土壤水分动态随机模型研究进展

土壤水是地球表层系统的重要组成,是水文循环的核心,控制着最基本的陆地生态系统格局与过程,是陆地生态系统健康运行的关键。土壤水分动态是研究水文过程和陆地生态系统过程相互作用及反馈必不可少的一环,是一系列水文、气候和生态过程非线性动态作用的结果。因此,土壤水分动态表现为脉动、无规律和随机的过程,对其研究需要随机方法。本文综述了基于土壤水分平衡的土壤水分动态随机模拟的研究进展,主要关注土壤水分动态随机模型的分类比较和适用性。希望能为国内生态水文学的定量研究提供一些参考,促进对水文循环与陆地生态系统之间相互作用更好的理解,最终有助于水资源和生态系统的可持续管理。     

贡嘎山山地暗针叶林森林生态系统水循环及其空间分异规律

在全球气候变化下背景下,山区水循环加剧、水文过程和水资源变化更加复杂,客观认识变化环境下山区流域的水循环规律及其与气候、植被、土壤的相互作用机理,是全球变化及人类社会可持续发展共同面临的核心问题。本文从森林空间异质性结构对生态系统蒸散发、土壤水分、水量平衡和水碳关系的影响研究,结合国内外研究进展,系统阐述了贡嘎山高山生态系统观测试验站目前的研究工作和取得的研究结果。此外,针对复杂山地条件下生态系统水循环研究,提出了未来山地水文学重要的研究方向:系统开展土壤-植被-大气连续体(SPAC)系统下各连续体介质相关研究工作;开展生态水文过程多尺度综合研究;开展能够准确模拟山地水文过程的模型模拟工作。     

干旱区土壤水分微波遥感反演算法综述

土壤水分是气候、水文、生态和农业系统的关键组成要素,同时也是监控土地退化和干旱的重要指标,土壤水分信息的及时获取对于规划和管理这些系统来说具有极其重要的意义.微波具有全天候、穿透性以及不受云层影响的独特物理机制使其在研究大尺度土壤水分反演时具有明显优势,已成为当前土壤水分遥感研究的主要大气窗口.在干旱区微波遥感土壤水分...     

内蒙古温带草原典型草地生态系统生产力对水分在不同时间尺度上的响应

水分是干旱、半干旱区草地生态系统生产力的主要限制因素,但水分如何影响生产力的季节内变异,以往研究相对不足。本研究以内蒙古温带典型草原为研究对象,基于多通道自动原位监测箱系统获得的生态系统日尺度总初级生产力(GPP)及遥感植被归一化指数估算年尺度的地上净初级生产力数据,在不同时间尺度上研究了水分对生产力的影响。结果表明:年降水量对该典型草原草地生态系统地上净初级生产力年际变异无显著影响,但土壤水分显著影响GPP的季节变异,土壤水分解释了GPP季节变异的22%;其他环境因子对生产力的季节变异也有一定影响;温度是生态系统处于干旱时GPP的主要限制因素,GPP随温度的升高而降低;而辐射是生态系统处于湿润时GPP的主要限制因素,GPP随辐射的升高而升高。本研究结果将有利于提升未来降水格局改变对草地生态系统生产力影响的认识。     

青藏高原地表土壤水变化、影响因子及未来预估

土壤水分是地表和大气连接的纽带,在水文循环中扮演着重要角色。青藏高原作为“第三极”和“亚洲水塔”,其土壤水分对周边地区的气候如亚洲季风的形成和维持产生重要影响,也深刻影响着亚洲水资源的可利用量。基于分布在青藏高原3个气候区的100个站点的实测土壤水数据,对ECV、ERA、MERRA、Noah数据集进行评价,选择对土壤水分评估效果最好的数据集,分析各种气象要素对土壤水分时空格局的影响,并预估未来100年内青藏高原土壤水变化,探讨可能气候成因。结果表明：① Noah数据集对青藏高原历史时期土壤水分评估效果最好,相对其他地区,各数据集对那曲地区土壤水分评估效果最优;② 在各种气象因子中,降水是影响大部分地区土壤水分时空变化的最主要因子,但在喜马拉雅山脉地带,尤其山脉北坡,温度和太阳辐射有较高的影响;③ 1948-1970年土壤水分有明显的下降趋势,1970-1990年土壤水分呈波动变化,无明显趋势,1990-2005年土壤水分有一定的上升趋势,2005年后至今土壤水分有明显快速下降趋势：④ 不同未来情景,土壤水分有下降趋势,其中在CRP 8.5情景下,土壤水分下降最为明显,在2080年之后有更加显著的下降趋势;⑤ 未来降水和温度均呈上升趋势,其中干旱指数变化在RCP 8.5情景下呈下降趋势,在RCP 2.6和RCP 4.5情景下无明显变化,干旱指数在一定程度上能解释未来土壤水分的变化格局。     

