Streamside Forest Buffer Width Needed to Protect Stream Water Quality,Habitat, and Organisms: A Literature Review

This literature review addresses how wide a streamside forest buffer needs to be to protect water quality, habitat, and biota for small streams (≤~100 km² or ~5th order watershed) with a focus on eight functions: (1) subsurface nitrate removal varied inversely with subsurface water flux and for sites with water flux >50 l/m/day (~40% avg base flow to Chesapeake Bay) median removal efficiency was 55% (26‐64%) for buffers <40 m wide and 89% (27‐99%) for buffers >40 m wide; (2) sediment trapping was ~65 and ~85% for a 10‐ and 30‐m buffer, respectively, based on streamside field or experimentally loaded sites; (3) stream channel width was significantly wider when bordered by ~25‐m buffer (relative to no forest) with no additional widening for buffers ≥25 m; (4) channel meandering and bank erosion were lower in forest but more studies are needed to determine the effect of buffer width; (5) temperature remained within 2°C of levels in a fully forested watershed with a buffer ≥20 m but full protection against thermal change requires buffers ≥30 m; (6) large woody debris (LWD) has been poorly studied but we infer a buffer width equal to the height of mature streamside trees (~30 m) can provide natural input levels; (7, 8) macroinvertebrate and fish communities, and their instream habitat, remain near a natural or semi‐natural state when buffered by ≥30 m of forest. Overall, buffers ≥30 m wide are needed to protect the physical, chemical, and biological integrity of small streams.     

基于分形模型的城市空气质量评价方法研究

基于分形模型开展了城市空气质量的评价方法研究.首先利用分形求和模型分析大气污染物分布特征,用分维数定量描述其浓度分布随机程度,开展了城市空气质量评价的背景值和标准值的确定方法研究.然后在此基础上基于橡树岭大气环境质量指数评价方法,确定了基于二氧化硫、二氧化氮、PM10三项污染物的中国城市人为源空气质量评价方法模型.最后以西安市为示范区,利用本研究方法确定了西安市的大气环境背景值和评价标准值,建立了适用于西安市的大气环境质量指数模型,并开展了2010年该市全年环境质量分析评价工作.结果表明,基于分形模型的评价结果认为西安市空气质量年变化呈“U”字型分布,该方法比常规环境空气质量评价方法更能表现出空气质量的变化规律和季节分布特征.总体上,2010年西安市空气质量良好,未受到污染天数占83%,但是受沙尘天气影响比较大;西安市空气质量随季节变化特征比较明显,夏季和秋季空气质量较好,受污染程度较低,冬季和春季空气质量较差,受污染程度偏高.     

地铁站细水雾幕挡烟效果的数值模拟研究

地铁站台层发生火灾时,烟气会从站台层经过楼扶梯开口蔓延至站厅层,因此, 楼扶梯开口处的挡烟效果对人员安全疏散影响重大。通过搭建全尺寸地铁站数值模拟模 型,对细水雾幕和排烟系统作用下楼扶梯开口处的挡烟效果进行了模拟研究,结果表明 :当仅设置挡烟垂壁时,挡烟垂壁有一定的蓄烟作用,但仍有大量烟气通过楼扶梯开口 从站台层蔓延至站厅层;设置细水雾幕可在一定程度上阻止烟气通过楼扶梯开口从站台 层蔓延至站厅层,有效降低烟气温度,但由于细水雾向下的冲量破坏烟气层的稳定性, 使得细水雾幕附近的烟气层高度降低;同时设置细水雾幕和排烟系统可实现良好的挡烟 效果,在楼扶梯的中段附近已基本不受火灾烟气的影响。     

基于GIS和LSA的林地质量评价与保护分区

合理划定林地利用保护分区,对于稳定森林资源,维持生态平衡,协调经济建设与生态文明建设起到积极指导和规范作用.论文以海南省屯昌县为例,在科学评价林地质量的基础上,采用局部空间自相关分析法(LSA),探索林地质量在空间上的分布特性,耦合林地自然条件,社会经济及其空间属性,以作为林地保护分区的依据.结果显示:屯昌县林地质量分值在[5.40, 8.56]之间,整体水平中等偏上,内部差异性较小,其中,高等别林地主要分布在南坤镇与枫木镇交界处以及西昌镇西南部,低等别林地主要分布在坡心镇及南吕镇;全县林地质量在空间分布上表现出较强的正相关性,存在一定的空间聚集性特征;基于林地质量局部空间自相关分析的林地保护分区方案与林地质量评价结果基本吻合,可将全县分为重点保护区,积极保护区和一般保护区,不同保护区根据自相关类型的差异可采取不同的管护措施.该研究将空间属性纳入到林地保护分区方案的制定中,拓展了林地保护分区的手段,可为合理制定林地利用规划提供科学依据和思路借鉴.     

