Browsing by Subject "wetlands"

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Ancient Maya wetland fields revealed under tropical forest canopy from laser scanning and multiproxy evidence
(National Academy of Sciences, 2019-10-22) Beach, Timothy; Luzzadder-Beach, Sheryl; Krause, Samantha; Guderjan, Tom; Valdez Jr., Fred; Fernandez-Diaz, Juan Carlos; Eshleman, Sara; Doyle, Colin
We report on a large area of ancient Maya wetland field systems in Belize, Central America, based on airborne lidar survey coupled with multiple proxies and radiocarbon dates that reveal ancient field uses and chronology. The lidar survey indicated four main areas of wetland complexes, including the Birds of Paradise wetland field complex that is five times larger than earlier remote and ground survey had indicated, and revealed a previously unknown wetland field complex that is even larger. The field systems date mainly to the Maya Late and Terminal Classic (∼1,400–1,000 y ago), but with evidence from as early as the Late Preclassic (∼1,800 y ago) and as late as the Early Postclassic (∼900 y ago). Previous study showed that these were polycultural systems that grew typical ancient Maya crops including maize, arrowroot, squash, avocado, and other fruits and harvested fauna. The wetland fields were active at a time of population expansion, landscape alteration, and droughts and could have been adaptations to all of these major shifts in Maya civilization. These wetland-farming systems add to the evidence for early and extensive human impacts on the global tropics. Broader evidence suggests a wide distribution of wetland agroecosystems across the Maya Lowlands and Americas, and we hypothesize the increase of atmospheric carbon dioxide and methane from burning, preparing, and maintaining these field systems contributed to the Early Anthropocene.
Ciénegas - Vanishing Climax Communities of the American Southwest
(Desert Plants, 1985) Hendrickson, Dean A.; Minckley, W.L.
The term is here applied to mid-elevation (1,000-2,000 m) wetlands characterized by permanently saturated, highly organic, reducing soils. A depauperate flora dominated by low sedges highly adapted to such soils characterizes these habitats. Progression to ciénega is dependent on a complex association of factors most likely found in headwater areas. Once achieved, the community appears stable and persistent since paleoecological data indicate long periods of ciénega conditions, with infrequent cycles of incision. We hypothesize the ciénega to be an aquatic climax community. Ciénegas and other marshland habitats have decreased greatly in Arizona in the past century. Cultural impacts have been diverse and not well documented. While factors such as grazing and streambed modifications contributed to their destruction, the role of climate must also be considered. Ciénega conditions could be restored at historic sites by provision of constant water supply and amelioration of catastrophic flooding events.
An Overview of Aridland Ciénagas, With Proposals for Their Classification, Restoration and Preservation
(2015-08) Cole, A.T.; Cole, Cinda
Ciénagas are the American Southwest’s most unusual wetlands, yet they are dwindling. This paper addresses what they are, their uniqueness and importance, how they developed, and the causes for the loss of most ciénaga habitat. We also propose a classification system for ciénagas that will contribute to a more meaningful and better-focused discussion about ciénagas, provide an inventory of known ciénagas, and suggest a system of Ciénaga Coordinators with the goal of identifying, restoring, and preserving the few remaining ciénagas. Finally, the inventory from this paper is made available online in an interactive, open, moderated format that will allow anyone to contribute to the correction, evolution, and general improvement and growth of this database, and to download and use the content. A link to this system can be found in a permanent archive of this paper at http://hdl.handle.net/2152/30285. The data from Appendix B of the paper archived here later prompted formation of the the North American Ciénegas Project (https://www.google.com/fusiontables/DataSource?docid=1n9Z5nJ7BXY0TLBbGjFYzFcRooMWCWK_AQDQVAV24), which hopes to involve a broad community of interested individuals and citizen scientists in further improving and increasing openly shared information about all aridland ciénegas of western North America.
Sedimentation and Historical Changes in Fluvial Deltaic Wetlands Along the Texas Gulf Coast with Emphasis on the Colorado and Trinity River Deltas
(1990) White, William Allen, 1939-; Calnan, Thomas R.