土壤植被大气模式中水分和能量传输研究进展

 在分析过去地-气间相互作用的物理过程、研究进展基础上,探讨了土壤-植被-大气系统中水分与能量的传输过程在模型中不同的计算方法。同时对不同计算方法进行对比,确定了分析土壤-植被-大气系统中水分和能量传输方法的优缺点,提出了解决我国干旱地区土壤-植被-大气系统中水分和能量传输的一些思路,强调加强干旱地区观测资料积累,采用实测资料不断对不同分析计算进行验证,找出适用于西北干旱区的参数化方法,建立干旱区土壤-植物-大气模型。     

铵态氮沉降对内蒙古呼伦贝尔草地CO_2通量的影响（英文）

大气氮沉降可能会影响陆地生态系统的碳通量。本文主要目的是探讨在氮素缺乏的草地生态系统中,氮素添加是否会增加CO2通量。本研究于2008和2009生长季进行,采用静态箱-气相色谱法研究CO2通量对氮沉降增加的响应。结果表明,2年的氮素添加并没有显著影响土壤NH4+含量,NO3-含量只是在2009年生长季后期有所增加。高氮处理增加了CO2通量,而低氮处理在2008年抑制了CO2通量,2009年后期增加了CO2通量。而且氮素添加显著增加了地上生物量和根系的生物量。CO2通量与土壤水分、土壤温度的关系并没有因为氮素的添加而改变,但是氮素添加增加了CO2通量对土壤水分和土壤温度的敏感性。这些结果表明,在未来大气氮沉降增加的背景下,呼伦贝尔草甸草原CO2通量有可能会增加。     

北京山区林地土壤水分动态变化

应用时域反射仪(TDR)土壤水分定位监测方法,研究了北京山区4种主要林分(侧柏、油松、刺槐、栓皮栎)林地土壤水分动态.结果表明:林地土壤水分变化既有明显的季节特征,可以分为稳定期(11-4月)、消耗期(5-6月)、积累期(7-8月)、消退期(9-10月)4个阶段.其垂直变化呈现出先增加后减少(或趋于平缓)的趋势.单次降雨后持续干旱条件下,土壤水分及其损失率与雨后干旱天数均存在二次函数关系.无论是降水还是其后的持续干旱,主要影响的都是表层土壤.     

稳定性同位素在干旱区生态水文过程中的应用特征及机理研究

本文重点阐述了稳定性同位素18O和D在生态-水文过程研究中的研究进展,主要包括植物水分来源与比例、土壤水分动态变化与植物根系吸水、干旱区水分转化与补给等方面的研究成果。并针对我国干旱区生态水文过程研究中的具体问题,指出在今后应加强利用稳定性同位素技术在荒漠植被不同水分来源识别、植物水-地下潜水-土壤水-大气降水的转化过程、干旱区降水对不同尺度范围土壤水分和地下潜水的转化补给、具有水力提升和逆水力提升功能植物识别等方面研究中的应用。     

