Research advances in eco-hydrological process and function

Pcienceshttp://www.scar.ac.cnSciences in Cold and Arid RegionsSVolume 6, Issue 1, February, 2014Citation: Yang YG, Xiao HL, Qin ZD, et al, 2014. Research advances in eco-hydrological process and function. Sciences in Cold and AridRegions, 6(1): 8- 13. DOI: 10.3724/SPJ.1226. 2014.00008.Research advances in eco-hydrological process and functionYongGang Yang 12, HongL ang Xiao 2, ZuoDong Qin 1 , Na Kang , CaiMei Li1. Institute of Loess Plateau, Shanxi University, Taiyuan, Shanxi 030006, China2. Cold and Arid Regions Environmental Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu730000, China*Correspondence to: Dr. ZuoDong Qin, Institute of Loess Plateau, Shanxi University. No. 92, Wucheng Road, Taiyuan,Shanxi 030006, China. Tel: +86-351 -7010700; E-mail: qzdsxu@ 126.comReceived: February 15, 2013 Accepted: July 24, 2013ABSTRACTPresent studies on the coupling relationship and hydrology mechanism between basin ecosystem and hydrological processsummarizes research and presents a method of combining isotopic technology with hydro chemical methods, for the studyof eco-hydrological process and function in different landscape zones. We then examine research trends for future directionand development of this field.Keywords: eco-hydrological process; eco-hydrological function; landscape zone; isotope1 Introductionvironment is on the observation of hydrological pro-cesses. Ecological systems present a relationship be-Eco-hydrology is an emerging interdisciplinarytween vegetation and environmental factors, while thefield, gradually developed after the 1980s, and is in thehydrological process, as a main driving force of eco-forefront of hydrological research. Eco-hydrology islogical system succesion, controls vegetation struc-the interaction of plants and the hydrological process,ture and distribution patterns, and ecological processand describes ecological patterns and eco-hydrological(Zhao and Cheng, 2001). International research intomechanisms (Zhao and Cheng, 2001). The researcheco-hydrology is focused on the interaction among ice,purpose of eco-hydrology is to increase the under-frozen soil, precipitation, groundwater and the eco-standing of the coupling relationship between ecologi-logical environment (Petts and Bradley, 1997). Thecal and hydrological processes, and to provide a theo-main task for future scientific development and man-retical basis of restoring and establishing a healthyagement in the basin is to recognize the coupling rela-eco-hydrological environment (ecological engineering).tionship between ecosystem and hydrological process,There is a close relationship among ecological systemand to integrate the technical system of ecologicalpatterm, ecological process change and hydrologicalrestoration (Cheng, 2009).process. The target of eco -hydrology research includesdry land, wetlands, forest, grasslands, mountains, lakes2 Research of eco-hydrological processand rivers and is based on a theoretical relationshipbetween plants and water with the scale throughout theThe structure and function of the ecosystem andstudy (Xiao and Cheng, 2006).its hydrology ame heth i中国煤化工nents of reThe research focus in the field of resource and en-search in thisLips betweenTHCNMH GYongGang Yang et al, 2014 1 Sciences in Cold and Arid Regions, 6(1): 0008- 00139hydrological processes and biological dynamics mayresearch on hydrological process and ecosystems inalso shed light on how ecological patterns and chang-the basin helps to discover eco-hydrological restora-es are interlinked, and dependent on hydrologicaltion mechanisms, such as the relationship betweenmechanisms. The study of stability and interactiondiversity change under different moisture conditionsmechanism of hydrological process and the ecosystemand the relationship between vegetation communitycan provide a theoretical basis for eco-hydrologicalsuccession and hydrological processes. This mecha-layout and its dynamic balance maintenance, and pro-nism will be helpful for plant physiology and ecologyvide a scientific explanation for the relationship be-under small scale stress conditions.tween ecological succession and hydrological circula-tion changes (Wang et al., 2001). There are three im- 2.2 Simulation research of eco-hydrological processportant scientific problems on the study ofeco-hydrological process as follows.Simulation research is another important direc-tion of eco-hydrological process research. The com-2.1 Research of eco-hydrological restorationplexity of hydrological conditions, and the hetero-geneity and variability in temporal and spatial dis-One important problem of eco-hydrological pro-tribution of the elements influences hydrologicalcess research is eco-hydrological restoration. Thbehavior, making it difficult to directly quantifystudy of eco-hydrological restoration deals with theeco-hydrological changes.effect on