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1.
Aquatic dance flies (Empididae; Clinocerinae and Hemerodromiinae) are important components of freshwater assemblages, especially in running waters. They are predators as larvae and adults and thus essential for understanding aquatic food webs. This study was conducted in Plitvice lakes National Park (Croatia) representing a wide variety of freshwater habitats (springs, streams, lakes and tufa barriers). Adults were collected monthly from March 2007 until March 2009 using pyramid-type emergence traps at 13 locations. A total of 3865 specimens comprising 18 species were collected. The dominant genus was Chelifera, while the most abundant species was Hemerodromia unilineata. All species were univoltine except Chelifera precabunda, Chelifera pyrenaica and Chelifera stigmatica that were bivoltine. Considerable differences in composition and structure of aquatic dance flies assemblages were recorded along a longitudinal gradient of studied sites, primarily related to differences in physical and chemical parameters of water. Water temperature was the main factor influencing the timing of emergence. Hemerodromia species preferred variable water temperature throughout the year while the majority of the Chelifera species preferred stable water temperature characteristic of spring sites. Furthermore, discharge affected assemblage composition of aquatic dance flies. The highest abundance of aquatic dance flies was recorded in lotic habitats with fast water current over substrates of moss, gravel and particulate tufa with detritus. These results give a new insight on microhabitat preference and their distribution on unique karstic habitats.  相似文献   

2.
Springs are stable environments with constant abiotic factors and therefore of use in variety of ecological experiments. We investigated the influence of canopy coverage on abundance, diversity, phenology and feeding guilds among Diptera assemblages at two rheocrene karst springs located near each other. The springs differed by canopy coverage while physicochemical characteristics of the water were similar. We set six emergence traps for one year at each spring covering all available microhabitats proportionally. We hypothesized that canopy coverage will have a strong effect on assemblage composition of Diptera as well as on diversity, abundance, phenology and feeding guilds composition between sites and that it will have a stronger effect than microhabitat characteristics. Similarity of species composition among springs was only 37.5%, with 23 common species/taxa out of 74 species/taxa. Abundance of Diptera was 8.5× higher at the open canopy spring, while diversity and number of species/taxa was higher at closed canopy spring. Emergence started earlier at open canopy site and was prolonged even in winter months. The majority of species were detritus feeders followed by collectors and there was no substantial difference among sites. We conclude that at springs with similar water characteristics, canopy coverage is the main driver of Diptera assemblage structure, with water velocity as a complementary factor. Substrate and other physicochemical factors seem less important.  相似文献   

3.
About 87 % of the anuran species that occur in Brazil possess a larval stage, i.e., tadpoles. Throughout this stage of development, tadpoles are subject to predation and the conditions of their aquatic habitat, including environmental heterogeneity, physical and chemical properties of the water, and hydroperiod of the water body. We assessed the patterns of species composition and richness of tadpoles in permanent and temporary ponds, with the objective of evaluating how morphometric, physical and chemical factors of the ponds and environmental heterogeneity (surrounding vegetation and substrate cover and aquatic vegetation) affect anuran occupation of these environments. The study was performed in five permanent and four temporary ponds. Tadpoles of 20 anuran species differed in species composition between permanent and temporary environments. Environmental factors were significant drivers for tadpole richness: turbidity and dissolved oxygen were significantly related to richness in permanent ponds, while water temperature and pH were significantly correlated to richness in temporary environments. Higher species richness was related to the heterogeneity of the ponds and greater complexity associated with the stratification of the surrounding vegetation. In general, the results suggest that species sorting of tadpoles is probably related to the high environmental variation among permanent and temporary aquatic habitats. The spatial heterogeneity of these two types of environments increases local diversity by accommodating species that are unique to only one habitat type.  相似文献   