不同植被盖度沙质草地生长季土壤水分动态

水分是干旱半干旱沙地生态系统最大的限制因子,研究植被盖度和土壤水分之间的关系有助于沙地生态恢复和保护。基于生长季科尔沁沙质草地不同植被盖度下土壤水分动态和降水的观测试验,分析了沙质草地植被盖度和土壤水分的耦合关系。结果表明：在土壤剖面上土壤水分存在明显的分层结构,依次为水分剧变层（0~40 cm）、缓变层（40~100 cm）和稳定层（100~180 cm）;植被盖度对土壤水分有很大影响,不同植被盖度下土壤含水量存在显著差异,土壤水分与盖度之间呈倒“V”型关系,土壤水分状况在28%的盖度下最优;不同的植被盖度下土壤水分对降水的响应也存在差异,在13%盖度下响应最敏感,28%和46%的盖度下响应微弱,后二者的土壤水分也相对稳定。在沙地生态恢复建设过程中合理的植被盖度配置可提高降水利用效率,并能使土壤水分和植被达到一种良好的平衡状态,从而有利于生态系统的稳定。     

The progress and prospects of nebkhas in arid areas

Nebkhas are often extensively distributed in arid and semi-arid areas, and play an important role in the stabilization of ecological environment in these areas. This paper reviews the following aspects, including formation and succession, spatial distribution, shape and surface airflow characteristics, balance between erosion and deposition, ecological and physiological characteristics of vegetation, response to precipitation and groundwater, soil properties as well as the protection measures. We found that nebkhas were studied without differentiation of succession periods, and shape characteristics, surface airflow, soil properties as well as vegetation dynamics in different succession periods were not fully understood, which made it difficult to explain the succession dynamics of nebkhas and its affecting factors. Previous studies of nebkhas were over-emphasized for its role as an indicator of land degradation, while its ecological functions in degraded ecosystems were neglected, which was unfavorable for the ecological restorations in arid and semi-arid areas. Future studies should pay more attention to the variation of vegetation, soil as well as hydrological process in the succession of nebkhas and its interaction between different influencing factors. In addition, positive role of nebkhas in degraded ecosystems in arid and semi-arid areas should be fully discussed. According to the data got from the above, effective protection measures of nebkhas should be explored.     

The progress and prospects of nebkhas in arid areas

Nebkhas are often extensively distributed in arid and semi-arid areas, and play an important role in the stabilization of ecological environment in these areas. This paper reviews the following aspects, including formation and succession, spatial distribution, shape and surface airflow characteristics, balance between erosion and deposition, ecological and physiological characteristics of vegetation, response to precipitation and groundwater, soil properties as well as the protection measures. We found that nebkhas were studied without differentiation of succession periods, and shape characteristics, surface airflow, soil properties as well as vegetation dynamics in different succession periods were not fully understood, which made it difficult to explain the succession dynamics of nebkhas and its affecting factors. Previous studies of nebkhas were over-emphasized for its role as an indicator of land degradation, while its ecological functions in degraded ecosystems were neglected, which was unfavorable for the ecological restorations in arid and semi-arid areas. Future studies should pay more attention to the variation of vegetation, soil as well as hydrological process in the succession of nebkhas and its interaction between different influencing factors. In addition, positive role of nebkhas in degraded ecosystems in arid and semi-arid areas should be fully discussed. According to the data got from the above, effective protection measures of nebkhas should be explored.     

干旱地区灌丛沙堆研究现状与展望(英文)

Nebkhas are often extensively distributed in arid and semi-arid areas,and play an important role in the stabilization of ecological environment in these areas.This paper reviews the following aspects,including formation and succession,spatial distribution,shape and surface airflow characteristics,balance between erosion and deposition,ecological and physiological characteristics of vegetation,response to precipitation and groundwater,soil properties as well as the protection measures.We found that nebkhas were studied without differentiation of succession periods,and shape characteristics,surface airflow,soil properties as well as vegetation dynamics in different succession periods were not fully understood,which made it difficult to explain the succession dynamics of nebkhas and its affecting factors.Previous studies of nebkhas were over-emphasized for its role as an indicator of land degradation,while its ecological functions in degraded ecosystems were neglected,which was unfavorable for the ecological restorations in arid and semi-arid areas.Future studies should pay more attention to the variation of vegetation,soil as well as hydrological process in the succession of nebkhas and its interaction between different influencing factors.In addition,positive role of nebkhas in degraded ecosystems in arid and semi-arid areas should be fully discussed.According to the data got from the above,effective protection measures of nebkhas should be explored.     

