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At least 1,351 records · Page 75Linked to original sources
USGS1999

Spatial geologic data model for the Gunnison, Grand Mesa, Uncompahgre National Forests mineral resource assessment area, southwestern Colorado and digital data for the Leadville, Montrose, Durango, and Colorado parts of the Grand Junction, Moab, and Cortez 1° x 2° geologic maps

The digital geologic and geographic information system (GIS) data presented here were prepared to aid in Grand Mesa, Uncompahgre, Gunnison National Forest (GMUG) mineral resource assessment Project studies by the U.S. Geological Survey Mineral Resource Program. The goals of the GMUG Project is to provide mineral resource data and an assessment for undiscovered mineral resources in U.S. Forest Service (USFS) and Bureau of Land Management (BLM) lands in southwestern Colorado. The Project area covers a large region in southwestern Colorado that is bounded by latitudes 37o 45’ to 39o 30’ north and longitudes 106o to 109o west. The study area is covered by all or parts of six 1o x2o topographic and quadrangle geologic maps, which include geologic maps for the Leadville (Tweto and others, 1978), Montrose (Tweto and others, 1976), Durango (Steven and others, 1974), Grand Junction (Cashion, 1973), Moab (Williams, 1976), and Cortez (Haynes and others, 1972) quadrangles. These geologic maps were used inasmuch as a complete remapping and compilation effort for this study area was beyond the scope of the Project.

Colorado↗
USGS1984

Wilderness mineral potential: Assessment of mineral-resource potential in U.S. Forest Service lands studied in 1964-1984: Volume 1

Under the provisions of the Wilderness Act (Public Law 88-577, September 3, 1964) and subsequent related legislation, the U.S. Geological Survey (USGS) and the U.S. Bureau of Mines (USBM) have been conducting mineral surveys of wilderness and primitive areas, and of other national forest lands being considered for wilderness designation. The Wilderness Act directs that the results of these surveys are to be made available to the public and are to be submitted to the President and the Congress. This professional paper is a synopsis of the mineral surveys made from 1965 to 1983. It summarizes our current knowledge of mineral and energy resources and of the potential for the occurrence of undiscovered mineral and energy resources in 45 million acres of Federal lands, chiefly in national forests. This book, in two volumes, consists of 332 summary articles, arranged alphabetically by State, in which the mineral-resource potential of about 800 individual areas is discussed. The summaries of the mineral surveys were written during 1982-83, generally by those who made the surveys. Index maps of each state show the location of the areas studied, numerically keyed to an alphabetic list. The national distribution of the wilderness lands studied is shown on the frontispiece. Where lands were in proximity or were added to expand previously designated areas, they often are described in a single article. Each article begins with a short summary of the results of the mineral survey followed by a discussion of the character and geologic setting of the area. Mineral resources (if any) are discussed, and the potential for undiscovered mineral resources is assessed; these are keyed to the generalized geographic and geologic map of each area Areas that have geologic characteristics indicative of different degrees of potential for the occurrence of mineral resources are shown in shades of red on each map. Some articles have a section on suggestions for further study to better define the mineral-resource potential of the area A list of pertinent references (including many of the maps and reports prepared during the mineral survey) is provided at the end of each article. This introduction contains some basic concepts about mineral resources and mineral-resource potential to try to make the book more useful to those who are not familiar with the fields of earth science and mineral-resource assessments. The legislation dealing with the wilderness program is reviewed briefly, because this evolving legislation has imparted a continuing and changing influence on the mineral-resource surveys. The introduction concludes with a description of the publications of the Geological Survey that report in greater detail the results of the joint wilderness studies by the Geological Survey and the Bureau of Mines.

Alabama, Alaska, Arizona, Arkansas, California, Co↗
USGS2006

Sediment coring and sedimentation analysis on Rasmussen Lake in Ethel's Woods Forest Preserve near Old Mill Creek, Illinois in 2005

The Lake County Forest Preserve District (LCFPD) is investigating the possibility of modifying the dam on Rasmussen Lake in Ethel's Woods Forest Preserve. The lake is of low water quality with an eroding shoreline. Sediments have been deposited in the impoundment over the last 50 years. Twenty-eight sediment sampling locations were identified along seven transects over a 51.4 acre area in Rasmussen Lake to determine sediment thickness and obtain sediment material for physical and chemical analyses. The maximum sediment thickness was consistently 3.0-4.5 feet (ft) from the dam to the upper end of the lake. The sediment thickness was less than 2.5 ft near the shore and in transect 5, near the northern part of the lake. Sediment thickness did not increase either in the upstream or downstream direction. The average-transect sediment thicknesses ranged from 1.8 to 2.7 ft. The approximate total sediment volume that has accumulated in the 51.4 acres of the lake over the past 50 years is 115.1 acre-feet.

