Stand Level Co2 Flux Examination of Weed Species With Different Origin and Functional Groups

Abstract

Although the ecological attributes of many weed species are well-known, their ecophysiological relationsparticularly at stand levelare scarcely researched. Based on this the main objectives of our examination are to measure the stand level CO 2 flux (NEE) for 5 weed species generally widespread in Central Europe as well as to explore the dependence of NEE on air temperature, radiation and stand level evapotranspiration. The selected weed species represent archaeophyte and neophyte plants as well as different functional groups (C 3 , C 4 , therophytes and cryptophytes). The research covering an entire vegetation cycle of the weed species has been implemented ex situ in 15 patches of the Szent István University's Botanical Garden. Stands of the involved species showed really significant CO 2 uptake for months. This value is the multiple of what is indicated in literature regarding Central European herbaceous vegetation (e.g. grasslands)this fact can be one of the key factors leading to the success of this plant group. By comparing the average CO 2 fluxes of these five weed species in the entire vegetation period it can be concluded that the values of the two endemic species are almost completely identical exceeding the average values of non-endemic C 4 weed species. Furthermore, significant linear regression (P<0.05) has been observed between the net ecosystem CO 2 gas exchange of Ambrosia artemisiifolia and Chenopodium album and the values of stand level evapotranspiration.