广州白云山常绿阔叶林的结构特征

在线路调查和样方调查的基础上分析了广州白云山常绿阔叶林的结构特征，群落主要由亚热带科属组成，优势科为芸香科，五加科，茜草科，山茶科，壳斗科，鼠刺科，樟科等。优势树种也以相应的优势科属树种为主，群落中胸径≥3cm的个体密度较小，只有1964株/hm^2；群落较为低矮，平均高度只有6m；乔木垂直分化不明显，树种水平分布不均，白云山的植被是次生植被和人工造林改造的结果，只在山谷少数植被没受人类干扰，其现状植被是天然次生植被和人工植被的混合体，在一些由马尾松发展起来的群落，天然侵入的阔叶树种已在主要层中居优势；群落中可见马尾松衰退的痕迹。     

1982―1983年、2008―2010年东江东莞段水系小型浮游动物的群落特征比较

分两时段调查东江东莞段水系小型浮游动物的群落结构。结果表明,1982―1983年检出有61属109种,年际平均密度303.7个/L,生物量0.070 8 mg/L;2008―2010年检出有46属91种,年际平均密度1 350.4个/L,生物量0.845 6 mg/L。两时期的群落相似性指数为63%,纤毛虫最低仅26.3%,优势种相似性指数为50%;2008-2010年有23个物种没检出,新检出有23种。群落构成从1982―1983年的自养、食藻的原生动物与喜贫营养的轮虫群落为主,演替为2008–2010年以耐污食菌及碎屑的原生动物与喜富营养的轮虫群落为主,显现群落结构趋简单化,物种数减少,生物量增大,优势种的优势度非常明显,耐污(富营养)指示种大量出现。这与调查水质变化有关。     

湛江高桥红树林区虾类群落的时空变化

研究2005-2008年广东省湛江市英罗湾高桥3个红树林区(红坎、两头流、西村)虾类群落的变化特征,并分析虾类群落组成与水质指标(盐度,pH)和沉积物指标(pH、可溶性盐、有机质、黏土、粉砂、砂砾)的相关性。结果表明:3个区域捕获虾类13596尾,属3科5属9种,刀额新对虾是高桥虾类的优势种;虾类种类年际变化较大,年间相似度平均为70.4,区域间相似度平均为60.6;红坎虾类多样性较丰富,两头流虾类的优势种明显,各年优势度指数均达0.95以上;3个区域的主要生态因子年间差异不显著(P>0.05);红坎3个采样点的底质性状较复杂,其沉积物特性差异显著(P<0.05),两头流和西村的底质性状较为单一,其沉积物特性均差异不显著(P>0.05)。群落变化特征和沉积物性状有显著相关关系,表明高桥虾类的渔获量受人为因素影响,多样性和分布受环境影响。     

齐家文化时期(4200～3600 cal. a BP)青藏高原高庙盆地植被重建及与现今对比

高庙盆地是青藏高原史前文化重要活动区域,也是青藏高原东北缘植被垂直地带性最为显著的地域,是揭示自然环境与人类活动相互作用的典型区域。对高庙盆地店子坪遗址剖面开展了年代学与孢粉研究,重建了齐家文化时期的区域植被状况。结果表明:孢粉组合以松属、云杉属、蒿属为主,并伴有少量桦属、鹅耳枥属、榆属、沙棘属、藜科、菊科;结合高庙盆地现今地貌与植被分布特征,推测齐家文化时期(4 200～3 600cal.a BP)盆地内植被类型为森林草原,低阶地以松林为主,并有少量的榆、鹅耳枥和桤木等温带落叶阔叶性树种,属于温性针阔混交林,高阶地及中山地为以蒿属为主的温性草原,沟谷阴坡则可能生长以松、云杉为主的针叶林;与现今植被相比,青藏高原东北缘河谷地带低阶地现今已无松林,全被杨树林等人工林替代,云杉、松分布区较齐家文化时期显著萎缩,仅在中—高山地带呈岛状不连续分布,推测历史时期人类活动可能是青藏高原东北缘河谷地带植被变化的重要驱动力。     

基于DEM的广西宁明林地生产力的探讨

文章以广西宁明主要树种马尾松和桉树为例,在GIS技术的支持下,利用高精度的DEM数据快速提取了地形地貌因子参数,基于此建立了马尾松和桉树的生产力估算模型,并预测了研究区域潜在的森林生产力,以期为林业部门营造林树种提供决策依据.     