Scientific Investigations Report↗
USGS2008

Substrate Geochemistry and Soil Development in Boreal Forest and Tundra Ecosystems in the Yukon-Tanana Upland and Seward Peninsula, Alaska

We report on soil development as a function of bedrock type and the presence of loess in two high latitude ecosystems (boreal forest and tundra) and from two regions in Alaska?the Yukon-Tanana Upland (YTU, east-central Alaska) and the Seward Peninsula (SP, far-west coastal Alaska). This approach to the study of 'cold soils' is fundamental to the quantification of regional geochemical landscape patterns. Of the five state factors in this study, bedrock and biota (ecosystem; vegetation zone) vary whereas climate (within each area) and topography are controlled. The influence of time is assumed to be controlled, as these soils are thousands of years old (late Quaternary to Holocene). The primary minerals in soils from YTU, developed over loess and crystalline bedrock (metamorphic and intrusive), are quartz, plagioclase, and 2:1 clays; whereas in the SP, where loess and metasedimentary bedrock (schist and quartzite) predominate, they are quartz and muscovite. The A horizon of both regions is rich in peat. Examination of the ratio of mobile (K2O, CaO, and Fe2O3) to immobile (TiO2) major oxides, within each region, shows that very little difference exists in the chemical weathering of soils developed between the two ecosystems examined. Differences were observed between tundra soils developed in the two regions. These differences are most probably due to the dissimilarity in the geochemical importance of both loess and bedrock. A minimal loss of cadmium with soil depth is seen for soils developed over YTU crystalline bedrock in the boreal forest environments. This trend is related to the mobility of cadmium in these soils as well as to its biogenic cycling. Major differences were observed in the proportion of cadmium and zinc among the A, B, and C horizon material sequestered in various soil fractions as measured by sequential soil extractions. These trends followed such variables as the decrease with depth in organic matter, the change in clay minerals, and the change in the proportion of oxides/hydroxides. An analysis of the bulk soil mineralogy and the relation between CaO and MgO and Al2O3 and Fe2O3 indicates that the silty textured soils of the YTU are predominantly eolian (that is, of late Tertiary or Quaternary age) but not broad-regional in origin. Their composition instead is probably the result of locally derived dusts as well as input from long-term, in-place bedrock weathering.

Scientific Investigations Report↗
USGS2009

Modeling Flood Plain Hydrology and Forest Productivity of Congaree Swamp, South Carolina

An ecological field and modeling study was conducted to examine the flood relations of backswamp forests and park trails of the flood plain portion of Congaree National Park, S.C. Continuous water level gages were distributed across the length and width of the flood plain portion - referred to as 'Congaree Swamp' - to facilitate understanding of the lag and peak flood coupling with stage of the Congaree River. A severe and prolonged drought at study start in 2001 extended into late 2002 before backswamp zones circulated floodwaters. Water levels were monitored at 10 gaging stations over a 4-year period from 2002 to 2006. Historical water level stage and discharge data from the Congaree River were digitized from published sources and U.S. Geological Survey (USGS) archives to obtain long-term daily averages for an upstream gage at Columbia, S.C., dating back to 1892. Elevation of ground surface was surveyed for all park trails, water level gages, and additional circuits of roads and boundaries. Rectified elevation data were interpolated into a digital elevation model of the park trail system. Regression models were applied to establish time lags and stage relations between gages at Columbia, S.C., and gages in the upper, middle, and lower reaches of the river and backswamp within the park. Flood relations among backswamp gages exhibited different retention and recession behavior between flood plain reaches with greater hydroperiod in the lower reach than those in the upper and middle reaches of the Congaree Swamp. A flood plain inundation model was developed from gage relations to predict critical river stages and potential inundation of hiking trails on a real-time basis and to forecast the 24-hour flood In addition, tree-ring analysis was used to evaluate the effects of flood events and flooding history on forest resources at Congaree National Park. Tree cores were collected from populations of loblolly pine (Pinus taeda), baldcypress (Taxodium distichum), water tupelo (Nyssa aquatica), green ash (Fraxinus pennslyvanica), laurel oak (Quercus laurifolia), swamp chestnut oak (Quercus michauxii), and sycamore (Plantanus occidentalis) within Congaree Swamp in highand low-elevation sites characteristic of shorter and longer flood duration and related to upriver flood controls and dam operation. Ring counts and dating indicated that all loblolly pine trees and nearly all baldcypress collections in this study are postsettlement recruits and old-growth cohorts, dating from 100 to 300 years in age. Most hardwood species and trees cored for age analysis were less than 100 years old, demonstrating robust growth and high site quality. Growth chronologies of loblolly pine and baldcypress exhibited positive and negative inflections over the last century that corresponded with climate history and residual effects of Hurricane Hugo in 1989. Stemwood production on average was less for trees and species on sites with longer flood retention and hydroperiod affected more by groundwater seepage and site elevation than river floods. Water level data provided evidence that stream regulation and operations of the Saluda Dam (post-1934) have actually increased the average daily water stage in the Congaree River. There was no difference in tree growth response by species or hydrogeomorphic setting to predam and postdam flood conditions and river stage. Climate-growth analysis showed that long-term growth variation is controlled more by spring/ summer temperatures in loblolly pine and by spring/summer precipitation in baldcypress than flooding history.

