Spatial patch structure and adaptive strategy for desert shrub of Reaumuria soongorica in arid ecosystem of the Heihe River Basin     

Li  Wei  Li  Xiaoyan  Huang  Yongmei  Wang  Pei  Zhang  Cicheng 《地理学报(英文版)》2019,29(9):1507-1526

In many arid ecosystems, vegetation frequently occurs in high-cover patches interspersed in a matrix of low plant cover. However, theoretical explanations for shrub patch pattern dynamics along climate gradients remain unclear on a large scale. This context aimed to assess the variance of the Reaumuria soongorica patch structure along the precipitation gradient and the factors that affect patch structure formation in the middle and lower Heihe River Basin (HRB). Field investigations on vegetation patterns and heterogeneity in soil properties were conducted during 2014 and 2015. The results showed that patch height, size and plant-to-patch distance were smaller in high precipitation habitats than in low precipitation sites. Climate, soil and vegetation explained 82.5% of the variance in patch structure. Spatially, R. soongorica shifted from a clumped to a random pattern on the landscape towards the MAP gradient, and heterogeneity in the surface soil properties (the ratio of biological soil crust (BSC) to bare gravels (BG)) determined the R. soongorica population distribution pattern in the middle and lower HRB. A conceptual model, which integrated water availability and plant facilitation and competition effects, was revealed that R. soongorica changed from a flexible water use strategy in high precipitation regions to a consistent water use strategy in low precipitation areas. Our study provides a comprehensive quantification of the variance in shrub patch structure along a precipitation gradient and may improve our understanding of vegetation pattern dynamics in the Gobi Desert under future climate change.

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基于参与式制图方法的景观服务评估与空间结构研究     

朱亚茹  高峻  邴振华  张中浩  付晶 《地球信息科学学报》2020,22(5):1106-1119

景观服务评估核心是人与环境之间复杂的动态关系,基于利益相关者的参与式制图方法是建立景观服务分类体系和量化指标的有效途径。本文采用参与式制图方法,以九寨沟自然保护区为例,根据景观服务分类研究成果,并结合九寨沟自然资源特点和景观服务使用者半结构式访谈数据,提出了适用于九寨沟的景观服务指标体系。本研究方法以管理局工作人员、居民和游客等服务使用者作为参与式调研对象,分别就其需求和景观服务感知程度进行半结构式访谈,并利用GIS技术将数据空间位置和功能属性结合,得到九寨沟有3大类景观服务和17个相关指标,以及737个景观服务点。通过研究结果可知,当地村落建筑与众多景观服务指标（包括观鸟场所、野营旅游、民俗与节庆等13个指标）具有极强的空间关联性。同时,景观服务使用者感知的景观价值在空间上属于聚集分布形式,主要围绕着开放生态旅游的3条沟谷分布,并向外围扩散。其中景观服务的“高—高”空间聚集区主要分布在沟口等与人类需求密切联系的区域,而景观服务的“低—低”空间聚集区则主要分布在原始森林等与人类居住、活动相距较远的区域。综上,基于参与式制图方法建立的景观服务分类和空间分析,发现九寨沟景观服务的空间位置与使用者紧密相关,其景观价值的空间结构特征是服务使用者与环境长期互动的结果,该结果可以用来引导并进一步优化九寨沟的功能分区规划。  相似文献   

Evaluation of the temporal variations of groundwater storage and its interactions with climatic variables using GRACE data and hydrological models: A study from Turkey     

Behnam Khorrami  Orhan Gunduz 《水文研究》2021,35(3):e14076

Monitoring of the fluctuations of groundwater storage is particularly important in arid and semi-arid regions where water scarcity brings about various challenges. Remote sensing data and techniques play a preponderant role in developing solutions to environmental problems. The launch of Gravity Recovery and Climate Experiment (GRACE) satellites has eased the remote monitoring and evaluation of groundwater resources with an unprecedented precision over large scales. Within the scope of the current study, the latest release (RL06) of GRACE mass concentrations (Mascons) from Jet Propulsion Laboratory (JPL) dataset as well as Global Land Data Assimilation System (GLDAS) models of Noah and Catchment Land Surface Model (CLSM) were used to provide Groundwater Storage Anomalies (GWSA) over Turkey. The temporal interactions of the estimated GWSA with the climatic variables of precipitation and temperature (derived from the reanalysis datasets of CHELSA [Climatologies at High resolution for the Earth's Land Surface Areas] and FLDAS [the Famine Early Warning Systems Network Land Data Assimilation System], respectively) were investigated statistically. The results suggest that there is a descending trend (from 2003 to 2016) for Terrestrial Water Storage Anomalies (TWSA) and GWSA over Turkey with a total loss of 11 and 6 cm of water, respectively. The statistical analysis results also indicate that the monthly variations of GWSA over Turkey are highly correlated with precipitation and temperature at 2-month lag. The analysis of the climatology (long-term) values of monthly GWSA, precipitation and temperature also revealed high agreement between the variables.  相似文献   

