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Search Results: 1 - 10 of 111656 matches for " 邵明安? "
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黄土区土壤水分有效性的动力学模式

科学通报 , 1987,
Abstract: 以往的土壤水分有效性研究大多采用静态描述,然而用静态的概念来描述处于土壤-植物-大气连统体(SPAC)中的动态水流已失去物理意义。近年来,随着人们对SPAC中水分相互关系的深入认识,水分有效性的研究已涉及到植物根系吸水速率。本文将在植物根系吸水定量描述的基础上来建立土壤水分有效性模式。显然,探讨水分有效性的动力学模式有助于了解生态系统中土壤水分的动态功能和加强其水分管理。
论土壤-植物系统中水流电模拟时间常数的变性

科学通报 , 1991,
Abstract: 线性模式以欧姆定律为基础,以电势差拟水势差,以电流强度拟水流通量密度,定义水势差与通量密度之比为不变的水流阻力。该模式自VandenHonert(1948)首次应用以来,使用得非常普遍。然而,该模式的缺陷是明显的。一是它不能从现象上解释水流阻力随通量
Effects of rainfall intensity on rainfall infiltration and redistribution in soil on Loess slope land
雨强对黄土坡面土壤水分入渗及再分布的影响

李毅,
应用生态学报 , 2006,
Abstract: With simulation test, this paper studied the patterns of rainfall infiltration and redistribution in soil on typical Loess slope land, and analyzed the quantitative relations between the infiltration and redistribution and the movement of soil water and mass, with rainfall intensity as the main affecting factor. The results showed that rainfall intensity had significant effects on the rainfall infiltration and water redistribution in soil, and the microcosmic movement of soil water. The larger the rainfall intensity, the deeper the wetting front of rainfall infiltration and redistribution was, and the wetting front of soil water redistribution had a slower increase velocity than that of rainfall infiltration. The power function of the wetting front with time, and also with rainfall intensity, was fitted well. There was also a quantitative relation between the wetting front of rainfall redistribution and the duration of rainfall. The larger the rainfall intensity, the higher the initial and steady infiltration rates were, and the cumulative infiltration increased faster with time. Moreover, the larger the rainfall intensity, the smaller the wetting front difference was at the top and the end of the slope. With the larger rainfall intensity, both the difference of soil water content and its descending trend between soil layers became more obvious during the redistribution process on slope land.
新疆农田作物覆膜地温极值的时空变化
李毅,
应用生态学报 , 2004,
Abstract: 土壤温度的上限和下限值极大地影响农田作物的生长发育.根据对新疆农田2年度不同观测时刻、不同覆膜条件及不同作物的最高和最低地温的分析,可知2年度全生育期地温极值均发生在0cm位置.地温极值依观测时刻的不同而变动.覆膜最低温度始终高于裸地,说明覆膜对提高低温段土壤温度有明显作用.最低温度的日变化可用二次函数表达;14:00和20:00时最高地温可分别用深度的椭圆曲线和线性关系表达.不同条件下的地温极值和气温具有线性关系,其中裸地最低温度与气温的相关性高于覆膜;玉米最低温度与气温的相关性高于棉花;最高温度与气温的相关性比最低温度与气温的相关性差.
雨强对黄土坡面土壤水分入渗及再分布的影响
李毅,
应用生态学报 , 2006,
Abstract: 基于典型黄土的坡地人工降雨实验,对比研究了降雨、入渗及再分布规律;以雨强为主要影响因素,分析了降雨入渗及水分再分布过程中水土物质迁移的定量关系.结果表明,雨强变化对黄土坡面降雨入渗及土壤水分再分布的微观水分运动过程具有重要影响.雨强增大时,入渗和再分布湿润锋均随降雨历时延长而逐渐增加,但水分再分布过程的湿润锋增加速率比入渗慢得多;入渗湿润锋与时间关系可用幂函数表示,同时可表示为雨强的幂函数关系.再分布湿润锋与时间也存在定量关系.雨强越大,初始和稳定的土壤水分入渗率越高,累积入渗量随降雨时间增加得越快.此外,雨强越大,坡顶与坡脚湿润锋深度差异越小,坡面再分布过程的土壤含水量在各层的差异和递减趋势越明显.
间歇降雨和多场次降雨条件下黄土坡面土壤水分入渗特性
李毅,
应用生态学报 , 2008,
Abstract: 基于可控的坡面间歇降雨和多场次降雨试验,对黄土坡面土壤水分入渗及分布特征进行了研究.结果表明:间歇降雨条件下,两次降雨期间的累积径流量均随降雨历时的延长呈近似线性增加,湿润锋也随降雨时间的延长而增加;在两次降雨的间歇期,湿润锋增加缓慢.入渗率随着坡度的增大而减小,第2次降雨的入渗率随时间而减小的趋势更明显;15°坡面的累积入渗量比25°大,分别为178和88mm.多场次降雨条件下,各场次降雨的初始入渗率均较高,其中第1场降雨的土壤入渗率、累积入渗量在各时段均明显高于其他场次,后3场降雨的入渗率差异不大;降雨场次越多,湿润锋越深.
黄土高原退耕还林条件下的土壤干化问题*
王力?,
世界林业研究 , 2004,
Abstract: 介绍了土壤干化的概念及其对黄土高原生态环境的严重危害和对退耕还林还草工程的不利影响,说明了黄土高原地区土壤干化现象的出现是树(草)种选择不当和过分追求经济效益的结果,论述了黄土高原的植被建设几十年来没有取得成效的原因在于人类活动的逆向作用,包括植被类型选择失当,群落生产力过高,忽视了生物多样性在植被恢复演替中的重要作用等。这些不合理的措施一方面导致了大面积低效低产林的形成,另一方面又恶化了植被赖以生存的水分生态条件,加速了土壤干化现象的出现。由于其对植被建设的严重不良影响,必然影响到黄土高原生态环境的重建,在此意义上,解决土壤干化问题是目前退耕还林(草)工程面临的最为关键的课题之一。
土柱尺寸对扰动黏壤土饱和导水率的影响
曹瑞雪,
中国水土保持科学 , 2014,
Abstract: ?土壤饱和导水率ks是最基本的水力参数之一,而已知实验室内其值的确定受土柱尺寸的影响。以关中的塿土为研究对象,在室内,采用定水头法,研究5~30cm内6个不同土柱尺寸对扰动黏壤土ks测定的影响。结果表明:随着时间的延伸,ks逐渐减小,其值最初降幅较大,其后趋于稳定,且在5~30cm土柱直径范围内,ks随着土柱直径的变大,扰动黏壤土的ks递增,二者线性相关,y=0.0004x+0.0037(r2=0.9651)。研究结果可为测定ks合理测定时间段及合理尺寸的选择提供参考。
Soil hydraulic properties and their influences on soil water content under different land uses in Liudaogou watershed of Loess Plateau.
黄土高原六道沟流域不同土地利用方式下土壤水力特性及其对土壤水分的影响