South Carolina↗
USGS2025

Random forest regression models for estimating low-streamflow statistics at ungaged locations in New York, excluding Long Island

This report is currently being updated with re‑calibrated random‑forest models for StreamStats implementation. The basin‑characteristic inputs were modified to align with StreamStats requirements. Abstract Models to estimate low-streamflow statistics at ungaged locations in New York, excluding Long Island and including hydrologically connected basins from bordering States, were developed for the first time by the U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation. A total of 224 basin characteristics were developed for 213 unaltered streamgages (locations where the human effects on streamflow were limited), across the following categories: basin geometry, climate, land cover, soils, surficial geology, and other characteristics. The basins with unaltered streamgages were evaluated for potential redundancy, and streamgages in close proximity and with similar drainage areas were flagged and removed from the testing and cross-validation datasets to prevent data leaking from the training dataset to the testing dataset. Random forest regression models were created by using basin characteristics as predictor variables and by developing a workflow to train, tune, and test the model. Models were developed to estimate the ungaged lowest annual 7-day and 30-day average streamflow that occurs (on average) once every 10 years (7Q10 and 30Q10). The top four basin characteristics used for the 7Q10 and 30Q10 models were drainage area, total stream length, perimeter of the basin, and length of the longest flow path. Results for the 7Q10 and 30Q10 models had coefficients of determination ( R 2 ) of 0.796 and 0.853, respectively. The output model results were bias-corrected for ungaged locations across New York and are available within the interactive StreamStats tool.

New York↗
USGS2000

A decision support system for prioritizing forested wetland restoration in the Yazoo Backwater Area, Mississippi

A working prototype decision support system (DSS) was developed for the Yazoo Backwater Area, Mississippi, to help planners and managers prioritize, plan, conduct, and optimize forested wetland restoration activities. The DSS comprises geographic information system (GIS) spatial data themes, application programs that provide a cumulative analysis of the relative ability of sites to function as wetlands, and output data that are specific to a given restoration analysis scenario. The DSS input includes GIS data themes such as geomorphology, soils, land use, elevation, farmed wetlands, flood frequency, topographic depressions, streams, public lands, roads, and permanent water bodies, which can be used as spatial templates to define areal hydrologic settings. These GIS data themes can then be ranked and combined to estimate the relative suitability of a potential wetland restoration site, thereby, determining relative wetland equivalence on the landscape. The GIS applications used in this DSS perform the following three functions: assess the ecology (the Eco-Assessor); reclassify land-use in areas selected for restoration (the Tree-Translator); and generate output data to compare restoration scenarios (the Parameter-Generator). Areas selected for reforestation are translated (in the GIS) into ?forested? land use, and the tree species that are ?planted? on the landscape (in the DSS) either compose an ecologically optimal or an economically optimal community of tree species. Output from the DSS can be compared and analyzed by using economic, statistical, graphical, and tabular methods. Output data for seven selected scenarios were generated for the Yazoo Backwater Area and are presented as examples to illustrate the flexibility of the DSS to identify areas that meet restoration objectives.

