achieved, based on 26 laser-derived features. The corresponding relative root-mean-squared errors (RMSEs) were 10.03%, 21.35% and 45.77% (38% in best cases), which are similar to those obtained with the linear regression method, with maximum laser heights, laser-estimated DBH or crown diameters as predictors. With random forests, however, the forest models currently used for deriving the tree attributes are not needed. Based on the results, we conclude that the method is capable of providing a stable and consistent solution for determining individual tree attributes using small-footprint laser data.  相似文献   

Integrating agriculture and climate change mitigation at landscape scale: Implications from an Australian case study     

《Global Environmental Change》2014

Rural and regional hinterlands provide the ecosystem service needs for increasingly urbanised communities across the globe. These inter-related ecosystem services provide key opportunities in securing climate change mitigation and adaptation. Their integrated management in the face of climate change, however, can be confounded by fragmentation within the complex institutional arrangements concerned with natural resource management. This suggests the need for a more systemic approach to continuous improvement in the integrated and adaptive governance of natural resources.This paper explores the theoretical foundations for integrated natural resource management and reviews positive systemic improvements that have been emerging in the Australian context. In setting clear theoretical foundations, the paper explores both functional and structural aspects of natural resource governance systems. Functional considerations include issues of connectivity, knowledge use and capacity within the natural resource decision making environment. Structural considerations refer to the institutions and processes that undertake planning through to implementation, monitoring and evaluation.From this foundation, we review the last decade of emerging initiatives in governance regarding the integration of agriculture and forests across the entire Australian landscape. This includes the shift towards more devolved regional approaches to integrated natural resource management and recent progress towards the use of terrestrial carbon at landscape scale to assist in climate change mitigation and adaptation. These developments, however, have also been tempered by a significant raft of new landscape-scale regulations that have tended to be based on a more centralist philosophy that landowners should be providing ecosystem services for the wider public good without substantive reward.Given this background, we explore a case study of efforts taken to integrate the management of landscape-scale agro-ecological services in the Wet Tropics of tropical Queensland. This is being achieved primarily through the integration of regional natural resource management planning and the development of aggregated terrestrial carbon offset products at a whole of landscape scale via the Degree Celsius initiative. Finally, the paper teases out the barriers and opportunities being experienced, leading to discussion about the global implications for managing climate change, income generation and poverty reduction.  相似文献   

Governing agriculture-forest landscapes to achieve climate change mitigation     

《Global Environmental Change》2014

This introduction to the special section on “Governing Agriculture-Forest Landscapes to Achieve Climate Change Mitigation” reviews external interventions to improve forest conditions and reduce deforestation, and by extension, influence carbon storage in agriculture-forest landscapes. The review is based on a careful survey of 123 cases of project-based and policy interventions to influence land use and forest cover outcomes. We propose that outcomes of interventions can be explained in terms of rights, incentives, and technologies related to land use and apply this framework to examine 12 types of interventions in agriculture-forest landscapes. The analysis of the identified 123 cases raises concerns about consistency of data and comparability of cases. Our preliminary evidence suggests limited association between the stated objective of an intervention and its success. This evidence also suggests that smaller scale and effective enforcement may be positively associated with improved forest outcomes. But the effectiveness of interventions across different agriculture-forest landscapes varies and available evidence does not permit easy generalizations. The variable effects of interventions across different agriculture-forest landscapes point to the need to better understand the forms and functions of interventions and to problems associated with assessing their relative efficacy.  相似文献   

Landslide hazard zonation mapping in ghat road section of Kolli hills,India   总被引：2，自引：0，他引：2  

Siddan Anbazhagan  Veerappan Ramesh 《山地科学学报》2014,11(5):1308-1325

Landslides are the most common natural disaster in hilly terrain which causes changes in landscape and damage to life and property. The main objective of the present study was to carry out landslide hazard zonation mapping on 1：50,000 scale along ghat road section of Kolli hills using a Landslide Hazard Evaluation Factor（LHEF） rating scheme. The landslide hazard zonation map has been prepared by overlaying the terrain evaluation maps with facet map of the study area. The terrain evaluation maps include lithology, structure, slope morphometry, relative relief, land use and land cover and hydrogeological condition. The LHEF rating scheme and the Total Estimated Hazard（TEHD） were calculated as per the Bureau of Indian Standard（BIS） guidelines（IS： 14496（Part-2） 1998） for the purpose of preparation of Landslide Hazard Zonation（LHZ） map in mountainous terrains. The correction due to triggering factors such as seismicity, rainfall and anthropogenic activities were also incorporated with Total Estimated Hazard to get final corrected TEHD. The landslide hazard zonation map was classified as the high, moderate and low hazard zones along the ghat road section based on corrected TEHD.  相似文献