vegetation cover sensitivity, ecological effectCurrently, the models used for eco-hydrologicalof water behavior in its watershed, the physiologicalprocess research are: SPAC, SWAT, WAVES, SWIMV,and ecological processes, and the performance of and PATTERN, which are used to simulate the mate-plants under drought conditions (Kang et al, 2008).rial and energy transfer process of soil-vegetation-Cairns (1980) elaborated on the main theoretical andatmosphere interaction, and analyze eco-hydrologicalpractical problems in the process of damaged ecosys-effects of vegetation (Kremer et al, 1996); RHES,tem restoration. Over the past 20 years, numerousXAJ, TANK, and SLT, are used for eco-hydrologicalstudies have focused on remediation technology of thesimulation in the basin, especially for hydrologicaleco-hydrological environment, involving restorationprocess simulation (Uso-domenech et al,， 1995;and management of grasslands, mines, water and soil.Mulligan, 1996); RUTTER， MASSMAN， andSince the 1950s, China has provided long-term ob-PHILIP, are used for forest eco-hydrological process,servation and comprehensive renovation research ofand the influence of plants on water studies; anddegraded ecosystems, and numerous small watershedLUCID，is used to simulate how land use changeecological restoration projects have proved suecessful.affects the hydrological processes (Thornes, 1990;Research focused on the causes, solutions, technologyCheng and Zhao, 2006; Xia et al, 2007). The de-methods of restoration and reconstruction, the selec-velopment of GIS (Geographic Information System)tion of plant species, and the ecological effects of re-nd RS (remote sensing) has greatly influenced thecovery and rebuilding. Special attention was given toeco- hydrological models. The improvement of vari-the ecological restoration process while emphasizingous high-precision spatial eco-environmental datathe ecological succession theory and biodiversity res-and the popularization of high spatial and temporaltoration (Huang et al, 2003). The Shapotou Desertresolution of remote sensing data made it possible toResearch Station of Chinese Academy of Sciencesachieve eco-hydrological models based on GIS andhave provided practical experience and data accumu-RS，and the coupling relationship among GIS, RSlation for ecosystem restoration in degraded arid re-and mathematical models helps to quantifygions, such as in areas with less than 200 mm precipi-eco-hydrological changes. Although eco-hydrologytation (Kirkby et al, 1996). Vegetation in differentmodels have undergone improvements in recentlandscape zones effects rainfall, runoff and evapora-years, they are mostly limited by scale, when they aretion on many levels. Consequently, water resourcesapplied in other scales, re-parameterization and preci-are allocated, which influences the hydrological cir-sion problems appear. Although there have been nu-culation process. Different landscape zones have dif-ferent hydrological processes, from which some fea- process models， they cannot be regarded as atures of the landscape can be analyzed. The hydrolog-eco-hydrological process model in a strict sense.ical process controls many basic ecological patternsTherefore, it is necessary to strengthen the coupledand ecological processes, especially basic vegetationmodel research on eco-hydrological process.distribution patterns, and is one of the main drivingtraditional basin model lacks information requiredforces of ecological system succession. Therefore,for modeling, thus it is a conceptual model. An im-vegetation dynamics and ecosystem succession can beportant tool for futyure hydrnlgov research is use ofcontrolled by hydrological process adjustment. Thusthe hydrologic中国煤化工ally the iso-YHCNMHG1YongGang Yang et al, 2014 1 Sciences in Cold and Arid Regions, 6(1): 0008- 0013tope tracer technique. This technique can provideand ecological water demand of oasis vegetation atmore detailed information for the study of waterthe plant/community level in Ejina, and in the evalua-flow in soils, hydrological model structure， andtion of ecological water demand for the entire oasis.identification parameters.However, the conversion methods of different scalesamong individual, community, ecosystem2.3 Research on ecological water requirementslandscape needs to be improved. These aforemen-tioned achievements have provided a theoretical ref-The study of ecological water requirements is anerence for ecological environmental construction andimportant research subject in eco-hydrology, and isthe implementation of sustainable development strat-influential in ecology, hydrology and water resourceegy. In recent years, the study of ecological water re-sciences. These requirements maintain a stable eco-quirements in China has focused on arid and semi-aridsystem structure and ecological function, and canregions with contrasting supply and demand of waterprotect theecological environment