基于农用地分等的耕地等级折算研究——以呼和浩特市为例

耕地占补平衡由数量型向数量—质量型综合平衡管理的升级,已成为当前土地资源管理工作的重要任务。本文以呼和浩特市为例,在农用地分等成果的基础上,以单位标准粮产量为桥梁,确定耕地质量数量等级折算系数,从而实现耕地占补的数量—质量综合平衡。     

Geospatial analysis for utilizing the marginal land in regional biofuel industry: A case study in Guangdong Province,China

Due to the intensive and exhaustive land use in China, the so-called marginal land is expected to play a major role in supporting the biofuel industry of the country. We developed a regional-level framework of using geospatial information technologies to achieve an optimal utilization of the marginal land for biofuel production. The framework includes identifying marginal lands, evaluating optimality of the land for growing certain bioenergy crops, estimating local potential feedstock production, and finally selecting optimal sites for biofuel factories. We present a case study of farming Jatropha (Jatropha curcas L.) and Cassava (Manihot esculenta Crantz) in Guangdong, China. The marginal land was identified from satellite imageries at a 30-m resolution. The optimality for growing the two species was evaluated using the Ecological Niche Models (ENMs), which incorporates local temperature, precipitation, soil, and terrain. The optimality value was then converted into potential feedstock production using a conversion model. The site selection for the factories incorporated the local potential feedstock production, the transportation cost measured by road distance, and the farming cost related to the land patch geometry. Each candidate site received an overall optimality score derived based on those factors. We identified five sites that have high scores and also minimal or none spatial overlaps of their supporting areas. Three of them (Zhanjiang, Yunfu, and Jieyang) are for Cassava, located on in southern Guangdong. Two (Qingyuan and Meizhou) are for Jatropha in northern Guangdong.     

建立中国矿产地战略储备探讨

全球目前开展矿产地储备国家不多,美国是开展矿产地储备比较成功的国家,在储备原则、对象、目的和管理部门等方面都有明确的规定。影响矿产地战略储备的因素主要有综合国力、资源禀赋、科技水平、国际政治和经济环境等。相比矿产品储备,中国矿产地战略储备有显著的优势和功能。中国短缺矿产资源尽量以矿产品储备为主,优势矿产资源尽量采取矿产地储备;矿产地储备的基本思路是优势矿产进行优质资源地储备,短缺矿产储备边界品位资源。矿产地储备备选区主要有7类。     

Evaluating the Impact of Daily Net Radiation Models on Grass and Alfalfa-Reference Evapotranspiration Using the Penman-Monteith Equation in a Subhumid and Semiarid Climate

Net radiation (Rn) is the main driving force of evapotranspiration (ET) and is a key input variable to the Penman-type combination and energy balance equations. However, Rn is not commonly measured. This paper analyzes the impact of 19 net radiation models that differ in model structure and intricacy on estimated grass and alfalfa-reference ET (ETo and ETr, respectively) and investigates how climate, season and cloud cover influence the impact of the Rn models on ETo and ETr. Datasets from two locations (Clay Center, Nebraska, subhumid; and Davis, California, a Mediterranean-type semiarid climate) were used. Rn values computed from the 19 models were used in the standardized ASCE-EWRI Penman-Monteith equation to estimate ETo and ETr on a daily time step. The influence of seasons on the estimation of Rn and on estimated ETo and ETr was investigated in winter (November–March) and summer (May–September) months. To analyze the influence of clouds on the impact of Rn models, relative shortwave radiation (Rrs) was used as a means to express the cloudiness of the days as: 0 ≤ Rrs ≤ 0.35 for completely cloudy days; 0.35相似文献   

Participatory landscape analysis to guide restoration of ponderosa pine ecosystems in the American Southwest

Over the past 5 decades, stand-replacing crown fires have increased in size and frequency throughout the long-needled pine forests of the American Southwest. Suppression of frequent, low-intensity ground fires has resulted in dense stands of fire-prone trees over large areas. Efforts to restore forest structure to conditions that would permit a return to historical fire regimes, characterized by frequent ground fire, are hindered by the inability of managers and the public to compare the effects of alternative forest management practices on fire behavior and a host of other issues. Currently, forest management is mired in controversy, endangering ecosystem function, biodiversity, public safety, and municipal watersheds. Our research program, motivated by the need to examine cumulative effects of many independent management decisions over large planning areas, focuses on the development of spatial data and modeling tools that enable diverse stakeholders to work together to guide landscape-scale planning efforts. Data layers describing forest composition and structure facilitate modeling of fire threat and wildlife habitat over areas of several hundred thousand hectares. Modeling alternative forest management scenarios via a collaborative, public process fosters informed discourse and helps conflicting parties forge appropriate policy and identify management responses that meet restoration objectives.     

神府东胜煤田开发中扰动地面径流泥沙模拟研究

神府东胜国家级特大煤田在开发建设过程中,严重扰动了原有的土壤结构层次,破坏了地面的植被,造成了严重的新增水土流失,本文采用野外放水冲刷实验的研究方法,对神府东胜煤田开发建设中人为扰动地面侵蚀产沙规律进行了模拟研究。结果表明:5°条件下在流量为15 L/min2、0 L/min2、5 L/min时产沙量与径流量呈幂函数关系,10 L/min时呈线性关系。11°条件下在各放水流量时的产沙量与径流量呈线性关系。17°条件下流量为10 L/min1、5 L/min时产沙量与径流量呈对数函数关系,20 L/min2、5 L/min时呈线性关系。产沙量与坡度在放水流量10 L/min2、5 L/min时呈对数函数关系,在放水流量15 L/min2、0 L/min时呈线性关系变化。径流量与放水流量呈线性关系,产沙量与放水流量呈对数函数关系。     

林地调查中的面积单元线性测量法（SL法）

林业调查中采用的基本方法是全林调查法和局部估测法,而局部估测方法中最常用的是角规测量法与标准地法,在林地调查中角规法误差较大,而标准地法又存在着难于布设的问题。本研究提出的面积单元线性测量法,可方便快捷地进行局部估测,节省人力和时间,同时又达到了较高的精度,特别适用于不规则林分的调查。     

城市混合用地停车共享需求模型——以北京市华贸中心为例

基于停车泊位共享的思路,通过停车需求调查,分析了典型混合用地北京市华贸中心的停车需求特性,建立了基于单一用途建筑物停车需求叠加模型和停车需求共享模型,通过比较,停车共享模型计算的误差明显低于利用叠加方法的误差.     

发达国家矿地复垦保证金制度及对中国的启示

采矿业是国民经济的支柱产业，但矿产资源的开采也带来了一系列矿山环境问题。发达国家自20世纪70年代就开始制定矿地复垦法律，建立了矿山环境恢复与土地复垦保证金制度。我国矿山环境问题比较严重，而矿山土地复垦资金不足。因此，我国有必要借鉴国外发达国家成熟的矿地复垦立法经验，建立矿山环境治理保证金制度，以恢复矿产资源开采过程中被破坏的土地。     

松嫩平原盐碱地研究存在的两个问题

论述松嫩平原盐碱化研究中存在的两个问题:①对松嫩平原盐碱化土地面积有多种不同的表达,且各种表达之间差异较大;②对松嫩平原盐碱化程度判别标准不尽一致.同时分析了出现这些问题的原因.笔者建议有关方面通力协作,规范松嫩平原土地盐碱化的判定标准,对当前松嫩平原盐碱化土地面积做出相对准确的分析和判断,为振兴东北工业基地、建立可持续发展环境提供科学决策依据.