刘春利,
应用生态学报 , 2008,
Abstract: By the method of cross correlation coefficient in geo-statistics, this paper studied the soil hydraulic properties and their influences on soil water distribution under four land uses, i.e., farmland, waste-grassland, forestland, and alfalfa land in Liudaogou watershed of Loess Plateau. The results showed that farmland soil and waste-grassland soil had the similar physical characteristics, as did forestland soil and alfalfa land soil. For any given soil suction, farmland soil had the highest water content, while forestland soil had the lowest one. The opposite was observed for the saturated hydraulic conductivity of soil water. In forestland and alfalfa land, soil water content increased with increasing depth during water consumption period, but decreased with soil depth at any other time. The influence range of saturated hydraulic conductivity on soil water content depended on soil water condition. During the compensation period of soil water, the influenced lag distance of saturated hydraulic conductivity to water content was 0-40 cm, and that of water content to saturated hydraulic conductivity was 0-50 cm; while during the stable period of soil water, the influenced lag distances of saturated hydraulic conductivity and water content were both 0-60 cm. There were positive correlations between the two properties under all land uses during these two periods. During water consumption period, saturated hydraulic conductivity was positively correlated with soil water content in farmland and waste-grassland. The influence range of saturated hydraulic conductivity to water content was about 0-80 cm, while that of water content to saturated hydraulic conductivity was 0-60 cm. However, negative correlation was observed in forestland and alfalfa land, and the influence ranges were also about 0-60 cm.
Distribution characteristics of soil pH, CEC and organic matter in a small watershed of the Loess Plateau
黄土高原小流域土壤pH、阳离子交换量和有机质分布特征

魏孝荣,
应用生态学报 , 2009,
Abstract: Soil chemical properties play important roles in soil ecological functioning. In this study, 207 surface soil (0-20 cm) samples were collected from different representative landscape units in a gully watershed of the Loess Plateau to examine the distribution characteristics of soil pH, cation exchange capacity (CEC) and organic matter, and their relations to land use type, landform, and soil type. The soil pH, CEC and organic matter content ranged from 7.7 to 8.6, 11.9 to 28.7 cmol·kg-1, and 3.0 to 27.9 g·kg-1, and followed normal distribution, log-normal distribution, and negative binomial distribution, respectively. These three properties were significantly affected by land use type, landform, and soil type. Soil CEC and organic matter content were higher in forestland, grassland and farmland than in orchard land, and soil pH was lower in forestland than in other three land use types. Soil pH, CEC and organic matter content were higher in plateau land and sloping land than in gully bottom and terrace land. Soil CEC and organic matter content were higher in dark loessial soil and rebified soil, while soil pH was higher in yellow loessial soil. Across all the three land scape factors, soil CEC and organic matter content showed the similar distribution pattern, but an opposite distribution pattern was observed for soil pH.
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