The Tisza River Basin is an important area as it is a green corridor in which there are highly endangered habitats and a high level of biodiversity. The patterns in the species richness of invertebrates and the environmental conditions affecting these patterns are poorly studied in the grassy habitats in the lower reaches of the Tisza River Basin. The present study focuses on the effects of flooding, habitat and landscape features on the species richness of orthopterans at 24 grassland sites in two different landscapes. The relations between the explanatory variables and the pattern of diversity of orthopterans with different life-history traits were studied, using ordination and Generalized Linear Mixed Models. Although the influential factors for the different trait groups differed, we suggest that landscape features are the most important in shaping orthopteran assemblages, whereas habitat characteristics and flooding have comparatively little effect. Habitat characteristics affected only the non-xerophilous and Ensifera species and only the species richness of non-xerophilous orthopterans in flooded and non-flooded sites differed. We emphasize that even in countries where there are still considerable areas of high value natural grasslands, such as Hungary, non-protected meadows, linear grassy habitats (dikes, ditch banks, road verges, etc.) need more attention and should be given higher priority in the conservation of invertebrates., Attila Torma, Miklós Bozsó., and Obsahuje bibliografii
The distribution of Alisma gramineum in the Czech Republic was determined using herbarium specimens, data in the literature and the authors’ own records. Comparison of records from four periods (before 1900, 1901–1945, 1946–1970, 1971–2001) revealed that the total number of localities has not decreased, but the occurrence changed considerably both in terms of the localities and regions where the species is found. Abundant populations were observed on exposed shores of water reservoirs. It has colonized the Třeboň Basin, S Bohemia, over the last few decades. Effect of water regime, light/darkness regime and temperature on germination and dormancy was studied. A. gramineum is adapted to germinate in water and in the dark; germination occurs in late spring, i.e. a period of high temperature. The high variation in the germination response to particular environmental factors may be accounted for the irregular occurrence of A. gramineum at certain localities. Best conditions for seed production are shallow water and recently exposed shores of water reservoirs, where plants can grow and set seed within one growing season. The ability to survive in a vegetative stage is more important in deep water, but seed banks in the mud at the bottom of reservoirs is the only way the species can persist when adult plants die.
Periodic flooding of trees in tropical floodplains and reservoirs where water levels fluctuate is a common phenomenon. The effects of flooding and subsequent recovery on gas exchange, chlorophyll fluorescence and growth responses of Melaleuca alternifolia seedlings, a tall shrub species used in floodplain and reservoir forest restoration in southern China, were studied during a grow season (from March to December in 2007). M. alternifolia seedlings were flooded for 180 days, drained and left to recover for another 60 days. Survival rates of the seedlings were 100% during the 180-day flooding period. Chlorophyll (Chl) content, net photosynthetic rate
(PN), stomatal conductance (gs), and transpiration rate (E) of the flooded seedlings were all significantly lower than those of the control. Significant reductions of photochemical quenching coefficient (qp) and increases of nonphotochemical quenching (NPQ) in the flooded seedlings were observed. However, there were no significant differences in the maximal quantum yield of PSII photochemistry (Fv/Fm) between treatments. All seedlings survived during the two-month recovery period after the flooded treatment was drained, and the biomass and height of the recovered seedlings approached those of the control at the end of the experiment. During the first-month recovery period, Chl content, PN, gs and E in the recovered seedlings were all obviously low, then increased gradually and rose to the levels similar to the control by the end of the experiment. Quenching analysis revealed significant reductions of qp and increments of NPQ in the recovered seedlings at the beginning of draining, and a nearly complete recovery for both parameters by the end of the experiment. However, Fv/Fm of the recovered seedlings did not differ significantly from the control during the recovery period. Our study demonstrated that M. alternifolia seedlings can survive and grow through 180 days of flooding with a subsequent 60-day recovery period in drained conditions, indicating that seedlings of this species would be suitable for afforestation in areas exposed to intermittent flooding. and Y. X. Ying ... [et al.].
