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At least 1,459 records · Page 81Linked to original sources
USGS2011

Chemical ecology of red mangroves, Rhizophora mangle, in the Hawaiian Islands

The coastal red mangrove, Rhizophora mangle L., was introduced to the Hawaiian Islands from Florida 100 yr ago and has spread to cover many shallow intertidal shorelines that once were unvegetated mudflats. We used a field survey approach to test whether mangroves at the land-ocean interface could indicate watershed inputs, especially whether measurements of leaf chemistry could identify coasts with high nutrient inputs and high mangrove productivities. During 2001-2002, we sampled mangroves on dry leeward coasts of southern Moloka'i and O'ahu for 14 leaf variables including stable carbon and nitrogen isotopes (delta 13 C, delta 15 N), macronutrients (C, N, P), trace elements (B, Mn, Fe, Cu, Zn), and cations (Na, Mg, K, Ca). A new modeling approach using leaf Na, N, P, and delta 13 C indicated two times higher productivity for mangroves in urban versus rural settings, with rural mangroves more limited by low N and P nutrients and high-nutrient urban mangroves more limited by freshwater inputs and salt stress. Leaf chemistry also helped identify other aspects of mangrove dynamics: especially leaf delta 15 N values helped identify groundwater N inputs, and a combination of strongly correlated variables (C, N, P, B, Cu, Mg, K, Ca) tracked the mangrove growth response to nutrient loading. Overall, the chemical marker approach is an efficient way to survey watershed forcing of mangrove forest dynamics.

Hawai'i↗
USGS1974

Shore zone land use and land cover: Central Atlantic Regional Ecological Test Site

Anderson's 1972 United States Geological Survey classification in modified form was applied to the barrier-island coastline within the CARETS region. High-altitude, color-infrared photography of December, 1972, and January, 1973, served as the primary data base in this study. The CARETS shore zone studied was divided into six distinct geographical regions; area percentages for each class in the modified Anderson classification are presented. Similarities and differences between regions are discussed within the framework of man's modification of these landscapes. The results of this study are presented as a series of 19 maps of land-use categories. Recommendations are made for a remote-sensing system for monitoring the CARETS shore zone within the context of the dynamics of the landscapes studied.

Natural Resources Report↗
USGS2001

A framework for ecological decision support systems: Building the right systems and building the systems right

Workshops in the late 1990's launched the commitment of the U.S. Geological Survey's Biological Resources Division (BRD) to develop and implement decision support systems (DSS) applications. One of the primary goals of this framework document is to provide sufficient background and information for Department of the Interior (DOI) bureau stakeholders and other clients to determine the potential for DSS development. Such an understanding can assist them in carrying out effective land planning and management practices. This document provides a definition of DSS and its characteristics and capabilities. It proceeds to describe issues related to meeting resource managers needs, such as the needs for specific applications, customer requirements, information and technology transfer, user support, and institutionalization. Using the decision process as a means to guide DSS development and determine users needs is also discussed. We conclude with information on method to evaluate DSS development efforts and recommended procedures for verification and validation.

