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Caleb Grant
Geology, GIS
Interests: rocks
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Carbon dioxide and methane are natural compounds that occur as part of the carbon cycle. Methane concentration in the atmosphere has mostly increased from human influence by the production of black carbon. Carbon dioxide is an important yet potentially dangerous compound. It is consumed by plants via photosynthesis but also traps heat within the atmosphere. An imbalance of carbon dioxide and methane concentrations in the atmosphere can disrupt consummation rates as well as increase global temperature. Green carbon is stored in terrestrial ecosystems, blue carbon is stored in coastal ecosystems by carbon sequestration, and black carbon is generated by the burning of fossil fuels. These major sources of carbon are important to regulate as we look into the future. Too much carbon dioxide in the atmosphere can favor invasive plant species which would decrease community composition. For example; experiments on the Phragmite australis species show a response to increased carbon dioxide concentration. The Phragmites began rooting deeper into the soil then native plant species which increases resilience to change. Nitrogen concentrations have been increasing due to humans manufacturing massive amounts of nitrogen based fertilizers to apply in agricultural areas. Adding too much fertilizer can overload the soil nitrogen capacity where excess nitrogen is transported through runoffs or streams. Fertilizers are also favoring plant communities in these areas to species that can withstand this change. With Global Climate Change becoming more and more prominent, it is important to understand the interactions between carbon, nitrogen, methane, and invasive plant species because they all contribute to each other. If the conditions for one of these systems change, every other system will see an impact.
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1) The first section ‘Trophic ecology’ was packed with new information for me. Because I do not have much of an ecology background, the various information listed in this section provide me a better foundational knowledge of wetlands. Some of the facts that stood out to me are the impacts of beavers and waterfowl. I was unaware that beavers can consume up to 60% of wetland plant biomass. Beavers are known for creating dams but it never occurred to me the amount of resources needed to create one which can be devastating to surroundings. Also, Waterfowl species feed on a variety of aquatic plants and seeds which has the potential to impact the complexity or richness of a wetland. After reading this section, it is apparent that an abundance of one type of species can cause an imbalance in important wetland dynamics. In the section ‘Community ecology’, I enjoyed reading about edge effects or ecotones. At ecotones, species diversity is higher because this area contains species from both adjacent habitats. Wetland ecotones do not stay in the same position as wetlands and other land covers are constantly losing or gaining new land. 2) The two species I chose are muskrats and beavers. Muskrats can equally decimate a wetland as well as make it flourish. Muskrats are large rodents measuring about 60 cm in length. These rodents are herbivores and eat various plant species such as cattails and bulrushes. An abundance of muskrats can eliminate wetland plants. However, muskrat activity increases nitrogen mineralization and nitrification rates which can influence soil nitrogen dynamics. Beavers are the only organism capable of creating wetlands as they regulate the availability of resources to other species by causing changes in biotic or abiotic materials. Beavers create dams which causes a series of events to occur in that wetland. First, the channel behind the dam floods and turns into a pond. Trees and shrubs die off from becoming anoxic. As trees and shrubs die, the pond canopy opens allowing aquatic plants to form.
