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1.
河西走廊地势狭长,位于两山之间,主要由荒漠构成,生境一旦遭到破坏,当地物种将很难找到替代的栖息地。本文以河西走廊中部典型砾质戈壁为研究区,经由2019—2020年红外相机和人工观测等方式监测到的兽类和鸟类数据为基准,探讨其群落动态及活动节律。结果表明：砾质戈壁兽类中的国家Ⅱ级重点保护及“三有”（有重要生态、科学、社会价值）动物有6种,而砾质戈壁鸟类中的国家Ⅱ级重点保护及“三有”动物有8种。兽类群落的季节变化小,春季鹅喉羚（Gazella subgutturosa）等的相对多度指数略高于其他季节,三趾跳鼠（Dipus sagitta）在4月大量出现;鸟类群落季节变化明显,春、夏季和秋季鸟类的相对多度指数高于冬季,物种数在夏季和秋季达到峰值。兽类和鸟类的相对多度变化趋势相似,均在夏末和春季达到顶峰。兽类的月相对多度指数与土壤含水量呈极显著的负相关,鹅喉羚和沙狐（Vulpes corsac）等日活动节律受人类活动影响出现在夜间、黄昏或黎明。鸟类的月相对多度指数与人类活动、空气温度、土壤温度和节肢动物均呈显著正相关,但人类活动在生长季会降低一些鸟类的活动频率。总之,河西走廊中部戈壁是鹅喉羚、沙狐、红隼（Falco tinnunculus）、锲尾伯劳（Lanius sphenocercus）、黑尾地鸦（Podoces hendersoni）、沙鵖（Oenanthe isabellina）、漠鵖（Oenanthe deserti）和短趾百灵（Calandrella cheleensis）等兽类和鸟类的主要栖息地,建立沙化土地封禁保护区对保护荒漠动物多样性具有重要的生态意义。 相似文献
2.
This paper provides a brief introduction to the physical environment of Namaqualand as well as an overview of patterns of plant diversity. The diverse array of parent material and geological processes that have shaped the region since the break up of Gondwanaland have created a complex, and sometimes dynamic physical environment, that is partly responsible for the patterns and processes observed in the biota today. The contemporary climate is characterised by relatively reliable, albeit low (50–250 mm pa), winter rainfall (>60% winter precipitation) arriving between May and September. East of the central mountains, tropical thunderstorms penetrate the region in late summer (February–April). The presence of the cold Atlantic Ocean in the west not only moderates temperatures throughout Namaqualand (mean max summer temperature <30 °C), but also provides alternative sources of moisture in the form of coastal fog and heavy dew experienced in winter months. Recent analyses show that the flora of the Succulent Karoo is part of the Cape Floral Kingdom, now termed the Greater Cape Floral Kingdom. It is one of only two desert regions recognised as a global biodiversity hot-spot and contains an estimated 6356 plant species in 168 families and 1002 genera. Namaqualand, which comprises about one quarter of the area of the Succulent Karoo, contains about 3500 species in 135 families and 724 genera, with about 25% of this flora endemic to Namaqualand. This remarkable diversity, however, is not distributed evenly throughout the region, but is concentrated in many local centres of endemism usually associated either with quartzite mountain complexes or lag-gravel plains (quartz-patches). A major exception to the general pattern of centres of diversity is the true Fynbos vegetation of the highest Kamiesberg peaks where rainfall exceeds 400 mm pa. Suggested determinants of the region's exceptional floral diversity include the complex physical environment, a unique past and present climate and the region's diverse fauna, most notably insects. The challenge for the current inhabitants and scientists working in the region is to develop a better understanding of this ecosystem so that they will be equipped to deal with the challenges posed by the demands for land and the prospect of global climate change. 相似文献
3.
