Sex allocation in Carex (Cyperaceae): effects of light, water, and nutrients

2007 ◽  
Vol 85 (4) ◽  
pp. 377-384 ◽  
Author(s):  
Robert I. Bertin
Keyword(s):  
Sex Allocation ◽  
High Water ◽  
Sex Expression ◽  
Water Levels ◽  
Female Function ◽  
Light Levels ◽  
The Face ◽  
Part Selection ◽  
Selection For ◽  
Female Flowers

Sedges of the genus Carex L. are mostly wind-pollinated, self-compatible, monoecious herbs in which female flowers are receptive before pollen is released (protogyny). One hypothesis was examined for the adaptive importance of the monoecious sexual system, namely that having two flower types permits flexibility in allocation of resources to male and female reproductive functions in the face of changing environmental conditions. Fourteen greenhouse experiments were conducted on a total of six Carex species in which I manipulated one or more of three environmental variables: nutrients, water, and light. These variables had small effects on the proportion of female flowers, though the effects were significant for at least one variable in 8 of the 14 experiments. High nutrient and light levels were generally associated with increased femaleness, while high water levels were associated with increased maleness. Increased female allocation in response to enhanced resource availability has been demonstrated in many species and is thought to reflect the greater potential fitness gains via the female function than via the male function when resources are plentiful. The opposite effects of water are anomalous and contrary to results in the literature. Because the effects of environmental manipulations on sex allocation are modest, the evolution and maintenance of monoecy in sedges probably reflect advantages other than flexible sex expression, at least in part. Selection for avoidance of self-pollination may have been particularly important in favoring the combination of protogyny and monoecy in Carex.

Das waldreiche obere Theresiental (Transkarpatien, Ukraine) – geografisch-ökologische und sozioökonomische Beschreibung | The forest-rich upper Theresian Valley (Transcarpathia, Ukraine): a geographic-ecological and socio-economical description

2007 ◽  
Vol 158 (1-2) ◽  
pp. 14-21
Author(s):  
Vasyl Sabadosh ◽  
Oleg Suprunenko
Keyword(s):  
Forest Management ◽  
High Water ◽  
The State ◽  
Water Levels ◽  
Private Companies ◽  
Foreign Investors ◽  
Wood Processing ◽  
Job Opportunities ◽  
Orange Revolution

The upper Theresian Valley lies along the southwest-facing ridge of the Ukrainian Carpathians. Despite expansive forestation high water levels are frequent. The forest belongs to the state and is centrally administrated. Felling is sometimes outsourced to private companies and private companies have also been founded to process the timber. Job opportunities have become fewer and illegal work is increasing. A new democratic awareness has emerged since the «Orange Revolution» in 2004. With foreign investors, however, new risks emerge. The authors recommend giving monies from forest management to the communities, the founding of new wood processing enterprises and more transparent information.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

scholarly journals Thioredoxin-dependent control balances the metabolic activities of tetrapyrrole biosynthesis

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Daniel Wittmann ◽  
Neha Sinha ◽  
Bernhard Grimm
Keyword(s):  
Environmental Changes ◽  
Nuclear Gene ◽  
Tetrapyrrole Biosynthesis ◽  
Nuclear Gene Expression ◽  
Light Levels ◽  
Organ Specific ◽  
Intracellular Compartments ◽  
The Face ◽  
Metabolic Activities ◽  
The Impact

AbstractPlastids are specialized organelles found in plants, which are endowed with their own genomes, and differ in many respects from the intracellular compartments of organisms belonging to other kingdoms of life. They differentiate into diverse, plant organ-specific variants, and are perhaps the most versatile organelles known. Chloroplasts are the green plastids in the leaves and stems of plants, whose primary function is photosynthesis. In response to environmental changes, chloroplasts use several mechanisms to coordinate their photosynthetic activities with nuclear gene expression and other metabolic pathways. Here, we focus on a redox-based regulatory network composed of thioredoxins (TRX) and TRX-like proteins. Among multiple redox-controlled metabolic activities in chloroplasts, tetrapyrrole biosynthesis is particularly rich in TRX-dependent enzymes. This review summarizes the effects of plastid-localized reductants on several enzymes of this pathway, which have been shown to undergo dithiol-disulfide transitions. We describe the impact of TRX-dependent control on the activity, stability and interactions of these enzymes, and assess its contribution to the provision of adequate supplies of metabolic intermediates in the face of diurnal and more rapid and transient changes in light levels and other environmental factors.