Information and Technology Report↗
USGS2010

Hydrology and Ecology of Freshwater Wetlands in Central Florida - A Primer

Freshwater wetlands are an integral part of central Florida, where thousands are distributed across the landscape. However, their relatively small size and vast numbers challenge efforts to characterize them collectively as a statewide water resource. Wetlands are a dominant landscape feature in Florida; in 1996, an estimated 11.4 million acres of wetlands occupied 29 percent of the area of the State. Wetlands represent a greater percentage of the land surface in Florida than in any other state in the conterminous United States. Statewide, 90 percent of the total wetland area is freshwater wetlands and 10 percent is coastal wetlands. About 55 percent of the freshwater wetlands in Florida are forested, 25 percent are marshes and emergent wetlands, 18 percent are scrub-shrub wetlands, and the remaining 2 percent are freshwater ponds. Freshwater wetlands are distributed differently in central Florida than in other parts of the State. In the panhandle and in northern Florida, there are fewer isolated wetlands than in the central and southern parts of the State, and few of those wetlands are affected by activities such as groundwater withdrawals. In southern Florida, the vast wetlands of the Everglades and the Big Cypress Swamp blanket the landscape and form contiguous shallow expanses of water, which often exhibit slow but continuous flow toward the southwestern coast. In contrast, the wetlands of central Florida are relatively small, numerous, mostly isolated, and widely distributed. In many places, wetlands are flanked by uplands, generating a mosaic of contrasting environments-unique wildlife habitat often adjacent to dense human development. As the population of central Florida increases, the number of residents living near wetlands also increases. Living in close proximity to wetlands provides many Floridians with an increased awareness of nature and an opportunity to examine the relationship between people and wetlands. Specifically, these residents can observe how wetlands are affected by human activities. Freshwater wetlands are unique and complex ecosystems defined by characteristic properties. Wetlands usually have standing water during at least part of the year, although water depths can vary from a few inches to as much as several feet from one wetland to another. The hydrologic behavior of wetlands is influenced by drainage basin characteristics, as well as by natural variations in climate. Wetlands in central Florida (especially forested wetlands) often have acidic waters that are darkly stained from organic substances released by decomposing leaves and other plant material. Wetlands are characterized by biogeochemical cycles in which vital elements such as carbon, nitrogen, phosphorus, and others are transformed as they move between wetland soils and sediments, the open water, and the atmosphere. Wetlands are populated with plants that can thrive under conditions of saturated soils and low dissolved-oxygen concentrations. The bottoms of many wetlands, especially marshes, are covered with decayed plant material that can accumulate over time to form brown peat or black muck soils. Wetlands are inhabited by animals that need standing water to complete some or all of their life cycles, and they also provide periodic food, water, and shelter for many other animals that spend most of their lives on dry land. The complex and interrelated components of wetlands directly affect one another and there are numerous feedback mechanisms.

Circular↗
USGS2013

Challenge theme 1: Understanding and preserving ecological resources: Chapter 3 in United States-Mexican Borderlands: Facing tomorrow's challenges through USGS science

The notable biodiversity within the United States–Mexican border region is driven by the wide variety of natural landscapes in the area and its biologically unique transition zone of habitats for xeric, temperate, and subtropical species. Six diverse ecoregions cover the length of the border (fig. 3–1): California Coastal Sage, Chaparral, and Oak Woodlands; Sonoran Desert; Madrean Archipelago; Chihuahuan Desert; Southern Texas Plains; and Western Gulf Coastal Plain. The unique geology and many of the distinctive geographic features and climatic conditions that have given rise to the diverse populations of plants and animals found in the Borderlands also attract human populations. The number of people living in the Borderlands has increased dramatically over recent years, from about 7 million in 1980 to almost 12 million in 2003; the population is estimated to be more than 18 million by 2020 (Peach and Williams, 2003). The human population increase and associated change in land use have contributed to habitat fragmentation and habitat loss for native species, thus threatening their survival. Some ways in which humans negatively affect plants and animals in the Borderlands include dewatering of aquatic ecosystems, water pollution, introduction and spread of invasive species, outdoor lighting, military and border enforcement activity, and energy development and transmission.

United States-Mexico Borderlands↗
USGS1960

Ecological systems and the water resources

In ancient Sparta there were two principal classes of society, the citizen and the helot. The citizen was trained principally to be a warrior. The helot, a serf, was the tiller of the land but could be called to military duty. The history of Herodotus makes it amply clear that making war was the biggest business of the times. Because the Spartans were always marching off to war with someone, they found the landbound position of their city, located as its is in a small central basin nearly surrounded by mountains, somewhat of a disadvantage. When they were under attack, of course, this situation was a favorable one inasmuch as a seaborne enemy had to march inland to come to grips with the Lacedaemonians. The relatively small size of the independent states meant that the Spartans had no direct access through their own lands to the sea. There is evidence that the Spartans reached an agreement with surrounding states concerning a free corridor. There would be maintained by all the Grecian states of the Peloponnesus an access route stretching essentially from Sparta to Corinth, through which a marching army could have access to a seaport. As a secondary benefit, this no man's land, which in our western lingo might be called a stock driveway, allowed merchants and their caravans to move freely between the flourishing trading port of Corinth and the inland cities to the south and west. Apparently one portion of the agreement between the states with regard to the use of this access zone was that there should be no permanent agricultural or grazing in the driveway. As a result, through several centuries B.C. during which there was high population density in the Aegean area, one strip of land was exempted from the pressures of grazing, lumbering, and agriculture which characterized most of the rest of the landscape. Today this driveway maintains a forest cover. In contrast, mountainsides nearby with an even larger annual rainfall support hardly a tree. It is not entirely apparent why subsequent centuries did not see this area denuded. Even with the scanty details known to me it seems clear that the peculiar history of this one area potentially offers us a greater insight into some aspects of forest and land conditions of classical times than extant written records. The several references to sources of timber and cutting of forests contained in the vivid chronicle of Herodotus are valuable, but they lack species identification for the most part. Though rich in human understanding and psychological insight, his history strongly resembles the travel sagas of the Spanish Conquistadors of our Southwest, who had no real eye for "country." Even a careful reading of the works of early travelers such as Coronado, Garces, and Espejo, gives no picture of the nature of the country, its vegetation, or its rivers. To describe a biota there is no substitute for a sample. It is logical to ask what one might want to know which would require the preservation of a sample. Whether such a question is asked at all is a reflection on the stage of intellectual maturity of a civilization. We take for granted that there is social gain in the erection and maintenance of a museum of fine arts, a museum of natural history, or a historical museum. Sooner or later we should be mature enough to extend this concept to include a "museum" consisting of samples of land types as nearly as possible unaffected by man.