Water-Resources Investigations Report↗
USGS2002

Ecological effects on streams from forest fertilization: Literature review and conceptual framework for future study in the western Cascades

Fertilization of forests with urea-nitrogen has been studied numerous times for its effects on water quality. Stream nitrogen concentrations following fertilization are typically elevated during winter, including peaks in the tens-of-thousands of parts per billion range, with summer concentrations often returning to background or near-background levels. Despite these increases, water-quality criteria for nitrogen have rarely been exceeded. However, such criteria are targeted at fish toxicity or human health and are not relevant to concentrations that could cause ecological disturbances. Studies of the responses of stream biota to fertilization have been rare and have targeted either immediate, toxicity-based responses or used methods insensitive to ongoing ecological processes. This report reviews water-quality studies following forest fertilizations, emphasizing Cascade streams in the Pacific Northwest and documented biological responses in those streams. A conceptual model predicting potential ecological response to fertilization, which includes effects on algal growth and primary production, is presented. In this model, applied fertilizer nitrogen reaching streams is mostly exported during winter. However, some nitrogen retained in soils or stream and riparian areas may become available to aquatic biota during spring and summer. Biological responses may be minimal in small streams nearest to application because of light limitation, but may be elevated downstream where light is sufficient to allow algal growth. Ultimately, algal response could be greatest in downstream reaches, although ambient nutrient concentrations remain low due to uptake and benthic nutrient recycling. Ground-water flow paths and hyporheic processing could be critical in determining the fate of applied nitrogen. A framework is provided for testing this response in the Little River watershed, a tributary to the North Umpqua River, Oregon, at basic and intensive levels of investigation.

Oregon↗
USGS1979

Water-quality characteristics of streams in forested and rural areas of North Carolina

Data collected in North Carolina during 1973-78 from a statewide network of 39 rural sampling sites were used to define unpolluted or baseline stream quality. The basins were 90 to 100 percent forested and, except for the unknown effects of air pollution, were relatively unaffected by man 's activities. Five distinct geochemical zones were delineated across the State. The chemical characteristics of surface waters in each zone are similar. Mean and other statistical values for major dissolved constituents, nutrients, and minor elements in base runoff and storm runoff were determined. Twenty additional rural sites were located in basins where farming activities ranged from 15 to 55 percent of basins ' land area. Data from these 20 sites were used for comparison with data from the 39 unpolluted sites to determine the increase in constituent levels caused by man. For basins where farming activities accounted for 20 or more percent of total land use, phosphorus levels were 2 to 13 times greater than those from the forested basins and several major constituents were 2 to 3 times greater. Concentrations of minor elements were essentially the same in both developed and undeveloped basins. (Kosco-USGS)

North Carolina↗
USGS1979

Forest and flooding with special reference to the White River and Ouachita River basins, Arkansas

The observed response of trees to hydrologic stress and distribution of trees in relation to habitat indicate that flooding, ground-water level, soil moisture, soil factors, and drainage characteristics exert a strong influence on bottomland forest species distribution. The dominant hydrologic factor influencing the distribution of bottomland tree species is flooding. Individual tree species are distributed as a function of frequency and duration of flooding. In the lower White and Ouachita River basins, the flood plains consist of a series of terraces, progressively higher terraces having less frequent flooding and less duration of flooding, and a significantly different composition of forest tree species. The sites studied can be divided into four basic groups and several subgroups on the basis of flood characteristics. On Group I (water hickory-overcup oak) sites, flooded near annually 32 to 40 percent of the time, the dominant species are water hickory and overcup oak. On Group II (nuttall oak) sites, flooded near annually 10 to 21 percent of the time, a more varied flora exists including nuttall oak, willow oak, sweetgum, southern hackberry, and American elm. The third group (Group III or shagbark hickory-southern red oak) of sites is flooded at intervals from 2 to 12 years. This group includes southern red oak, shagbark hickory, and black gum. The presence of blackjack oak in addition to Group III species marks Group IV (not flooded in historic time). (Kosco-USGS)

Arkansas↗
USGS1986

Quality of water resources of the Ouachita National Forest, Arkansas

Surface water and groundwater quality was documented in the Ouachita National Forest by collecting surface water quality data at 15 points and groundwater quality data at 11 sites from April 1984 through August 1985. The data were compared to drinking water standards and the results are tabulated. Surface water in the Ouachita National Forest is relatively abundant. It is low in mineralization and chemically suitable for most uses with minimal treatment. Groundwater is relatively scarce. The low yields of wells limit the use of groundwater primarily to domestic use. The water is chemically suitable for most purposes but may require treatment for the removal of iron. (Peters-PTT)

