Haldy (odvaly), které na Ostravsku vznikaly jako průvodní jev dolování černého uhlí v první polovině 20.stol, se již staly typickým krajinným prvkem této oblasti. Později zde byly snahy dolováním pozměněnou krajinu „uzdravit“ finančně nákladnými technickými rekultivacemi. Výstupy z našich studií prokázaly, že spontánní sukcese na nerekultivovaných haldách probíhá rychleji a společenstva bezobratlých jsou zde lépe strukturovaná. Navíc nerekultivované haldy podporují populace ochranářsky cenných druhů bezobratlých. Jednoznačně proto doporučujeme haldy ponechat spontánní sukcesi, před finančně náročnými technicky vedenými rekultivacemi., The spoil heaps in Ostrava were created during mining of black coal in the first half of the 20th century. Later, there were efforts to “heal” the landscape by technical reclamations, which are rather expensive. Our studies showed that spontaneous succession on non-reclaimed spoil heaps is faster then succession on their reclaimed counterparts. The communities of invertebrates on non-reclaimed spoil heaps are also more mature and contain rare species in comparison with the reclaimed ones., and Jiří Hodeček, Tomáš Kuras.
Giant rosettes are ones of the most striking features of the vegetation in the high tropical Andes, with Coespeletia moritziana reaching the highest altitudes up to 4,600 m a.s.l. Different from other giant rosettes, this species grows on rock outcrops with poorly developed soils and where water availability may be limited. Two questions are addressed in this study: How does this species respond in terms of water relations to maintain favorable gas-exchange conditions? Considering that adult plants rely on a water-reserving central pith, how do early stages respond to this environment’s extreme conditions? Water relations and gas-exchange studies were carried out on juveniles, intermediate and adult C. moritziana plants during wet and dry seasons in Páramo de Piedras Blancas at 4,200 m a.s.l. Adult plants maintained higher leaf water potentials (ΨL) during the wet season, however, no differences between stages were found for the dry season. Minimum dry season ΨL were never near the turgor loss point in any of the stages. Juveniles show a more strict stomatal control during the dry season to maintain a favorable water status. Net photosynthesis significantly decreased in intermediate and juvenile stages from wet to dry seasons. Our results suggest that
C. moritziana resists more extreme conditions compared to other Andean giant rosettes., F. Rada, A. Azócar, A. Rojas-Altuve., and Obsahuje bibliografii
Among various epiphytic ferns found in the Brazilian Atlantic Forest, we studied Vittaria lineata (L.) Smith (Polypodiopsida, Pteridaceae). Anatomical characterization of the leaf was carried out by light microscopy, fluorescence microscopy, and scanning electron microscopy. V. lineata possesses succulent leaves with two longitudinal furrows on the abaxial surface. We observed abundant stomata inside the furrows, glandular trichomes, paraphises, and sporangia. We examined malate concentrations in leaves, relative water content (RWC), photosynthetic pigments, and chlorophyll (Chl) a fluorescence in control, water-deficient, and abscisic acid (ABA)-treated plants. Plants subjected to drought stress (DS) and treated by exogenous ABA showed significant increase in the malate concentration, demonstrating nocturnal acidification. These findings suggest that V. lineata could change its mode of carbon fixation from C3 to the CAM pathway in response to drought. No significant changes in RWC were observed among treatments. Moreover, although plants subjected to stress treatments showed a significant decline in the contents of Chl a and b, the concentrations of carotenoids were stable. Photosynthetic parameters obtained from rapid light curves showed a significant decrease after DS and ABA treatments., B. D. Minardi, A. P. L. Voytena, M. Santos, Á. M. Randi., and Obsahuje bibliografii
Responses to drought were studied using two maize inbred lines (B76 and B106) and a commercial maize hybrid (Zea mays L. cv. Silver Queen) with differing resistance to abiotic stress. Maize seedlings were grown in pots in controlled environment chambers for 17 days and watering was withheld from one half the plants for an additional 11 days. On the final treatment date, leaf water potentials did not differ among genotypes and were -0.84 and -1.49 MPa in the water sufficient and insufficient treatments, respectively. Greater rates of CO2 assimilation were retained by the stress tolerant maize inbred line, B76, in comparison to the other two genotypes 11 days after watering was withheld. Rates of CO2 assimilation for all three genotypes were unaffected by decreasing the measurement O2 concentration from 21 to 2% (v/v). Activities of phosphoenolpyruvate carboxylase (PEPC), NADP-malic enzyme (NADP-ME), and NADP malate dehydrogenase were inhibited from 25 to 49% by the water deficiency treatment. Genotypic differences also were detected for the activities of NADP-ME and for PEPC. Changes of transcript abundance for the three C4 pathway enzymes also varied among watering treatments and genotypes. However, examples where transcripts decreased due to drought were associated with the two stress susceptible genotypes. The above results showed that enzymes in the C4 photosynthetic pathway were less inhibited by drought in stress tolerant compared to stress susceptible maize genotypes., R. Sicher, J. Bunce, J. Barnaby, B. Bailey., and Obsahuje bibliografii
Ostrov La Gomera je součástí Kanárského souostroví a patří k výjimečným místům ve světovém měřítku. Jde o jeden z nejstarších a nejmenších ostrovů souosroví s velmi pestrou a bohatou endemickou faunou. V článku představíme faunu nosatcovitých brouků (Curculionoidea), kteří nejsou zajímaví pouze svou obrovskou radiací v rámci nik, které využívají, ale také svými životními strategiemi., La Gomera is an island in the Canaries archipelago and an extraordinary location on a worldwide scale. It belongs among the oldest and smallest islands, with highly varied and rich endemic fauna. This article presents the local fauna of weevils (Curculionoidea). These beetles are of interest not only because of their enormous radiation within the niches they inhabit, but also due to their life strategies., and Filip Trnka.