Ecological and species diversity of arid Mediterranean grazing land vegetation

This study was conducted in the arid Mediterranean Reserve located in northern Jordan, representing a continuous grazed arid rangeland ecosystem. Quantitative analyses on species diversity in addition to phytogeographical analysis were conducted. Some ecological parameters such as, life forms, growth forms, species density and frequency were investigated. A total of 93 vascular plant taxa belonging to 78 genera and 26 families were reported. This constitutes about 4.3% of the total flora of Jordan. Reported taxa include 13 species of grasses, 69 forbs and 10 shrubs and semi-shrubs. The botanical survey pointed to the presence of four rare species in Jordan. Plant species were classified into 28 functional groups. Pairwise correlation analyses among the most abundant species, showed that neutral associations dominated (75%) those communities, followed by positive associations (19%), while only (6%) showed negative association. Positive association may be attributed to direct facultative mutualism, or to physical environmental heterogeneity. Such a positive cooperation in the plant community can significantly maintain species diversity in adverse environments.The relationship between primary productivity and species richness showed a humpbacked pattern. Maximum richness corresponded to a biomass level of 300–400 g m⁻². However, a sinusoidal curve-fitting model explained the relationship between graminoids biomass and species richness. These findings pointed to the adaptation of plant taxa to livestock grazing and to the small-scale spatial and environmental heterogeneity in arid Middle Eastern Mediterranean rangelands. Results suggest that optimal biodiversity conservation for the arid Middle Eastern grazing lands should consider their high level of spatial heterogeneity. Rangeland managers should adopt grazing plans that apply a range of grazing pressure across the area so as to maintain diversity at local and regional scales.     

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.     

我国沙拐枣属(Calligonum L.)天然群落物种多样性与土壤因子的耦合关系

对我国沙拐枣属(Calligonum L.)天然群落15个物种所形成的群落多样性指数和土壤指标进行回归分析。结果表明,颗粒度组成、土壤酸碱度、有效P、K 、Na 、HCO3-、Cl-与物种多样性指数有显著相关关系(P<0.05)。粗砂粒(0.5~0.25 mm)、土壤酸碱度、有效P和K 与物种多样性指数的最好拟合为二项式,即高或低的物种多样性出现在梯度中间位置;细砂粒(0.1~0.05mm)和Cl-与物种多样性的关系表现较为复杂,包括线性和二项式关系;Na 和HCO3-分别与物种多样性指数表现为显著线性负相关和正相关关系,表明Na 含量越多,物种多样性越小,HCO3-含量越多,物种多样性则越高。年降雨量仅与均匀度指数拟合为二项式,而与其他指数的关系表现不显著,年均温与物种多样性指数拟合较好的为二项式,仅与丰富度指数以及均匀度指数表现出显著负相关与正相关。     

塔里木河中游天然植物群落结构与数量特征分析

运用典型样地法,对塔里木河中游30个天然植被样地的群落结构和数量特征做了调查分析。结果表明:(1)塔里木河中游沙吉力克、沙子河、乌斯满、阿其河、铁依孜五个断面的天然植物隶属11科,20属,22种。(2)塔里木河中游植物群落结构可分三层,即乔木层、灌木层与草本层,但这种乔、灌、草的三层现象不明显。生境条件差,植物对环境利用不充分。(3)荒漠植物群落物种多样性水平较低,群落结构简单,物种组成单一。从多样性指数的数量特征来看,Simpson多样性指数的变化范围为0.47~0.609,Shannon-Wiener指数变化范围0.849~1.302;Menhinick丰富度指数的变化范围为2.309~3.175,Margalef 2.731~5.461;JSW均匀度指数的变化范围为0.6~0.778,JSI指数的变化范围0.633~0.805。五个断面盖度的变化范围是0.259~0.563。     

Effects of camel grazing on the ecology of small perennial plants in the Dubai (UAE) inland desert

Camel grazing is recognized as a primary cause of ecological degradation in the UAE. A study of perennial plant species <1 m in height was conducted along a fence separating continuously camel grazed land from land in which camels had been replaced by oryx and gazelle species for 5 years (Al Maha). Vegetation regeneration in Al Maha in the absence of camels was considerable on all substrates (gravel, stable sand, and semi-stable sand) but was greatest on the gravel substratum, indicating that ecology in this habitat is most at risk. Observed regeneration was primarily through vegetative reproduction and growth of existing plants, showing that existing species can tolerate heavy grazing. Therefore, an equilibrium grazing model of continuous and reversible vegetation dynamics is most suitable for management of this ecological zone. Species richness was greater in Al Maha due to the greater number of plants, but biodiversity was unaffected. There was some evidence of localized dune stabilization within Al Maha due to increased vegetative cover. Further recovery of vegetation within Al Maha is discussed. This study highlights the need for reduced grazing pressure throughout the Dubai inland desert, and in particular on gravel substrata.     