4.
During the high water season, the flooding reduces environmental heterogeneity in aquatic ecosystems of the Pantanal wetland. When the water level recedes, lakes and channels are formed as individual systems. Therefore, we expected the spatial heterogeneity during the low water phase resulting in changes on biological communities leading to high phytoplankton abundance, biomass and diversity within and between habitats. To test this hypothesis, we analyzed eight freshwater systems (five oxbow lakes, two channels, and the river) during the low water period. Phytoplankton biomass, abundance, diversity (alpha, beta, gamma) and diversity metrics as richness (species per sample), Shannon diversity (H′) and evenness were measured in all systems along with nutrient concentrations, zooplankton and bacteria abundances. We found 97 species as gamma diversity. The alpha diversity was unexpectedly low in comparison to most other South American floodplain systems (38 species in river, 24 in channels and 29 in lakes). Also, the systems are relatively similar in composition (beta diversity, 28%). Connectivity differences between systems highlighted differences in phytoplankton abundance and biomass (fresh weight) ranging from 1428 ind mL−1 (river) to 3710 ind mL−1 (lakes) and from 0.71 mg L−1 (river) to 2.9 mg L−1 (lakes), respectively. However, our results did not indicate significant differences in phytoplankton species richness between the systems during the low water. Our main conclusions are that local factors may be responsible for changes on phytoplankton community and the time of isolation during the low water phase was not sufficient to promote changes in phytoplankton diversity between the habitats.  相似文献   

5.
王朝  周立志  戴秉国  古辰  蒋忠冠 《湖泊科学》2019,31(5):1403-1414
水位的洪枯变化通过江湖连通影响泛滥平原湖泊鱼类的组成和分布,因而江湖过渡带是反映泛滥平原生态系统鱼类交流和多样性变动的关键区域.尽管如此,针对江湖过渡带鱼类群落随水位洪枯变化的研究十分匮乏.本研究以菜子湖江湖过渡带为例,分别在洪水和枯水期选取包括静水和流水生境的样点对鱼类群落进行系统的调查采样,探讨水位洪枯变化对菜子湖江湖过渡带鱼类物种和功能多样性的影响.共采集到鱼类6目12科37属52种,其中,洪水期和枯水期物种数差异显著,分别采集到鱼类50和42种,而静水生境和流水生境物种数差异不明显,分别采集到鱼类47和48种.与洪水期相比,枯水期山溪河流性鱼类的物种数、重量、尾数和优势度百分比分别减少了7.3%、6.3%、14.4%和12.0%;与静水生境相比,流水生境山溪河流性鱼类的物种数、重量、尾数和优势度百分比分别增加了5.3%、14.6%、18.0%和22.3%.SIMPER分析结果显示,麦穗鱼（Pseudorasbora parva）、蛇鮈（Saurogobio dabryi）、（Hemiculter leucisculus）、鲤（Cyprinus carpio）、鲫（Carassius auratus）、短颌鲚（Coilia brachygnathus）、似鳊（Pseudobrama simoni）、翘嘴鲌（Culter ilishaeformis）、达氏鲌（Culter dabryi）、光唇蛇鮈（Saurogobio gymnocheilus）和无须鱊（Acheilognathus gracilis）是引起水位洪枯变化以及不同生境类型鱼类群落结构差异的主要物种.优势度分析结果表明枯水期和静水生境的优势种鱼类相似,重要值较高的优势种鱼类为鲤、鲫、和似鳊;而洪水期和流水生境的优势种鱼类同样相似,重要值较高的优势种鱼类为麦穗鱼、蛇鮈、光唇蛇鮈和短颌鲚.通过双因素方差分析解析了水位洪枯变化和不同生境类型对鱼类物种和功能多样性的影响.发现洪枯水位变化仅对物种多样性指数中的物种数（Richness）产生显著差异,而对功能多样性的3个指数（功能丰富度指数（FRic）、功能离散指数（FDiv）和功能分散指数（FDis））均有显著影响.洪水期鱼类的Richness、FRic、FDiv和FDis指数均显著高于枯水期.同时,静水生境条件下的FRic指数要显著高于流水生境.本研究发现,与传统的物种多样性相比,基于功能性状的功能多样性对水位的洪枯变动更为敏感,河流周期性洪泛是泛滥平原生态系统中鱼类功能补充的重要方式.  相似文献   