Water-Resources Investigations Report↗
USGS1993

Hydrology and water quality of the Forest County Potawatomi Indian Reservation, Wisconsin

This report presents data from a study by the U.S. Geological Survey, in cooperation with the Forest County Potawatomi Community of Wisconsin, to document the hydrology and water quality of the Potawatomi Indian Reservation in southern Forest County. Data were collected from October 1981 through September 1987. Glacial sand and gravel forms the primary aquifer on the reservation. This aquifer is unconfined, and its saturated thickness ranges from approximately 200 feet to zero feet in areas where the bedrock crops out. Horizontal hydraulic conductivity of the glacial deposits is estimated to range from 0.4 to 48 feet per day. Three watersheds encompass the Reservation: The Wolf, the North Branch Oconto, and the Peshtigo. Estimates of base-flow discharge that will occur on the average once every 2 years for a 7- day period for Reservation streams range from 7.5 ft3/s (cubic feet per second) for North Branch Oconto at Wabeno to 32 ft3/s for the Rat River near Wabeno. Ground water in the study area is a calcium magnesium bicarbonate type and is suitable for most uses. The ground water sampled during the study was slightly alkaline and moderately hard to very hard; median hardness was 135 mg/L (milligrams per liter) as calcium carbonate. Alkalinity of ground water ranged from 79 to 318 mg/L; median alkalinity was 123 mg/L as calcium carbonate. With the exception of nitrate in water from one well sampled, constituent concentrations were less than the U.S. Environmental Protection Agency's Maximum Contaminant Levels (MCL's) for drinking water. Nitrate plus nitrite concentration was 15 mg/L as N, or 50 percent greater than the MCL, in one well located one-half mile northeast of Lake Lucerne. Secondary Maximum Contaminant Levels (SMCL's) for iron were exceeded in water from two wells. In one of these two well waters, the manganese concentration equaled the SMCL. Streams on the Reservation also contain a calcium magnesium bicarbonate type water. The stream waters are slightly alkaline and are considered soft to moderately hard; median hardness in stream samples was 56 mg/L as calcium carbonate. The alkalinity in stream samples ranged from 46 to 59 mg/L as calcium carbonate; the median value was 51 mg/L. Stream water is intermediate between hard, alkaline ground water and soft, acidic precipitation and surface runoff. Low but detectable concentrations of chromium, copper, iron, magnesium, mercury, and zinc were detected in most bottom-material samples. Water quality of three lakes on the Reservation is variable and depends on the degree of connection with the ground-water system. In general, Bug Lake and Devils Lake are in poor hydraulic connection with the ground-water system, and their waters contain low concentrations of dissolved solids and alkalinity and low pH. King Lake is in good hydraulic connection with the ground-water system, and its waters contain higher concentrations of dissolved solids and alkalinity and higher pH than Bug and Devils Lakes.

Wisconsin↗
USGS1994

Use of a precipitation-runoff model for simulating effects of forest management on streamflow in 11 small drainage basins, Oregon Coast Range

The Precipitation-Runoff Modeling System (PRMS) model of the U.S. Geological Survey was used to simulate the hydrologic effects of timber management in 11 small, upland drainage basins of the Coast Range in Oregon. The coefficients of determination for observed and simulated daily flow during the calibration periods ranged from 0.92 for the Flynn Creek Basin to 0.68 for the Priorli Creek Basin; percent error ranged from -0.25 for the Deer Creek Basin to -4.49 for the Nestucca River Basin. The coefficients of determination during the validation periods ranged from 0.90 for the Flynn Creek Basin to 0.66 for the Wind River Basin; percent error during the validation periods ranged from -0.91 for the Flynn Creek Basin to 22.3 for the Priorli Creek Basin. In addition to daily simulations, 42 storms were selected from the time-series periods in which the 11 basins were studied and used in hourly storm-mode simulations. Sources of simulation error included the quality of the input data, deficiencies in the PRMS model-algorithms, and the quality of parameter estimation. Times-series data from the Flynn Creek and Needle Branch Basins, collected during an earlier U.S. Geological Survey paired-watershed study, were used to evaluate the PRMS as a tool for predicting the hydrologic effects of timber-management practices. The Flynn Creek Basin remained forested and undisturbed during the data-collection period, while the Needle Branch Basin had been clearcut 82 percent at a midpoint during the period of data collection. Using the PRMS, streamflow at the Needle Branch Basin was simulated during the postlogging period using prelogging parameter values. Comparison of postlogging observed streamflow with the simulated data showed an increase in annual discharge volume of approximately 8 percent and a small increase in peak flows of from 1 to 2 percent. The simulated flows from the basins studied were generally insensitive to the number of hydrologic-response units used to replicate basin surface detail. The average number of hydrologic-response units used in the storm-period simulations was one-half the average number of hydrologic-response units used in the daily period simulations. With the exception of one basin, however, the coefficient of determination between observed and simulated daily flow differed by only 3 percent. Calibration and validation of the PRMS for 11 basins--that encompass a variety of forest, soil, and topographic conditions--provided regionalized parameter values. The parameter values assist the PRMS hydrologic simulations of other gaged and ungaged basins in the Coast Range with landscape conditions similar to those of the basins studied.