Seasonal changes in the relationship between species richness and community biomass in grassland under grazing and exclosure, Horqin Sandy Land, northern China

How species diversity–productivity relationships respond to temporal dynamics and land use is still not clear in semi-arid grassland ecosystems. We analyzed seasonal changes of the relationships between vegetation cover, plant density, species richness, and aboveground biomass in grasslands under grazing and exclosure in the Horqin Sandy Land of northern China. Our results showed that in grazed and fenced grassland, vegetation cover, richness, and biomass were lower in April than in August, whereas plant density showed a reverse trend. Vegetation cover during the growing season and biomass in June and August were higher in fenced grassland than in grazed grassland, whereas plant density in April and June was lower in fenced grassland than in grazed grassland. A negative relationship between species richness and biomass was found in August in fenced grassland, and in grazed grassland the relationship between plant density and biomass changed from positive in April to negative in August. The relationship between the density of the dominant plant species and the total biomass also varied with seasonal changes and land use (grazing and exclosure). These results suggest that long-term grazing, seasonal changes, and their interaction significantly influence vegetation cover, plant density, and biomass in grasslands. Plant species competition in fenced grassland results in seasonal changes of the relationship between species richness and biomass. Long-term grazing also affects seasonal changes of the density and biomass of dominant plant species, which further affects the seasonal relationship between plant density and biomass in grasslands. Our study demonstrates the importance of temporal dynamics and land use in understanding the relationship between species richness and ecosystem function.     

Impact of rainfall variability and grazing pressure on plant diversity in Mongolian grasslands

Climate and grazing are the main drivers of plant community composition and species richness in arid environments. This study aimed to examine the vegetation response to a spatial precipitation gradient, interannual rainfall variability, and grazing pressure in Mongolia. To examine the effect of a spatial precipitation gradient, we compared species richness among six sites. To investigate the effects of interannual rainfall variability and grazing pressure, we compared species richness for 2 years at two sites, in desert-steppe and steppe areas. The regional gradient in annual precipitation showed positive and negative relationships with grass richness and shrub richness, respectively, although total species richness did not vary significantly. The proportions of the different functional groups were affected by grazing pressure and rainfall variability in both zones. In the desert-steppe zone, species richness was lower in the drier year but did not vary with grazing pressure. In the steppe zone, species richness varied significantly with grazing pressure but did not vary between years. Precipitation would be more important than grazing pressure on vegetation changes in drier areas with high rainfall variability.     

Patterns of lizard species richness within National Parks and Biosphere Reserves across North America's deserts

Warm deserts world-wide provide habitats for rich lizard species assemblages; North American deserts are no exception, however the desert regions of the US and Mexico are experiencing increasing habitat changes from multiple anthropogenic sources. Our objective here was to document current lizard species richness patterns across the North American deserts within the existing network of conservation areas. We identified 110 lizard species occurring across one or more of the 19 sites we analyzed. Three species richness hot spots were identified; a northern Baja California faunal extension into southern California in the US, and in Mexico, two sites within the state of Coahuila, as well as high endemism in the Cape Region of Baja California Sur. Species richness was associated with sites where desert ecoregions overlap and with insular isolation. Our uncertainty regarding how species will respond to the multifaceted aspects of global change is such that large protected natural areas with complex topography may be the most effective strategy for protecting desert lizards along with overall biodiversity. The 19 sites we analyzed represent the cores of a more robust conservation network that will be needed for the protection of biodiversity across North American Deserts.     