6.
Riparian vegetation is an important determinant of the physical, chemical, and biological condition of streams, and odonates are useful indicators of riparian condition. To identify environmental factors that structure Odonata assemblages in tropical forest streams, we collected adult odonate specimens and habitat data from 50 stream sites located in the Brazilian municipality of Paragominas (Pará state). We collected 1769 specimens representing 11 families, 41 genera, and 97 species. Of these species, 56 were Zygoptera, and 41 were Anisoptera. Improved environmental condition was reflected in increased Zygoptera species richness and reduced Anisoptera species richness. Channel shading was strongly and positively related to Zygoptera richness, and negatively to Anisoptera richness. Zygoptera species richness, but not Anisoptera species richness, was related positively to bank angle, quantity of wood in the stream bed, electrical conductivity, and decreased water temperature. Altered riparian vegetation structure was the principal determinant of odonate assemblage structure. Our results indicate that maintaining intact riparian vegetation is fundamental for conserving or re-establishing aquatic odonate assemblage structure.  相似文献   

7.
Patterns in aquatic Clitellata assemblage composition are known to be driven by several environmental gradients, with water chemistry and substratum characteristics being particularly important. In this study we explored 54 isolated spring fens across the eastern Czech Republic and Slovakia. These fens varied in calcium and magnesium concentrations, forming a sharp and well defined environmental gradient running from calcium-poor acidic fens to extremely calcium-rich tufa-forming fens. We found that the main changes in clitellate species composition were controlled by this gradient, and/or total organic carbon content, over a wide area, including fen sites differing in other environmental conditions and historical development. However, this pattern was weakened in sites with a high organic matter content, which represented a second driver of change in assemblage composition along with water temperature. Three main types of fens were determined using cluster analysis based on clitellate assemblage composition. However, only the first type, which included tufa-forming fens, was found to fit with the previously established spring fen types based on vegetation (i.e. extremely mineral-rich fens with a tufa, brown-moss mineral-rich fens, mineral-rich Sphagnum fens and mineral-poor Sphagnum fens). The second clitellate type included sites with low temperatures and occasional desiccation, while the third type was characterised by high temperatures and trophy. Using eight environmental predictors, we were able to significantly explain changes in the population abundances of all 12 common species (i.e. recorded at 15-plus sites). The results from individual species modelling also suggests that an increase in organic matter content can trigger compositional shifts towards assemblages of common eurytopic tubificid species. Thus, human-induced eutrophication and negative changes in spring fen hydrology, mainly drying up, can represent a serious threat for species-specific assemblages of aquatic clitellates, especially at alkaline sites due to their isolated and spatially limited nature.  相似文献   

8.
The high mediolittoral rocky-shore community on the island of Groix (Brittany, France), was studied for the year immediately following the Erika oil spill (12/12/1999). The macrofaunal assemblages of three habitats (exposed bedrock, crevices, boulders) under three situations (non-impacted, impacted and not washed, impacted and washed) were monitored monthly. The assemblage of each habitat showed specific responses to the impacts and initiated various patterns of succession: the bed rock assemblage changed in terms of abundance but no species-richness variations occurred; in the crevices richness variations occurred both in the disappearance of some species and the immigration of opportunistic ones; the boulder assemblage lost many species and remained unstructured one year after the oil spill. These first results of this most recent oil spill in Europe, raised the question of the relative importance of habitat-species and species interactions on the community structure.  相似文献   