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1) Precipitation, groundwater discharge, and surface water inflows are all major water sources for wetlands. The location of a wetland determines the quantity and quality of water received. Wetlands that receive water via precipitation tend to be nutrient poor because of the lack of nutrients in rain (such as Carolina bays or pocosins). Wetlands that interact mainly with groundwater are more nutrient rich due to dissolved minerals from bedrock (such as fens). Wetlands that have major surface water inflows are also richer in nutrients because as water transports it picks up dissolved minerals or erodes bedrock which also has the potential to dissolve minerals. 2) Variable hydrologic conditions are critical for maintaining growing and germination conditions because plants are dependent on water fluctuation. Germination is only able to occur during dryer conditions so the plant is able to establish itself in the soil. However, in order to become a healthy plant community, a source of water must be present for nutrients. For example; In Carolina bays, rainfall is the main source of water therefore there must be times when rain is not present allowing for germination of new plants. 3) Previously, the idea of a ‘climax ecosystem’ was accepted by ecologists who believed plant communities had endpoints where these communities would essentially stop flourishing over time. Now we are supporting the idea of succession where plant communities go through transitional states due to changes in the environment. These transitions could be due to an increase or decrease in water input or a change in temperature. Transitions can cause plant communities to revert to previous characteristics or develop into a new community. 4) The process of ‘Hydrarch Succession’ is being debated by wetland scientist because there are still observations that support this process. Some terrestrial habitats occupy sites that previously were wetlands but that does not prove the transition occurred through autogenic processes. Furthermore, wetlands are rarely converted to a terrestrial ecotone. Generally, succession leads to a different type of wetland. 5) The C-S-R model describes the basic forces in structuring terrestrial plant communities. Competitor species have low reproduction and high growth rates due to being in an undisturbed habitat with plentiful resource availability. Stress-tolerant species have low reproduction as well as low growth rates occurring in undisturbed areas with less production resource availability. Rudetal species have high reproductively, fast growth rates, and short life spans occurring in disturbed and productive environments. 6) The concept of functional groups of plants, or guilds, is important in wetland construction or restoration because it helps match plant traits with the corresponding wetland system in order to effectively restore a certain wetland. 7) In prairie pothole wetlands, annuals have one year to distribute their seeds in the community and grow whereas perennials have multiple seasons to distribute seed and grow giving them a better chance to reproduce. Annual and perennial species are further broken down into seed or vegetative propagule groups according to longevity and availability of propagules. Reproducing by seed depends on the current water flux while vegetative propagules flourish in the changing environment. Persistent seed bank can create a wider window for proper reproduction conditions. Mudflats are better at regenerating than flooded areas due to some plants need for drawn-down conditions to germinate. 8) Purple loosestrife, Eurasian watermilfoil, reed canary grass, and hybrid cattail are all perennial forbs except the cattail which is a dicot. These invasive plants are usually found within wetland areas. 9) Nutrient enrichment has not benefited wetland plant communities as it has increased invasive species availability as well as decreased biodiversity due to nitrogen runoff or other human activity. 10) The difference between nutrients commonly limiting plant growth in terrestrial environments vs. freshwater wetlands is nitrogen. Wetlands that accumulate organic matter and nitrogen in soils are limited by nitrogen/phosphorus ratios.
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1) The general procedure used to study and quantify loss or gain of coastal wetlands is to randomly select 4 square mile sample plots and digital high-resolution imagery to identify change in wetlands. As a whole, we are losing wetlands at an alarming rate. Between 2004 and 2009, at least 360,000 acres of coastal watersheds have been lost. Losses of saltwater estuarine wetlands are high in areas such as the Gulf of Mexico where there is deep saltwater habitats. These new freshwater ponds are the result of urban development in the form of water detention ponds or ornamental ponds versus wetland reestablishment projects. The “no net loss” strategy does not seem to be effective because of the backed research stating both saltwater and freshwater have a net loss between 2004 and 2009. The creation or reestablishment of coastal wetlands is ineffective as the losses outweigh the gains in some coastal regions. 2) Human population density is changing coastal watersheds due to the amount of development in these coastal areas. From the construction of impervious or implementation of agriculture techniques, natural surfaces are disturbed which impacts water flow, pollution, and overall habitat. The nation’s fourth seacoast is recognizes as the Great Lakes system and corresponding channels and rivers that connect the world’s largest body of freshwater. Coastal wetlands are different in the Pacific coast because they are characterized by steep topographic relief between land and sea versus elsewhere in the US (such as the east coast) where the topography is not as pronounced. This is due to plate tectonics where the west coast is part of an active boundary while the east coast is part of a passive plate boundary. 5) ‘Simple changes’ has a slightly ambiguous meaning. This aerial photograph shows a snippet of an entire wetland ecosystem therefore it is important to understand that the changes at this scale are not necessarily prominent throughout the system. 7) The basic problem with loss of coastal wetlands to siviculture is that forest plantation complications can eliminate the site’s hydrology which, in turn, creates a net loss of wetlands. 8) The biggest causes of coastal wetland loss is due to urban development from an increasing population density along the coasts and a rising sea level from the melting of polar ice caps.