雷州半岛东部近岸海域大型底栖甲壳动物群落结构及其影响因子

【目的】研究雷州半岛东部近岸海域大型底栖经济甲壳动物的群落结构及其影响因素,为甲壳类资源评估与合理利用提供参考依据。【方法】于2016年4月至2017年2月按季度在该海域开展4个航次的渔业资源底拖网调查,采集经济甲壳动物样品,并进行分类鉴定,同时采集环境数据。采用聚类分析和冗余分析(RDA),评价该海域不同季节甲壳动物群落结构特征及其与环境因子的关系。【结果】共有甲壳动物98种,隶属2目24科43属;全年优势种有变态蟳(Charybdis variegata)、哈氏仿对虾(Parapenaeopsis hardwickii)和须赤虾(Metapenaeopsis barbata)等10种;各季节丰富度指数(D)、多样性指数(H′)、均匀度指数(J′)均以夏季最高,冬、春季次之,秋季最低;各季节均可划分为两个群落(Anosim test:0.579相似文献   

流沙湾贝类资源调查

对流沙湾潮间带及湾内浅水地带(20°22'103″～20°28'526″N,109°55'341″～109°59'185″E)的贝类资源进行周年调查,定性、定量分析该海湾贝类种类、生态分布、区系性质、群落结构及生物量的季节变化规律。结果表明:在流沙湾采集到的贝类有3纲7亚纲13目42科79属104种,其中帘蛤科24种,牡蛎科、贻贝科各6种,汇螺科和蜒螺科各5种,其他各科均小于5种;贝类组成表现出温带性质,温带种类占绝对优势,该海湾贝类区系属印度—西太平洋的中国-日本亚区,生物量的季节变化明显。     

夏、冬季杭州湾北部游泳动物群落结构

利用相对重要性指数、等级聚类和多元统计等方法对该海域游泳生物种类组成、优势种及群落结构进行分析,研究杭州湾北部游泳动物群落结构特征。夏、冬季共发现40种游泳生物,隶属12目22科33属,鲈形目及十足目生物所占比率最高,分别为32.5%和35%,而鲈形目、十足目中又分别以石首鱼科(38.5%)和长臂虾科(28.6%)所占比率最高;夏季优势种为棘头梅童鱼(Collichthys lucidus)和安氏白虾(Exopalaemon annandalei),冬季优势种为刀鲚(Coilia ectenes)、焦氏舌鳎(Cynoglossus joyneri)、髭缟虾虎鱼(Tridentiger barbatus)、葛氏长臂虾(Palaemon gravieri)、日本鼓虾(Alpheus japonicas)和狭颚绒螯蟹(Eriocheir leptognathus),两时期无共同优势种。等级聚类和非度量多维标序排序表明,杭州湾北部游泳生物群落可分为夏季和冬季2个组群,相似性检验(ANOSIM)显示2个组群差异极显著(R=0.881,P0.01)。BIOENV表明温度是影响杭州湾北部游泳动物群落结构的最主要环境因子,相关系数为0.773。杭州湾海域是棘头梅童鱼、凤鲚等多种游泳动物产卵和索饵场所,群落结构具有典型的季节特征。     

脱硫海水受纳海域浮游桡足类对环境因子的群落响应

【目的】研究电厂排水口附近海域周年浮游桡足类群落对脱硫海水受纳海域环境因子的群落响应。【方法】2016年4、7、9、12月分别对湛江自备电厂附近海域的浮游桡足类群落结构及相关环境因子进行了调查。【结果与结论】共鉴定出浮游桡足类41属83种和11类幼体,其中四季种类数为春季27种,夏季31种,秋季47种,冬季43种,分别占浮游动物种类数的18.2%、20.9%、31.9%、29%。种类最多的是大眼剑水蚤属达8种,其次为长腹剑水蚤属7种,唇角水蚤属5种,隆哲水蚤属和歪水蚤属各4种。其中优势种共有8种,无四季优势种,3季都为优势种的有钳形歪水蚤Tortanusforcipatus和太平洋纺锤水蚤Acartiapacifica。浮游桡足类丰度呈现秋季夏季春季冬季的规律,大致符合涨潮丰度增加,落潮丰度减小,远岸丰度低于近岸的规律。Sperman相关性表明,浮游桡足类丰度与夏季pH和温度呈现显著负相关关系,与夏季盐度呈现极显著正相关关系,且温盐是解释夏季浮游桡足类丰度差异的最佳组合。从4个断面分析结果可知,秋季浮游桡足类分布受断面影响显著,秋季断面pH值差异显著。     