9.
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10.
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11.
Several studies have shown that fish assemblages are structured by habitat features, most of them have proposed that there is a positive relationship between habitat structural complexity and species diversity. In this study, we aimed to test this positive-relationship idea in three habitats types (creeks, oxbow lakes and river sandbanks) distributed along the Bita River Basin in South America. Standardized surveys were conducted during January and February of 2016 (low water period) in 30 sites distributed along the entire basin. We recorded 23,092 individuals representing 191 species. To investigate possible relationships between habitat structural complexity and species diversity, we calculated the first three Hill’s numbers, and performed a Non-metric Multidimensional Scaling (NMDS), a Principal Component Analysis (PCA) and a Canonical Correspondence Analysis (CCA). Our results showed that river sandbanks and creeks had the highest species richness. Results from the NMDS analysis (stress = 0.19) showed that fish community composition was different in the assessed habitats (ANOSIM < p = 0.001). According to the results of the principal component analysis, sand percentage, dissolved oxygen, and vegetation width separated river sandbanks from the other habitats. Results from the Hill’s numbers, forward selection procedure, and canonical correspondence analysis suggested that species composition and diversity were significantly influenced by the habitat structural complexity index and conductivity.  相似文献   

12.
We examined the spatial structure of macroinvertebrate assemblages in surface-flowing waters of a glacially-influenced floodplain. The floodplain main-channel responded longitudinally to changes in hydrology with evident coarse-scale zones of upwelling and downwelling; the lower floodplain main channel fell dry in late winter. Physico-chemical attributes differed among tributaries and the main channel. The main channel had lower values of conductivity, alkalinity and nitrate–N than tributaries, with right-side (east-facing) tributaries having the highest values. Left-side (west-facing) tributaries flowing over an exposed rock-face had warmer water temperatures than the main channel and right-side tributaries. The biomass of benthic organic matter and periphyton was highest in right-side tributaries, followed by main channel sites then left-side tributaries. Similarly, macroinvertebrate density and richness were higher in right-side tributaries, intermediate in main channel sites, and lowest in left-side tributaries. Macroinvertebrate assemblages clearly differed between main channel sites, right-side tributaries, and left side tributaries based on an NMDS analysis. Minor differences were observed among main channel sites, although most upstream sites showed some structural differences from downstream sites. Ephemeropterans and plecopterans were most common in main channel sites and right-side tributaries, whereas chironomids and trichopterans also were common in right-side tributaries. Although the main channel changed longitudinally in physico-chemical characteristics, no real patterns of zonation were evident in macroinvertebrate assemblages. Coarse spatial patterns in macroinvertebrate assemblages in the floodplain were reflected in the physico-chemical differences between the main channel and tributaries, and between left-side and right-side tributaries. We conclude that coarse-scale floodplain properties enhance the overall diversity of lotic macroinvertebrates. Consequently, floodplain alterations that reduce surface water heterogeneity/connectivity limits the potential macroinvertebrate diversity of floodplains.  相似文献   

13.
为了解西藏拉鲁湿地浮游植物群落时空分布特征及其驱动因子,于2021年7月、10月和2022年5月在拉鲁湿地主要水系进行定性和定量样品采集,共采集浮游植物水样126个,从不同季节和不同生境浮游植物种类组成、多样性等方面入手,探讨拉鲁湿地浮游植物群落时空分布特征及其驱动因子,为研究拉鲁湿地生态系统和稳定发展提供基础资料。结果表明:1)拉鲁湿地共鉴定出浮游植物532种(含变种和变型),隶属于8门13纲36目74科130属,物种组成表现为硅藻-绿藻-蓝藻型。2)拉鲁湿地浮游植物群落特征参数在不同季节和不同生境之间存在差异。夏季浮游植物群落的Shannon-Wiener多样性指数显著高于秋季和春季,Simpson优势度指数显著高于秋季。秋季浮游植物群落的Pielou均匀度指数显著低于夏季和春季。春季浮游植物群落的Margalef丰富度指数显著低于夏季和秋季。沼泽生境的浮游植物群落的Margalef丰富度指数显著高于湿草甸生境。3)季节是浮游植物群落组成差异的关键因素,生境对浮游植物群落组成的影响较弱,夏季的距离衰减模式比秋季和春季更强。4)拉鲁湿地不同的浮游植物群落参数与不同环境因子之间存在显著的关联。5)空间因素在解释浮游植物群落变异方面具有显著贡献,而快速变化的水质变量在决定浮游植物的季节变化中起着重要作用。季节和缓慢变化水质因子的解释能力相对较弱,但仍对浮游植物群落的变异有一定影响。  相似文献   