Performance of Light Coastal Structures Under Normal and High Water Conditions

1975 ◽  
Vol 2 (4) ◽  
pp. 381-391 ◽  
Author(s):  
J. W. Kamphuis
Keyword(s):  
Lake Erie ◽  
High Water ◽  
Water Levels ◽  
Coastal Protection ◽  
Coastal Structures ◽  
Water Conditions ◽  
Protection Structures

A number of lightweight coastal protection structures, built on the Lake Erie shore are discussed in this paper. There were two constraints on the design; limited funds and a very precarious downdrift beach. Thus the structures were inexpensive and the protection was low-key to prevent damage downdrift. In 1972–1974 these structures were subjected to a combination of large waves and high water levels and thus they were tested well beyond their design limits.The paper discusses the structures, their performance under normal conditions, and their performance during and after the abnormally high water levels. It is found that inexpensive, low-key structures are sufficiently strong to survive normal conditions, but fail by overtopping and flanking under conditions beyond their low design limits.

Supreme Scooper

1998 ◽  
Vol 74 (4) ◽  
pp. 511-513
Author(s):  
Tom Appleton
Keyword(s):  
High Water ◽  
Initial Attack ◽  
Water Capacity ◽  
The Earth ◽  
The Face ◽  
The Way

Canadair's CL-415 amphibious aircraft is arguably the most advanced firefighting waterbomber on the face of the earth. With its high water capacity and advanced performance, it leads the way in rapid initial attack to contain fires.

scholarly journals PRE- and POST-STORM LiDAR SURVEYS FOR ASSESSMENT OF IMPACT ON COASTAL EROSION

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 261-266
Author(s):  
A.-L. Montreuil ◽  
M. Chen ◽  
A. Esquerré ◽  
R. Houthuys ◽  
R. Moelans ◽  
...  
Keyword(s):  
Management Practices ◽  
Morphological Changes ◽  
Storm Surges ◽  
High Water ◽  
Water Levels ◽  
Airborne Lidar ◽  
Coastline Change ◽  
The Mean ◽  
The Impact

<p><strong>Abstract.</strong> Sustainable management of the coastal resources requires a better understanding of the processes that drive coastline change. The coastline is a highly dynamic sea-terrestrial interface. It is affected by forcing factors such as water levels, waves, winds, and the highest and most severe changes occur during storm surges. Extreme storms are drivers responsible for rapid and sometimes dramatic changes of the coastline. The consequences of the impacts from these events entail a broad range of social, economic and natural resource considerations from threats to humans, infrastructure and habitats. This study investigates the impact of a severe storm on coastline response on a sandy multi-barred beach at the Belgian coast. Airborne LiDAR surveys acquired pre- and post-storm covering an area larger than 1 km<sup>2</sup> were analyzed and reproducible monitoring solutions adapted to assess beach morphological changes were applied. Results indicated that the coast retreated by a maximum of 14.7 m where the embryo dunes in front of the fixed dunes were vanished and the foredune undercut. Storm surge and wave attacks were probably the most energetic there. However, the response of the coastline proxies associated with the mean high water line (MHW) and dunetoe (DuneT) was spatially variable. Based on the extracted beach features, good correlations (r>0.73) were found between coastline, berm and inner intertidal bar morphology, while it was weak with the most seaward bars covered in the surveys. This highlights the role of the upper features on the beach to protect the coastline from storm erosion by reducing wave energy. The findings are of critical importance in improving our knowledge and forecasting of coastline response to storms, and also in its translation into management practices.</p>

scholarly journals Changes in composition of aquatic bird assemblages associated with changing in water levels in the Aquatic Terrestrial Transitional Zone of the Pantanal wetland Brazil

