广西气象业务传输质量统计及查询系统的设计与实现     

黄志  詹利群 《广西气象》2013,(4):101-102

采用IIS和基于Visual studio.Net建站模式,辅以Linux＋MySql数据库作为后台支撑,嵌入功能强大的FusionCharts图片显示控件兼以JavaScript实现界面特效,使得网站显示独具特色,有效减轻了日常值班的传输监控负担,实现各项气象实时资料传输完成实效的统计汇总分析.  相似文献   

Nitrogen limitation in arid-subhumid ecosystems: A meta-analysis of fertilization studies     

L. Yahdjian  L. GherardiO.E. Sala 《Journal of Arid Environments》2011,75(8):675-680

Evidence supporting water limitation in arid-semiarid ecosystems includes strong correlations between aboveground net primary production (ANPP) and annual precipitation as well as results from experimental water additions. Similarly, there is evidence of N limitation on ANPP in low precipitation ecosystems, but is this a widespread phenomenon? Are all arid-semiarid ecosystems equally limited by nitrogen? Is the response of N fertilization modulated by water availability?We conducted a meta-analysis of ANPP responses to N fertilization across arid to subhumid ecosystems to quantify N limitation, using the effect-size index R which is the ratio of ANPP in fertilized to control plots. Nitrogen addition increased ANPP across all studies by an average of 50%, and nitrogen effects increased significantly (P = 0.03) along the 50-650 mm yr⁻¹ precipitation gradient. The response ratio decreased with mean annual temperature in arid and semiarid ecosystems but was insensitive in subhumid systems. Sown pastures showed significant (P = 0.007) higher responses than natural ecosystems. Neither plant-life form nor chemical form of the applied fertilizer showed significant effects on the primary production response to N addition. Our results showed that nitrogen limitation is a widespread phenomenon in low-precipitation ecosystems and that its importance increases with annual precipitation from arid to subhumid regions. Both water and N availability limit primary production, probably at different times during the year; with frequency of N limitation increasing and frequency of water limitation decreasing as annual precipitation increases. Expected increase N deposition, which could be significant even in arid ecosystems, would increase aboveground net primary production in water-limited ecosystems that account for 40% of the terrestrial surface.  相似文献   

Implications of local-scale productivity on compensatory growth in a semi-arid shrubland     

M. Gruntman  A. Novoplansky 《Journal of Arid Environments》2011,75(3):279-283

Grazing is a dominant determinant of aboveground net primary production (ANPP) and composition of plant communities. However, ANPP can be maintained following grazing due to compensatory growth, the level of which might depend on additional environmental factors, such as precipitation and edaphic conditions. Several studies have shown that along large-scale regional gradients, community-level compensatory ability is positively correlated with ANPP and soil resource availability. However, community-level responses to grazing are also expected to be affected by local-scale heterogeneity in ANPP, particularly under low primary productivity typical to arid environments. Here, we studied the effect of local-scale variations in ANPP on the compensatory growth of an annual community in a semi-arid region. For two consecutive years, ANPP was evaluated following shoot damage in sites with different primary productivity. The results demonstrated that annual ANPP varied significantly among sites and among plots within sites; however, compensatory ability was negatively correlated with annual ANPP, with overcompensation in the least productive patches and under-compensation in the most productive patches. This pattern contradicts the positive correlation between ANPP and compensatory ability commonly found along large-scale productivity ecoclines, suggesting that the effects of ANPP on compensatory ability might be scale-dependent.  相似文献   

Carbon and water exchange in semiarid ecosystems in SE Spain     

F. Domingo  P. Serrano-Ortiz  A. Were  L. Villagarcía  M. García  D.A. Ramírez  A.S. Kowalski  M.J. Moro  A. Rey  C. Oyonarte 《Journal of Arid Environments》2011,75(12):1271-1281

The changing climate is affecting biological and physical processes occurring in the biosphere, including the biogeochemical cycles of water and carbon. The response of ecosystem carbon exchange to changes in temperature and the water balance is still very uncertain, a fact that highlights the need for research in order to understand the role of the biosphere in the future global carbon budget. South east Spain is on the borderline between the tropical and mid-latitude climate zones, with climates ranging from sub-humid to arid, and the majority representing the driest area in Europe. Initial predictions on climate change for this region point to decreases in total precipitation and the number of precipitation events, meaning a decrease in water availability underlining the vulnerability of the region to desertification. This region, due to these special climatic conditions, has been the subject of experimental carbon and water field research in recent years. This paper defines the state of the art of carbon and water balance measurement and modelling studies in this region, analyses the different processes involved in aggregate exchanges (vegetation and soil; net ecosystem carbon balance–evapotranspiration, photosynthesis–transpiration, soil respiration–evaporation), and identifies needs for future research.  相似文献   

反射技术在数据实体和界面布局松耦合设计中的应用     

吴飞 《地理空间信息》2011,(4):118-119

在管理信息系统开发过程中,业务逻辑都围绕数据展开。在软件项目分析设计过程中,一般首先分析数据实体并设计系统界面,这些过程都依赖数据实体的稳定性,当实体数据发生变化时,比如在数据库设计中修改了数据结构,系统设计包括界面设计则需要相应变化,这样势必会提高软件的开发成本,同时给系统的运行维护带来更多困难。提出了一种使用.Ne...  相似文献   

Phytoplankton distribution and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)     

