Maciej Gąbka

Barley straw has been used around the world for decades as a simple, cost-effective and harmless phytoplankton growth inhibition method. Although the effect of this method on algal blooms is quite well depicted, it has not yet been tested what effect it has on submerged vascular plants and if it could be used to control the spread of alien macrophytes. In this study two highly invasive plant species: Cabomba caroliniana and Elodea nuttallii were exposed to different concentration of the barley straw extract (BSE) in laboratory conditions for a duration of four weeks. In the course of the investigations, responses of 8 traits associated with growth, biomass and chlorophyll concentration of specimens to three dosages (Low, Medium, High) of BSE corresponding to concentrations: 0.03, 0.30 and 1.50 ml l⁻¹ were analysed. The result showed that although dry mass and total length of the plants did not differ significantly between the test groups, increase in tillering and internodes number was observed for certain concentrations of the extract. This shows that if BSE has any effect on submerged macrophytes it is a positive one and thus the method is not suitable for invasive submerged aquatic plant control. Furthermore, it is recommended that before using barley straw for algae bloom control one should make sure that there are no alien aquatic submerged plants in the area that could benefit from such a treatment.

A critical revision of charophytes collected in Slovakia from 1887 up to present, based on herbaria specimens, provided us with the opportunity to compile an updated checklist and to revaluate their threat status in order to obtain the current red list of charophytes of Slovakia. The data obtained will fill the gap in knowledge about these macroscopic algae in Central Europe. The revised list of charophytes includes 19 representatives of three genera: Chara (11), Nitella (7), and Nitellopsis (1). Following the latest IUCN red-list categories and criteria (version 3.1) and using the modified category regionally extinct (RE), derived from the category extinct (EX), 36.8% of charophytes are classified as RE (Chara connivens, C. subspinosa (=rudis), Nitella capillaris, N. confervacea, N. flexilis, N. gracilis, and N. opaca); 21% as EN (endangered; Chara braunii, Nitella mucronata, N. syncarpa, and Nitellopsis obtusa); 21% as VU (vulnerable; Chara contraria, C. gymnophylla, C. hispida, and C. virgata); 10.6% as NT (near-threatened; Chara globularis, C. vulgaris); and 5.3% as CR (critically endangered; Chara canescens) species; finally, 5.3% species could not be assessed (DD; Chara aspera).

In this study, we are testing a proxy for red and far-red Sun-induced fluorescence (SIF) using an integrated fuzzy logic modelling approach, termed as SIF_fuzzy and SIF_fuzzy-APAR. The SIF emitted from the core of the photosynthesis and observed at the top-of-canopy is regulated by three major controlling factors: (1) light interception and absorption by canopy plant cover; (2) escape fraction of SIF photons (fesc); (3) light use efficiency and non-photochemical quenching (NPQ) processes. In our study, we proposed and validated a fuzzy logic modelling approach that uses different combinations of spectral vegetation indices (SVIs) reflecting such controlling factors to approximate the potential SIF signals at 760 nm and 687 nm. The HyPlant derived and field validated SVIs (i.e., SR, NDVI, EVI, NDVIre, PRI) have been processed through the membership transformation in the first stage, and in the next stage the membership transformed maps have been processed through the Fuzzy Gamma simulation to calculate the SIF_fuzzy. To test whether the inclusion of absorbed photosynthetic active radiation (APAR) increases the accuracy of the model, the SIF_fuzzy was multiplied by APAR (SIF_fuzzy-APAR). The agreement between the modelled SIF_fuzzy and actual SIF airborne retrievals expressed by R² ranged from 0.38 to 0.69 for SIF₇₆₀ and from 0.85 to 0.92 for SIF₆₈₇. The inclusion of APAR improved the R² value between SIF_fuzzy-APAR and actual SIF. This study showed, for the first time, that a diverse set of SVIs considered as proxies of different vegetation traits, such as biochemical, structural, and functional, can be successfully combined to work as a first-order proxy of SIF. The previous studies mainly included the far-red SIF whereas, in this study, we have also focused on red SIF along with far-red SIF. The analysis carried out at 1 m spatial resolution permits to better infer SIF behaviour at an ecosystem-relevant scale.

Peatlands are one of the most important ecosystems due to their biodiversity and abundant organic compounds; therefore, it is important to observe how different plant species in peatlands react to changing environmental conditions. Sphagnum spp. are the main component of peatlands and are considered as the creator of conditions favorable for carbon storage in the form of peat. Sphagnum angustifolium and Sphagnum fallax are taxonomically very close species. To examine their adaptability to climate change, we studied the morphology and pigment content of these two species from environmental manipulation sites in Poland, where the environment was continuously manipulated for temperature and precipitation. The warming of peat was induced by using infrared heaters, whereas total precipitation was reduced by a curtain that cuts the nighttime precipitation. Morphology of S. angustifolium stayed under climate manipulation relatively stable. However, the main morphological parameters of S. fallax were significantly affected by precipitation reduction. Thus, this study indicates S. angustifolium is better adapted in comparison to S. fallax for drier and warmer conditions.