土库曼斯坦物种多样性及其与中国新疆的比较

土库曼斯坦与中国新疆在地理地形、景观带以及气候特征等诸多方面具有相似之处,这些因素共同决定了二者在物种多样性方面的相似性与可比性,加之人类活动影响加剧,两地物种多样性均遭受着严重的威胁。在对土库曼斯坦和中国新疆现有物种多样性数据进行总结的基础上,分析了二者的物种多样性现状、珍稀动植物特征以及濒危种和入侵种相关研究进展,对比了二者在物种多样性年际尺度上的异同,总结了土库曼斯坦与中国新疆物种多样性保护现状与相关政策,以期为深入开展两地生物多样性合作与交流提供支持。     

Life in sandy deserts: the scorpion model

The biology, ecology, biogeography, phylogeny, and evolution of sand-dwelling scorpions are reviewed. We present general features of sand that form the ecological theatre on which psammophiles have evolved. Sand scorpions, compared to those that live off sand, are not very diverse in any one local habitat, although they are often relatively abundant. Worldwide, they are represented by 29 genera, 11 of which exist exclusively in sand. Endemic genera belong to non-related families, suggesting that psammophilic adaptations evolvedin situin different sand deserts of the world.     

放牧对准噶尔荒漠植物群落及土壤特性的影响

通过比较封育6年的围栏内外植物群落种类组成、结构差异,以及土壤特性,研究了家畜啃食对新疆准噶尔荒漠植物群落及土壤特性的影响.使用X2-test和U-test分析表明,围栏内外相比,植物种数(n=7.03)、半灌木种数(n=2.40)、草本植物种数(n=4.63)、植被盖度(35.77%)和生物量(144.19 g/m2)在围栏内显著增加,而植被密度在围栏外显著降低(87.93株/m2).灌木中,梭梭(Haloxylon ammodendron)在围栏内出现的频率和密度显著增加(X2=4.63,p＜0.05;z=2.56,p＜0.05).小半灌木中,博乐绢蒿(Seriphidium borotalense)在围栏内出现的频率和密度显著高于围栏外(X2=13.08,p＜0.01;Z=4.01,p＜0.01).4种多年生草本植物的密度在围栏内均显著升高,有3种在围栏内出现的频率也同时明显高于围栏外.二年生草本植物沙生婆罗门参(Tragopogon sabulosus)在围栏内出现的频率和密度显著高于围栏外(X2=4.71,p＜0.05;Z=2.51,p＜0.05).4种一年生草本植物在围栏内外出现的频率均无显著差异,其中3种在围栏内外的密度也无明显变化.研究结果表明,过度放牧导致灌木和半灌木衰败;多年生和二年生草本植物几近绝迹;一年生植物所受影响则较小.土壤理化特性中,围栏内土壤水分显著低于围栏外(Z=2.65,p＜0.01),HCO3、Cl-和速效K含量在围栏内外土壤中差异显著.作者建议在准噶尔荒漠建立一定数量和面积的永久性围栏以维系物种多样性.     

Is the analysis of plant community structure better than common species-diversity indices for assessing the effects of livestock grazing on a Mediterranean arid ecosystem?

Grazing in arid Mediterranean ecosystems brings about changes in species diversity, but the best way to measure such changes is unclear. In this study we compared various methods in order to identify indicators that might be useful for the management and conservation of grazed arid Mediterranean ecosystems.Changes in community structure and composition were compared along a previously studied grazing gradient in Cabo de Gata-Nijar Natural Park. Plant diversity was measured by calculating diversity (Shannon information index), evenness (Pielou index) and richness (species number). Rarefaction curves were used to measure plant species richness and the results were compared with traditional richness values. Community structure was measured as the percentage of bare ground and the coverage of overall perennial grasses, Stipa tenacissima L., perennial shrubs and annual plants. Our results showed that the proportion of bare ground, the cover of perennial shrubs and the relative abundance of S. tenacissima are good indicators of grazing effects on vegetation. Overall plant community structure was more sensitive to the grazing gradient than were the diversity indices. Finally, the adequacy of standardized methods for comparing species richness (i.e. rarefaction curves) along a grazing gradient are discussed.     