Water-Resources Investigations Report↗
USGS1982

Water-quality characteristics of streams in forested and rural areas of North Carolina

Data collected in North Carolina during 1973-78 from a statewide network of 39 rural sampling sites were used to define unpolluted or baseline stream quality. The basins were 90 to 100 percent forested and, except for the unknown effects of air pollution, were relatively unaffected by man 's activities. Five distinct geochemical zones were delineated across the State. The chemical characteristics of surface waters in each zone are similar. Mean and other statistical values for major dissolved constituents, nutrients, and minor elements in base runoff and storm runoff were determined. Twenty additional rural sites were located in basins where farming activities ranged from 15 to 55 percent of basins' land area. Data from these 20 sites were used for comparison with data from the 39 unpolluted sites to determine the increase in constituent levels caused by man. For basins where farming activities accounted for 20 or more percent of total land use, phosphorus levels were 2 to 13 times greater than those from the forested basins and several major constituents were 2 to 3 times greater. Concentrations of minor elements were essentially the same in both developed and undeveloped basins.

Water Supply Paper↗
USGS1982

Production and decomposition of forest litter fall on the Apalachicola River flood plain, Florida: Chapter B, Apalachicola River quality assessment

Measurements of litter fall (leaves and other particulate organic material) and leaf decomposition were made on the bottom-land hardwood swamp of the Apalachicola River flood plain in 1979-80. Litter fall was collected monthly from nets located in 16 study plots. The plots represented five forest types in the swamp and levee areas of the Apalachicola River flood plain. Forty-three species of trees, vines, and other plants contributed to the total litter fall, but more than 90 percent of the leaf material originated from 12 species. Nonleaf material made up 42 percent of the total litter fall. Average litter fall was determined to be 800 grams per square meter per year, resulting in an annual deposition of 3.6 ? 105 metric tons of organic material in the 454-square-kilometer flood plain. The levee communities have less tree biomass but greater tree diversity than do swamp communities. The levee vegetation, containing less tree biomass, produces slightly more litter fall per unit of ground surface area than does the swamp vegetation. The swamps are dominated by three genera: tupelo (Nyssa), cypress (Taxodium) and ash (Fraxinus). These genera account for more than 50 percent of the total leaf fall in the flood plain, but they are the least productive, on a weight-perbiomass basis, of any of the 12 major leaf producers. Decomposition rates of leaves from five common floodplain tree species were measured using a standard leaf-bag technique. Leaf decomposition was highly species dependent. Tupelo (Nyssa spp.) and sweetgum (Liquidambar styraciflua) leaves decomposed completely in 6 months when flooded by river water. Leaves of baldcypress (Taxodium distichum) and diamond-leaf oak (Quercus laurifolia) were much more resistant. Water hickory (Carya aquatica) leaves showed intermediate decomposition rates. Decomposition of all species was greatly reduced in dry environments. Carbon and biomass loss rates from the leaves were nearly linear over a 6-month period, but nitrogen and phosphorus leaching was nearly complete within 1 month. Much of the organic substance may be recycled in the forest ecosystem, but annual flooding of the river provides an important mechanism for mobilization of the litter-fall products.