The most extensive losses in coastal wetlands in the United States over the last two decades have occurred along the Gulf Coast. Wetlands are disappearing at an alarming rate on the Mississippi River Deltaic Plain, indicating a reversal in the trend of net progradation of the delta that characterized much of the past 5,000 years (Gagliano and others, 1981). The land-loss rates have accelerated geometrically during the 20th century, apparently as a result of natural and artificial processes, the latter including artificial levees and control structures that have harnessed the Mississippi River and virtually eliminated the deltaic sedimentation processes of overbank flooding, crevassing, and upstream diversion; extensive canalization and accelerated subsidence related to mineral extraction compound the problem (Gagliano and others, 1981). Investigations of marsh losses in Louisiana indicate that marsh aggradation (vertical accretion) rates are not keeping pace with relative (apparent) sea-level rise (Delaune and others, 1983; Hatton and others, 1983; Baumann and others, 1984; Boesch and others, 1984). Although less extensive than in Louisiana, losses in wetlands along the Texas coast have also been documented (McGowen and Brewton, 1975; Gosselink and others, 1979; Johnston and Ader, 1983; White and others, 1984; 1985; 1987). Some of the most dramatic changes have occurred in fluvial-deltaic areas such as near the mouths of the San Jacinto and Neches Rivers where wetland losses totaled more than 4,000 hectares (10,000 acres) between the mid-1950s and the late 1970s (White and others, 1985; 1987). The losses are characterized by submergence and displacement of marshes, swamps, and fluvial woodlands by shallow subaqueous flats and open water, indicating, as in Louisiana, that marsh aggradation rates are not keeping pace with relative sea-level rise.
Sedimentation in Fluvial Deltaic Wetlands and Estuarine Areas, Texas Gulf Coast
(1989) White, William Allen, 1939-; Calnan, Thomas R.
Deltaic and associated riverine deposits near the mouths of rivers that discharge into estuaries along the Texas coast are the sites of extensive salt, brackish, and fresh-water marshes that are essential components of biologically productive estuarine systems. These bay-head depositional features are constructed primarily by fluvial sediments, sediments transported and deposited by the major rivers that enter estuarine waters. The loss of over 10,000 acres of wetlands in alluvial and deltaic areas of the Neches (White and others, 1987) and San Jacinto Rivers (White and others, 1985) emphasized the need to examine in more detail the processes that establish and maintain, as well as degrade, these important natural resources along the Texas coast.
Sedimentation in Fluvial Deltaic Wetlands and Estuarine Areas, Texas Gulf Coast - Summary
(1990) White, William Allen, 1939-; Calnan, Thomas R.
Deltaic and associated riverine deposits near the mouths of rivers that discharge into estuaries along the Texas coast are the sites of extensive salt-, brackish-, and freshwater marshes that are essential components of biologically productive estuarine systems. These bay-head depositional features are constructed primarily by fluvial sediments, sediments transported and deposited by the major rivers that enter estuarine waters. The loss of over 10,000 acres of wetlands in alluvial and deltaic areas of the Neches (White and others, 1987) and San Jacinto Rivers (White and others, 1985) emphasized the need to examine in more detail the processes that establish and maintain, as well as degrade, these important natural resources along the Texas coast.
Sedimentation in Fluvial Deltaic Wetlands and Estuarine Areas, Texas Gulf Coast -- Literature Synthesis
(1990) White, William Allen, 1939-; Calnan, Thomas R.
Deltaic and associated alluvial areas at the mouths of rivers that discharge into the bay-estuary-lagoon system along the Texas coast are the sites of extensive salt-, brackish-, and freshwater marshes that are essential components of these biologically productive estuarine systems. These bayhead depositional systems are constructed primarily by fluvial sediments, sediments transported and deposited by the major rivers that enter estuarine waters. The loss of over 10,000 acres of wetlands in alluvial and deltaic areas of the Neches (White and others, 1987) and San Jacinto Rivers (White and others, 1985) has emphasized the need to examine in more detail the processes that establish and maintain, as well as degrade, these important natural resources along the Texas coast.
Under the Forest Canopy: Prehispanic Wetland Agroecosystems in Global Context
(2020-01-24) Beach, Timothy
Wetlands Education Center - by The Reserve
(The University of Texas Marine Science Institute, 2015-07-07) Mission-Aransas National Estuarine Research Reserve
Wetlands Education Center Port Aransas, Texas Docent Manual
(The University of Texas Marine Science Institute, 2012-12-20) Mission-Aransas National Estuarine Research Reserve