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Republic, Dukelská 145, T r eboň, CZ-379 82 Czech Republic Summary• Focusing on characters related to its survival in flooded soils, the anatomy and differentiation of roots of Phragmites australis is reported here.• Roots were examined by anatomical methods and permeability tests using periodate-, Fe 2+ -and berberine-based apoplastic tracers.• Root development was characterized by the differentiation of a multiseriate exodermis with suberin lamellae and Casparian bands that formed close to the root tip. Impregnation of the exodermis with lignin and/or suberin appeared closer to the apex than in the endodermis, which is not commonly observed in other plant species. The early developed exodermis proved to be an effective barrier restricting the passive apoplastic penetration of solutes from the rooting medium into the root tissues. Relationships between exodermis, endodermis, aerenchyma and lateral root primordia development were also recorded.• It is concluded that early differentiation of the exodermis was advantageous in flooded substrates. Only a limited proportion of tissue without this apoplastic barrier might be crucial to reduce radial oxygen loss to the sediment and restrain the action of unfavourable factors, such as phytotoxins, in a flooded sediment.

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AimThe response of L. salicaria and P. australis plants originating from a broad latitudinal gradient to mineral nutrient and water supply was studied. We suggest implications for mechanisms possibly underlying the invasiveness of these two plant species.Location A common garden tub experiment was carried out at T r ebo ˜ , Czech Republic (49 ° N 14 ° 47 ′ E, altitude 433 m). MethodsPlants of 30 L. salicaria and 6 P. australis populations originating from a wide geographical area in Europe and in Israel (60 °− 32 ° N latitude, 6 ° W − 20 ° E longitude) were cultivated for one growing season at two water levels and three ( L. salicaria ) or two ( P. australis ) nutrient doses, respectively. At the end of cultivation, basic morphological and growth characteristics were recorded. ResultsThe latitude of the original geographical location was the most significant factor, affecting both the phenology and most of the plant morphological and growth characteristics measured in both plant species, with the characteristics related to plant size being negatively correlated with latitude. The effect of nutrient dose was very strong in both species, while the effect of water level was more pronounced in P. australis than in L. salicaria . Main conclusionsThe results confirmed the existence of a large phenotypic variability in both plant species within their native ranges of occurrence. In both plant species, the latitudinal variation in plant morphological and growth characteristics most probably indicates the differentiation of genotypes adapted to local geographical conditions. The plants of both species originating from all geographical locations tested responded to the respective nutrient treatments in a similar manner. Exceptions were found in growth characteristics related to reproduction in L. salicaria , indicating that better nutrient supply could enhance the reproductive ability of certain genotypes. Based on the results obtained, we suggest implications for mechanisms possibly underlying the invasiveness of the plant species studied.

The present area of European wetlands is only a fraction of their area before the start of large-scale human colonization of Europe. Many European wetlands have been exploited and/or managed for various purposes. Large wetland areas have been drained and reclaimed mainly for agriculture and establishment of human settlements. These threats to European wetlands persist. The main responses of European wetland to ongoing climate changes will vary according to wetland type and geographical location. Sea level rise will probably be the decisive factor affecting coastal wetlands especially along the Atlantic coast. In the boreal part of Europe, increased temperatures will probably lead to lowered annual evapotranspiration and lowered organic matter accumulation in soil. The role of vast boreal wetlands as carbon sinks may thus be suppressed. In central and western Europe, the risk of floods may support the political will for ecosystem-unfriendly flood defence measures, which may threaten the hydrology of existing wetlands. Southern Europe will probably suffer most from water shortage, which may stregthen the competition for water resources between agriculture, industry and settlements on the one hand and nature conservancy, including wetland conservation, on the other. The main responses of European wetland to ongoing climate changes will vary according to wetland type and geographical location. Sea level rise will probably be the decisive factor affecting coastal wetlands especially along the Atlantic coast. In the boreal part of Europe, increased temperatures will probably lead to lowered annual evapotranspiration and lowered organic matter accumulation in soil. The role of vast boreal wetlands as carbon sinks may thus be suppressed. In central and western Europe, the risk of floods may support the political will for ecosystem-unfriendly flood defence measures, which may threaten the hydrology of existing wetlands. Southern Europe will probably suffer most Manuscript Click here to download Manuscript: European_wetlands_20110124. doc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 from water shortage, which may stregthen the competition for water resources between agriculture, industry and settlements on the one hand and nature conservancy, including wetland conservation, on the other.

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