Water Supply Paper↗
USGS2001

Desertification and a shift of forest species in the West African Sahel

Original field data show that forest species richness and tree density in the West African Sahel declined in the last half of the 20th century. Average forest species richness of areas of 4 km2 in Northwest Senegal fell from 64 ?? 2 species ca 1945 to 43 ?? 2 species in 1993, a decrease significant at p < 0.001. Densities of trees of height ???3 m declined from 10 ?? 0.3 trees ha-1 in 1954 to 7.8 ?? 0.3 trees ha-1 in 1989, also significant at p < 0.001. Standing wood biomass fell 2.1 t ha-1 in the period 1956-1993, releasing CO2 at a rate of 60 kgC person-1 yr-1. These changes have shifted vegetation zones toward areas of higher rainfall at an average rate of 500 to 600 m yr-1. Arid Sahel species have expanded in the north, tracking a concomitant retraction of mesic Sudan and Guinean species to the south. Multivariate analyses identify latitude and longitude, proxies for rainfall and temperature, as the most significant factors explaining tree and shrub distribution. The changes also decreased human carrying capacity to below actual population densities. The rural population of 45 people km-2 exceeded the 1993 carrying capacity, for firewood from shrubs, of 13 people km-2 (range 1 to 21 people km-2). As an adaptation strategy, ecological and socioeconomic factors favor the natural regeneration of local species over the massive plantation of exotic species. Natural regeneration is a traditional practice in which farmers select small field trees that they wish to raise to maturity, protect them, and prune them to promote rapid growth of the apical meristem. The results of this research provide evidence for desertification in the West African Sahel. These documented impacts of desertification foreshadow possible future effects of climate change.

Climate Research↗
USGS2026

A little-known piñon from the Mogollon Highlands: Natural history of Pinus x fallax in the Prescott National Forest, Arizona, USA

The Mogollon Highlands is an area of rich biodiversity in central Arizona and western New Mexico. The piñon-juniper/chaparral in the Mogollon Highlands is unique from other piñon-juniper woodlands in both taxonomy and structure. The hybridization of the common piñon there, Pinus × fallax (Mogollon Highlands piñon, MHP), is hypothesized to render it more tolerant to heat and aridity than one of the parent plants, Pinus edulis (Colorado piñon). Yet as Climate Water Deficit continues to increase, so does concern for the future of these woodlands and the MHP. Using demographic data on MHP from the last four decades, we evaluate fecundity and mortality patterns in woodlands where MHP is co-dominant with three Juniperus species and numerous perennial shrubs. Our data indicate that MHP stands continue to reproduce and that mortality is low relative to the more northern P. edulis stands. We also present a simple calculation of historical fire rotation in Prescott National Forest woodlands, estimating a fire rotation of two centuries, far shorter than other piñon-juniper associations. We also explore fire patterns since 1985 across the ecoregion; abundant charcoal indicates small patchy fires were common. In spite of widespread fires, most Mogollon Highlands fires have occurred in Pinus ponderosa (ponderosa pine) forests, leaving piñon-juniper/chaparral intact. Together these trends indicate that MHP and associated perennial co-dominants are tolerant of current climates. We suggest that hybrid genetic combinations, the complex perennial understory (e.g., actinorhizal shrubs, rich diversity of nurse microsites), and fire patterns are responsible for this resiliency.

Arizona↗
USGS2019

Giving ecological meaning to satellite-derived fire severity metrics across North American forests

Satellite-derived spectral indices such as the relativized burn ratio (RBR) allow fire severity maps to be produced in a relatively straightforward manner across multiple fires and broad spatial extents. These indices often have strong relationships with field-based measurements of fire severity, thereby justifying their widespread use in management and science. However, satellite-derived spectral indices have been criticized because their non-standardized units render them difficult to interpret relative to on-the-ground fire effects. In this study, we built a Random Forest model describing a field-based measure of fire severity, the composite burn index (CBI), as a function of multiple spectral indices, a variable representing spatial variability in climate, and latitude. CBI data primarily representing forested vegetation from 263 fires (8075 plots) across the United States and Canada were used to build the model. Overall, the model performed well, with a cross-validated R 2 of 0.72, though there was spatial variability in model performance. The model we produced allows for the direct mapping of CBI, which is more interpretable compared to spectral indices. Moreover, because the model and all spectral explanatory variables were produced in Google Earth Engine, predicting and mapping of CBI can realistically be undertaken on hundreds to thousands of fires. We provide all necessary code to execute the model and produce maps of CBI in Earth Engine. This study and its products will be extremely useful to managers and scientists in North America who wish to map fire effects over large landscapes or regions.

Remote Sensing↗