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Caddo Lake, situated on the border of northeast Texas and northwest Louisiana, USA is a medium-sized lake dominated by stands of baldcypress (Taxodium distichum). A study of tree growth was initiated at Caddo Lake to address concerns about the health of the balcypress ecosystem. The lake has been subjected to several dramatic water-level changes over the past 200 years, including water-level stabilization...
Greentree reservoir (GTR) management is a common waterfowl habitat management technique used in both the northeastern and southeastern United States. However, this management technique is controversial because greentree reservoir management can cause changes in forest composition and structure. We studied the effects of GTR management at the Montezuma National Wildlife Refuge in central New York by...
A study was conducted under greenhouse conditions to examine the effects of various soil moisture regimes on black willow (Salix nigra) posts (cuttings). Five treatments representing a range of soil moisture regines, from continuous flooding to mild drought, were imposed separately. A well-watered, welldrained treatment served as the control. Leaf gas exchange (stomatal conductance and net photosynthesis),...
We examined the response of first year saltcedar (Tamarix ramosissima) and plains cottonwood (Populus deltoides subsp.monilifera) seedlings to flooding in fall (25 days) and spring (28 days) using potgrown plants (12–18 individuals/26.5-liter pot). Seedlings were initially counted in all pots prior to fall treatment. Survival was calculated as the proportion of seedlings in cach pot still alive following...
Lake Chicot, in south central Louisiana, USA, was created in 1943 by the impoundment of Chicot Bayou. Extensive establishment of woody seedlings occurred in the lake during a 1.5 year period, including the growing seasons of both 1986 and 1987, when the reservoir was drained for repair work on the dam. Study plots were established in September 1986 to document woody vegetation establishment and to...
Cogongrass (Imperata cylindrica), an invasive perennial introduced from Southeast Asia, is currently spreading throughout the southeastern United States from Florida to Louisiana. In the U.S., cogongrass is generally not considered a wetland species, although it’s range is expanding in regions with high wetland abundance. The objective of this study was to determine if excessive soil moisture might...
Ligustrum sinense (Chinese privet) is an introduced species in the United States. Dense stands of L. sinense are found in the understory in many bottomland forests in western Tennessee. The widespread abundance of this species is problematic because of the potential loss of valuable native bottomland species due to competition. Flooding has been proposed as a potential means of eradicating this species...
Zooplankton structure and dynamics were studied in a freshwater wetland subject to strong hydrologic fluctuations. This wetland underwent a six-year drought that terminated at the end of 1996. At that time, inundation area and water level increased, diminishing macrophyte cover in some cases and enhancing a continuing eutrophication problem. Sampling was performed monthly from January 1996 to December...
Because germination requirements of the exotic saltcedar (Tamarix ramosissima) and native cottonwood (Populus deltoides subsp. wislizenii) are similar, efforts to establish cottonwoods often result in concurrent establishment of saltcedars. We evaluated the success of fall flooding to reduce saltcedar seedling density in the Rio Grande floodplain of central New Mexico, USA. We also evaluated the effects...
Plant communities of tidal freshwater marshes fluctuate in composition seasonally and among years, but the influence of changes in hydrology on vegetation of these systems has not been examined. We investigated the effects of hydrology on vegetation of tidal freshwater marshes along the Patuxent River in Maryland, USA with a two-year field experiment, a one-year greenhouse experiment, and a seed-bank...
We characterized canopy disturbance patterns in a bottomland hardwood forest and identified linkages to tree species characteristics and interannual flooding patterns. We located 116 newly formed canopy gaps created by 136 gapmakers of 13 species. Over 83% of the gapmakers were snapped or uprooted (i.e., windthrow). The probability of any given gapmaker snapping or uprooting differed among years,...
Riparian forest ecosystems are important for their high productivity of biomass, their biodiversity, and ecological services including control of floods and erosion, removal of nutrients from agricultural runoff, alleviation of pollution effects, and as habitats for birds and mammals. Intermittent cycles of flooding by meandering streams followed by soil drainage are essential for regeneration, optimal...
Studies were undertaken on seeds of the summer annual mudflat species Ammannia coccinea and Rotala ramosior to determine the (1) effects of flooding during late autumn to late spring on dormancy break and (2) optimum temperature for dormancy break. At maturity in autumn, about 65–100% of the seeds of these species were dormant. Seeds of both species buried under flooded and under nonflooded conditions...
In riparian ecosystems, river flow is the dominant driver influencing ecological process and pattern, including the recruitment of riparian tree species. In a four-year field study (1997–2000) of seedling recruitment on sandbars in the Wisconsin River, I evaluated the hypothesis that the timing of seed dispersal and river flow interact to determine the annual composition of pioneer tree seedling cohorts...
Alnus maritima (seaside alder) occurs in wet or flooded soils on the Delmarva Peninsula (southern Delaware and adjacent counties of eastern Maryland, USA) and in small niches in Georgia and Oklahoma. Although some A. maritima exist in coastal estuaries, responses of the species to salt, and whether salt resistance depends on provenance of plant origin, are not known. We first compared salt injury...
It is well documented that Louisiana is experiencing wetland loss at rates greater than any other locale in the world. High rates of relative sea-level rise, a combination of eustatic sea-level rise and subsidence, is anticipated to compound this problem further in the future through increased flooding and encroachment of saline water into freshwater wetlands. The research presented in this paper...
Elevated CO2 generally stimulates C3-type photosynthesis, but it is unclear how an increase in CO2 assimilation will interact with other factors that influence plant growth. In wetlands, the response of plants to elevated CO2 will interact with soil saturation, particularly in forested wetlands where soil saturation is a strong regulator of plant productivity. We performed a four-month experiment...
Saxicolous lichen trimlines are relatively level and distinct transition zones found on bedrocklined shores. They occur as a result of disturbance to the rock lichen community, typically due to high water events. Trimlines can inform about previous high water conditions, and in conjunction with lichenometry, can be dated. In wetlands which fluctuate in water level, dated trimlines may be useful in...
The purpose of this experiment was to investigate the survival and biomass accumulation of wetland plant species under different water depths in controlled microcosms. In the greenhouse, two-weekold seedlings were randomly assigned to one of seven water-depth treatments (−6, −4, −2, 0, +2, +4, and +6 cm relative to the soil surface) and allowed to grow for six months. Species included five perennial...
We assessed short-term temporal and spatial variation of metal contents in the upper 100 cm sediment profile of intertidal marshes vegetated by common reed (Phragmites australis) along the Scheldt estuary in Belgium. The upper 0–100 cm sediment profile was sampled in three reedbeds at 56, 94, and 131 km from the river mouth. Sampling was repeated five times, at approximately two month intervals. Sediment...
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