[Adaptation of Suaeda salsa to water/sediment conditions and nitrogen input in tidal flat wetlands in the Yellow River Delta, China]

The application of Water-Sediment Regulation Project provides abundant freshwater for the Yellow River Delta, changes water and sediment condition, as well as brings lots of exogenous substances. Using orthogonal test with three factors and four levels, we examined the effects of water condition, sediment burial depth and exogenous nitrogen input on the growth of wetland plant, Suaeda salsa. The results showed that sediment burial had great effect on protein content and SOD activity. Nitrogen input had great effect on POD activity. CAT activity was not affected by sediment burial, nitrogen input and water depth. The water depth manipulation had significant effect on leaf, stem and total dry weight. With the increases of water depth, leaf, stem and total dry weight showed a decreasing trend, with the maximum values (25.70, 40.86, 69.73 g) at the 2 cm water depth. There was no effect of nitrogen input and sediment burial on dry weight. The results of range analysis showed that the effect of water depth on leaf, stem, root and total dry weight was great, and followed by nitrogen input and sediment burial, with an optimal combination of 2 cm water depth +12 cm sediment burial + 9 g·m^-2 nitrogen input. These findings suggested that water condition played a decisive role in affecting the growth of S. salsa. Consequently, more attention should be paid to the control of water depth in the process of water and sediment regulation.

[Effects of Sediment Burial and Exogenous Cd Input on Biomass Allocation and Antioxidative Enzyme Activities of Suaeda salsa in the Coastal Wetland of the Yellow River Delta]

The Yellow River Delta has been facing the threat of functional degradation during the recent years. The Water-Sediment Regulation Project not only supplements abundant freshwater, but also alters the sediment burial and heavy metal levels, which affects vegetation growth. Thus, we selected the pioneer species Suaeda salsa, to study the effects of different sediment burial depths (0, 3, 6, 12 cm) and exogenous Cd inputs (0, 0.5, 1.0, 1.5 mg·kg^-1) on biomass allocation and activities of antioxidative enzymes in the coastal wetlands of the Yellow River delta. The results showed that a shallow or moderate burial depth had a stimulatory effect on chlorophyll content, while an excessive burial depth inhibited the growth of Suaeda salsa and chlorophyll content. With increasing Cd input, chlorophyll content and dry mass decreased. At a lower Cd input and moderate burial depth, activities of CAT and SOD increased, and at high levels, SOD activities decreased, while activities of CAT at a 12 cm burial depth and 1.0 mg·kg^-1, 1.5 mg·kg^-1 Cd input were higher than those for the control (62.66% and 58.56%). CAT activities reached high values (15.76 U·mg^-1) at a high Cd input (1.5 mg·kg^-1) and burial depth (12 cm). Analysis of variance showed that Cd input had a significant effect on protein content, and CAT and SOD activities, and sediment burial depth had a significant effect on the protein content and SOD activities. Interaction between Cd input and sediment burial depth had a significant effect on CAT and SOD activities (P<0.05). These results demonstrated that sediment burial depth and Cd input had a great influence on the growth of Suaeda salsa, and to some extent, Suaeda salsa could change its biomass allocation and antioxidative enzyme activities to adapt to severe environments.

Effects of experimental sedimentation on the phenological dynamics and leaf traits of replanted mangroves at Gazi bay, Kenya

Sedimentation results in the creation of new mudflats for mangroves to colonize among other benefits. However, large sediment input in mangrove areas may be detrimental to these forests. The dynamics of phenological events of three mangrove tree species (Avicennia marina, Ceriops tagal, and Rhizophora mucronata) were evaluated under experimental sediment burial simulating sedimentation levels of 15, 30, and 45 cm.While there was generally no shift in timing of phenological events with sedimentation, the three mangrove tree species each responded differently to the treatments.Partially buried A. marina trees produced more leaves than the controls during the wet season and less during the dry season. Ceriops tagal on the other hand had higher leaf loss and low replacement rates in the partially buried trees during the first 6 months of the experiment but adapted with time, resulting in either equal or higher leaf emergence rates than the controls.Rhizophora mucronata maintained leaf emergence and loss patterns as the unaffected controls but had a higher fecundity and productivity in the 15-cm sedimentation level.The results suggest that under incidences of large sedimentation events (which could be witnessed as a result of climate change impacts coupled with anthropogenic disturbances), mangrove trees may capitalize on "advantages" associated with terrestrial sediment brought into the biotope, thus maintaining the pattern of phenological events.

Correlations of cave levels, stream terraces and planation surfaces along the River Mur-Timing of landscape evolution along the eastern margin of the Alps

The transition zone of the Eastern Alps to the Pannonian Basin provides one of the best sources of information on landscape evolution of the Eastern Alpine mountain range. The region was non-glaciated during the entire Pleistocene. Thus, direct influence of glacial carving as a landscape forming process can be excluded and relics of landforms are preserved that date back to at least the Late Neogene. In this study, we provide a correlation between various planation surfaces across the orogen-basin transition. In particular, we use stream terraces, planation surfaces and cave levels that cover a vertical spread of some 700 m. Our correlation is used to show that both sides of the transition zone uplifted together starting at least about 5 Ma ago. For our correlation we use recently published terrestrial cosmogenic nuclide (TCN) burial ages from cave sediments, new optically stimulated luminescence (OSL) ages of a stream terrace and U-Th ages from speleothems. Minimum age constraints of cave levels from burial ages of cave sediments covering the last ~ 4 Ma are used to place age constraints on surface features by parallelizing cave levels with planation surfaces. The OSL results for the top section of the type locality of the Helfbrunn terrace suggest an Early Würm development (80.5 ± 3.7 to 68.7 ± 4.0 ka). The terrace origin as a penultimate gravel deposit (in classical Alpine terminology Riss) is therefore questioned. U-series speleothem ages from caves nearby indicate formation during Marine Isotope Stages (MIS) 5c and 5a which are both interstadial warm periods. As OSL ages from the terrace also show a time of deposition during MIS 5a ending at the MIS 5/4 transition, this supports the idea of temperate climatic conditions at the time of deposition. In general, tectonic activity is interpreted to be the main driving force for the formation and evolution of these landforms, whilst climate change is suggested to be of minor importance. Obvious hiatuses in Miocene to Pleistocene sediments are related to ongoing erosion and re-excavation of an uplifting and rejuvenating landscape.