2020 ◽  
Vol 9 (10) ◽  
pp. e4479108555
Author(s):  
Josué Ribeiro da Silva Nunes ◽  
Carolina Joana da Silva ◽  
Solange Kimie Ikeda-Castrillon ◽  
Nilo Leal Sander
Keyword(s):  
Aquatic Macrophyte ◽  
Transitional Zone ◽  
High Water ◽  
Flood Pulse ◽  
Water Levels ◽  
Aquatic Birds ◽  
Mato Grosso ◽  
Paraguay River ◽  
The Difference ◽  
Pantanal Wetland

The Pantanal wetland Mato Grosso, Brazil is among the largest floodplains in the world, with a mosaic of different habitats and rich aquatic and terrestrial biota. The habitat mosaics are found in the Chacororé and Sinhá Mariana lake System. These parental lakes of the Cuiabá River, a left tributary of the Upper Paraguay River, are known for their aquatic productivity and scenic beauty. The characteristics of these lakes and their floodplains are showed through the difference between their waters, the diversity of the aquatic macrophytes communities, fish communities and aquatic birds. Our study looked at changes in limnological variables as well as diversity of aquatic birds, during high water or flooded phase; medium water or receding phase; and the low water or dry phase. We used a temporary small lagoon in the floodplain of this system as our study area. The flood pulse is the main ecological factor affecting the Pantanal; it modifies ecological process and species composition. The water depth decreases during the season, decreasing electrical conductivity, dissolved phosphate and nitrate, water transparency, dissolved oxygen and biomass of aquatic macrophyte; and increasing calcium, total phosphorus and total nitrogen. We also observed increase in species richness and abundance of aquatic birds during the receding phase. Results show that the number of species (density) of aquatic birds increased from 10 to 30 species and the numbers of individuals from 40 to 936. The maximum richness and abundance of aquatic birds was registered during the receding phase.

scholarly journals Combined measurements of Subglacial Water Pressure and Surface Velocity of Findelengletscher, Switzerland: Conclusions about Drainage System and Sliding Mechanism

1986 ◽  
Vol 32 (110) ◽  
pp. 101-119 ◽  
Author(s):  
Almut Iken ◽  
Robert A. Bindschadler
Keyword(s):  
Functional Relationship ◽  
Water Pressure ◽  
Drainage System ◽  
High Water ◽  
Water Levels ◽  
Surface Velocity ◽  
Glacier Surface ◽  
Measured Velocity ◽  
Sliding Mechanism ◽  
Velocity Variations

AbstractDuring the snow-melt season of 1982, basal water pressure was recorded in 11 bore holes communicating with the subglacial drainage system. In most of these holes the water levels were at approximately the same depth (around 70 m below surface). The large variations of water pressure, such as diurnal variations, were usually similar at different locations and in phase. In two instances of exceptionally high water pressure, however, systematic phase shifts were observed; a wave of high pressure travelled down-glacier with a velocity of approximately 100 m/h.The glacier-surface velocity was measured at four lines of stakes several times daily. The velocity variations correlated with variations in subglacial water pressure. The functional relationship of water pressure and velocity suggests that fluctuating bed separation was responsible for the velocity variations. The empirical functional relationship is compared to that of sliding over a perfectly lubricated sinusoidal bed. On the basis of the measured velocity-pressure relationship, this model predicts a reasonable value of bed roughness but too high a sliding velocity and unstable sliding at too low a water pressure. The main reason for this disagreement is probably the neglect of friction from debris in the sliding model.The measured water pressure was considerably higher than that predicted by the theory of steady flow through straight cylindrical channels near the glacier bed. Possible reasons are considered. The very large disagreement between measured and predicted pressure suggests that no straight cylindrical channels may have existed.

scholarly journals Role of intertidal wetlands for tidal and storm tide attenuation along a confined estuary: a model study

