棉花的防灾减灾     

吕凯  ;魏凤娟 《商界．城乡致富》2013,(11):45-47

棉花在整个生长期,都可能发生各种气象灾害,导致严重减产。介绍了棉花播种-苗期冷（冻）害、棉花雹灾、棉花雨涝害、棉花旱灾、棉花干热风害、棉花热害、棉花吐絮期霜冻害等灾害的症状,并且针对各种灾害提出了相应的防灾救灾措施。  相似文献   

Microclimate in agroforestry systems in central Amazonia: does canopy closure matter to soil organisms?   总被引：7，自引：0，他引：7  

Christopher Martius  Hubert Höfer  Marcos V.B. Garcia  Jörg Römbke  Bernhard Förster  Werner Hanagarth 《Agroforestry Systems》2004,60(3):291-304

Microclimate was recorded and soil organisms were collected 1997-1999 in ecosystem stands of contrasting structure in central Amazonia (a primary forest, a 12-year secondary forest, two different agroforestry systems, a rubber tree (Hevea brasiliensis) plantation, and a peach palm (Bactris gasipaes) monoculture with a densely closed canopy). The aim was to look at the effects of canopy closure on microclimate and soil organisms. Monthly maxima temperature, average air and soil temperatures, and saturation deficit were highest in September 1997, and total annual rainfall in 1997 was 12-28% lower than in the other study years. The monthly average litter temperatures were consistently 2-4 °C higher in the plantation sites than in the rainforest and the secondary forest, and temperatures on single days (not the monthly averages) in the plantations were up to 10 °C higher than in the primary forest. The highest average litter and soil temperatures and the highest temperature maxima were recorded in the agroforestry plantations. Canopy closure strongly determined the litter temperatures in the sites. Soil macrofauna biomass was also strongly correlated to canopy closure (linear regression, P = 0.05). We conclude that a well developed canopy effectively protects the soil macrofauna from high temperature variation and drought stress. Therefore, optimizing these agroforestry systems for canopy closure may contribute to a better management of the beneficial soil decomposer community. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

Experimental studies on rain splash erosion of forest soils after clearing in Okinawa using an artificial rainfall apparatus     

Yasuhiro?OhnukiEmail author  Akira?Shimizu 《Journal of Forest Research》2004,9(2):101-109

The main island of Okinawa, in southwestern Japan, is characterized by a subtropical climate, coral reefs, and reddish soils, which contain Acrisols and Cambisols (FAO/UNESCO classifications). Recently, due to soil erosion on hilly lands, the coral reefs have been damaged by an inflow of reddish soil. Forest clearing is thought to one of the factors increasing rain splash erosion rates on hilly lands, because it is believed that clearing disturbs the forest floor and causes the supply of litter to stop. After clearing, A0, A and B horizons will be denuded, one after the other, by rain splash. In this study, we measured rain splash erosion rates of undisturbed samples of A0, A and B horizons using an artificial rainfall apparatus. The results of experiments on rain splash erosion clarified several aspects of the erosion process in a clearing site. First, it was found that the rain splash erosion rates were higher in fresh litter than in decomposed litter, in decomposed litter than in the A horizon, and in the A horizon than in the B horizon. Thus, the erosion rate increases with soil depth. Secondly, surface-gleyed red and yellow soils are mostly vulnerable to rain splash erosion. The erosion rates of these soils are two to three times higher than those of the red soil and the yellow soils. Thirdly, the erosion rates are affected mainly by bulk density and saturated hydraulic conductivity, not by clay ratio and dispersion ratio. Lastly, the difference between erosion rates of surface-gleyed red and yellow soils and other soils will be even greater if a soil crust has formed, because the formation of a soil crust increases the rain splash erosion rate.  相似文献   

自贡市近50年来降水变化特征分析     

袁立新 《安徽农业科学》2012,40(9):5546-5549

[目的]分析自贡市近50年来降水变化特征。[方法]利用自贡市1961～2010年3个测站逐日降水资料,运用线性趋势法、累计距平法等数理统计方法,研究了近50年来自贡市年、季、月降水总量与雨日的气候变化特征。[结果]自贡市年降水量总体呈减少趋势,其变化倾向率为-28.0 mm/10a。年雨日明显减少,且雨日的减少比降水量的减少明显得多,其变化倾向率为-5.6 d/10a,雨日的减少主要表现为小雨日数的减少。夏、秋、冬季降水量均呈负趋势,且四季的雨日都呈负趋势,其中,秋季的雨量和雨日减少最明显也最多。逐月降水量呈单峰型分布,逐月降水日数呈双峰型分布。自贡各地年内出现的各级雨日数几乎一致,且不同强度雨日随量级的增加而减少。年降水量和雨日数的同步减少是自贡市近50年来降水变化的一个明显特征。[结论]总的来说,自贡市自然降水资源正趋于减少,秋干明显。  相似文献   

2009年2月抚顺一次雨转暴雪天气过程分析   总被引：3，自引：1，他引：3  

吴春英  李金义  徐全辉 《安徽农业科学》2009,37(30):14784-14789

利用常规气象资料,分析了2009年2月12～13日抚顺一次历史罕见雨转暴雪天气过程的环流背景、影响天气系统、卫星云图和雷达资料,并对数值预报产品进行了释用检验。结果表明：该次强降水产生在欧亚中高纬度呈一槽一脊径向环流形势下,500hPa北涡、南支槽、地面江淮气旋、850hPa切变线是主要影响天气系统。强降水发生在低层辐合、高层辐散的有利动力条件下。该次降水过程有2支低空急流在辽宁汇合,水汽条件充沛。冷平流由低层侵入,低层冷暖空气交汇形成强锋区,为强降水产生提供了动力条件。低层高温高湿的不稳定能量为雷暴和强降水的发生提供了热力条件。该次降水预报过程中,欧洲、日本形势预报、降水预报稳定且准确,德国降水预报前期48h预报偏小．24h预报与实况接近．中尺度预报过程降水量级偏大。  相似文献   

