The impact of environmental factors on the distribution pattern of aquatic macrophytes in a middle-sized Mediterranean stream

摘要: Abstract We studied the aquatic macrophyte assemblage structure along a Mediterranean lotic ecosystem from upper reaches to most downstream areas. examined how environmental characteristics affect composition and abundance of communities spatially temporally. Field survey data were collected Acheron river catchment, between 2005 2007. The identification plant assemblages hierarchical each group species analyzed using classification (Bray–Curtis) Indicator Species Analysis (ISA). relationships community water quality Redundancy (RDA) while temporal variability was assessed Canonical Variate (CVA). A total 81 taxa recorded Bray–Curtis identified 6 different vegetation groups. ISA results produced bryophyte pteridophyte indicator for fast flowing sites near springs lower parts dominated by Phragmites australis, Potamogeton pectinatus macroalgae species. In mid-river sections 4 groups identified: (i) Scirpus holoschoenus–Polygonum salicifolium–Plantago major occupied waters riffle habitat, (ii) Arundo donax–Scirpus lacustris–Fontinalis antipyretica located at urban sites, (iii) Brachythecium rutabulum–Pellia endiviifolia–Equisetum telmateia shaded with low nutrient concentration; (iv) hydrophytes helophytes which found be dominant in Acherons tributaries associated slower water, clarity high nitrate ammonia nitrogen concentrations. Life form analysis indicated that mosses liverworts (bryophytes) dominate part basin emergent plants (helophytes) abundant both middle reaches. Monte Carlo permutation testing revealed NO3–N, NH4–N, pH, conductivity, temperature, mean velocity are strongly correlated distribution. Variates (CVA) Correspondence (CCA's) showed strong seasonal signal nutrients (nitrite, nitrate, ammonium), dissolved oxygen, pH temperature all significant discriminating variables. Nitrogen appeared important since it as nitrite ammonium forms seasons.