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1) The oxidized soil layer is a thin layer that sits above the reduced soil layer, it is critical for chemical reactions and nutrient cycles that occur in wetlands. The oxidized soil layer contains ions such as Fe3+, Mn4+, NO3-, and SO42-. The reduced soil layer does not contain these oxidized ions and can be distinguished by a bluish-gray to greenish-grey color from Fe2+ versus the brownish-red color of the oxidized layer. 2) The nitrogen cycle is important in wetlands because nitrogen is a limiting nutrient in flooded soils. Nitrates are the ‘go-to’ electron acceptor after the disappearance of oxygen in soil which is important in the oxidation of organic matter. Also, microbial denitrification allows the production and releasing of N2O which is a greenhouse gas that can influence global warming. 3) Swamp gas/methane is released into the atmosphere when sediments are disturbed which mostly occurs in nonflooded wetlands. Methane production is high in these areas and is converted by methanotropic bacteria back into CO2. Swamp gas is a greenhouse gas which directly affects global warming but is a natural part of the wetland carbon cycle. 4) Nutrient cycling in wetlands occurs in sediment and peat as wetlands strongly depend on soil quality to thrive. Nutrient cycling in deepwater aquatic habitats occur in the water column as that is where autotrophic activity is dependent. 5) Even though playa evaporation rates are high, water does percolate though the soil which helps balance the surface’s salinity. Water is able to percolate through the soil because underlying limestone or ‘caliche’ has been dissolved from carbonic acid. You do not see muskrats in playa lakes because there are no water corridors available for them to migrate to other wetlands. Playas are important to waterfowl because of their diverse vegetation that can provide habitat for a variety of waterfowl.
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Understanding the fundamentals of wetland hydrology is important for wetland managers and conservationists because when you break down the distribution of Earth’s water, only 3% is considered fresh or consumable. Since humans and wetlands depend on fresh water, it is important that that we understand what happens to that water. In the current world, water is a hot topic when considering the number of people (and organisms) that need it to live. At the rate we pump water for agricultural irrigation, ground water supplies are unable to refill fast enough to meet our demand. Knowing that, we must understand the effects that directly correlate to our groundwater supplies. Wetlands are a very important part of the hydrologic cycle as they reintroduce quality H2O back into groundwater and aquifer systems. Wetlands are essentially a ‘filter’ for water in a couple different ways. As water moves through wetlands, biota remove and/or change the chemical composition of the water by either adding nutrients or altering the pH level. Also, as water percolates through soil and underlying bedrock, particles continue to filter out – the rate at which water percolates is directly proportional to the rate at which particles are filtered out. Irrigation techniques have become a huge problem in the current world because of the volume of pesticides, herbicides, and fertilizers being used. These chemicals contain harsh elements such as ammonia, urea, formaldehyde, and sulfur which are very difficult to filter out – especially in the quantity we use them. These chemicals are easily transported by rain which leads them back into our water. Understanding wetland hydrology is important for the future of global climate change because as the temperature gradually rises, wetland behavior will change. For example: certain plant species are susceptible to temperature change and will not be able to thrive. Also, drought will become more prominent in areas, therefore; water will have a harder time attracting to those areas since wetlands behave like a sponge. Natural water cycles and hydroperiods are being altered majorly by humans. Impervious surfaces in urbanized areas create kinks in the hydrologic cycle as water is unable to freely percolate back into the groundwater supply. Instead, water is manually relocated to runoffs which devastates those areas by creating deeper water levels and faster moving currents. Because of this, hydroperiods in these wetlands can become inconsistent due to the imbalance of inflows and outflows.
