Tom 3 2009

abcm3

Vegetation of watercourses and their margins under intense anthropopressure in the Żuławy Wiślane region (northern Poland)

Roślinność cieków i ich obrzeży w warunkach silnej antropopresji na Żuławach Wiślanych (północna Polska)

Renata Afranowicz

Katedra Taksonomii Roślin i Ochrony Przyrody, Uniwersytet Gdański,
ul. Wita Stwosza 59, 80-308, Gdańsk – Oliwa,
e-mail: biora@univ.gda.pl

ABSTRACT: The main aim of the study was to characterize types of vegetation connected with watercourses of different origin and morphometry and to evaluate the role of artificial watercourses as potential refuges for natural vegetation in the anthropogenic landscape of the Wisła river delta.

The research was conducted on 241 sites within the Żuławy Wiślane region during 2001-2003. The study concerned the vegetation of contemporary watercourses and their margins. In each site phytosociological data (releves) were collected; altogether 326 releves were made. The studied objects were characterized by the width and depth of watercourse as well as by the type of its bottom. Also the watercourse condition was described, including the maintaining techniques and land use type in the adjacent area. Habitat diversity was estimated according to Ellenberg’s bioindicators of reaction (R), nitrogen (N) and salinity (S). Ordination of vegetation samples was made with Detrended Correspondence Analysis (DCA) method, in CANOCO 4.5 program.

The results indicated that vegetation of artificial watercourses (canals and drainageditches) shows considerable similarity to vegetation of natural watercourses. The half of all plant communities observed in the studied area is connected with both natural and artificial watercourses and doesn’t express clear preference to their size. Moreover, patches of those plant associations are the most frequently observed. Watercourse type and morphometry have in turn an effect on distribution of community types and size of the area covered by them. The intense human impact, especially maintenance of canals and drainage ditches, causes disturbance of vegetation and habitats. Newly uncovered places are often being overgrown by expansive plant species.

KEYWORDS: vegetation, natural and artificial watercourses, anthropopressure, the Żuławy Wiślane region

AFRANOWICZ R. 2009. Vegetation of watercourses and their margins under intense anthropopressure in the Żuławy Wiślane region (northern Poland) – Roślinność cieków i ich obrzeży w warunkach silnej antropopresji na Żuławach Wiślanych (północna Polska). – Acta Bot. Cassub., Monogr. 3: 1-94. – PDF