China's endemic vertebrates sheltering under the protective umbrella of the giant panda

The giant panda attracts disproportionate conservation resources. How well does this emphasis protect other endemic species? Detailed data on geographical ranges are not available for plants or invertebrates, so we restrict our analyses to 3 vertebrate taxa: birds, mammals, and amphibians. There are gaps in their protection, and we recommend practical actions to fill them. We identified patterns of species richness, then identified which species are endemic to China, and then which, like the panda, live in forests. After refining each species' range by its known elevational range and remaining forest habitats as determined from remote sensing, we identified the top 5% richest areas as the centers of endemism. Southern mountains, especially the eastern Hengduan Mountains, were centers for all 3 taxa. Over 96% of the panda habitat overlapped the endemic centers. Thus, investing in almost any panda habitat will benefit many other endemics. Existing panda national nature reserves cover all but one of the endemic species that overlap with the panda's distribution. Of particular interest are 14 mammal, 20 bird, and 82 amphibian species that are inadequately protected. Most of these species the International Union for Conservation of Nature currently deems threatened. But 7 mammal, 3 bird, and 20 amphibian species are currently nonthreatened, yet their geographical ranges are <20,000 km² after accounting for elevational restriction and remaining habitats. These species concentrate mainly in Sichuan, Yunnan, Nan Mountains, and Hainan. There is a high concentration in the east Daxiang and Xiaoxiang Mountains of Sichuan, where pandas are absent and where there are no national nature reserves. The others concentrate in Yunnan, Nan Mountains, and Hainan. Here, 10 prefectures might establish new protected areas or upgrade local nature reserves to national status.     

近35年广东省区域灰霾天气过程的变化特征及突变分析

利用广东省86个地面观测站1980～2014年逐日能见度、相对湿度资料,在对“区域灰霾过程”与“单站灰霾过程”进行定义的基础上,分区域诊断典型灰霾天气过程（即连续三站3d及以上出现灰霾日的天气过程）,并对其长期变化趋势及特征进行分析.结果表明：广东省的灰霾过程主要出现在珠江三角洲、粤北及粤东个别地区,并以珠江口以西的珠江三角西侧最为严重.“区域灰霾过程”以日平均能见度在5～10km之间的过程为主,没有出现过日平均能见度低于2km的重度灰霾过程.各“区域灰霾过程”的特征有所差异：首先是各“区域灰霾过程”出现峰值的时间略有差异.尽管灰霾过程均主要出现在10月～翌年4月,但粤北和粤东、西两翼最多出现在冬季（12月～翌年1月）、春季次之,而珠江三角洲地区则最多出现在春季（3～4月）、冬季次之.其次是各“区域灰霾过程”变化趋势的差异.珠江三角洲地区和粤北地区灰霾过程变化趋势比较相似,在2008年以前总体呈增多趋势,珠江三角洲地区增势最为显著的时段是2000～2008年,而粤北地区则是1991～2011年;粤西地区灰霾过程在2000年以前变化都比较平稳,2004年开始快速增多;粤东地区的灰霾过程近35年来虽有小的波动,但总体变化不大,呈稳中略减的趋势.利用M-K法和滑动t检验的突变分析表明,珠江三角洲地区灰霾过程的增多是一种不连续的突变现象,发生突变的时间点是1986年;粤北地区灰霾过程则在1992～1994年出现了突发性增多的现象;粤西地区灰霾过程也在2001年发生了突变.     

响应突发事件的大型装备应急备件调度模型研究

研究大型装备备件供应网络面临大规模突发事件时的应急备件调度问题。首先采用信息熵理论对应急维修点进行优先度权重排序;其次建立应急响应时间和需求满意度函数,并将量化后的时间满意度和需求满意度以作为模型的目标函数,构建了网络供应状态下应对突发事件的备件调度规划模型;最后以某大型装备企业备件的应急备件调度为例,验证了模型的有效性,给出调度优化方案。     

Analysis of deforestation pattern in the Niger Delta region of Nigeria

This study examines deforestation in a part of the Niger Delta region of Nigeria between 1987 and 2013 using remote sensing data and geographic information systems. The results indicate an increasing rate of deforestation, an increasing rate of water body loss and a decreasing rate of exposed surface/settlement increase. The results also show that the rate at which cropland/secondary vegetation is increasing is above average while sandbar is increasing below average. The implications of these changes include environmental degradation resulting from loss of biodiversity and loss of forest goods and services. These losses can also affect the social and economic conditions of local people. The study recommends that policies and strategies targeted at slowing down the rate of forest loss and degradation should be pursued.     

Spatially explicit models of land abandonment in the Amazon

Given growing concerns about biodiversity loss and carbon emissions stemming from tropical deforestation, it is important to identify the factors associated with land abandonment as they might indicate areas that were deforested but are unsuitable for long-term cultivation. This article utilizes a high-resolution, Landsat-based data-set called TerraClass to relate land abandonment to precipitation, slope, farmgate price of beef, market access, soil quality, and land tenure characteristics in the Brazilian Amazon. The spatially explicit statistical models reveal that rates of land abandonment increase with higher rainfall and slope values, even when controlling for distance to roads, farmgate prices, type of settlement, and soil quality. Moreover, land adjacent to a major road is more likely to be consistently cultivated, but land near large rivers and far from highways is more likely to be abandoned. Land ownership type also influences the likelihood of land abandonment as settlements based on communal property rights have higher rates of land abandonment than settlements with private lots. These results suggest that policies aimed at occupying tropical forests such as the Amazon must consider these biophysical and socioeconomic factors in order to foster human development aligned with sustainability principles.     

Book Reviews

The study focused on the so-called dark coniferous forest belt on the northern slope of Changbai Mountain, at an altitude of 1100 to 1700 m. Forty tree species, 50 shrub species and 165 herb species were recorded in a series of transects. The main impact factors on forest diversity and proposals for sustainable management of this diversity were studied using an altitude and area gradient pattern method. The results showed that the diversity of dark coniferous forest gradually decreased from lower to upper altitude; while the importance value of key species increased. The methodology used to assess attributes for conservation of dark coniferous forest diversity involved measurement of individual trees, number of species, age structure, stand structure, diameter at breast height (DBH), and cumulative wood storage. Different conservation strategies have been developed and are discussed for different parts of the forest.