共查询到19条相似文献，搜索用时 171 毫秒
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干旱半干旱区占中国陆地面积一半以上,生态环境脆弱,对全球气候变化和人类活动的响应敏感,极端气候事件呈多发、强发态势。该区域的气候异常不仅受到大气内部变率的调制,还受海温、海冰和积雪等下垫面影响,这些物理因子对干旱半干旱区气候异常起关键性作用。文章系统性地回顾和梳理了这些物理因子对中国干旱半干旱区气候异常影响的研究。研究表明：大气遥相关作为气候异常的内部影响因子,其位相转变造成的环流异常会通过调控急流位置、行星波活动、阻塞强度、槽脊位置等造成干旱半干旱区气候异常;而海温则通过影响季风强度、沃克（Walker）环流强度、西太平洋副热带高压位置及激发大气罗斯贝（Rossby）波响应等方式对干旱半干旱区气候异常产生影响;积雪通过反照率效应和水文效应,改变地表辐射、土壤温湿度等下垫面热力状况,进而通过非绝热加热或改变大气斜压性等方式对干旱半干旱区气温和降水产生显著作用。文章在总结已有研究进展的基础上,指出不同因子之间的协同作用机制以及各因子对中国干旱半干旱区气候异常的贡献仍有待进一步研究。 相似文献
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土壤水分动态随机模型研究进展 总被引：6，自引：0，他引：6
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。 相似文献
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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 总被引：3，自引：0，他引：3
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。 相似文献
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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。 相似文献
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干旱半干旱区山地土壤水分动态变化 总被引：100，自引：1，他引：100
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。 相似文献
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黄土高原典型半干旱区水热变化及其土壤水分响应 总被引：12，自引：8，他引：4
利用黄土高原典型半干旱代表区68 a(1937-2004年)降水、气温资料和34 a(1971-2004年)土壤湿度资料,研究黄土高原半干旱区水热变化及土壤水分响应。结果表明:黄土高原半干旱区在近70 a中气温以下降为主,3-6月降水存在显著增多趋势,气温、降水倾向具有明显时段差异。干旱年份或少雨时段长周期振荡加强、短周期衰减;相对冷的时期气温振荡周期明显,反之不明显。干旱是该地区土壤的基本气候特征,生长期土壤水分波动式下降,蓄水期土壤水分波动式上升,总体上以下降为主,20世纪70年代中后期土壤水分较好,80年代土壤水分较差,90年代末到21世纪初转好。土壤水分对短期降水变化、降水气温气候变化及短周期振荡都存在明显响应。 相似文献
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世界上近一半的国家和地区不同程度地受到干旱问题的影响。干旱区的最显著特征是降水的极端稀少和不确定。任何降雨以外的水资源输入,即使数量很微小,也对荒漠生态系统的维持和存续有重要意义,因此凝结水作为可能性水源成为研究热点。基于文献资料,本文从干旱、半干旱地区凝结水对生物的影响,对生物结皮及土壤水分平衡的作用,对地下水的补给以及凝结水的人为利用等几个方面阐述国内外的凝结水研究现状,着重分析凝结水生态水文效应方面的研究历程和趋势,总结凝结水研究中存在的问题,展望未来研究工作的重点。 相似文献
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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. 相似文献
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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. 相似文献
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《地理学报(英文版)》2010,(5)
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. 相似文献
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古尔班通古特沙漠表层土壤凝结水水汽来源特征分析 总被引：2，自引：0，他引：2
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。 相似文献
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基于地统计学的甘肃臭草群落土壤水分空间异质性 总被引：1，自引：0，他引：1
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. 相似文献
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干旱人工固沙植被区土壤水分动态随机模拟 总被引：1，自引：0，他引：1
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。 相似文献
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《寒旱区科学》2021,13(3)
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. 相似文献
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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. 相似文献
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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. 相似文献