贵州亚热带地区的野生珍稀观赏植物资源

贵州亚热带地区的野生珍稀观赏植物资源有４７科７３属９３种，分布在海拔１３７－１０００ｍ的林下，灌丛和岩隙中，处于淑危，渐危及稀有状态。就该区资源的分布规律，属类型，现状及栽培利用等方面进行了探讨。     

Species composition and diversity of fish larvae in the Subtropical Convergence Zone of the Sargasso Sea from morphology and DNA barcoding

Specific regions of otherwise oligotrophic oceans seem to attract fish spawning and sustain significant abundances of fish larvae. The Sargasso Sea in the North Atlantic subtropical gyre is known as the spawning area of the Atlantic eels, but numerous other fish species also spawn in the area. In order to evaluate spatial variability of larval fish in the region, we examined species diversity, composition and abundances at eight stations in the Subtropical Convergence Zone (STCZ) using morphological identification and DNA barcoding. From a total of approximately 3500 specimens collected, at least 154 species from 50 families could be identified. The family Myctophidae had the highest species richness, with at least 32 species represented. The myctophids Lepidophanes gaussi, Bolinichthys indicus, Notolychnus valdiviae and Ceratoscopelus warmingii were the four most abundant species. Other common species included the three eels: Nemichthys scolopaceus, Ariosoma balearicum and Anguilla anguilla. Larval fish species composition differed substantially between the relatively closely spaced stations on either side of prominent hydrographic fronts in the study area, presumably because of the strong environmental gradients. Common eel species were concentrated between the fronts whereas common myctophids were of highest abundance at the outer edges of the fronts. The abundances of most species were generally enhanced in the vicinity of the fronts. The use of combined morphological and DNA‐barcoding identification methods facilitated species identification, and we could document substantially higher levels and a larger degree of spatial variability in species diversity of fish larvae than previously shown for oligotrophic ocean areas.     

亚热带典型农业小流域井水水质季节 变化与空间分布特征

井水是亚热带农业区域农民的饮用水源,其水质状况直接影响到当地农民的身体健康。本文选取亚热带典型农业小流域中井水铵态氮(NH4+-N)、硝态氮(NO3--N)、总氮(TN)和总磷(TP)为研究对象,采用地统计学方法,分析其季节变化和空间分布特征。结果表明,研究区农户井水中NH4+-N、NO3--N、TN和TP含量在全年4个季节的平均值分别为0.05~0.10 mg(N)·L-1、3.0~4.9 mg(N)·L-1、3.4~5.1 mg(N)·L-1和0.03~0.17 mg(P)·L-1,超标率分别为2.3%、10.4%、9.5%和7.9%。在季节动态变化上,NH4+-N在全年变化不显著(P0.05),这主要与土壤的吸附有关;而NO3--N、TN和TP均在夏季达到最高,春季最低,并且两个季节之间的变化具有显著性(P0.05),这主要与农业施肥活动和降水条件有关。在空间变异性上,NH4+-N、NO3--N、TN和TP含量在各季节的块金值与基台值的比值都为0,并且各变量在各季节的变程各不相同,说明这4个变量在各季节分别在不同尺度范围内表现出较强的空间自相关性。在空间分布上,NH4+-N、NO3--N、TN和TP含量都具有斑块状分布,而斑块的位置、大小和形状各不相同。NO3--N和TN在全年的空间分布与研究区地形和土地利用方式有关,在东南部和西南部地势较低的水稻种植区含量较高,而在北部地势较高的林地含量较低。而NH4+-N和TP的空间变异系数高于NO3--N和TN,这主要是由于NH4+-N易被土壤吸附,而磷素在土壤中易被固定,迁移较困难,导致NH4+-N和TP在不同地方的含量差异比较大。地形、水文气候条件、土壤类型、土地利用方式和农业施肥等是造成亚热带农业区域井水水质季节动态变化和空间分布格局差异的主要因素。     

