Diversity of floristic, habitat and energy value of selected species of genus Carex L.

Background. Sedges play an important role in various types of ecosystems due to, inter alia, participation in their biomass not only as components of phytocenoses, but also as important components in the organic sediments of various types of peatbogs. Moreover, sedge meadows perform many positive functions in the natural environment including being a place for the existence and breeding of many animal species, especially avifauna. They also have aesthetic and landscape significance. The aim of this study was to characterize the floristic, habitat and energy diversity of rush communities of the class Phragmitetea against the background of some ecological factors determined by the laboratory and phyto-indication methods. Material and methods. Materials for the study were collected from natural sites from the Wielkopolska region, mainly the Noteć Bystra valley and the inter-embankment zone of the Warta river, around Raków and Trzebiszewo, during the growing periods of 2013, 2015 and 2016. The study concerned five rush communities: Caricetum appropinquatae, Caricetum distichae, Caricetum ripariae, Caricetum rostratae and Caricetum vesicariae. These are naturally valuable phytocenoses with a natural or semi-natural character that are found in very moist marshy habitats, the coastal zones of rivers, ox-bow lakes, drainage ditches and even overgrown water holes. Results. The specified associations occurred on slightly acidic or acidic soils, often devoid of oxygen, with high levels of groundwater that were rich in nitrogen. Structural carbohydrate content was: cellulose 36.5%–42.3%, lignin 19.2%–23.6%, and holocellulose 60.8%–65.5%. The amount of extractive substances ranged from 5.2%–6.4%. Conclusion. The energy value of the studied communities is very high, which is confirmed by a heat of combustion ranging from 17.6 to 18.1 ($MJ·kg^(-1)$ DM) and a calorific value ranging from 16.6 to 17.3 $MJ·kg^(-1)$ DM.

Badania dotyczyły pięciu zbiorowisk szuwarowych: Caricetum appropinquatae, Caricetum distichae, Caricetum ripariae, Caricetum rostratae i Caricetum vesicariae. Są to fitocenozy przyrodniczo cenne, o naturalnym lub półnaturalnym charakterze, spotykane w siedliskach silnie uwilgotnionych, zabagnianych, w strefie brzegowej rzek, starorzeczach, rowach melioracyjnych, a nawet zarastających oczkach wodnych. Wyróżnione zespoły występują na glebach o odczynie lekko kwaśnym lub kwaśnym, często pozbawione tlenu, o wysokim poziomie wód gruntowych zasobnych w azot. Materiały do badań zostały pobrane z naturalnych stanowisk z Wielkopolski, głównie z doliny Noteci Bystrej i strefy międzywala rzeki Warty wokół Rakowa, Trzebiszewa w okresach wegetacyjnych 2013, 2015 i 2016. Strukturalna zawartość węglowodanów wynosiła: celulozy 36,5–42,3%, ligniny 19,2–23,6% i holocelulozy 60,8–65%. Zawartość substancji ekstrakcyjnych wahała się od 5,2 do 6,4%. Wartość energetyczna biomasy zbiorowisk z dominacją turzyc jest bardzo wysoka, o czym świadczy ciepło spalania wynoszące od 17,6 do 18,1 $MJ·kg^(-1)$ s.m. i wartość opałowa od 16,6 do 17,3 $MJ·kg^(-1)$ s.m.