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Research about Louisiana, Mississippi

Source-linked reports with geographic coverage including Louisiana, Mississippi.

25 records · Page 2Linked to original sources
USGS2003

Survival and growth of Atlantic white cedar plantings in Louisiana and Missisippi

Atlantic white cedar (cedar) is a native forest dominant in isolated areas throughout the Atlantic Coastal Plain and in a portion of the Gulf of Mexico Coastal Plain. Although the range of this species extends west to southern Mississippi, stands are uncommon in this area. In addition, most of the existing Mississippi stands are privately owned and afforded little long-term protection. To examine the feasibility of planting cedar at the western edge of its range and to determine if the species is a viable replacement for pine in wet areas, one-year-old seedlings were planted at three pine plantation sites in Louisiana and wildings at two bay-head locations in Mississippi. Overall, survival was high (87%), especially in the Louisiana sites, and after 10 growing seasons the trees averaged 5.3 m in height and 6.1 cm in diameter. This growth rate compared favorably with cypress and slash pine of other studies. The results of this study have shown that cedar can be a viable choice for restoration efforts or forest product plantings.

Louisiana, Mississippi↗
USGS2001

Nest survival of forest birds in the Mississippi Alluvial Valley

In the Mississippi Alluvial Valley, flood control has led to a drastic reduction in the area of forest habitat and altered the patchwork of forest cover types. Silvicultural management of the remaining fragmented forests has changed to reflect the altered hydrology of the forests, current economic conditions of the area, and demand for forest products. Because forest type and silvicultural management impact forest birds, differences in avian productivity within these forests directly impact bird conservation. To assist in conservation planning, we evaluated daily nest survival, nest predation rates, and brood parasitism rates of forest birds in relation to different forest cover types and silvicultural management strategies within this floodplain. Within bottomland hardwood forests, nest success of blue-gray gnatcatcher ( Polioptila caerulea , 13%), eastern towhee ( Pipilo erythrophthalmus , 28%), indigo bunting ( Passerina cyanea , 18%), northern cardinal ( Cardinalis cardinalis , 22%), and yellow-billed cuckoo ( Coccyzus americanus , 18%) did not differ from that within intensively managed cottonwood plantations. However, average daily survival of 542 open-cup nests of 19 bird species in bottomland hardwoods (0.9516 ± 0.0028, ∼27% nest success) was greater than that of 543 nests of 18 species in cottonwood plantations (0.9298 ± 0.0035, ∼15% nest success). Differences in daily nest survival rates likely resulted from a combination of differences in the predator community -- particularly fire ants ( Solenopsis invicta ) -- and a marked difference in species composition of birds breeding within these 2 forest types. At least 39% of nests in bottomland hardwood forests and 65% of nests in cottonwood plantations were depredated. Rates of parasitism by brown-headed cowbirds ( Molothrus ater ) were greater in managed cottonwoods (24%) than in bottomland hardwoods (9%). Nest success in planted cottonwood plantations for 18 species combined (∼14%), and for yellow-breasted chat ( Icteria virens , 7%), eastern towhee (14%), indigo bunting (14%), and northern cardinal (17%) did not differ from nest success in cottonwood plantations that were coppiced from root sprouts following pulpwood harvest. Within bottomland hardwood forests, uneven-aged group-selection timber harvest reduced the combined daily nest survival of all species from 0.958 to 0.938, which reduced nest success by about 14%. Specifically, timber harvest reduced nest success of species that nest in the forest midstory and canopy, such as Acadian flycatcher ( Empidonax virescens ), from 32% before harvest to 14% after harvest. Conversely, those species that nest primarily in the shrubby understory-such as northern cardinal-were not affected by timber harvest and maintained an overall nest success of about 33%. Thus, birds nesting in the understory of bottomland hardwood forests are not adversely impacted by selective timber harvest, but there is a short-term reduction in nest success for birds that nest in the canopy and midstory.

Louisiana, Mississippi↗
USGS1997

A structural equation model of plant species richness and its application to a coastal wetland

Studies of plant species richness have often emphasized the role of either community biomass (as an indicator of density effects) or abiotic factors. In this article we present a general model that simultaneously examines the relative importance of abiotic and density effects. General and specific models were developed to examine the importance of abiotic conditions, disturbance, and community biomass on plant species richness. Models were evaluated using structural equation modeling based on data from 190 plots across a coastal marsh landscape. The accepted model was found to explain 45% of the observed variation in richness, 75% of biomass, and 65% of light penetration. Model results indicate that abiotic conditions have both direct effects on the species pool and indirect effects on richness mediated through effects on biomass and shading. Effects of disturbance were found to be indirect via biomass. Strong density effects on richness were indicated by the results, and canopy light penetration was found to be a better predictor of richness than was biomass. Overall, it appears that richness in this coastal landscape is controlled in roughly equal proportions by abiotic influences on the species pool and density effects, with disturbance playing a lesser role. The structure of the general model presented should be applicable to a wide variety of herbaceous plant communities.

Louisiana, Mississippi↗
USGS1968

Stratigraphy and structure of the tatum salt dome area, southeastern Mississippi and northeastern Washington Parish, Louisiana

In the 3000-square-mile area of southeastern Mississippi and northeastern Washington Parish , Louisiana , which has Tatum dome in its center, rocks of known Jurassic to Recent age are more than 20,000 feet thick. They are underlain by an unknown thickness of Louann Salt of Jurassic (?) age. The age, thickness, and nature of the sedimentary rocks between the salt and the basement, as well as the character of the basement, are unknown. The salt in the northern half of the area has moved upward to shallow depths as diapirs in overlying rocks. Outside of the area of shallow-piercement domes there are more deeply seated domes, ridges, and anticlines that may be the result of vertical movement of the salt . The Wiggins anticline in the south and, southwest of it, an area dipping more steeply to the southwest probably were not affected by salt movement. Structural maps of four horizons and isopach maps of rocks in the three intervals between them give information about the sedimentary and structural history of the region since the end of Early Cretaceous time. The horizons contoured mark either unconformities or the upper boundaries of zones of fairly uniform structural history. The top of the Lower Cretaceous rocks dips generally to the west. Upper Cretaceous rocks dip to the west-southwest and thicken to the northeast. Pre-Miocene Tertiary rocks dip to the southwest and thicken to the northwest. Miocene and later rocks dip and thicken to the south-southwest. The structure of the older formations is considerably more irregular than that of the younger ones; domes, ridges, and basins that were conspicuous in the Early Cretaceous became less pronounced as younger sediments progressively covered them. Of the eight shallow-piercement domes with which the author is familiar, three are known to have penetrated Oligocene rocks; two, middle Eocene; one, lower Eocene; one, Upper Cretaceous; and one, Lower Cretaceous. Some movement has taken place at Tatum dome since the sandy, gravelly Citronelle Formation was laid down.

Louisiana, Mississippi↗