塔克拉玛干沙漠地表潜热时空特征分析 总被引：6，自引：4，他引：2
利用1979年3月至2004年2月月平均的NCEP/DOE再分析地表潜热资料,在分析塔克拉玛干沙漠四季潜热基本气候特征的基础上,通过EOF方法,对沙漠地表潜热异常变化的空间结构和时间演变趋势作了诊断研究。结果表明：①沙漠地区夏季潜热最大,春季和秋季次之,冬季最小;靠近山区的沙漠西部、西北部地区四季明显大于中、东部地区。②根据四季地表潜热距平场的EOF分析,该区潜热异常主要有全区一致型、南北差异型以及西北—东南差异型三种常见的分布模态。③25 a期间,塔克拉玛干沙漠地表潜热在第一空间尺度上四季都有不同程度增强的趋势;在第二空间尺度上,春季沙漠北部、西北部有减弱的趋势,南部、东南部有增强的趋势,而冬、夏、秋季变化趋势不是很大。 相似文献
4.
5.
Riparian plant species richness along lateral and longitudinal gradients of water stress and flood disturbance, San Pedro River, Arizona, USA 总被引：2，自引：0，他引：2
Diversity theory predicts that species numbers should be highest at intermediate levels of both disturbance and environmental stress. We examined woody and herbaceous plant species richness and cover in the San Pedro River flood plain, along lateral gradients of water availability (ground-water depth), flood disturbance (inundation frequency), and distance from and elevation above the channel, and along longitudinal gradients of water availability (ground-water depth, surface flow permanence, and rainfall) and flood disturbance (total stream power). Herbaceous species were recorded during four sampling periods, and spatial patterns for this group were time-dependent, reflecting temporal variation in limiting factors. During the summer dry season of a dry year, when overall richness was low, richness and cover of herbaceous species declined laterally from the stream channel with increasing ground-water depth, consistent with the idea that low resource levels can limit species richness. Following the summer monsoon rains and floods, when water was less limiting and annuals were seasonally abundant, lateral patterns shifted such that herbaceous species richness and cover increased with increasing plot location above or from the channel. The relationship of herbaceous species richness with tree canopy cover also varied seasonally, shifting from positive (greater richness under canopy) in dry seasons to negative (lesser richness under canopy) in wet seasons. Longitudinally, herbaceous species richness and cover were limited primarily by stream flow and/or ground-water availability during the summer dry season of a dry year. Following the summer monsoon rains and floods, patterns were weighted by the seasonally abundant annuals, and richness increased among sites primarily with distance upstream (and related rainfall gradients). Richness and cover patterns also varied between years with different flood conditions. During the two sampling seasons in the year following a large flood, herbaceous species richness increased with flood disturbance intensity but declined at the few most intensely disturbed sites, consistent with intermediate disturbance theory.For woody species, richness within plant functional groups varied in opposing ways along the lateral gradients: hydromesic pioneer species decreased and hydromesic and xeric competitors increased with distance from or above the channel, with no overall change in species richness. Among sites, woody species richness patterns were related to water availability, but not to flood disturbance. However, richness of woody hydromesic pioneer species increased with both increasing site moisture and flood disturbance. Woody and herbaceous species richness both increased among sites as a function of increasing flood-plain width, likely due to species–area effects. Overall, results indicate that flood disturbance and water availability both influence species richness of riparian plants in the flood plain of this semi-arid region river, with the relative influence of each factor varying among plant groups and over time. 相似文献
6.
库姆塔格沙漠大尺度风场特征分析 总被引：4，自引：4，他引：0
利用美国NCEP/NCAR1979—2006年27 a地面10 m高度的日平均风场再分析-2资料以及46 a的地面常规气象站观测资料和1 a的沙漠中自动气象站观测资料,对库姆塔格沙漠地区风场进行了统计与诊断分析。结果表明：沙漠地区,一年四季北风和东北风为近地面主要存在的风向,春季风速最强,夏季次之,秋冬季最弱;在夏秋冬季节,由于北风的逐渐减弱,加上受到南侧阿尔金山和青藏高原风场的影响,南下的气流在沙漠南侧分为三支,分别流入新疆、青海和甘肃。春夏季节在沙漠北侧基本都是以东北风或者西北风吹向库姆塔格沙漠,秋冬季节,沙漠地区出现西南风。根据沙漠周围6个气象站风场风速显示,库姆塔格沙漠地区风速存在明显的周期变化,在过去的10多年中库姆塔格沙漠周围风场风速处于一个低谷期,但最近几年风速有不断加强的趋势。 相似文献
7.
