Effects of grazing and climate change on species diversity in sandy grassland, Inner Mongolia, China

To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Horqin Sand Land, Inner Mongolia. The results showed that (1) the grazing was primary responsible for changes of the vegetation richness and diversity in the grazing grassland and that changing climate was the main reason for changes in the species richness and diversity in the grassland protected from grazing; (2) light and moderate grazing can promote restoration of the richness and the diversity in the degraded grassland, and heavy grazing could result in a decrease of the richness and diversity; (3) heavy grazing can result in significant decrease of the perennial diversity, and moderate and light grazing promotes increase of the perennial diversity; the grazing, whether heavy or moderate and light grazing, was beneficial to increase of the annual diversity; (4) heavy grazing was not beneficial to diversity of Graminean and Chenopodiaceae, and moderate and light grazing was favorable the diversity of Compositae and Chenopodiaceae; (5) the warm-humid climate was favorable to increase of the richness and the diversity, and the warm-drought climate could result in decease of the richness and the diversity; (6) increased precipitation was favorable to perennial diversity and the diversity of Graminean, Leguminosae, and Compositae, and decreased precipitation had few effects on the annual diversity and Chenopodiaceae diversity.     

EFFECT OF DRY COLD AIR ACTIVITY ON THE OFFSHORE RAPID INTENSIFICATION OF SUPER TYPHOON SAOMAI (2006): A NUMERICAL SIMULATION RESEARCH

Employing the mesoscale WRF (Weather Research and Forecast) model, Super Typhoon Saomai (2006) is simulated. The variation of track and intensity and its offshore rapid intensification process are well demonstrated by the model, and the temperature and humidity patterns associated with the dry cold air activity and their impact on and mechanism of the offshore rapid intensification of Saomai are mainly studied in this paper. The results indicate that high-resolution water vapor imagery can visually reveal the development, evolution, interaction as well as the mutual complementation of the dry cold air activity accompanied with the development of Saomai. The offshore rapid intensification phenomenon of Saomai is closely related to the dry cold air which originates from the upper- and mid- troposphere. Besides, the dry cold air from the upper troposphere is stronger than that from the mid-troposphere. Saomai intensifies as the dry cold air from the northwest moves toward its circulation but weakens when the dry cold air from the southwest is drawn into the storm. Dry cold airflows and their cold advection effect caused by the downward motion across the isentropic surface are favorable to the development of Saomai. The dry cold air always moves along an isentropic surface from the upper troposphere to the mid-troposphere around the typhoon circulation and contributes to Saomai’s abrupt intensity change.     

南京市紫外线辐射强度的变化及影响因子

利用南京市2005-02—2009-01共4 a的紫外线辐射观测资料,分析了到达地面的紫外线辐射强度的变化特征,并探讨了云、污染物浓度和雾、霾天气等对紫外线辐射强度的影响。结果表明,低云量对紫外线强度的衰减更明显,最大达58.15%,蔽光性云层对紫外线辐射强度的衰减可达71%～80%;紫外线辐射强度与污染物浓度呈负相关,其中与NO2的相关性最好,为-0.39;晴空条件下,严重霾对紫外线辐射强度的衰减率可达20%以上,浓雾对紫外线辐射强度的衰减接近50%。     

近四十年我国东部盛夏日降水特性变化分析

基于中国地区740台站的日降水资料,细致分析了近40年我国东部盛夏即7、8月份降水长期趋势和年代际变化特征。按小雨、中雨、大雨以及暴雨降水强度分类,探讨了不同强度降水在我国东部降水变化中的贡献。结果表明,中国东部地区盛夏降水变化主要受暴雨强度降水变化的影响,占总降水变化60%以上。近40年来,盛夏长江流域降水量、 降水频率、极端降水频率以及暴雨降水强度均呈增大趋势,在华北地区则呈减小趋势,除降水频率在长江流域的变化趋势绝对值比华北地区小外,另三个指标在长江流域的趋势变化值大约是后者的2倍。降水强度在中国东部表现出一致的增大趋势,但华北地区增大趋势不显著。华北地区降水的减少主要是小雨强度降水频率减小的结果,强降水的频率和强度在该地区也呈微弱的减小趋势,其中小雨强度降水频率减小趋势大值中心值达到-3%/10a,比中雨以上强度降水频率变化趋势值大一个量级;长江流域降水的增多,是各强度降水频率和强度增大共同作用的结果。长江流域和华北地区在区域平均降水频率、降水强度、极端降水频率、最大降水量的时间序列上,彼此均为负相关关系,其中降水频率和极端降水频率序列在两区域的相关系数通过99%的信度检验。Mann-Kendall检验表明,除华北地区降水强度外,其他降水指标均存在显著的年代际跃变。与1970年代末的气候跃变相对应,华北地区降水频率较之长江流域的跃变明显;但长江流域极端降水在1970年代末的跃变较之华北地区更显著,其降水强度、极端降水频率以及最大降水量均于1970年代末期前后发生显著年代际跃变。     