泛北极地区植被数据集与制图：回顾与展望

泛北极地区位于北半球高纬度地区,主要属于低温限制型生态系统,因而泛北极地区植被对全球变暖敏感。要明确泛北极地区陆地生态系统对全球变暖响应过程和机理,就需要高精度的植被类型分类数据作为基础资料。但是,目前泛北极地区植被数据的结果还不完善。为更好地认识泛北极地区植被类型分类的现状、发展历史和未来研究方向,本文综述了泛北极地区植被类型制图的数据来源、植被类型划分方法和植被类型制图研究方法。总体而言,泛北极地区的植被调查从20世纪20年代就陆续开展,目前部分区域尺度上的地表覆盖类型的结果,但具体的植被类型制图工作还存在一系列难题。主要原因包括植被野外调查实测数据较少和分布不均、植被类型分类标准不一、苔原植被群落的异质性大、制图技术和分类算法优化困难等。因此,在下一步泛北极植被类型制图工作中,需要制定标准化分类策略,规范数据获取及数据库的整理工作,并发展新的制图方法,从而促进植被类型制图研究工作。     

信息化社区浅谈

本文简要论述了信息化社区的基本概念及其特点 ;同时分析了信息化住宅与社区的结构特征。另外 ,介绍了信息化社区的功能及小区管理任务。这对现代城市化的信息化社区的建设有现实意义.     

国际矿产勘探面临的社会挑战

随着矿业由发达国家向发展中国家的渗透、发展，矿业界所面临的当地公众关系、社会政治压力和环境保护等。社会问题也日趋扩大和严重，矿业公司从勘探阶段就建立良好的公司—公众关系，已成为国际勘探项目是否成功的关键因素之一。     

Plant diversity as a good indicator of vegetation stability in a typical plateau wetland

Biotic indicators have been widely used to monitor wetland health. However, few studies have explicitly evaluated if plant diversity could serve as a useful community-level indicator of wetland stability, especially when wetlands are confronted with anthropogenic perturbations. Based on three-year record of wetland plant species abundance in Napahai plateau wetland, Shangri-la under the influence of varying anthropogenic perturbation types, our study tests the impact of such perturbations on plant richness and the relationship between ecosystem temporal stability and plant richness, and further assesses the effectiveness of using plant diversity indicator to probe ecosystem temporal stability of Napahai plateau wetland and the potential mechanisms. The results showed that anthropogenic perturbations could have contributed significantly to realistic variation in plant diversity, and further demonstrated that ecosystem temporal stability was positively related to realistic variation in plant diversity. In particular, communities with high levels of diversity might have better capacity to dampen perturbation impacts than communities with low levels of diversity, and statistical averaging could have played an important role in causing greater stability in more diverse communities. Also, asynchrony might have a stabilizing effect on community stability, and diversity could have stabilized communities through both species asynchrony and population stability propagation. Therefore, our results suggest that plant diversity could be used as a useful indicator of the stability conditions of plateau wetland ecosystems confronted with anthropogenic perturbations, and the preservation of plant communities at sufficient abundance and diversity is necessary for maintaining healthy plateau wetlands and for sustaining their essential ecosystem functions and services.     

Production dynamics and life cycle of dominant chironomids （Diptera, Chironomidae） in a subtropical stream in China： adaptation to variable flow conditions in summer and autumn

The production dynamics and trophic basis of 7 dominant species of chironomids were investigated in the area of a second-order river of the Hanjiang River basin, in central China from June 2003 to June 2004. The results showed that Tvetenia discoloripes was by far the most abundant chironomid, dominating the overall standing stock of the taxa. In terms of life cycle, Chaetocladius sp., Eukiefferiella potthasti and T. discoloripes developed 1 generation a year, whereas Microtendipes sp. and Pagastia sp. developed two, while Pentaneura sp. and Polypedilum sp. developed three. T. discoloripes was the most productive chironomid with 120.305 8 g/m2.a, Pentaneura sp. and E. potthasti had relatively high production values of >17 g/m2.a, and the rest were <10 g/m2.a. All the production temporal variation tended to follow biomass patterns. T. discoloripes, Chaetocladius sp. and Pagastia sp. concentrated most of their production in winter, whereas E. potthasti, Pentaneura sp. and Polypedilum sp. had relatively higher production throughout the year. Only Microtendipes sp. had a production that peaked in summer. The overlap in temporal distribution of production among the chironomid species was generally high (>0.5), especially for filter-collectors Microtendipes sp., Chaetocladius sp., Chaetocladius sp., T. discoloripes and Pagastia sp. All species except Pentaneura sp. consumed a large portion of amorphous detritus, constituting more than 90% of their diets, and contributing nearly 90% to their secondary production. All the 7 chironomids represent obvious adaptation to local highly variable climate in summer and autumn in life cycle pattern, production dynamics, and food type.     