14.
Artificial drainage of forested wetlands to increase timber production has profoundly altered the hydrology of North-European landscapes during the 20th century. Nowadays, drainage ditches and small dredged streams can comprise most fluvial water bodies there, but the resulting ecological effects are poorly documented. In the current study, we explored, using fish as an indicator group, consequences of the transformation of natural stream networks to a mixture of natural and artificial watercourses. We asked whether the transformation results in impoverishment, enrichment or re-assembling of the communities both at watercourse and the landscape scales. We sampled fish in 98 sites in five well-forested regions in Estonia where ditches formed 83–92%, dredged streams 4–7%, and natural streams 3–10% of the total length of small watercourses. Based on a total of 6370 individual fish of 20 species, we found that, compared to natural streams, ditches had an impoverished fauna at both scales and both in terms of species richness and assemblage composition. Only natural streams hosted characteristic species (with Barbatula barbatula, Lampetra planeri and Lota lota emerging as significant indicators), while dredged streams had intermediate assemblages. The habitat factors explaining those drainage-related differences included a reduced flow velocity, loss of stream channel variability, less transparent water, and abundant aquatic vegetation. Hence, for stream-dwelling fish, drained forest landscapes represent degraded habitats rather than novel ecosystems, which contrasts with the transformation of terrestrial assemblages. Future studies should address whether that reflects the situation for whole aquatic assemblages, and how is the functioning of the hydrological systems affected. We suggest that the critical management issues for environmental mitigation of ditching effects on fish include basin scale spatial planning, protecting of the remaining natural streams, and rehabilitation of ditch channels in flat landscapes lacking beavers.  相似文献   

15.
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16.
水体和沉积物是湖泊生态系统中迥异但又紧密相连的两类生境,栖息在这两类生境中的细菌在维持生态系统平衡和驱动元素循环中起着关键性作用。为了探究湖泊水体和沉积物细菌群落的分布格局,本文对太湖四个湖区水体和沉积物中细菌群落进行调查,基于高通量测序技术和统计分析手段,分析这两类生境中的细菌群落组成和多样性水平、分布特征及其驱动因素。结果表明:放线菌门(Actinobacteria)、变形菌门(Proteobacteria)和蓝细菌门(Cyanobacteria)是水体细菌群落中最主要的细菌门,而沉积物中Proteobacteria占据优势地位。在两类生境中,太湖西部区域细菌群落丰富度和独特性(LCBD)相对较高,各区域群落结构表现出显著性差异。对水体而言,电导率、pH值、PC1(重金属组成)和沉积物孔隙度是驱动细菌丰富度的重要因子,PC1、水温及pH值是影响细菌群落LCBD的重要因子,而细菌网络复杂性随pH值的增加而增加,且在高pH环境中占主导地位;对沉积物而言,其丰富度和LCBD的重要影响因子均是沉积物中总磷和锂,细菌网络复杂性随金属元素施加的环境压力增大而降低,但随总磷、磷酸盐和铵态氮浓度的...  相似文献   