2015 ◽  
Vol 3 (5) ◽  
pp. 3181-3224 ◽  
Author(s):  
S. Smolders ◽  
Y. Plancke ◽  
S. Ides ◽  
P. Meire ◽  
S. Temmerman
Keyword(s):  
Surface Area ◽  
Wave Attenuation ◽  
Spring Tide ◽  
Storm Surges ◽  
High Water ◽  
Water Levels ◽  
Storm Tide ◽  
Flood Risks ◽  
Model Study

Abstract. Coastal lowlands and estuaries are subjected to increasing flood risks during storm surges due to global and regional changes. Tidal wetlands are increasingly valued as effective natural buffers for storm surges by dissipating wave energy and providing flood water storage. While previous studies focused on flood wave attenuation within and behind wetlands, this study focuses on the effects of estuarine wetland properties on the attenuation of a storm tide that propagates along the length of an estuary. Wetland properties including elevation, surface area, and location within the estuary were investigated using a numerical model of the Scheldt estuary (Belgium, SW Netherlands). For a spring tide lower wetland elevations result in more attenuation of high water levels along the estuary, while for a higher storm tide higher elevations provide more attenuation compared to lower wetland elevations. For spring and storm tide a arger wetland surface area results in a better attenuation along the estuary up to a threshold wetland size for which larger wetlands do not further contribute to more attenuation. Finally a wetland of the same size and elevation, but located more upstream in the estuary, can store a larger proportion of the local flood volume and therefore has a larger attenuating effect on upstream high water levels. With this paper we aim to contribute towards a better understanding and wider implementation of ecosystem-based adaptation to increasing estuarine flood risks associated with storms.

scholarly journals Partitioning CO<sub>2</sub> net ecosystem exchange fluxes on the microsite scale in the Lena River Delta, Siberia

2018 ◽  
Author(s):  
Tim Eckhardt ◽  
Christian Knoblauch ◽  
Lars Kutzbach ◽  
Gillian Simpson ◽  
Evgeny Abakumov ◽  
...  
Keyword(s):  
Water Table ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Arctic Tundra ◽  
High Water ◽  
Water Levels ◽  
River Delta ◽  
Lena River ◽  
Hydrological Conditions ◽  
Lena River Delta

Abstract. Arctic tundra ecosystems are currently facing rates of amplified climate change. This is critical as these ecosystems store significant amounts of carbon in their soils, which can be mineralized to CO2 and CH4 and released to the atmosphere. To understand how the CO2 net ecosystem exchange (NEE) fluxes will react to changing climatic conditions, it is necessary to understand the individual responses of the physiological processes contributing to CO2 NEE. Therefore, this study aimed: (i) to partition NEE fluxes at the soil-plant-atmosphere interface in an arctic tundra ecosystem; and (ii) to identify the main environmental drivers of these fluxes. Hereby, the NEE fluxes were partitioned into gross primary productivity (GPP) and ecosystem respiration (Reco) and further into autotrophic (RA) and heterotrophic respiration (RH). The study examined flux data collected during the growing season in 2015 using closed chamber measurements in a polygonal tundra landscape in the Lena River Delta, northeastern Siberia. The measured fluxes on the microscale (1 m–10 m) were used to model the NEE, GPP, Reco, RH, RA and net ecosystem production (NPP) over the growing season. Here, for the first time, the differing response of in situ measured RA and RH fluxes from permafrost-affected soils to hydrological conditions have been examined. It was shown that low RA fluxes are associated to a high water table, most likely due to the submersion of mosses, while an effect of water table fluctuations on RH fluxes was not observed. Furthermore, this work found the polygonal tundra in the Lena River Delta to be a sink for atmospheric CO2 during the growing season. Spatial heterogeneity was apparent with the net CO2 uptake at a wet, depressed polygon center being more than twice as high as that measured at a drier polygon rim. In addition to higher GPP fluxes, the differences in NEE between the two microsites were caused by lower Reco fluxes at the center compared to the rim. Here, the contrasting hydrological conditions caused the CO2 flux differences between the microsites, where high water levels lad to lower decomposition rates due to anoxic conditions.

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