上海世博园后滩湿地大型底栖动物群落特征与环境分析 总被引：1，自引：0，他引：1
上海世博园后滩湿地是中国2010年上海世界博览会规划区的重点建设项目。对世博园后滩湿地潮间带底栖动物群落特征与生物多样性进行了春、夏、秋、冬4个季节的调查研究,并对该湿地水体污染状况及影响底栖动物分布的因素进行分析与评估。结果表明:世博园后滩湿地底栖动物主要由环节动物、软体动物、节肢动物与纽形动物组成,共计18种;物种数在夏季最丰富,春季次之,冬季物种数最少,其中A断面物种数大于B断面;群落生活类群面上生活类群(GS)/面下生活类群(GSB)在冬季最大,春季次之,秋季群落生活类群GS/GSB最小,其中B断面群落生活类群GS/GSB大于A断面;底栖动物群落的Margalef物种丰富度指数(d)在夏季最大,春季次之,冬季丰富度指数最小;Shannon-Wiener指数(H′)在夏季最大,春季次之,秋季最小;Pielou均匀度指数(J)为:冬季最大,夏季次之,秋季最小;Simpson优势度指数(D)为:秋季最大,春季次之,夏季最小;采用寡毛生物指数值和生物多样性指数对该湿地水体污染状况进行了评价,该园区水质污染程度为中度污染。 相似文献
8.
The diversity and abundance of epigaeic ant species were determined across three habitats (riverine areas, gently sloping grassland areas and steep slope areas) in summer (November–December) and winter (May–June) of 1998 at Tussen die Riviere Nature Reserve in the Karoo, to determine temporal and spatial variations in the availability of potential prey species of the aardvark (Orycteropus afer). Pitfall trapping, dig sampling and quadrat sampling were used to ensure as complete a sampling effort as possible. Forty-five ant species of five sub-families and 17 genera were recorded. The grassland habitat yielded the highest abundance and diversity, followed by the steep slope and riverine areas. Ant abundance and diversity were higher during summer than winter in all three habitats. Anoplolepis custodiens was the most abundant species in summer, whilst Monomorium albopilosum was the most abundant species in winter. Pitfall trapping was responsible for recording more species than dig sampling or quadrat sampling. No method recorded all of the species present. 相似文献
9.
库姆塔格沙漠极端干旱,而其南部阿尔金山比较湿润.研究库姆塔格沙漠及南部阿尔金山的降水特征,对揭示库姆塔格沙漠水源补给机制和地貌形成原因具有重要作用.本文利用中国自动气象站与CMORPH融合逐时降水量0.1°网格数据集,分析了库姆塔格沙漠及阿尔金山的降水特征.结果表明:(1)库姆塔格沙漠降水主要集中在夏季,其他季节降水较少;而阿尔金山降水主要集中在春、秋两季,并存在一条降水量大值带,3月范围最大而夏季消失;(2)阿尔金山对库姆塔格沙漠的水源补给作用主要体现在春、秋两季,夏季降水基本与库姆塔格沙漠持平,春季降水超出库姆塔格沙漠最多;(3)阿尔金山各月平均逐小时降水量演变特征有很大不同,冬季12、1月及夏季6、7月每月逐时降水演变特征以"凌晨型"为主,可能与凌晨云顶辐射冷却引起的大气层结不稳定有关;春、秋两季每月逐时降水演变特征以"午后-黄昏型"为主, 可能与午后太阳辐射地面加热引起的大气层结不稳定有关;2、8月是两种类型的过渡时期.本文研究结果可为探索库姆塔格沙漠水源补给机制以及"羽毛状沙丘"独特的沙漠景观形成原因提供一定的参考依据. 相似文献
10.