17.
Andean Patagonian lakes are ultraoligotrophic and deep, have simple food webs and low fish diversity and abundance. In this work the distributional abundance data of fish was studied in two interconnected Andean Patagonian lakes with varying proportions of contrasting habitat types. Hydroacoustic data (120 kHz) were used to analyze fish abundance and habitat use during the mixis and stratification periods. Three types of habitat (near shore, surface pelagic and deep pelagic) and two groups of fish, based on size (Big Fish >12 cm total length and Fish Larvae and Small Fish <12 cm total length) were defined. The distribution of both fish groups in these lakes revealed differences in habitat use for each lake and period. Fish group abundance was related to the availability of habitat types, according to the morphology of each lake. The Big Fish group showed preference for the near shore habitat during lake stratification and always appeared as individual targets. The Fish Larvae and Small Fish group used mainly the pelagic habitat during mixis, where they formed dense sound scattering layers. However, during lake stratification many individual targets from this group were found both in pelagic and near shore habitats, which would seem to indicate a change in distributional behavior. This is possibly associated with niche changes in the Galaxiids (Galaxias spp), a key component of Northern Patagonian lake food webs. Lakes like Moreno Oeste, which are morphologically and structurally more complex, could have more diverse fish ensembles with higher abundances. In contrast, lakes of simple morphology with low development of near shore habitats and ample deep zones, like Lake Moreno Este, could present lower Big Fish abundance. The contrasting habitat availability between lakes accounts for the abundances and distribution patterns of each fish group. While in these lakes fish assemblage species composition could depends on the environmental filter, the particular structure of a fish assemblage in terms of the proportional abundances of species depends on proportional habitat type availability. We can speculate that in Andean Patagonian lakes Galaxiids mediate a habitat coupling process critical for the transfer of energy and matter in oligotrophic lakes. We may also consider that the Small Puyen in this type of lake is a keystone prey species that relieves predation pressure on other potential prey. The existence of deep pelagic habitats in numerous deep lakes in the Northern Patagonian Andean region provides not only daytime refuge for Galaxiids, which allows them to maintain their high numbers in the lakes, but could also, in the long term, act as a Galaxiid source for other water bodies.  相似文献   

18.
Fish assemblage structure in Palair reservoir, a medium tropical reservoir along the river Paleru, a tributary of river Krishna in Southern India, was studied along the spatial gradient of the impoundment. The abundance and assemblage structure of wild fish aggregated around the fish cage units installed in the reservoir were assessed and compared with other sites. Seasonal sampling was carried out and fish community structure in terms of species composition and abundance, trophic guild, niche, tolerance, resilience and conservation status were analyzed. A total of 38 fish species were recorded wherein the family Cyprinidae dominated in the number of species (15) followed by Cichlidae and Channidae (3 each). Margalef richness index (d), Pielou’s evenness index (J’), Simpson’s index (1-λ) and Shannon index (H’) revealed significant variation across different zones. Species richness was maximum in the Site1 (d = 4.44–5.12), whereas the abundance of individuals was maximum at Site4 (H’ = 2.65–2.86) i.e. near cage in the lacustrine zone. The important species contributing to the dissimilarities among the zones were identified and percentage of their contribution was estimated using SIMPER analysis. Trophic guild of fishes indicated the dominance of omnivorous species followed by carnivores, indicating the heterotrophic phase of the reservoir. The spatial and seasonal variations in the fish assemblage structure were tested applying statistical analyses such as PERMANOVA and nMDS. The results indicated a positive impact of cage farming in supporting the wild fish fauna, influencing the large aggregations of fishes around the cages. The temporal variability in the cage-associated fish assemblage was related to recruitment periods of juveniles (e.g. E. maculates and E. suratensis in summer, and S. seenghala in monsoon seasons). The links between fish assemblages and environmental parameters were explored through DISTILM and the deterministic factors for fish abundance in the reservoir were phosphate, pH, dissolved Oxygen, total hardness and depth. The study also indicated the impacts of cage culture with record of accidental escapes of farmed fish to the reservoir system. The baseline information generated and recommendations formulated in the study are crucial for the conservation of fish diversity, fisheries enhancement and management planning of tropical peninsular reservoirs.  相似文献   