中国沙漠微生物分布及特征

微生物是沙漠生态系统的重要组成部分,对生态系统功能和稳定性具有重要意义,目前中国对沙漠微生物的研究基本覆盖了主要的荒漠区。本文基于中国沙区已有研究成果对微生物学研究方法的进展、沙漠微生物群落组成及多样性变化规律、沙漠微生物群落分布特征及影响因子、沙漠微生物群落功能多样性和微生物资源等进行了总结,以期为沙区微生物资源开发利用提供重要依据。     

南极欺骗岛土壤细菌群落结构和多样性分析

采用基于16S r DNA克隆文库的非培养方法和传统培养方法相结合的手段,对南极欺骗岛土壤细菌群落结构及多样性进行了初步分析。对来自16S r DNA克隆文库的118个阳性克隆进行测序和序列比对,结果显示细菌来自放线菌门(Actinobacteria)、变形杆菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)3大门的39个操作分离单元(OTU),其中优势菌群为放线菌门和变形杆菌门,分别占65.25%和28.81%。放线菌门的主要优势属为鱼孢菌属(Sporichthya)、类诺卡式氏菌属(Nocardioides)、束缚菌属(Conexibacter)、Gaiella和节杆菌属(Arthrobacter)。变形杆菌门的主要优势属为鞘氨醇单胞菌属(Sphingomonas)、硫杆菌属(Thiobacillus)、寡养单胞菌属(Stenotrophomonas)和热单胞菌属(Thermomonas)。采用6种培养基对细菌进行培养和分离,共得到57株菌,来自放线菌门、变形杆菌门、拟杆菌门和厚壁菌门4大门的13个OTU,其中优势菌群为放线菌门和变形杆菌门,分别占57.89%和31.58%。优势属是放线菌门的节杆菌属(Arthrobacter)、雷夫松氏菌属(Leifsonia)和变形杆菌门的假单胞菌属(Pseudomonas)。本论文为研究欺骗岛土壤细菌多样性以及有益菌种资源的开发和利用奠定了基础。     

塔里木河下游物种多样性恢复速率分析

通过塔里木河下游生态输水后植物群落及其环境因子的系统取样调查,采用β多样性指数,从时空维上分析了生境差异与物种的恢复速率差异.结果表明:物种多样性差异与环境水分条件有着密切的关系,在地下水埋深小于5 m时,物种恢复速率的发生率达100%,而在地下水埋深大干5 m时;多样性恢复的率达46%.生境异质性较高的群落,水分条件较好,其物种恢复速率相对较高,表现为河边低地、地表未起沙生境与人工灌溉生境具有较高的物种恢复速率.生态恢复过程中,人类的干预对局部生境中物种多样性恢复产生了一定的影响,但物种替代速率与恢复速率的大小最终决定于水分条件的可利用性与环境劣变程度.     

中国戈壁综合自然区划研究

中国戈壁广泛分布于北方的干旱与极干旱区域,直至目前尚未系统地开展戈壁分区研究。本文在综合分析戈壁特征与形成发生机制关系后认为,我国戈壁的最主要特征是地表砾质覆盖;表层具孔状漆漠结皮,其下具棕红色紧实层及石膏层;植物覆盖度极低,生长旱生极旱生灌木—半灌木。戈壁形成发生的区域仅限于干燥度4以上的干旱、极干旱区域。根据戈壁特征及发生条件的区域分异,选取干温指标、区域地质地貌建造指标、地表物质成因形态指标,将中国戈壁分布区划分为温性干旱极干旱戈壁区、暖性干旱极干旱戈壁区和青藏高原北部亚寒干旱极干旱戈壁区3个一级区(区),其下按区域地质地貌建造特征划分出9个二级区(地区),再按戈壁地表物质成因与形态差异划分出19个三级区(亚地区)。还可根据土壤和植被的地域分异进一步划分出若干个四级区(小区)。     

Vegetation patterns and diversity along an altitudinal and a grazing gradient in the Jabal al Akhdar mountain range of northern Oman

Little is known about the effects of grazing on vegetation composition on the Arabian Peninsula. The aim of this study therefore was to analyse the vegetation response to environmental conditions of open woodlands along an altitudinal and a grazing gradient in the Jabal al Akhdar mountain range of Oman. The species composition, vegetation structure, grazing damage and several environmental variables were investigated for 62 samples using a nested plot design. Classification analysis and a Canonical Variate Analysis (CVA) were used to define vegetation types and to identify underlying environmental gradients. The relationship between environmental variables and diversity was analysed using correlation coefficients and a main-effects ANOVA. The plant species richness followed a unimodal distribution along the altitudinal gradient with the highest number of species at the intermediate altitudinal belt. The cluster analysis led to five vegetation groups: The Sideroxylon mascatense–Dodonaea viscosa group on grazed and the Olea europaea–Fingerhuthia africana group on ungrazed plateau sites at 2000 m a.s.l., the Ziziphus spina-christi–Nerium oleander group at wadi sites and the Moringa peregrina–Pteropyrum scoparium group at 1200 m a.s.l, and the Acacia gerrardii–Leucas inflata group at 1700 m a.s.l. The CVA indicated a clear distinction of the groups obtained by the agglomerative cluster analysis. The landform, altitude and grazing intensity were found to be the most important variables distinguishing between clusters. Overgrazing of the studied rangeland is an increasing environmental problem, whereas the plant composition at ungrazed sites pointed to a relatively fast and high regeneration potential of the local vegetation.     