Toggle Commented Sep 22, 2015 on Unit 4 - Hydrology at Wetland Ecology & Management
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From the article “Response of aquatic plants to abiotic factors: a review”, adaptions that can occur for aquatic plants are: pressurized tissue systems, minimal oxygen for root growth, compaction of leaves, CAM photosynthesis and metabolism, aerenchyma, areal roots, growing in less light and lower temperatures, and anchorage. Key challenges that might happen to aquatic plants in response to climate change are dealing with temperature changes and an increase in global atmospheric CO2 which could increase the growth rate of macrophytes. Mudflat annuals or drawdown species are terrestrial species only found when wetlands do not have any standing water. The author suggests that wetlands with longer wet-dry cycles tend to have higher floral and faunal diversity because wetlands are generally always wet which creates a fit environment for wildlife and plant growth. For example fish species are able to habit the area for a longer period before the cycle restarts. Hydrological studies reveal that prairie wetlands commonly have ground and surface water connections because aerial photos are unable to see water that is not immediately above the surface even though water is able to flow through soil and underlying beds within the wetlands. Experimental studies of wetlands in MERP suggest that prolonged water for two years will eliminate emergent species.
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1) The cosmic origin hypothesis for the formation of Carolina Bays does not seem plausible to me. From the evidence of perfect dimension ratios, bay thickness, soil composition, and lack of impact features; I do not believe Carolina Bays were formed from cosmic activity. Meteor impacts would leave evidence throughout the area such as mineral recrystallization and regional deformation. Glacier activity seems like a more reasonable hypothesis, however; I would not expect to see isolated groves that are characteristic of Carolina Bays. The new information gives me a new perspective as I have never studied Carolina Bays. I am intrigued by the fact that scientists are not in agreement with the formation of these wetlands. Initially, I figured these formations could easily be studied and correlated since there are thousands, but this proves to be another barrier. Understanding the geologic origins and geomorphology of wetlands is critical for fully understanding the processes that take place. For example: permeability of underlying beds directly impacts the behavior of overlying fluids. Or, the amount of water in soils varies the rate of change in organic matter decomposition. 2) The term isolated in the legal ruling of an isolated wetland is causing concern among wetland scientists and conservationists because ‘isolated’ is “not a precise scientific term” according to Johnson (2001). Furthermore, “an isolated wetland refers to a wetland that does not have downstream connection to rivers and bays” (Johnson, 2001). Because the court ruling states the previous, they are assuming pocosins are hydrologically isolated when in reality, this cannot be true considering all aspects of water movement. 3) The primary driver of the hydrology of Carolina Bay wetlands is rainfall and evapotranspiration. 4) The basal area of the conifer, Pondcypress generally seems to be greater in medium-depth swamps because the growth rate is related to organic matter depth. Medium-depth swamps have deep organic matter which allows for Poncypress to flourish. 5) Fens in the Oregon Cascades are particularly susceptible to the predicted impacts of climate change because they are supplied by perched aquifers in glacial till instead of deeper regional aquifer systems. Therefore, the fens’ water supply is practically ‘unprotected’ in the sense that water can more readily evaporate. 6) Fens are critical for biodiversity conservation because they house the most diverse plant species as well as uncommon animals. It is important to keep these uncommon species thriving – which, in turn means it is important to keep fens thriving. Bogs are mossy wetlands low in oxygen that receive water mostly from rain and snow. Water in bogs is very acidic because decomposition happens slowly which helps form peat. Fens are bog-like wetlands that form when glaciers retreat. Fens are like bogs because they have peat deposits in them but are unlike bogs because some water comes from small streams and or groundwater thus the soil and water are richer in nutrients.
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Aug 30, 2015