干旱半干旱区山地土壤水分动态变化

水分是干旱半干旱区山地植物生长的主要限制因子，在这些地区开展土壤水分动态变化研究对农业生产和生态恢复的重要性是不言而喻的。近年来土壤水分测定技术有了很大进步，中子水分仪和时城反射仪已成为常规测量仪器，新型仪器不断出现，总的趋势是仪器的精度和自动化水平不断提高。土壤水分有其时空变化规律，一方面土壤水分随季节变化而变化，另一方面土壤水分随土壤深度和水平位置的变化发生相应变化。降水是影响干旱半干旱区山地土壤水分的最重要因素，气温、太阳辐射等其它气象因子对土壤含水量也用一定影响。此外，坡向、坡度、坡位等地形因子以及土壤特性、地表植被、土地利用情况等对土壤含水量空间分布也有重要影响。总之土壤含水量的时空变化是各种环境因子综合作用的结果。目前土壤水分动态变化的研究重点是对其影响因子的研究。就我国而言，宜加强干旱河谷区土壤水分动态变化的研究，促进土壤水分动态变化研究工作全面深入地开展。     

古尔班通古特沙漠表层土壤凝结水水汽来源特征分析

水分条件是决定干旱沙漠区生态环境的关键因素,凝结水是干旱区植物和低等生物的重要水分来源。利用自制蒸渗计在春、夏、秋3个季节对古尔班通古特沙漠苔藓、地衣、藻类及流沙4种地表类型表层原状土壤凝结水形成进行了观测研究。结果表明,在2 cm、5 cm、10 cm、20 cm 4种高度原状土中,用纱网封底土壤表层2 cm和5 cm土壤的凝结水测定结果能够真实的代表古尔班通古特沙漠不同类型地表土壤凝结水形成特征;凝结水主要集中产生在土壤表层2 cm范围内;凝结水的水汽来源于空气和土壤且以空气来源为主,春季由于表层土壤含水率较高,来自于土壤的水汽所占的比重较高,地衣0~2 cm表层凝结水来源于土壤水汽补充的比例春季为35.5%,夏季和秋季分别降到15.5%和11.3%;秋季55 d的观测结果表明,凝结水形成总量随流沙、藻类、地衣和苔藓依次增加,分别为3.46 mm、4.07 mm、4.89 mm和5.15 mm,说明在干旱的沙漠地带,凝结水是除降水以外补充表层土壤水分最重要的水分来源。     

基于地统计学的甘肃臭草群落土壤水分空间异质性

土壤水分是植被格局形成和演变的主要因素,土壤水分的空间异质性对于认识干旱区草原植物对环境的响应机制具有重要意义.应用地统计学方法,对祁连山北坡甘肃臭草(Melica przewalskyi)退化草地土壤表层含水量的变异性进行研究.结果表明,臭草型退化草地浅层(0 ～30 cm)土壤水分符合正态分布,土壤含水量沿垂直方向逐渐增大,介于9.56％ ～11.21％.各层土壤水分的变异系数分别为12.97％ (0～10 cm)、8.8％ (10～20 cm)和14.09％ (20～30 cm),均属弱变异;0～ 30 cm土壤含水量具有高度的空间异质性,其中34.92％～42.71％的空间异质性是由空间自相关部分引起的,主要体现在16.87 ～ 69.14 m尺度上.在0～ 10 cm土层,引起土壤水分空间变异的主要因素是植被覆盖度的不同,而在10 ～ 30 cm土层,土壤水分空间变异性主要是根系分布的差异引起的.     