Biological invasions are a major threat for natural ecosystems. Deserts are characterized by their scarce, highly variable rainfall and thus considerably susceptible to invasions, especially by annual plants that can quickly capitalize sporadic rainfall events. In this study we evaluated the potential of an invasive winter-annual species native to the Mediterranean region (Schismus barbatus) to invade a summer-rainfall desert in the Central-Northern Monte Phytogeographical Province, Argentina, where the native annual flora is mainly composed of summer species. We recorded the number of germinated seeds from soil samples collected in four seasons (during one year) coinciding with four important life-stages of Schismus (pre-germination, post-germination I and II and post-dispersal), and contrasted our results with data obtained from the literature. Almost 33,000 Schismus seeds were estimated to germinate per m2, and about 90% percent of them germinated from samples collected in the pre-germination stage. Compared to deserts in USA and Australia, where Schismus has been a successful invader, the density of germinated seeds we observed was especially high even though the amount of rainfall for the vegetative period of Schismus was considerable lower. Our results suggest that S. barbatus has a great invasive potential in the Central-Northern Monte. The low number of annual plant populations that are able to compete for highly variable cool-season rains may be a key feature determining the invasibility of these deserts during the winter. 相似文献
11.
通过在亚热带杉木林内设置不同隔离降雨强度试验:完全隔离降雨、隔离60%降雨、隔离20%降雨和对照(自然降雨),研究隔离降雨对0~20 cm土层可溶性有机碳(DOC)和微生物生物量碳(MBC)含量的影响,结果表明:0~10 cm和10~20 cm土层,除完全隔离降雨处理土壤DOC峰值出现在春季外,其他处理均出现在秋季。0~10 cm土层中完全隔离降雨和隔离60%降雨处理的土壤MBC峰值出现在春季,而隔离20%降雨和对照的则出现在夏季,10~20 cm土层各处理对应的MBC最大值分别出现在春季、夏季、夏季和秋季。随着土层加深,4种处理土壤DOC、MBC含量均显著降低。0~10 cm土层,完全隔离降雨处理的土壤DOC、隔离60%降雨土壤MBC均与土壤含水量显著正相关,杉木林土壤DOC和MBC对降水变化响应具有明显的季节性。 相似文献
12.
广东的洪涝及其对农业的危害与防御对策 总被引：1，自引：2，他引：1
对广东省的洪涝灾害进行了分类，主要从气候的角度揭示洪涝的成因，及其对农业生产的危害。广东的洪涝按水分过多的程度，可分为洪水、涝害和湿害；按季节划发，洪涝分成春季洪涝、春夏洪涝、夏秋洪涝和连阴雨等几种类型。洪涝与湿害的气候指标常用年或某的降雨异常来描述。洪涝和湿害的农业气象指标用水分平均旱涝指标来表示。洪涝灾害的形成与季风活动密切有关。地形对洪涝影响明显，洪涝对农业的危害主要有物理性破坏、生理性损伤、生态性危害。防御洪涝的对策主要有加强防灾减灾的组织管理，改善生态环境，提高天气预报准确率等措施。 相似文献
13.
新疆大气可降水量的气候特征及其变化 总被引：13，自引：2，他引：11
利用1961—2000年NCEP/NCAR再分析逐日资料,分析了新疆地区不同季节大气可降水量（APW）的气候分布特征和变化趋势。结果表明:新疆夏季APW小于季风区界限25 mm,从该角度表明新疆为非季风区。APW空间分布呈塔里木盆地和准格尔盆地为高值区,海拔高的阿勒泰山、天山和昆仑山为低值区。APW夏季最大,但小于同纬度东部季风区,春、秋次之,冬季最少,春、秋和冬季APW与同纬度东部季风接近。APW的地理分布与实际降水量分布相反,其最大（最小）区域却为降水量最小（最大）区,受西风带影响,新疆APW模态主要表现全疆一致变化,分布稳定,与降水模态分布差异性大有显著不同,且近40 a来无显著变化趋势,表明决定新疆降水差异的根本原因不在于水汽的多少,而是由降水产生的动力条件、水汽辐合和其他因素差异决定的。 相似文献
14.
