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  • 1995-1999  (3)
  • Egypt  (1)
  • Elodea canadensis  (1)
  • South America  (1)
  • desert vegetation  (1)
  • Pattern of breathing
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Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    The plant biodiversity of the Wadi Allaqi Biosphere Reserve (Egypt): impact of Lake Nasser on a desert wadi ecosystem (1997)
    Springer
    Biodiversity and conservation 6 (1997), S. 1259-1275 
    Details
    ISSN: 1572-9710
    Keywords: desert vegetation ; plant biodiversity ; flood impacts ; phytogeography ; Egypt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A data set comprising 95 stands of desert vegetation, collected from the Wadi Allaqi Biosphere Reserve and its environs within the South-Eastern Desert of Egypt during 1985–90, was analysed using multivariate procedures (two-way indicator species analysis: TWINSPAN; detrended correspondence analysis: DCA; canonical correspondence analysis: CCA), to produce a classification of plant communities in the area, and to examine the relationships of these plant communities to natural and man-induced features of the physical environment of the area (in particular, the influence of Lake Nasser, a major impoundment of the River Nile formed in 1964). The vegetation classification produced groupings broader, in both floristic and ecological terms, than those found by earlier studies of this area. In total 78 plant species were recorded from four phytogeographic elements. Four principal vegetation groups were identified, of which one is new to the area, and is the result of major environmental changes affecting the downstream part of the Wadi Allaqi system, following periodic flooding of the wadi by Lake Nasser during the past 30 years. This community was indicated by Tamarix nilotica. There was a strongly-zoned (downstream–upstream) pattern to the vegetation within this lower part of Wadi Allaqi, which appears to be a function of the probability of flooding by the lake. The remaining three vegetation groups occur higher in the wadi basin. Groundwater-dependence appeared to be important in defining a group indicated by Acacia tortilis, as well as the Tamarix nilotica group. The two remaining groups, characterized respectively by Acacia ehrenbergiana and Cullen plicatum, represent vegetation groups which are precipitation-dependent, and which tolerate drier conditions within the Allaqi system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:BIOC.0000034012.93599.c0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Response of Elodea canadensis Michx, and Myriophyllum spicatum L. to shade, cutting and competition in experimental culture (1996)
    Springer
    Hydrobiologia 340 (1996), S. 219-224 
    Details
    ISSN: 1573-5117
    Keywords: weed control ; competition ; disturbance ; Elodea canadensis ; Myriophyllum spicatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Elodea canadensis Michx. and Myriophyllum spicatum L. are widespread nuisance aquatic plant species. Their ecology is regarded as similar. Both species have been previously classified in terms of established-phase survival strategy as ‘competitive disturbance-tolerant’ species. Experimental data are presented to show that although this broad categorisation of strategy is probably correct for the two species, it is possible to demonstrate significant differences in terms of response to disturbance and competition. Less difference was discernible in their comparative response to stress. The drawbacks of applying broad descriptive terminology when dealing with two species of similar strategy are addressed. The results help explain reports of variable success in attempting to manage these two species using disturbance-based weed control measures, and suggest that Elodea is even less susceptible to such measures than Myriophyllum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012758
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Interrelationships of fish and channel environmental conditions with aquatic macrophytes in an Argentine irrigation system (1998)
    Springer
    Hydrobiologia 380 (1998), S. 15-25 
    Details
    ISSN: 1573-5117
    Keywords: Macrophytes ; irrigation and drainage channels ; turbidity ; Cyprinus carpio ; South America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study examines the relationships between fish, environmental variables and submerged macrophytes within the irrigation system of the lower valley of the Río Colorado in southern Argentina. Using Canonical Correspondence Analysis (CCA), the strongest environmental gradients detected were conductivity and carp ( Cyprinus carpi) biomass per unit area of channel cross-section. These variables were positively associated with each other and also with water turbidity. Sites scoring high on these gradients were mainly drainage channels; those scoring lowest were irrigation channels. The main fish species associated with high carp biomass, high turbidity and high conductivity were carpa ( C. carpio), pejerrey ( Odontesthes bonariensis), madrecita ( Jenynsia lineata lineata) and lisa ( Mugil liza). Dientudo ( Oligosarcus jenynsi) and mojarra ( Astianax eigenmanniorum) were more strongly associated with clearer water, with low carp biomass. In all CCA analyses macrophytes were arranged in similar order along the main conductivity-turbidity-carp biomass gradient. Lowest on this main environmental gradient, and scoring very close to each other, were Potamogeton pectinatus and Chara contraria. Salinity-tolerant species such as Ruppia maritima, Zannichellia palustris and Enteromorpha flexuosa tended to score highest, followed by the surface floating Azolla filiculoides and the filamentous alga Cladophora surera. Within the constraints imposed by conductivity, turbidity was a key predictor of both abundance and distribution of the two dominant plants of the irrigation scheme ( P. pectinatus and C. contraria). Turbidity was strongly predicted by biomass of carp per unit channel cross sectional area, when fine sediment particle content was taken into account. The positive association between carp biomass and water turbidity was both substantial and predictable, and was in turn associated with reduction in submerged plant growth. The biomass of the most widespread nuisance-causing plant species in the channels, Potamogeton pectinatus, could best be predicted ( R = 0.592, P 〈 0.05) using a multiple regression model utilising four predictor variables: conductivity, nitrate, phosphate and carp biomass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003215513435
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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