from further de-resources, and a relatively weak ecological environ-terioration, leading to a gradual improvement. Thement. Thus, for future basin research on ecologicalecological water demand can be divided into two cat-water requirements, one needs to combine the studyegories, namely vegetation and ecology (Si et al,of ecological process and hydrological process with2005). At present, the study of ecological water de-new theories and methods (He et al, 2005).mand is still at the initial stage, focusing mostly onIn summary, present studies focus on the relation-the establishment of eco-hydrological models, param-hip between vegetation and water in the ecologicaleter estimation and calculation system. The researchsystem, the eco-hydrological process and ecologicalprogress of temporal and spatial variability and scalepatterns. Studies on the coupling relationship betweenof ecological system is slow, and the study of correla- hydrological process and landscape structure of thetion among hydrology, ecology and climate is stillecosystem in the basin are rare, and only a deep under-under exploration. Therefore, future research shouldstanding of the eco-hydrological rules can be helpfulfocus on the spatial and temporal variability of eco-for the construction of an ecological environment andsystems, growing season and characteristics of vege-management of water resources.tation, and natural geography, thus ecological systemwater demand in particular conditions can be objec-3 Research on eco-hydrological functiontively evaluated. The research on formation mecha-nism is scarce (Feng et al., 2008). Thus, future re-Research on basin eco-hydrological function ex-search should apply a comprehensive analysis on theamines hydrological mechanism of change and cou-theoretical system of ecological water demand inpling relationship between land surface ecosystemterms of internal and external influencing factors andpattern and hydrological process. This offers guidanceconduct systematic experimental research on differentfor protection and improvement of natural landscapeecosystems to reveal the ecological water demand.in fragile ecological areas, promoting environmentalRelatively speaking, eco-hydrology research in Chinaconstruction and water resource management (Zhaostarted late but quickly developed in recent years,and Cheng, 2001). Change of ecosystem pattern andwith tremendous progress in conceptual, theoreticalecological process are closely related to the hydrologi-mechanism, and estimation methods. Si et al. (2005)cal process. The basic eco-hydrological relationship ispresented a quantitative understanding of the ecologicalbetween stability of the hydrological pro-water requirements of a desert riparian forest by study-cess-ecosystem and coordinative mechanism of hydro-ing: (1) water-heat transfer model for the soil-vegetationlogical process-ecosystem. The coupling mechanism-atmosphere system; (2) ecosystem effect on the hy-and rule of hydrological and ecosystem process is thedrological process; (3) ecological water requirementskey for the basin research (Wang et al, 2005). Basinbased on the eco-hydrological process; (4eco-hydrology focuses on the coupling relationshipevapo-transpiration and water consumption character-between hydrological and ecosystem process, empha-istics involving leaves, plants, forest and area. Basedsizing the mechanism and process of scale transfor-on the study of ecological water demand in themation. Research focuses on correlations of ecosystemeco-hydrological process, Feng et al. (2008) calculat-stability and water environment, ecosystem recovered the demand downstream of the Heihe River by thetechnology and comprehension on a basin scale,water balance method. They also calculated the phys-eco-hydrological influence of landscape pattern change,iological water demand, the evaporation of phreaticand the coordination of water-used relations betweenwater among trees and its patches during the growingnatural and artificial ecosystems. Basically,season, and the evaporation of phreatic water in vege-eco-hydrology examines how the hydrological processtation covered area during the non-growing season.influences ecos中国煤化ir，functionThere has been limited progress in water consumptionand dynamics,ological pro-YHCNMHGYongGang Yang et al, 2014 1 Sciences in Cold and Arid Regions, 6(1): 0008- 00131cesses influences the hydrologic cycle. In order tothe hydro- chemical method.improve predictability of environmental change underthe influence of natural and anthropogenic activities,4 Application of isotope progress in eco-hydrologyand reveal the influence on water resources, socialeconomy and the ecosystem, research is required onThe isotopic composition of different water is rel-the relationship between vegetation and hydrologicalatively stable, which can be used to judge the cause ofprocess from the angle of eco-hydrology (NRC, 1992).water