基于稳定同位素的土壤水分运动特征   总被引：7，自引：1，他引：7  

靳宇蓉  鲁克新  李鹏  王琦  张铁钢  刘莹 《土壤学报》2015,52(4):792-801

土壤水分受降雨和地下水的共同补给作用,是陆地水循环的重要环节。通过模拟试验,结合土壤水同位素特征,以黄土高原黄绵土为研究对象,研究降雨入渗和地下水补给方式下土壤水分的运移变化特点。结果表明:土壤体积含水量随时间的延长而增大,最终趋于稳定,土壤水分的运移有明显滞后效应;土壤水氢同位素受补给水源、交换混合以及蒸发的影响,随时间的延长,补给水源的影响逐渐减弱,水分的交换混合和蒸发作用逐渐显现,土壤水最终达到动态平衡状态;两种补给条件下,土壤水运移方式均为活塞式推进,降雨入渗方式土壤水δD随土层深度的增加先减小后增大最终趋于稳定,表层0~5cm土壤水由于蒸发富集重同位素,5~20cm土壤水滞留时间最长,保水能力最强,地下水补给方式下土壤水δD随土层深度的增加而减小,上层土壤水δD由于蒸发富集重同位素,下层受地下水补给影响贫化;两种补给方式下土壤水δD与δ18O有良好线性关系,降雨入渗方式土壤水蒸发分馏作用大于地下水补给方式,地下水补给具有较好的保水效果。  相似文献   

南昌市大气硫沉降的空间变化和来源   总被引：1，自引：0，他引：1  

朱仁果  肖化云  谢志英  吴亮红  吴代赦 《安徽农业科学》2010,38(13):6787-6789

[目的]探讨苔藓组织硫含量和雨水硫酸根浓度的相关性及南昌市大气硫的来源。[方法]在南昌市南昌大学北区、南昌大学前湖校区、电厂、梅岭4个采样点采集石生细叶小羽藓[Bryohaplocladium microphyllum（Hedw.）R.Watanabe et Iwats]样品29个,并在南昌电厂采集煤样9个,然后测定苔藓组织和煤的硫含量和硫同位素值。[结果]南昌大学北区苔藓组织硫含量（0.45%±0.059%）高于南昌大学苔藓组织硫含量（0.26%±0.002%）,能反映南昌市雨水硫酸根浓度变化规律。南昌市苔藓硫同位素的变化范围是-0.64‰～9.71‰,其中南昌市市郊梅岭苔藓组织硫同位素值最高（4.02‰～9.71‰）,明显高于南昌大学前湖校区（0.55‰～0.56‰）和电厂苔藓组织硫同位素值（-0.64‰～0.45‰）。[结论]对苔藓组织硫含量和硫同位素值相关性的研究表明,南昌市大气硫源主要受到中国北方远距离传输硫和生物成因硫的共同影响。  相似文献   

影响雨季造林成活率的主要因素   总被引：3，自引：0，他引：3  

邢景阳  柳旺波  郝文学  纪连军  刘艳霞 《防护林科技》2002,(4):35-36,63

通过对朝阳油松、侧柏混交试验调查分析 ,得出选择造林树种、造林时间、造林时机、坡向和坡位是影响该地区雨季造林成活的主民因素。造林时间以 6月中下旬至 7月中旬为好 ;造林时机以小雨或阴天成活率最高 ;坡向以北坡、坡位以下部为好  相似文献   

Comparing micrometeorology of rain forests in Biosphere-2 and Amazon basin     

Muhammad Altaf Arain  William James Shuttleworth  Blake Farnsworth  John Adams  Omer Lutfi Sen 《Agricultural and Forest Meteorology》2000,100(4)

Micrometeorological variables measured in the BIOSPHERE-2 Center (B2C) enclosed rain forest biome for 1 year were compared with similar measurements made in the Amazon rain forest. In the B2C rain forest, the overlying glass and supporting structure significantly reduces (by approximately a factor of two) the incoming solar radiation. Monthly mean values of above-canopy and within-canopy air temperature, vapor pressure, and vapor pressure deficit are reasonably similar to those of the Amazon rain forest, but there are marked differences in the above-canopy values of these variables in the Arizona summer. Monthly mean diurnal trends also show significant differences. Measurements of vertical air temperature gradient clearly showed two very distinct environments in the 27.4 m high rain forest dome during daylight hours. There is a comparatively cool and fairly well-mixed environment (which is reasonably similar to that found in a natural rain forest) below about 10 m and a hot, thermally stable environment above about 15 m. The nature of the atmospheric turbulence within the B2C rain forest also is significantly different from that normally found in natural rain forests. There is little turbulent mixing above the forest canopy in this enclosed environment. These findings are important for guiding the operation and use of this experimental rain forest facility in future research and for understanding how the rain forest biome functions in an enclosed environment.  相似文献   

基于PLC的新型太阳能烟叶晾晒装置设计     

狄敬国  王亮 《安徽农业科学》2016,(23):240-241

采用运动可靠稳定的PLC作为控制核心设计了一种新型太阳能烟叶晾晒装置,该装置所需能源由太阳能电池板进行转换提供,通过湿敏传感器检测雨水信号,以PLC为控制核心,利用触摸屏实现操作,通过智能化控制可方便地实现在无人的情况下对烟叶进行晾晒和收集。该装置设计合理,工作可靠稳定,特别是在农村市场具有极高的推广价值。  相似文献