The effects of floods on the temperature of riparian groundwater          下载免费PDF全文

Jeffery A. Watson  M. Bayani Cardenas  Stephen B. Ferencz  Peter S.K. Knappett  Bethany T. Neilson 《水文研究》2018,32(9):1267-1281

The transition area between rivers and their adjacent riparian aquifers, which may comprise the hyporheic zone, hosts important biochemical reactions, which control water quality. The rates of these reactions and metabolic processes are temperature dependent. Yet the thermal dynamics of riparian aquifers, especially during flooding and dynamic groundwater flow conditions, has seldom been studied. Thus, we investigated heat transport in riparian aquifers during 3 flood events of different magnitudes at 2 sites along the same river. River and riparian aquifer temperature and water‐level data along the Lower Colorado River in Central Texas, USA, were monitored across 2‐dimensional vertical sections perpendicular to the bank. At the downstream site, preflood temperature penetration distance into the bank suggested that advective heat transport from lateral hyporheic exchange of river water into the riparian aquifer was occurring during relatively steady low‐flow river conditions. Although a small (20‐cm stage increase) dam‐controlled flood pulse had no observable influence on groundwater temperature, larger floods (40‐cm and >3‐m stage increases) caused lateral movement of distinct heat plumes away from the river during flood stage, which then retreated back towards the river after flood recession. These plumes result from advective heat transport caused by flood waters being forced into the riparian aquifer. These flood‐induced temperature responses were controlled by the size of the flood, river water temperature during the flood, and local factors at the study sites, such as topography and local ambient water table configuration. For the intermediate and large floods, the thermal disturbance in the riparian aquifer lasted days after flood waters receded. Large floods therefore have impacts on the temperature regime of riparian aquifers lasting long beyond the flood's timescale. These persistent thermal disturbances may have a significant impact on biochemical reaction rates, nutrient cycling, and ecological niches in the river corridor.  相似文献   

基于地学信息图谱的河道、海岸线演变对黄河三角洲景观格局影响研究   总被引：1，自引：0，他引：1  

李丹  王庆  徐洋  战超  刘现彬  王龙升  崔步礼  于祥  孙晓  王秋贤 《海洋与湖沼》2018,49(6):1220-1229

本文利用1988、1998、2009和2016年四期遥感影像,运用GIS技术,将地学信息图谱的图形思维与景观生态学的定量思维相结合,以距今不同时期的亚三角洲和滨海湿地为研究区,从景观结构和景观演替两个方面探究黄河三角洲河道、海岸线演变对景观格局的影响。结果表明:(1)距今不同时间的河道对黄河三角洲景观结构的影响程度不同,距今时间越长的亚三角洲研究区内耕地占总面积的比例越大且耕地是亚三角洲研究区中的第一优势景观类型。在1855—1889亚三角洲研究区内,除耕地和建筑用地外,其他各类景观占总面积的比例都较小且随时间变化不明显;在1929—1934亚三角洲研究区内,盐田、养殖池占总面积的比例从2009年到2016年增加了近40%,涨幅明显;在1964—1976亚三角洲研究区内,各类景观占总面积的比例趋于平均;在2017至今的亚三角洲研究区内,耕地和光滩占总面积的比例较高,达到24%左右。(2)距今不同时间的海岸线对黄河三角洲景观结构的影响程度也不同,在1855滨海湿地研究区内,耕地占总面积比例为60%左右,而海域占总面积比例接近于0,极差较大;在1934和1974滨海湿地研究区内,光滩、柽柳、碱蓬群落、芦苇、白茅群落占总面积比例随时间变化几乎呈逐渐下降趋势,而建筑用地和盐田、养殖池则呈逐渐上升趋势;2009滨海湿地研究区,河流、人工水域占总面积比例在2009年和2016年均达到32%以上。(3)根据景观类型重心变化特征,分析河道、海岸线演变对景观演替的影响程度,将不同时期亚三角洲和滨海湿地研究区景观演替分为如下几类:亚三角洲人类活动主导型、废弃河道主导型、行水河道主导型、滨海湿地人类活动主导型、废弃海岸主导型、新海岸主导型。  相似文献   

Time–space fractional governing equations of transient groundwater flow in confined aquifers: Numerical investigation          下载免费PDF全文

Tongbi Tu  Ali Ercan  M. Levent Kavvas 《水文研究》2018,32(10):1406-1419

In order to model non‐Fickian transport behaviour in groundwater aquifers, various forms of the time–space fractional advection–dispersion equation have been developed and used by several researchers in the last decade. The solute transport in groundwater aquifers in fractional time–space takes place by means of an underlying groundwater flow field. However, the governing equations for such groundwater flow in fractional time–space are yet to be developed in a comprehensive framework. In this study, a finite difference numerical scheme based on Caputo fractional derivative is proposed to investigate the properties of a newly developed time–space fractional governing equations of transient groundwater flow in confined aquifers in terms of the time–space fractional mass conservation equation and the time–space fractional water flux equation. Here, we apply these time–space fractional governing equations numerically to transient groundwater flow in a confined aquifer for different boundary conditions to explore their behaviour in modelling groundwater flow in fractional time–space. The numerical results demonstrate that the proposed time–space fractional governing equation for groundwater flow in confined aquifers may provide a new perspective on modelling groundwater flow and on interpreting the dynamics of groundwater level fluctuations. Additionally, the numerical results may imply that the newly derived fractional groundwater governing equation may help explain the observed heavy‐tailed solute transport behaviour in groundwater flow by incorporating nonlocal or long‐range dependence of the underlying groundwater flow field.  相似文献   

