Impacts of termites on selected soil physicochemical characteristics in the highlands of Southwest Ethiopia

Termites are reported to improve soil physicochemical properties thereby enhance soil fertility of their mound and foraging areas. Empirical study pertaining to these effects is missing in Southwest Ethiopia. For this study, soil samples affected by termite activities were collected at 1 m interval within 0–3 m distance from the base of six termite mounds on gently sloping and sloping land and analyzed for physicochemical parameters. The result of the analysis depicted that soil bulk density (1.38–1.15 g cm^?3) and moisture content (21.1–9.9%) decreased with increased distance from the mound base. While clay content decreased with increased distance from the mound base from72.0% to 45.5%, sand and silt contents increased from 8.0% to 21.3% and 19.3% to 28.5%, respectively. PH (6.23), organic carbon (3.85%), total nitrogen (0.4%), cation exchange capacity CEC (30.43 cmol kg^?1), exchangeable Ca (13.73 cmol kg^?1), Mg (3.15 cmol kg^?1), and PBS (56.8%) were higher on termite mounds. While, electrical conductivity (0.03 dS m^?1–0.06 dS m^?1), exchangeable K (0.52–0.93 cmol kg^?1) and Na (0.02–0.03 cmol kg^?1) showed increasing trend with the distance from the mound base. Our results indicated that termite mounds are important sinks of organic matter and mineral nutrients, and hence contribute to the enhancement of soil fertility. Thus, for subsistent farmers the uses of termite mounds as a fertilizer present an opportunity to improve agricultural production.     

Serum cardiac troponin I in canine syncope and seizures

Objective

To determine if serum cardiac troponin I (cTnI) concentration distinguishes between cardiogenic syncope and collapsing dogs presenting with either generalized epileptic seizures (both with and without cardiac disease) or vasovagal syncope.

崩岗侵蚀对土壤速效养分质量分数及化学计量比的影响

为揭示崩岗侵蚀对土壤速效养分及化学计量比的影响,选取福建省长汀县黄泥坑崩岗群微度、中度和强度崩岗3处为研究对象,测定和分析了0 ～ 30 cm土层集水坡面、崩壁、崩积体以及沟道部位的土壤基本物理性质、速效养分及化学计量特征.结果表明:1)随着侵蚀强度的增加,硝态氮和速效磷质量分数表现为强度＞中度＞微度,中度侵蚀崩岗铵态氮质量分数最低,速效钾质量分数最高;从水平方向上,各速效养分质量分数表现为速效钾(AK)＞铵态氮＞硝态氮＞速效磷(AP);垂直方向上,各速效养分质量分数大致随着土层深度而降低,但同一侵蚀强度内各质量分数差异较小.2)土壤速效氮为铵态氮与硝态氮的总和(AN),AN/AP比表现为微度＞强度＞中度,微度与中度差异显著(P ＜0.05);AK/AN比为中度＞微度＞强度,中度与强度差异显著(P ＜0.05);AK/AP比为微度＞中度＞强度,微度与中度差异显著(P＜0.05).3)从集水坡面、崩壁、崩积体至沟道,3种类型崩岗的铵态氮和硝态氮平均值都呈降低的趋势,速效磷逐渐升高,速效钾在崩积体处最低,其他3个部位变化不大;土壤AN/AP、AK/AP比呈降低的趋势,AK/AN比在沟道处最高.4)速效养分化学计量比与砂粒、粉粒、pH和有机质皆密切相关,黏粒、容重和含水率对其影响相对较小.     

鄂东南崩岗洪积扇土壤物理性质空间分异特征

【目的】研究崩岗洪积扇农田土壤颗粒组成、容重、土壤孔隙度、土壤持水情况、有机质并分析它们之间的相互关系,同时探索崩岗洪积扇农田土壤物理性质空间分异规律,不仅有利于农业用地规划,也为崩岗洪积扇农田土壤改良提供理论依据,对山区农林业生产具有重要的意义。【方法】运用野外调查结合室内分析的方法,以通城县杨垄小流域崩岗洪积扇农田为研究对象,选定水田和旱地两种洪积扇土地利用方式,分别采集洪积扇农田扇顶、扇中、扇缘以及对照4个区域测定其土壤物理性质,运用Pearson相关系数分析法对各指标之间的内在联系进行探究,研究崩岗对洪积扇农田的影响规律。【结果】崩岗侵蚀导致洪积扇农田土壤严重沙化,土壤结构性恶化。洪积扇农田土壤粗颗粒物质（砾石和砂粒）平均比对照区多75.89%,土壤细颗粒物质（粉粒和黏粒）平均比对照区减少39.13%。土壤有机质含量减少,洪积扇土壤有机质含量平均比对照区减少58.70%;容重增大,相对对照区平均增加0.25 g·cm^-3;土壤孔隙度均小于对照区,饱和持水性和毛管孔隙度显著低于对照区。同时,沿着洪积扇扇缘到扇顶,土壤砾石和砂粒含量呈现逐渐增加,而粉粒和黏粒含量逐渐减少,容重随之增大,土壤孔隙度减少,持水性能也逐渐减弱,有机质逐渐减少的趋势。相关性分析得出,土壤容重与有机质含量呈极显著的负相关（R=-0.907^**）,土壤容重与土壤孔隙性和土壤持水特性呈极显著的负相关,总孔隙度、毛管孔隙度与土壤持水特性均呈极显著的正相关,非毛管孔隙度与各物理性质之间没有明显的相关性。土壤各粒级大小与土壤容重、土壤持水性指标、总孔隙度和毛管孔隙度之间呈显著或极显著相关性。【结论】崩岗侵蚀发生后,洪积扇农田以土壤颗粒组成、有机质、土壤容重、孔隙度以及持水性能为代表的土壤物理性质退化严重。此外,崩岗洪积扇农田土壤物理性质存在空间分异规律,离扇顶越近,土壤物理结构性越差。洪积扇农田土壤指标间存在息息相关的联系,尤其是土壤颗粒组成和其他物理性指标之间的关系,突出了改良洪积扇土壤从土壤颗粒方面入手是可行的,如采取客土法和深耕法可有效改良被侵蚀的土壤结构。研究结果为明确洪积扇农田土壤物理性质提供了依据,为改良崩岗洪积扇土壤结构性奠定了基础,对农业生产和提高农业经济效益有重要意义。     