Study on the dominant species of Pteropoda in East China Sea

1 INTRODUCTION Pteropoda is a group of marine pelagic mol- lusks, which belongs to Opisthobranchia of Gastro- poda. Although Pteropoda is not a major group in pelagic zooplankton in terms of abundance and number of species, their ecological characters are…     

集聚空间组织型式对中国地市尺度工业SO2排放的影响

集聚外部性是集聚影响工业污染排放的重要机制,不同的集聚空间组织型式具有不同的污染排放行为和减排效果。以中国285个地市工业SO₂排放为例,依据集聚经济理论,将集聚空间组织型式细分为集聚密度、企业地理临近度、专业化、多样性、相关多样性、非相关多样性等不同类型,在系统分析工业SO₂排放与集聚空间格局的基础上,通过构建计量经济模型,考察了不同集聚空间组织型式对工业SO₂排放强度的影响。结果表明：① 工业SO₂排放强度与工业集聚密度在空间上具有非对称性,污染排放强度西高东低,工业集聚密度、企业地理临近、多样性、相关和非相关多样性为东中高西部低;② 工业集聚对工业SO₂排放强度的影响存在空间溢出效应,相邻地区集聚密度、多样性和相关多样性水平的上升有利于本区域工业污染排放强度的下降,但专业化水平的上升则会提升本区域的工业污染排放强度;③ 提高集聚密度、引导企业集中布局有利于工业SO₂排放强度下降,多样且关联的产业组织结构有利于污染减排,而专业化和非关联产业的集中会提高污染排放强度;④ 集聚型式对工业SO₂排放强度的影响存在区域和城市规模上的异质性,集聚密度、企业地理临近、多样性和相关多样性对中西部污染减排的作用比东部明显,专业化和非相关多样性不利于东中部地区的污染减排;城区人口规模20万以下的小城市提高集聚密度、减少多样性特别是非相关多样性更有利于污染减排;城区人口规模20~50万的小城市和50~100万的中等城市,提高企业的地理接近度和多样性水平特别是相关多样性水平,有利于其降低污染排放强度;城区人口规模在100万以上的大城市,提高集聚密度和产业多样性水平在一定程度上有利于其污染减排,但其减排效果因拥挤效应而明显下降;⑤ 进一步降低工业SO₂排放强度,需要走集聚化道路,坚持提高集聚密度,因地制宜引导企业集中布局,着力提高产业在关联基础上的多样性水平,加强区域间联防联控,重视区域间的产业联系与环保合作。     

Characteristics of the Asymmetric Flow of Tropical Cyclone Shanshan (2006) During Its Turning and Intensification Period

In this paper,characteristics of the asymmetric flow of Tropical Cyclone (TC) Shanshan (2006) during its turning and intensification period over the oceanic area east of Taiwan are investigated,based o...     

辐射传输模式中地表参数对大气长波辐射的影响

本文利用Liou-Ou一维宽带辐射传输模式，对地表热力参数取值部分作了改进，使用模式大气和青藏高原实测资料对下垫面温度与地表空气温度两者不能合二为一的问题进行了分析，同时还讨论了下垫面温度的日变化对大气长波辐射通量日变化的影响及地表比辐射率的变化对大气长波辐射通量计算结果的修正作用。     

东北地区建设用地开发强度格局演变的空间分异机制

建设用地开发强度是区域建设用地开发利用程度及其对区域人口和经济社会承载强度的综合反映。本文以东北地区179个县域空间为基本研究单元,应用冷热点、空间变差函数、GWR模型等定量方法对建设用地开发强度的时空分异格局演变及分异机制进行了探讨,得出以下结论：① 2000-2015年东北地区建设用地开发强度总体呈现出增长态势,但空间分异显著,各单元间建设用地开发强度高低的相互作用及联动效应较为明显,但建设用地开发强度的空间分布逐渐趋于非均衡,建设用地开发强度的冷热点分布格局与全局分异变化及空间异质性态势基本吻合;② 2000年东北地区开发强度格局分异由政府财政投入力度、用地投资强度和产业结构水平共同影响,到2005-2015年发展演化为政府财政投入力度、用地投资强度、经济发展水平和产业结构水平共同影响;③ 2000-2015年政府财政投入力度、用地投资强度、经济发展水平和产业结构水平与东北地区建设用地开发强度格局分布态势具有一定的关联性,但在不同区域呈现出影响程度的差异性。     

UV-B辐射对海洋微藻抗氧化系统的影响

研究了UV－B辐射对两种海洋微藻－小新月菱形藻（Ntzschia closterlum)和亚心形扁藻（Platymonas subcordiforming)的抗氧化系统的影响。结果表明：在本实验的辐射剂量范围内，随着UV－B辐射剂量的增强，两种藻的抗氧化防御系统的非酶性组分还原型谷胱甘肽（GSH）和类胡萝卜素（CAR）的含量随之下降；抗氧化防御系统的酶性组分超氧化歧化酶（SOD）和过氧化氢酶（CAT）的活性逐渐降低。加入外源性抗氧化剂GSH可减轻UV－B辐射对藻的伤害。分析表明海洋微藻的UV－B伤害是由于抗氧化防御系统遭到破坏而导致活性氧积累的结果。