乌梁素海是干旱半干旱地区典型的湿地。其位于东亚—澳大利西亚及中亚—印度两条迁徙路线上,是迁徙候鸟极其重要的繁殖地和停歇地。从2009到2012年,我们采用样线法和样点法对水鸟及其栖息地进行调查,共记录了98种水鸟,隶属于6目、14科,同时记录到水鸟个体超过100 000个。其中夏候鸟55种(在此繁殖)、旅鸟39种(在此短暂停留),分别占所记录物种数的56.12%和39.80%。对所记录的鸟类及其种群的迁徙规律进行进一步分析,结果表明:春季迁徙期主要为3月上旬到5月中旬,比秋季迁徙期(8月上旬到11月中旬)短。水鸟繁殖的高峰期是4月上旬到5月下旬。重点保护水鸟(包括IUCN红色名录中的受胁物种以及中国重点保护野生动物名录中的Ⅰ、Ⅱ级保护物种)的集中分布时间是4月上旬到5月下旬以及9月上旬到11月上旬;相比春秋迁徙季节,夏季水鸟的群落结构相对稳定。基于研究,我们建议将乌梁素海湿地列入国际重要湿地名录及迁徙路线网络。此外,栖息地管理对鸟类分布的决定作用同样在文中加以讨论。 相似文献
15.
统计2013-2014年度敦煌黑山嘴地区沙漠-绿洲过渡带气象资料,对区域风沙活动特征进行系统研究。结果表明：区域内合成起沙风以偏南风为主,即由沙漠指向绿洲。从沙漠腹地到绿洲内部,由于植被和房屋增多,起沙风频次和合成输沙势减小,风沙活动减弱,且春季风沙活动最强烈。夏秋季节植被可有效降低风速,减少起沙风频次,改善局地气候。平均气温与平均空气湿度负相关。月平均气温与月平均风速呈现同步性,越靠近沙漠腹地,两者同步性越强;日间气温与风速变化存在同步性,但夜间沙漠与绿洲气温差对风速存在影响,温差越大,风速波幅越大。 相似文献
16.
塔克拉玛干地区气候变化对全球变暖的响应 总被引：14，自引：5，他引：9
从地面水汽压(大气含水量)、平均风速、湿润指数、相对湿度和气压的角度分析在全球变暖的情况下,塔克拉玛干地区气候的年和季节变化特征,结果表明:①年和四季平均风速呈阶梯式下降趋势,具有显著减小的线性趋势,并于1973年发生了由大到小的突变。②夏、秋、冬季和年地面水汽压(大气含水量)自20世纪80年代以来呈较大幅度波动式上升,具有显著的线性增加趋势。夏、秋季地面水汽压于1969年和1973年发生了由少到多的突变。秋、冬季大气含水量的显著增加并没有导致降水量的增加,降水量的变化不能充分反映大气含水量的变化。③夏季湿润指数有显著增加趋势,春季有微弱的上升趋势,而降水量夏季和年有显著增加趋势,春季有微弱的上升趋势,说明综合反映气候干湿变化的湿润指数变化与单用降水量表示的气候干湿变化不完全一致。④夏、秋季和年相对湿度呈波动式上升趋势,夏季和年相对湿度分别于1970年和1974年发生了由低到高的突变。⑤年和四季的平均气压40a来无变化。 相似文献
17.