红火蚁多蚁后型种群婚飞新形成蚁巢的局域空间分布特征

采用野外定点调查的方法,研究了红火蚁Solenopsis invicta多蚁后型种群婚飞新形成蚁巢的局域空间分布规律.结果表明,短期内婚飞形成的活动蚁巢在局域平面空间上呈均匀分布,分布的基本成分为单个蚁巢,且蚁巢间相互排斥.在平面空间上不同间隔距离间该类型蚁巢半方差值呈明显规律性变化,具有空间相关性.建立了5个球状模型,其变程分别为12.6、14.1、9.7、13.3和14.5 m,平均为12.8 m.     

不同播期、烧堆措施和定期喷药在缅甸马铃薯晚疫病综合防治中的作用

调查在农民田和缅甸山州农业试验农场山区进行，根据病害测报评价定期用药、播期、烧堆措施在马铃薯晚疫病综合防治中的效果。试验1的结果表明，在未施药的不同播期小区晚疫病严重，而施达克尼尔的小区病情明显轻。在试验2中，Wallin‘s测报系统准确地预测马铃薯晚疫病的初发生期，并建议开始施药。降雨量12．7mm时施药比每周定期施药更有效。不同施药处理比不施药的对照增产30．1％－62．2％。病害造成的产量损失23．1％－38．3％。烧堆措施对防治晚疫病无效，不过可增产39．2％。     

天祝高寒草甸高原鼢鼠鼠丘植被演替调查

高原鼢鼠鼠丘植被演替是反映草地恢复的重要指标之一。以定点标记的方法对天祝高寒草甸高原鼢鼠鼠丘植被演替进行了调查。结果表明,鼠丘植被在不同演替阶段外貌特征及植物组成差异较大。随演替的进行,1~2年生植物和多年生杂类草比例呈递增趋势,禾本科和莎草科植物也伴随出现,但在群落中所占比例相对较低。α多样性表明,鼠丘植物的丰富度指数随演替进行呈显著递增趋势,但都低于原生植被。Shamon-wiener指数表明,形成4年的鼠丘植被群落达到演替后期,物种组成接近原生植被。植物功能群组成显示,演替各阶段1~2年生植物生物量在各自群落中的比例显著高于原生植被。     

Paleolandscape and paleoenvironmental interpretation of spring-deposited sediments in Dakhleh Oasis,Western Desert of Egypt

Iron-rich sediments in Dakhleh Oasis, Western Desert of Egypt, have been recognized as spring mounds and as archaeological sites where Paleolithic materials have been recovered. Detailed sedimentologic investigation and mapping of these features reveal that spring mound sediments were deposited in a shallow vegetated wetland formed by the discharge of iron-rich Nubian Aquifer waters along the southern margin of the oasis, controlled largely by localized faulting and the variable paleotopography of the basin floor. The spring sediments represent peri-lacustrine or lake independent features and can be differentiated from fully lacustrine deposits on the basis of their sedimentary characteristics as well as the presence of goethite and jarosite in a region where authigenic deposition during Pleistocene pluvial activity principally resulted in tufas and lacustrine marls. Spring mound formation incorporated sediment through the ponding of surface water, aeolian entrapment by local vegetation, and the formation of iron precipitates in a low-energy, oxidative and acidic environment that was not dependent upon surface water inputs into the Dakhleh basin. The potentially interpluvial nature of this water resource makes it an important sedimentary archive for archaeological investigations in the basin. The Dakhleh spring mounds record a unique groundwater controlled paleoenvironment, providing the first evidence of a bog iron in Egypt and one of the few occurrences of iron-rich wetland remnants in the modern Sahara.     

地下开采对农村的影响

对地下开采引起的岩体移动变形问题建立了数学模型,通过工程实际分析验证了该数学模型的准确性,并对其引发的农村房屋开裂破坏、农田塌陷问题进行了预测分析,为矿产开采、安全生产提供了科学指导。     

基于植物多样性指数对汶川地震灾区崩塌山体的微生境植被自然恢复力评价

本文将地震灾区的崩塌山体划分为碎石坡面、巨石坡面、碎石地、洼地和沟槽地5种微生境类型.在此基础上,基于植物多样性指数,对崩塌山体不同微生境的植被自然恢复力进行了测定.结果表明,不同微生境的植被自然恢复力不同,其恢复力指数大小为：沟槽地＞洼地＞碎石地＞巨石坡面＞碎石坡面.这客观上反应了地震灾区不同生境的植被天然恢复现状,可为灾区有针对性地采取不同恢复措施提供参考.