Role of anthropogenic volatile organic compounds and nitrogen oxides as ozone precursors in the wintertime over East Asia

As an exercise in model sensitivity, the Models-3 Community Multiscale Air Quality (CMAQ) modeling system with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to study the response of photochemical oxidants to systematic increases in anthropogenic volatile organic compounds (VOC) and nitrogen oxides (NO_x) emissions in January 1997 over East Asia. Three simulations-one base case and two sensitivity simulations were carried out. Two sensitivity simulations were performed by assuming a 35% separate increase in anthropogenic VOC and NO_x emissions comparing with the base case. Biogenic VOC emissions were held constant across the sensitivity simulations. To evaluate the model performance, ozone mixing ratios (O₃) from the base case simulation were compared with surface observations at five remote sites in Japan, and it was found that the model reproduces most of the important features in the observations. Monthly average O₃ concentrations in the daytime were examined to gain an understanding of how the increase in anthropogenic emissions affected the overall chemical system for each sensitivity simulation.     

Community tourism as practiced in the mountainous Qiang region of Sichuan Province, China — a case study in Zhenghe Village

In China, community tourism is still a relatively new phenomenon, but the villagers of a small Qiang village in the Qiang Autonomous County of Beichuan in Southwestern Sichuan have initiated tourism in a way which conforms to the basic theory of community tourism development. This demonstrates that community tourism possesses a strength and vitality that can promote the development of tourism in the rural and mountainous areas. In the district of Zhenghe Village, the tourism industry, based on the community tourism model, is the mainstay of its economy. The practice of community tourism in the village not only promotes the economic development of the village community, but also leads to the protection of the mountainous natural environment and of the culture of the Qiang people. This paper investigates the development process of community tourism in Zhenghe and shows how the local residents participate in this process. It also looks at how profits have been distributed within the community. It demonstrates that community tourism is a correct choice by the Zhenghe people as they have dearly been moving from poverty to prosperity, while the local ecology and environment have been simultaneously protected. The authors hope that other minority villages with similar local conditions and natural resources will be able to use this example to develop their own community tourism.     

Community responses to mountain tourism: A case in Bhyundar Valley, Indian Himalaya

Tourism industry has become an important part of Indian economy, and tourism development has been, however, concentrated to a few areas. Accumulation of tourism activities has reached the critical stage in most of the tourism centers, which pose serious threats to the natural environment. The Bhyundar Valley of Nanda Devi Biosphere Reserve （NDBR） in Uttarakhand State of the Indian Himalaya is a burning example of such problems. Land use/cover changes, deforestation and accumulation of garbage are some of the negative impacts of unregulated tourism in the valley. Unsustainable activities of tourists and villagers in the valley make such problems very severe. To deal with the ongoing problems and ensure community involvement in tourism management and environmental conservation, the Biosphere Reserve Authority introduced ecotourism in the form of Eco Development Committees （EDCs） in the Bhyundar Valley. Study reveals that many problems associated with tourism have been minimized to some extent with the help of EDCs but few are still prevailing in valley. However, the existing attempts to conserve the valley from the negative effects of tourism are inadequate and modifications are needed in the current initiatives.     

Community characteristics of wild fruit forests along elevation gradients and the relationships between the wild fruit forests and environments in the Keguqin Mountain region of Iii

In this paper,the quantitative relationship between the wild fruit communities and direct environmental factors is discussed on the basis of detailed data on landscape scale habitats obtained through field vegetation investigation.The results from TWINSPAN and DCCA showed that:1) In the distribution sections of the wild fruit forest in the Keguqin Mountain region,the basic patterns characteristic of the different habitats are due to topographic factors,nutrients and moisture conditions;2) The elevation affected the most basic differentiation of plant communities in the study area,indicating that the elevation condition was the most important factor restricting the distribution of the wild fruit communities in the study area;3) The close relationship between the moisture content in the upper soil layer and the elevation reflected the influence of moisture conditions on both wild fruit and herb-layer communities;4) Nutrient differences not only indicated that the habitat conditions were different in themselves but also showed that the present nutrient conditions of the habitats were seriously affected by human activities.In summary,under complicated mountainous topographic conditions,the habitat conditions for the communities differed very significantly,and the combination of elevation,soil moisture content,total nitrogen,slope aspect,and pH value influenced and controlled the formation of community distribution patterns in the study area.