Circular↗
USGS2012

Bioclimatic predictors for supporting ecological applications in the conterminous United States

The U.S. Geological Survey (USGS) has developed climate indices, referred to as bioclimatic predictors, which highlight climate conditions best related to species physiology. A set of 20 bioclimatic predictors were developed as Geographic Information Systems (GIS) continuous raster surfaces for each year between 1895 and 2009. The Parameter-elevation Regression on Independent Slopes Model (PRISM) and down-scaled PRISM data, which included both averaged multi-year and averaged monthly climate summaries, was used to develop these multi-scale bioclimatic predictors. Bioclimatic predictors capture information about annual conditions (annual mean temperature, annual precipitation, annual range in temperature and precipitation), as well as seasonal mean climate conditions and intra-year seasonality (temperature of the coldest and warmest months, precipitation of the wettest and driest quarters). Examining climate over time is useful when quantifying the effects of climate changes on species' distributions for past, current, and forecasted scenarios. These data, which have not been readily available to scientists, can provide biologists and ecologists with relevant and multi-scaled climate data to augment research on the responses of species to changing climate conditions. The relationships established between species demographics and distributions with bioclimatic predictors can inform land managers of climatic effects on species during decisionmaking processes.

Data Series↗
USGS2000

Fire ecology in the southeastern United States

Fire has played an important role in the structure of natural ecosystems throughout North America. As a natural process, fire helps clear away dead and dying plant matter and increases the production of native species that occur in fire prone habitats. It also reduces the invasion of exotic species and the succession to woody species in pitcher plant bogs, pine savannas, coastal prairies, marshes, and other natural plant communities of the southeastern United States.

Fact Sheet↗
USGS2002

History and ecology of mangroves in the Dry Tortugas

Dry Tortugas National Park, which includes Bush, Long, Loggerhead, Garden, and Bird Keys, is a cluster of islands and coral reefs approximately 112.9 km (70 miles) west of Key West, Florida ( fig. 1 ). These islands were explored in 1513 by Ponce de León, who named them for the abundance of sea turtles, “tortugas,” and the lack of fresh water in the area. Historically, the Tortugas shoals have been valued as a military outpost, and the area is now additionally recognized as nesting grounds for diverse seabirds. The Dry Tortugas were declared a national treasure and bird sanctuary as early as 1908 and were incorporated into the National Park Service in 1935. These islands have been the setting for the U.S. Geological Survey’s National Wetlands Research Center (NWRC) research into mangroves and their relationship to bird life.

Florida↗
USGS2005

Roads and traffic: Effects on ecology and wildlife habitat use; applications for cooperative adaptive management

The land of the United States in dissected by more than 4 million miles of roads that fragment wildlife habitat on both public and private lands. Traffic on these roads causes additional effects. On secondary roads, which provide access to the most natural habitat, the levels, timing, and types of traffic are seldom known. In order to understand the effects of traffic on wildlife, USGS is conducting research cooperatively with the Bureau of Land Management, the U.S. Forest Service, the National Park Service, and the Colorado Division of Wildlife.

Colorado↗