and different water source division. The isotopePresent research on the coupling relationship be-application on basin hydrological processes can effec-tween multi-scale hydrological and plant models hastively prevent the distortion of simulated natural con-made only preliminary progress. Limited researchditions, thus explaining the natural hydrological char-has been performed on basin wide ecosystem repairacteristicle. Stable isotope technology has been usedtechnology, ecological hydrologic effect of landscapein many aspects, including water cycle, rainfall-flowpattern changes and the coordination of water-usedprocess line segmentation， groundwater rechargerelations between natural ecosystem and artificialsource and update cycle, temporal and spatial changeecosystems (NRC, 1992). In respect to the interac-of soil moisture and root water absorption (Keith,tion between vegetation and hydrology, research in-2000; Mul et al, 2008). This application can also de-volves hydrology mechanism of ecological structuretermine plant water source and utilization in commu-and ecological processes, the temporal and spatialnities such as desert, forest, river bank and coastcoupling of hydrological and ecological process, and(Zhang et al, 2007). Stable isotope technology hasmost important, suitable saturated ecological waterbeen applied to related eco-hydrological research onrequirements. At present, research on eco-hydrologicalthe temporal and spatial changes of water use effi-function mainly focuses on forest vegetation and hy-ciency, influencing factors and plant water source,drology. The function of soil and water conservation,concerning vegetation ecosystems of different region-and flood disaster resistance in forest ecology areuniversally accepted, yet there is limited research on2007). Research on vegetation water source， soildifferent vegetation ecosystems， and far less onmoisture dynamic change and plant root water ab-catchment eco-hydrological function in terms of hy-sorption and release, and plant water use efficiencydrology. Different vegetation patterns have differenthave benefited by use of comparing hydrogen andimpacts on basin hydrology. At present, most studiesoxygen isotopes of plants, soil, water sources underconcentrate on the impact of basin runoff from a cer-natural conditions (Tratton et al, 2000; Zhao et al,tain landscape pattern, which is not comprehensive.2008; Cao et al, 2009). Isotope technology has prov-Thus, a basin wide systematic study should be insti-en its advantages and application prospect in thetuted on vegetation zone composition and spatial dis- eco-hydrological field, concerning plant water-usetribution patterns (Song et al, 2005). At present theefficiency of various vegetation types, temporal andmain methods employed in the study of hydrologicspatial changes, differences of various life forms, dif-effect and eco-hydrologic function include vegetationference of efficiency in different environmental gra-NDVIindex，"3S" technology and thedients, influencing factors and relations between theeco-hydrological model. Cheng (2007) researched theplant water-use source and water-used efficiencyecological function of a meadow steppe in the Yellow(Zhao et al, 2008). Isotope technology will provideRiver catchments by vegetation NDVI and landscapefuture potential and application on eco-hydrologicalpattern indices (Wainwright, 1996; Liu, 2004). Basedresearch.on "3S" technology and model simulation, Li et al.(2005) performed space analysis on vegetation spatial5 Research prospectdistribution pattern and its eco-hydrology functionup-stream of Minjiang River. Combining Arc GIS andResearch on the coupling relationship betweenthe hydrology model, Yang et al. (2004) researchedhydrological processes and ecosystem is very weak,forest landscape patterns and hydrologic characteris-and how glaciers, snow and frozen soil affect the in-tics in Dayekou and Haichao Ba basins, while other fluence of runoff remains unclear. Future studiesscholars performed similar researches by variousshould be based on field observation stations and fieldeco-hydrological models (Xu, 2005; Zhang et al,eco-hydrological observation and experiments, com-bined withisotope technology, water chemical andeco-hydrological function in different vegetationlandscape pattern analysis. Research objects shouldlandscape zones is very rare, and no research has beeninclude glaciers, snow, frozen soil, cold desert, swamp,done on eco-hydrological processes and function ofscrub, forest, meadow and steppe in alpine areas indifferent landscape zones in the basin by the combi-中国煤化工ocesses andnation of isotope technology, landscape patterns andeco-hydrologic:dscape zonesTYHCNMHG12YongGang Yang et al, 2014 1 Sciences in Cold and Arid Regions, 6(1): 0008- 0013on the basis of runoff segmentation. This research isof water use efficiency in plant. 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