Seasonal ecosystem variability in remote mountain lakes: implications for detecting climatic signals in sediment records 总被引：5，自引：0，他引：5
J. Catalan M. Ventura A. Brancelj I. Granados H. Thies U. Nickus A. Korhola A.F. Lotter A. Barbieri E. Stuchlík L. Lien P. Bitušík T. Buchaca L. Camarero G.H. Goudsmit J. Kopáćek G. Lemcke D.M. Livingstone B. Müller M. Rautio M. Šiško S. Sorvari F. Šporka O. Strunecký M. Toro 《Journal of Paleolimnology》2002,28(1):25-46
Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes. Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the lakes showed a number of common features. They were ice-covered between 5–9 months, and all but one were dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was greater in the most productive lakes. Two types of lakes were distinguished according to the number of production peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: one at the onset of stratification, and the other during the autumn overturn. Lakes with shorter stratification had a single peak during the ice-free period. All lakes presented deep chlorophyll maxima during summer stratification, and subsurface chlorophyll maxima beneath the ice. Phosphorus limitation was common to all lakes, since nitrogen compounds were significantly more abundant than the requirements for the primary production observed. The major chemical components present in the lakes showed a short but extreme dilution during thawing. Certain lake features may favour the recording of particular climatic fluctuations, for instance: lakes with two distinct productive periods, climatic fluctuations in spring or autumn (e.g., through chrysophycean cysts); lakes with higher oxygen consumption, climatic factors affecting the duration of the ice-cover (e.g., through low-oxygen tolerant chironomids); lakes with higher water retention time; changes in atmospheric deposition (e.g., through carbon or pigment burial); lakes with longer stratification, air temperature changes during summer and autumn (e.g., through all epilimnetic species). 相似文献
18.
Shrub is an important factor on structuring ground arthropod communities in desert ecosystems. In this study, in order to determine how shrubs and their species influence ground arthropod distribution patterns in a sandy desert scrubland dominated by two different shrub species, Calligonum mongolicum and Nitraria sphaerocarpa, the ground arthropods were sampled with pitfall traps during spring, summer and autumn. At the community level, total arthropod abundance was shown to be significantly higher under shrubs than in intershrub bare areas in spring; similar patterns occurred in terms of the richness of arthropod groups in the spring and over three seasons, suggesting season-specific shrub presence effects on arthropod activity. In addition, more arthropods were found under N. sphaerocarpa shrubs than under C. rnongolicum shrubs in autumn, suggesting season-specific effects of shrub species of arthropod activity, whereas more arthropods taxa were captured under C. mongoIicum than N. sphaerocarpa. At the trophic group level, the abundances of predator and herbivore arthropods were significantly greater under shrubs than in intershrub bare habitats, whereas herbivore arthropods were more abundant under N. sphaerocarpa than C. rnongolicum, and an opposite rule was detected for predator arthropods At the family level, the mean abundances of Carabidae, Curculionidae, Gnaphosidae and Lycosidae were significantly higher in the shrub microhabitats than in the intershrub bare habitat, there was no significant difference between habitats on the mean abundances of Formicidae and Tenebrionidae. The study results suggested that shrub presence and shrub species variation are important determinants of ground arthropod assemblages in this desert ecosystem, but the responses of ar- thropods differed among trophic and taxonomic groups. 相似文献
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20.
Sediment Fluxes and Varve Formation in Sihailongwan,a Maar Lake from Northeastern China 总被引：2，自引：0，他引：2
Data derived from monthly sediment traps in Sihailongwan, a maar lake in northeastern China, yielded a detailed record of seasonal sediment fluxes. Sediment fluxes correspond to seasonal climatic variations. The diatom flux shows two distinct peaks in September and November, whereas the flux of chrysophyte stomatocysts shows a maximum in May. The blooms of diatoms may be related to the subsequent deepening of the thermocline in September and lake overturn in spring and November, and influx of nutrient-rich groundwater sometime after the onset of the summer monsoon. The fluxes of organic matter and siliciclastics show a distinct seasonal pattern. They are varying between 0.03 and 0.56 g m−2 d−1 and reach a maximum in May. Quartz in the trap samples indicates that the siliciclastic matter may originate from distant aeolian sources. Sediment trap data and thin section investigations confirm the seasonality of Lake Sihailongwan sediments. Dark-colored layer, which mainly consists of valves of Cyclotella comta, might be deposited during autumn, and then is followed by a light-colored mixed layer starting with siliciclastics deposited after ice-out. The varved sediments in the U-shaped Lake Sihailongwan represent a sensitive siliciclastic and geochemical archive of paleoenvironmental variability in this data-sparse area. Detailed investigations of varved sediments should provide decadal to annual records of seasonal sediment flux and its relation to climatic parameters. Especially the diatomaceous layer is regarded to indicate summer climatic fluctuations, while the thick siliciclastic layer could be an indictor of dust events. 相似文献