干旱人工固沙植被区土壤水分动态随机模拟

土壤水分是陆地水循环过程的关键环节,是联系陆地水文过程与生态过程的纽带。随着全球极端气候事件的频繁发生,土壤水分随机模拟逐渐成为当前生态水文学研究的热点。利用2008-2011年生长季土壤湿度连续监测数据及1991-2011年日降水资料,结合Rodriguez-Iturbe土壤水分动态随机模型,模拟了沙坡头人工植被区生长季土壤水分动态与土壤湿度概率密度函数特征。结果表明：人工固沙植被区生长季土壤水分年际变化与降雨分布一致。2008-2011年生长季植物根际层（0~60 cm）土壤湿度概率分布基本呈单峰状,20 cm处的土壤水分峰的阔度较其他土层相对土壤湿度峰较宽,并且分布也出现了一定程度的跳跃。而随着土层厚度的增加,在40 cm和60 cm的土壤水分概率分布峰的阔度也较小,与Rodriguez-Iturbe土壤水分动态随机模型模拟结果一致。说明Rodriguez-Iturbe模型在干旱人工植被区也具有很好的适用性,可以对荒漠人工植被恢复区的土壤水分统计特征进行很好的模拟,为以后干旱沙区随机生态水文模型的建立奠定基础。     

Changes in morphology and soil nutrient patterns of nebkhas in arid regions along a precipitation gradient

Nebkhas, discrete mounds of sand and vegetation, are a common landscape feature critical to the stability of desert ecosystems and supported by limited precipitation. Nebkha morphology and spatial pattern vary in landscapes, but it is unclear how they change along precipitation gradients in arid and semi-arid regions. In this study we determined morphology and soil nutrient patterns of nebkha from different regions of northwestern China. The objective of this study was to understand zonal differences among nebkhas and how morphological characteristics and soil nutrient patterns of nebkha change along a precipitation gradient in northwestern China. Our results shows that mean annual precipitation(MAP) had significant effects on morphological characteristics of nebkhas such as height, area, and volume which significantly decreased with an increase in MAP. MAP had significant positive effects on shrub cover and species richness of nebkha. Soil nutrients such as soil organic matter(SOM), total carbon(TC), total nitrogen(TN), and total phosphorus(TP) in the 0-10 cm layer increased with an increase of MAP, and soil nutrient content within nebkhas was higher than in inter-nebkha areas.We concluded that nebkhas are "fertile islands" with an important role in ecosystem dynamics in study regions. Further,MAP is a key factor which determined zonal differences, morphological, and soil nutrients patterns of nebkhas. However,disturbance, such as animal grazing, and planted sand-stabilizing vegetation accelerated the degeneration of nebkha landscapes. We recommend implementation of protective measures for nebkhas in arid and semi-arid areas of China.     

Probabilistic modeling of soil moisture dynamics in a revegetated desert area

Soil moisture is the key link between land hydrological and ecological processes which plays an important role in the terrestrial water cycle. As extreme weather events have increased in recent years, the stochastic simulation of soil moisture has gradually become the focus of ecohydrology research. Based on continuous monitoring of soil moisture data from 2008 to 2011, and historical precipitation data from 1991 to 2011, combined with the Rodriguez-Iturbe soil moisture dynamic stochastic model, soil moisture dynamics and its probability density function in a revegetated desert area was simulated. Results show that annual soil moisture dynamic changes of the revegetated desert area during the growing season complied with rainfall distribution; soil moisture probability presents a single-peak distribution in the plant rhizosphere layer (0–60 cm). The peak width in the 20 cm topsoil was wider than in other soils, and the distribution presented the strong fluctuations and multiple aggregates. The peak widths of 40 cm and 60 cm soil moisture probability distribution were small, which are in accordance with simulated results of the Rodriguez- Iturbe model. This confirms that the Rodriguez-Iturbe model has good applicability and can well simulate the statistical characteristics of soil moisture in an arid revegetated desert area.     

A review on eco-hydrological effects of condensation water

Almost half the world is suffering from drought at different levels. Since arid and semi-arid regions are characterized by extreme shortage and precipitation uncertainty, water availability is the most important limiting factor in arid lands, and any additional source of moisture, such as condensation water, may have a positive impact upon the ecosystem. Therefore, extensive research has been carried out on condensation. Based on articles and relevant documents on the subject, this paper reviews systematically and comprehensively the latest research achievements in several main aspects, including eco-hydrological effects of condensation water on plants, small animals, microbiotic crusts, soil moisture balance, ground water recharge and anthropogenic utilization. History and trends of research about eco-hydrological effects of condensation water are intensively analyzed in order to summarize existing problems and offer opinions and suggestions for future study.