2017年7月15日周口短时强降水过程成因浅析

利用自动气象站资料、Micaps常规资料和T639资料等气象资料,通过天气学和天气动力诊断分析方法,对2017年7月15日周口强降水过程进行了综合分析。结果表明:副热带高压北抬、前期能量积蓄是这次强降水形成的主要环流背景;冷空气触发、低空急流配合切变线以及较强的垂直上升速度为此次降水过程提供了动力条件;西南急流带来的充沛水汽,为这次强降水发生提供了水汽条件。     

辽宁中东部一次区域性暴雨天气过程分析

利用常规天气图、数值预报产品、各种物理量场和卫星云图等资料,对2010年8月27~29日影响辽宁中东部地区的暴雨天气过程进行了综合分析。结果表明：该过程是由高空槽、副热带高压边缘的暖湿气流及南部海面上低压云系共同作用产生的。     

2010年辽宁本溪一次暴雨过程分析

受高空槽和副热带高压共同影响,2010年8月26～29日本溪地区出现暴雨、大暴雨天气过程。此次过程具有降水时间长、强度大、不断出现局地短历时强降水等特点,利用常规资料、卫星云图资料、雷达产品资料等对此次过程成因进行了分析,发现此次过程中副高位置的变化对预报降水起止时间、降水加强时间及降水落区的变化起了重要作用。     

鸡蛋花大型砧木嫁接新品种的关键技术

文章介绍了鸡蛋花的园林应用价值及一些新引进的品种;还详细介绍了大型鸡蛋花砧木嫁接新品种的关键技术,如嫁接砧穗的选择、嫁接方法和嫁接后的管理等。     

辽宁省一次区域性大暴雨天气过程分析

利用常规气象资料、卫星云图和雷达回波,对2010年7月19~22日发生在辽宁地区的区域性大暴雨、局地特大暴雨的天气过程进行分析。结果表明：西南涡、副热带高压是此次大暴雨产生的主要天气系统,低涡、高空槽、切变线是产生大暴雨的动力机制。大暴雨与低空急流有密切的关系,低空急流是通过中尺度脉冲的形式向下游传播动量、热量和水汽,充足的水汽来源于孟加拉湾。     

Toward a rule-based biome model

Current projections of the response of the biosphere to global climatic change indicate as much as 50% to 90% spatial displacement of extratropical biomes. The mechanism of spatial shift could be dominated by either 1) competitive displacement of northern biomes by southern biomes, or 2) drought-induced dieback of areas susceptible to change. The current suite of global biosphere models cannot distinguish between these two processes, thus determining the need for a mechanistically based biome model. The first steps have been taken towards the development of a rule-based, mechanistic model of regional biomes at a continental scale. The computer model is based on a suite of empirically generated conceptual models of biome distribution. With a few exceptions the conceptual models are based on the regional water balance and the potential supply of water to vegetation from two different soil layers, surface for grasses and deep for woody vegetation. The seasonality of precipitation largely determines the amount and timing of recharge of each of these soil layers and thus, the potential mixture of vegetative life-forms that could be supported under a specific climate. The current configuration of rules accounts for the potential natural vegetation at about 94% of 1211 climate stations over the conterminous U.S. Increased temperatures, due to global warming, would 1) reduce the supply of soil moisture over much of the U.S. by reducing the volume of snow and increasing winter runoff, and 2) increase the potential evapotranspiration (PET). These processes combined would likely produce widespread drought-induced dieback in the nation’s biomes. The model is in an early stage of development and will require several enhancements, including explicit simulation of PET, extension to boreal and tropical biomes, a shift from steady-state to transient dynamics, and validation on other continents.     

亚热带天然林4种树木细根生物量垂直分布和主要功能性状的差异

在江西大岗山常绿阔叶混交林中,采用土钻法,对不同树龄的刨花楠、山矾、山乌桕和油桐的细根生物量及其功能性状进行测定;运用多元方差分析方法,分析树种和树龄对细根垂直分布和功能性状的影响。结果表明:4个树种的树龄对细根的生物量的垂直分布没有显著影响,细根生物量随土壤深度的增加而减小;4种树木细根单位面积的生物量和比根长等功能性状有显著差异,但土壤深度对不同细根功能性状的影响不显著;树龄对山乌桕的比根长和组织密度有显著的影响,树龄对油桐的细根直径、表面积和组织密度有显著的影响。