青海湖沙柳河流域浅层地下水不同时期补给特征          下载免费PDF全文

杨羽帆  曹生奎  曹广超  雷义珍  刘英  兰垚 《干旱区地理》2020,43(3):633-643

地下水稳定同位素组成的时空变化特征可以反映不同时期、不同区域地下水补给来源的差异。通过青海湖沙柳河流域浅层地下水氢氧稳定同位素组成的时空变化特征以及地下水、河水与降雨之间的补给关系的分析，结果显示：季风时期，地下水主要受降雨入渗和河流侧向补给为主，在补给过程中蒸发作用是影响地下水稳定同位素值的主要因素；非季风期，冰雪融水对低值区的地下水影响显著，同时降水的快速入渗则是该时期高值区地下水的主要补给方式之一。地下水同位素高值区，地下水与河水间补给作用较弱，补给时间超过5个月；地下水同位素低值区，地下水与河水补给关系较为密切，补给时间在1~4个月间。本文所得结论可初步反映干旱半干旱内陆流域地下水稳定同位素特征以及补给方式的基本规律，在一定程度上可为流域地下水及其他水体间的转换研究提供科学依据，并为地下水资源管理和水环境治理提供一定理论指导。  相似文献   

陇中黄土高原丘陵沟壑区不同植被恢复模式下次降雨产流产沙特征   总被引：1，自引：0，他引：1       下载免费PDF全文

朱燕琴  赵志斌  齐广平  康燕霞  赵霞 《干旱区地理》2020,43(4):920-927

基于甘肃省清水县汤峪河径流小区2015—2017年的观测数据,研究不同植被恢复模式条件下坡面次降雨入渗、产流产沙特征。结果表明：不同植被恢复模式条件下的土壤入渗量与降雨强度呈二次函数关系,存在入渗量达到最大值的临界降雨强度。入渗速率与降雨历时可以用幂函数关系表达,符合考斯恰可夫入渗模型。不同植被恢复模式条件下的产流率在0.003 3~0.003 6 mm·min^-1之间,相对裸地的减流率为54%~58%。产流率与降雨强度之间呈二次函数关系（R²>0.88）,产流率的主要影响因素是降雨强度。径流含沙量平均值乔灌混合区（3.13 g·L^-1）>灌木林（2.95 g·L^-1）>乔木林（2.79 g·L^-1）>草地（2.58 g·L^-1）,径流含沙量与降雨强度呈线性递增函数关系。裸地的产沙量显著高于各植被小区（P<0.05）,是各植被小区的43~57倍,各植被小区的减沙率在93%~94%之间,减沙效益高于其减流效益。各植被坡面土壤流失量与降雨侵蚀力呈线性递增函数关系;产流率与侵蚀产沙率之间呈极显著正相关关系（P<0.01）,二者间可采用二次函数关系表达。本研究成果可为黄土高原丘陵沟壑区水土保持优化配置提供理论依据。  相似文献   

基于细分行业的安徽省创新型企业集聚研究     

白如山  胡森林  庄良  刘岩  刘恺恺  黄鹏娜 《世界地理研究》2020,29(6):1190-1201

创新型企业作为塑造创新地理格局的重要力量，其区位选择的外部特征及内在机理亟须予以系统化研究。基于对安徽省创新型企业的细分行业与空间建库，采用核密度估计和地理探测器等方法，对细分行业下的创新型企业空间集聚特征及影响因素进行研究。结果表明：（1）安徽省创新型企业类型以先进制造和自动化为主，并以生物与新医药、新材料、电子信息为辅；（2）创新型企业空间集聚的不均衡特征显著，呈现出“一核一带多节点”的集聚分布特征，且合肥、芜湖是两个重要集聚区；不同细分行业视角下创新型企业的空间分布形态各异，可归纳为点-轴式、极核式、双核式及多核分散式等4种空间组织形态。（3）创新型因子对于创新型企业的空间集聚最为重要，但传统型和政策型因子的重要性仍不容忽视。其中，产业基础、人力资本、创新投入是最核心的因素，但各行业创新型企业的影响因素作用力则表现出一定的异质性。  相似文献   

地理大数据挖掘——目标、内涵与研究问题     

裴韬  宋辞  郭思慧  舒华  刘亚溪  杜云艳  马廷  周成虎 《地理学报(英文版)》2020,30(2):251-266

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