Rochelle-Newall EJ  Chu VT  Pringault O  Amouroux D  Arfi R  Bettarel Y  Bouvier T  Bouvier C  Got P  Nguyen TM  Mari X  Navarro P  Duong TN  Cao TT  Pham TT  Ouillon S  Torréton JP 《Marine pollution bulletin》2011,62(11):2317-2329

Phytoplankton diversity, primary and bacterial production, nutrients and metallic contaminants were measured during the wet season (July) and dry season (March) in the Bach Dang Estuary, a sub-estuary of the Red River system, Northern Vietnam. Using canonical correspondence analysis we show that phytoplankton community structure is potentially influenced by both organometallic species (Hg and Sn) and inorganic metal (Hg) concentrations. During March, dissolved methylmercury and inorganic mercury were important factors for determining phytoplankton community composition at most of the stations. In contrast, during July, low salinity phytoplankton community composition was associated with particulate methylmercury concentrations, whereas phytoplankton community composition in the higher salinity stations was more related to dissolved inorganic mercury and dissolved mono and tributyltin concentrations. These results highlight the importance of taking into account factors other than light and nutrients, such as eco-toxic heavy metals, in understanding phytoplankton diversity and activity in estuarine ecosystems.  相似文献   

Carbon input, production and turnover in the interstices of a Lake Tegel bank filtration site, Berlin, Germany     

Anja Hoffmann  Günter Gunkel 《Limnologica》2011,41(3):151-159

The sandy littoral zone of Lake Tegel (Berlin, Germany) was investigated during 2004–2006 down to sediment depths ≥26 cm to derive a scheme of seasonal carbon turnover under induced bank filtration conditions. Carbon turnover processes were quantified regarding external and internal sources of dissolved and particulate organic matter (DOM and POM), primary production, community respiration, redox potential as well as specific loads of soluble chemical compounds such as nitrogen, iron, manganese and DOC.Over the course of the year, infiltrating DOC decreased by about 13–20% within the upper 26 cm sediment of the infiltration stretch. Gradients of all observed soluble compounds that are highly cross-linked to biological activities were highest in the topmost centimetre. In this depth mass balances (output–input) were negative concerning NO₃-N (−1 mg dm⁻² d⁻¹, summer mean) and DOC (−2 mg dm⁻² d⁻¹, winter mean), respectively, while specific loads of cations such as manganese reached up to 0.2 mg dm⁻² d⁻¹ during summer. Carbon mineralization ranged between 3 and 7 mg C dm⁻² d⁻¹ and was nearly twice as high in summer as in winter. The turnover of the infiltrating DOC contributed maximally 25% in summer to 50% in winter to the entire organic carbon mineralization. Gross and net primary production differed up to a factor of >10, indicating very fast turnover reactions and the predominance of community respiration and mineralization, respectively. The POC in the upper sediment layer (10 cm) temporally varied around 1% sediment d.w.; benthic algae, organic seston input and autumnal leaf fall contributed similar percentages to the POC pool.  相似文献   

Seasonal distribution of the inorganic carbon system and net ecosystem production in the north eastern shelf of the Gulf of Cádiz (Southwest Iberian Peninsula)     

Mariana Ribas-Ribas  Abelardo Gómez-Parra Jesús M. Forja 《Continental Shelf Research》2011,31(18):1931-1942

There is scatter information of the inorganic carbon system in the coastal zones and it is important to increment our knowledge and understand the global carbon cycle. We investigated the distribution of inorganic carbon system parameters and its controls in the coastal waters of the north eastern shelf of the Gulf of Cádiz (GoC) during four cruises that took place in June 2006, November 2006, February 2007 and May 2007. The objectives of this study are: (1) to describe the spatio-temporal distribution of inorganic carbon system parameters in waters of the north eastern shelf of the GoC using four cruises, each undertaken in one of the four seasons, (2) to calculate net ecosystem production (NEP) and (3) to examine factors controlling these distributions. The distribution of inorganic carbon system parameters in the north eastern shelf of the Gulf of Cádiz showed temporal and spatial variability. River input, mixing, primary production, respiration, CO₂ air-sea exchange, and remineralization were factors that controlled such distributions. The coastal zone of the GoC is autotrophic on an annual scale at a rate of 1.0 mmol m⁻² d⁻¹. Further measurements are needed it to improve the NEP calculation and to evaluated to intra-annual variability.  相似文献   

浅谈啧锚网技术在高边坡防护中的应用     

刘彦东 《中国勘察设计》2011,(2):42-44

喷锚同支护是靠锚杆、钢筋同和混凝上层共同工作来提高边坡岩土的结构强度和抗变形刚度,减小岩(土)体侧向变形,增强边坡的整体稳定性.  相似文献   

鄂西地区中二叠统栖霞组下部烃源岩形成机理   总被引：5，自引：1，他引：4       下载免费PDF全文

韦恒叶  陈代钊  遇昊  汪建国 《地质科学》2011,46(1):68-82

中二叠统柄霞组下部烃源岩广泛发育于扬子地台台内盆地和台地边缘.多种古环境参数V/(V+Ni)、V/Cr、Cu、Ni、Zn、Hf、Nb、自生U含量和烃类百分含量的研究表明,栖霞组烃源岩周期性变化的有机质埋藏量主要受控于海洋表层初级生产力,而生产力的变化受气候引起的海平面变化的影响.海平面的上升带来丰富的营养物质,提高海洋...  相似文献