19.
Harpacticoids are an important component of meiofaunal assemblages in springs. No information so far has been available on harpacticoid assemblages of the Western Carpathian spring fens, unique biotopes of high conservation value which cover a very long gradient of mineral content of groundwater, due to the variable geological background setting. Spring fens are isolated habitats of different age which can be assessed by radiocarbon dating of their basal sediment layers. This enables to test a possible effect of habitat age on species composition and species richness. In this study, we examined harpacticoid assemblages in 50 permanent tree-less spring fens (helocrenes) in the Western Carpathians (Slovakia and Czech Republic) in terms of species composition, total abundance, species density, and species richness. We tested mainly the effect of 12 explanatory variables describing water chemistry and temperature, climatic conditions, amount of nutrients, organic carbon, sediment structure, habitat age and size, using Canonical Correspondence Analyses (CCA) with stepwise forward selection. For the computation of species richness rarefaction was used. In total, 20 harpacticoid species were recorded with the total median density of 950 individuals in m−2. Three significant explanatory variables, Ellenberg Indicator Values of plant community for nutrients, in situ measured pH, and average January temperature, explained together 19.0% (adj. 13.7%) of the total variance in the species composition data. The relationships of harpacticoids to these three explanatory variables were species specific and no uniform response of the total assemblage to the environmental variables was found (in terms of total abundance and number of species). The only exception was the influence of overall unfavourable conditions in the mineral-poor acidic Sphagnum-fens. Pilocamptus pilosus was significantly associated with a higher amount of nutrients and warmer climate. Nutrient enrichment was clearly indicated by a decrease or absence of crenophile Bryocamptus cuspidatus, and accompanied by an increase in ubiquitous Attheyella crassa. Moraria brevipes was confined to low pH, B. cuspidatus showed a high tolerance for low pH, whereas Bryocamptus echinatus preferred alkaline conditions. Despite a significant correlation between habitat age and species density we found no clear evidence that any colonisation driven process could influence the number of harpacticoid species within the tested time scale. We hypothesize that rather other habitat characteristics connected with age, i.e. habitat heterogeneity and stability, may be determinant for species richness. The occurrence of some species (e.g. P. pilosus, B. cuspidatus) was clearly geographically limited, but due to the spatial structuring of significant environmental variables no conclusion on dispersal limitations could be made.  相似文献   

20.
A modified Jarvis–Stewart model of canopy transpiration (Ec) was tested over five ecosystems differing in climate, soil type and species composition. The aims of this study were to investigate the model's applicability over multiple ecosystems; to determine whether the number of model parameters could be reduced by assuming that site‐specific responses of Ec to solar radiation, vapour pressure deficit and soil moisture content vary little between sites; and to examine convergence of behaviour of canopy water‐use across multiple sites. This was accomplished by the following: (i) calibrating the model for each site to determine a set of site‐specific (SS) parameters, and (ii) calibrating the model for all sites simultaneously to determine a set of combined sites (CS) parameters. The performance of both models was compared with measured Ec data and a statistical benchmark using an artificial neural network (ANN). Both the CS and SS models performed well, explaining hourly and daily variation in Ec. The SS model produced slightly better model statistics [R2 = 0.75–0.91; model efficiency (ME) = 0.53–0.81; root mean square error (RMSE) = 0.0015–0.0280 mm h‐1] than the CS model (R2 = 0.68–0.87; ME = 0.45–0.72; RMSE = 0.0023–0.0164 mm h‐1). Both were highly comparable with the ANN (R2 = 0.77–0.90; ME = 0.58–0.80; RMSE = 0.0007–0.0122 mm h‐1). These results indicate that the response of canopy water‐use to abiotic drivers displayed significant convergence across sites, but the absolute magnitude of Ec was site specific. Period totals estimated with the modified Jarvis–Stewart model provided close approximations of observed totals, demonstrating the effectiveness of this model as a tool aiding water resource management. Analysis of the measured diel patterns of water use revealed significant nocturnal transpiration (9–18% of total water use by the canopy), but no Jarvis–Stewart formulations are able to capture this because of the dependence of water‐use on solar radiation, which is zero at night. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

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