The Changes of vegetation on forest wetland sites in North-Eastern Poland - Janusz Czerepko

Janusz Czerepko, Instytut Badawczy Leśnictwa, Sękocin Stary 2011. ISBN 978-83-878647-99-5, pp. 128 + 11 tables. In Polish, with abstract, tables and figures in English. Price 50 EUR.

Abstract. The goals of the studies were the determination of the direction and the rate of vegetation changes going on forest wetland communities. The studies were carried out on hydrogenic sites in NE Poland, where the marches habitats are the most natural. The vegetation science survey included 251 relevés which concerned 9 plant associations: Sphagnetum magellanici, Ledo-Sphagnetum magellanici, Vaccinio uliginosi-Pinetum, Sphagno-Betuletum pubescentis, Sphagno girgensohnii-Piceetum, Thelypteridi - Betuletum pubescentis, Ribeso nigri-Alnetum, Fraxino-Alnetum, Ficario-Ulmetum minoris. The study sites were located in the protected areas of the Białowieża, Knyszyńska, Augustowska and Romincka Forests. The vegetation studies were carried out two times, at first  ab. 40 years ago and were repeated in the period 2003-2010. In addition, the soil studies were carried out in 2003-2010 on the basis of the soil-core sampling descriptions and the chemical analysis of the collected probes. This study presents the results of the research on peat deposits of four mires. The changes are caused  by the decrease of sites moisture, which were conditioned of the global climate changes. It was explained by the analysis of an average species indicator values of soil moisture. The decrease of the soil moisture indicator value was connected with the increase of frequency of the species, which prefer the more dry habitat conditions. In the same time the results showed the decrease of share species with more requirement  of habitat fertility. This was the results of peat mineralization where some microelements obtained during the oxidation process became available for the plants. The share of birch, oak, maple and hornbeam in the stands growing in the marshy habitats increased significantly.
         The percentage cover of under layer of stands (second canopy, shrub, and ground vegetation) is relatively  higher  than was in the previous observations. The rare occurrence of the floods and of the stagnant water in the wetland habitats caused the decrease of the moss cover and the number of many moss species, especially the liverworts. The rate of the vegetation changes varied and the quickest was  in the Białowieża Forest and the slowest in the Romincka Forest.
        The bryophytes diversity decreased significantly – the 25 species were found to be extinct. The rate of vegetation changes varied and the quickest was  in the Białowieża Forest and the slowest in the Romincka Forest. The comparison of the plant species composition of the earlier and current plant communities in wetland habitats allows us to change the classification of plant associations. The biggest changes in the floristic composition occurred in the Sphagno girgensohnii-Piceetum, Thelypteridi-Betuletum pubescentis and Ledo-Sphagnetum magellanici associations. The highest rate of the peat accumulation was detected in the Mechacz Wielki reserve (Romincka Forest), while the slowest in the Michnówka reserve (Białowieża Forest).