We quantified the physiological responses of black willow to four soil moisture regimes: no flooding (control, C), continuous flooding (CF), periodic flooding (PF), and periodic drought (PD). Stomatal limitation was one of the factors that led to the reduced photosynthetic capacity in CF cuttings. Under PD, stomatal closure, decreased leaf chlorophyll content, and increased dark fluorescence yield contributed to photosynthetic decline. CF cuttings accumulated the lowest shoot biomass while the final height and root growth were most adversely affected by PD. PF cuttings tended to allocate more photoassimilates to root growth than to shoots. and S. Li ... [et al.].
Field and laboratory experiments were conducted to assess the time ground beetles (Coleoptera: Carabidae) survive during actual and simulated flood conditions. The effects of three variants of potential flood conditions were tested: (1) beetles trapped on the surface of flood water; (2) beetles trapped in air pockets; (3) submersion of beetles in flood water without access to air. Ground beetles trapped on the surface of water survived more than two weeks (Carabus granulatus – up to 16 days; Oxypselaphus obscurus – up to 22 days). Carabus granulatus in simulated hibernation chambers that had air-pockets also survived for 15 days. The time for which ground beetles submerged without access to air survived differed significantly among species and was affected by season. They survived longest in mid-spring and late-autumn when water temperature is low. In mid-spring, survival times for C. granulatus and Platynus assimilis were 12 days and 9 days, respectively. During late summer and early autumn all species survived for a shorter period of time. In August, at least half of the individuals tested were dead after three days of immersion (water temperature 16–18°C). Removal of both of the elytra of adult of C. granulatus resulted in them surviving immersion for a shorter period, which indicates that air stored in the sub-elytral cavity is used to prolong the period they can survive immersion. The results of these experiments broaden the knowledge of how adult beetles survive seasonal flooding and are able to persist in floodplain habitats., Felix N. Kolesnikov, Arevik N. Karamyan, W. Wyatt Hoback., and Obsahuje seznam literatury
We studied the effect of flooding on a carabid community inhabiting grassland in a large river valley (W Poland). We used pitfall-traps to catch beetles from April to November 1999–2001. Some of the samples collected were preceded by floods during the collecting period, which enabled us to evaluate the effects of flooding on species composition and abundance. We collected 17,722 individuals belonging to 108 species. The number of species and individuals per sample differed between plots and showed a nonlinear decrease over time, from spring to autumn. Carabids were more abundant in samples collected after floods than in the control samples. In contrast, the expected cumulative number of species as a function of the number of individuals collected was lower in samples collected after floods than in the control samples. In the case of the most abundant species the species-specific responses in terms of the numbers caught after flooding differed, with those of (e.g. Agonum micans) increasing and those of (Amara plebeja, Epaphius secalis) decreasing. This study shows that floods filter the community with the result that some species increase in abundance but the overall species richness decreases. Therefore natural floods are important in shaping the structure of communities of epigeic carabids on floodplains., Pawel Sienkiewicz, Michal Zmihorski., and Obsahuje seznam literatury
Previous work suggests that submergence of Lycaena dispar larvae during overwintering may play a significant role in this butterfly's population dynamics. Since potential re-introduction sites in eastern England are prone to regular seasonal flooding, we further studied the species' submergence tolerance with a view to formulating management protocols conducive to larval survivorship under periodic flood conditions. Simulated flooding regimes using captive-reared larvae showed that enforced submergence has a twofold effect: firstly, a direct increase in mortality after 28 days under water and, secondly, a longer term, post-diapause increase in mortality; manifest either as an inability of larvae to resume feeding, or a failure to complete development. Additionally, there was a marked difference in the response of "early" and "late" diapause larvae; the latter generally succumbing after shorter periods under water, and suffering higher total mortalities. Behavioural investigations suggest that, if afforded the opportunity, diapausing larvae can evade submergence by climbing onto the exposed sections of partially flooded host plants. Significantly, survival on partially flooded plants was found to be comparable to that on unflooded controls. Further re-introductions of L. dispar in the U.K. will probably necessitate a direct translocation of wild Dutch stock. As the flood tolerance of this source population remains largely undetermined, and given that re-introduction site hydrology will be generally unamenable to conservation-oriented manipulation, it is recommended that restoration management be directed towards creating structural diversity in the vegetation of overwintering habitats, thereby providing potential "flood refugia" for hibernating larvae.