中国北方地区沙漠与河流景观格局

本文运用景观生态学原理,借助ArcGIS技术,选择中国北方10个流域及其12个沙漠/沙地,并以西部的和田河和东部的西辽河为典型研究区,在流域与沙区、河道与沙丘两个尺度上,选取景观破碎度指数、景观多样性指数等指标,探讨中国北方干旱、半干旱区沙漠/沙地景观与廊道景观(河流)的空间镶嵌格局特征。结果表明：在流域与沙区尺度上,内流区较外流区沙区景观类型复杂,景观破碎度较小,外流区沙区景观结构较为相似;内流区沙区景观指数自西向东呈现出“景观破碎度递增、景观结构复杂性递减”的规律。在河道与沙丘尺度上,在缓冲带范围内,和田河较西辽河沙丘景观类型复杂,景观破碎度较小;景观指数随河道距离的变化呈现出“景观破碎度随距河道距离的加大而逐渐递减,丰富度指数随距河道距离的加大而呈阶梯状递增”的规律;从沙丘斑块类型景观指数上看,西辽河以固定、半固定的简单型沙丘为主,和田河以流动的综合型沙丘为主。主导的沙丘类型景观距离河道越远,面积比例越小,不同沙丘类型的水平景观破碎度随河道距离递减。     

全球创意城市的区域多样性与网络结构特征

创意城市是当前学术界讨论的热点之一。然而,当前研究主要关注创意城市构成要素,缺少从全球尺度分析不同地区创意城市发展的异同性。本文系统梳理创意城市的概念内涵,以联合国教科文组织“创意城市网络”成员城市为基础数据,通过聚类分析、社会网络分析等方法,考察了全球创意城市的类型与空间分布特征、区域多样性以及“创意城市网络”的结构特征。研究发现:(1)全球创意城市在类型上以手工艺和民间艺术、音乐为核心主题,在空间上呈现以西欧、东北亚、加勒比海和墨西哥湾为主要集聚地的发展态势。(2)全球创意城市因受到历史文化和地理邻近等因素的影响表现出很强的区域聚类现象,全球国家大致可分为四种类型:音乐媒体艺术类国家(以欧洲和加勒比海国家为主)、文学创意类国家(以印欧语系国家为主)、手工艺与民间艺术类创意国家(以古丝绸之路国家为主)、设计创意及美食类国家(以亚洲国家为主)。(3)韩国、澳大利亚、意大利、美国、中国等国家在全球创意城市网络中占据中心位置,中国创意城市数量较高,但网络中的度中心性有待进一步提升,这主要由于中国的创意城市存在较为严重的同质化现象,缺少多样化创意发展战略。     

文化多元与邂逅：电影作品中的华裔社区地方营造

经过艺术加工的影视作品反映现实的同时也高于现实,不断重构、书写现实空间。本研究援引邂逅地理及地方感等理论,以5部华裔社区空间题材的电影作品为主要分析对象,以文本分析法为主要研究方法,探讨五部影片中关于华裔社区的选择再现及其背后蕴涵的社会文化意义。研究发现：①影视文本首先从民俗仪式与风水文化两个空间文化符号出发,构建地方性;在此基础上,电影文本以景观符号为切入口再现华裔社区的物质空间,实现新的地方营造。②文化多元的背景下,华裔社区成为“我者”文化与“他者”文化邂逅的重要场所。③非表征理论通过强调人的“身体”与族裔社区的相互关系从而在地方协商和情感融入框架下探索新的邂逅。研究还进一步探讨了电影文本中族裔社区的文化多元性与地方治理的关系,为族裔社区在未来实现更好的地方治理提供参考与建议。