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At least 37 records · Page 2Linked to original sources
USGS1999

Sea-level rise and coastal forests on the Gulf of Mexico

In this report, we review literature pertaining to the response of coastal forests on the Gulf of Mexico to sea-level rise. The report is divided into chapters that discuss effects of sea-level rise on non-mangrove forests, effects of sea-level rise on mangrove forests, and responses of Gulf coast trees to increased flooding and salinity. An assessment of the extent of coastal forest likely to be affected by sea-level rise in the near future is beyond the scope of this report. Chapter 1 discusses sea-level effects on non-mangrove forests of the Gulf of Mexico including descriptions of how coastlines and, therefore, coastal forests have changed through the Holo~ene, a discussion of how coastal geomorphology and hydrology may affect interactions of coastal forest with sea-level rise, and an evaluation of the role that hurricanes might play in coastal forest retreat. Literature on geological changes throughout the Holocene is not fully reviewed; sufficient information is given to place current rates of coastal forest retreat into historical perspective. Similarly, effects of hurricanes on coastal forests are not fully reviewed. Information that is pertinent to the role of hurricanes in coastal forest retreat and to the effects of hurricanes on the forest's interaction with sea level is presented. For more extensive reviews of hurricane effects on coastal forests of the Caribbean and the southeastern United States, the reader is referred to issues of BioScience (1994, Vol 44, no. 4), Biotropica (1991, "Special Issue: Ecosystem, Plant, and Animal Responses to Hurricanes in the Caribbean", Vol. 23, No. 4, Part A) and the Journal of Coastal Research (1991, "Impacts of Hurricane Hugo, Special Issue No. 8; and 1995, "Imprcts of Hurricane Andrew on the Coastal Zones of Florida and Louisiana: 22-26 August 1992", Special Issue No. 21). Selected pertinent information from Virginia, South and North Carolina has been included in this review, because much of our knowledge of coastal forest response to hurricanes, salinity and flooding comes from the Atlantic coast. These areas are floristically similar to the northern Gulf of Mexico. Species distribution of coastal forest trees and shrubs on the Gulf of Mexico are listed in Appendix 1. Extensive research has been conducted on the responses of individual tree species to increased salinity and flooding. Synthesis of this research, although very important for evaluating effects of sea-level rise and various hydrological modifications on coastal forest, is beyond the scope of this review. These studies are included as an annotated bibliography (Appendix 2). Selected field studies on tree responses to changes in hydrology and salinity (impoundments, drainage, etc.) are referenced in Appendix 3. A review of mangrove response to sea-level rise is included in Chapter 2. Mangrove forests are discussed in the context of Holocene changes in geomorphology. Predictions of the fate of mangroves in the face of future sea-level rise, as well as a review of factors that affect interactions between mangroves and sea-level rise are discussed. Selected references from outside the United States are included, because much of our knowledge of how mangroves react to sea-level rise comes from other tropical areas of the world. A discussion of hurricane effects on the mangroves of south Florida highlights gaps in our knowledge of how hurricanes affect responses of mangrove vegetation to sea-level rise there. Mangrove responses to temperature and elevated CO2 are briefly mentioned. These factors, as well as sea level, are expected to change in the future and may affect mangrove distribution.

Open-File Report↗
USGS2018

Field observations of alongshore runup variability under dissipative conditions in presence of a shoreline sandwave

Video measurements of runup were collected at low tide along several profiles covering an alongshore distance of 500 m. The morphology displayed a complex shape with a shoreline sandwave in the lower beach face of about 250 m long mirrored in the inner sandbar. Wave conditions were stationary and moderate (offshore height of 2 m and peak period of nearly 13 s) but yet dissipative. Runup energy was dominated by infragravity frequencies. Alongshore variations in runup (by a factor up to 3) observed both in the incident and infragravity bands were much higher than reported previously (e.g., Guedes et al., 2012, https://doi.org/10.1016/j.csr.2012.08.022 ; Ruggiero et al., 2004, https://doi.org/10.1029/2003JC002160 ) while the alongshore variations in other environmental parameters (e.g., foreshore beach slope) appear to be much lower. Our data suggest that the beach morphology in the inner surf zone plays a crucial role by inducing rapid and significant modification in the incident wave pattern and the alongshore coherence length scales were consistent with the typical alongshore length scale of the morphology.

Journal of Geophysical Research C: Oceans↗
USGS2013

Effects of riparian vegetation on topographic change during a large flood event, Rio Puerco, New Mexico, USA

The spatial distribution of riparian vegetation can strongly influence the geomorphic evolution of dryland rivers during large floods. We present the results of an airborne lidar differencing study that quantifies the topographic change that occurred along a 12 km reach of the Lower Rio Puerco, New Mexico, during an extreme event in 2006. Extensive erosion of the channel banks took place immediately upstream of the study area, where tamarisk and sandbar willow had been removed. Within the densely vegetated study reach, we measure a net volumetric change of 578,050 ± ∼ 490,000 m 3 , with 88.3% of the total aggradation occurring along the floodplain and channel and 76.7% of the erosion focusing on the vertical valley walls. The sediment derived from the devegetated reach deposited within the first 3.6 km of the study area, with depth decaying exponentially with distance downstream. Elsewhere, floodplain sediments were primarily sourced from the erosion of valley walls. Superimposed on this pattern are the effects of vegetation and valley morphology on sediment transport. Sediment thickness is seen to be uniform among sandbar willows and highly variable within tamarisk groves. These reach-scale patterns of sedimentation observed in the lidar differencing likely reflect complex interactions of vegetation, flow, and sediment at the scale of patches to individual plants.

New Mexico↗
USGS2009

Fungal endophytes: diversity and functional roles

All plants in natural ecosystems appear to be symbiotic with fungal endophytes. This highly diverse group of fungi can have profound impacts on plant communities through increasing fitness by conferring abiotic and biotic stress tolerance, increasing biomass and decreasing water consumption, or decreasing fitness by altering resource allocation. Despite more than 100 yr of research resulting in thousands of journal articles, the ecological significance of these fungi remains poorly characterized. Historically, two endophytic groups (clavicipitaceous (C) and nonclavicipitaceous (NC)) have been discriminated based on phylogeny and life history traits. Here, we show that NC-endophytes represent three distinct functional groups based on host colonization and transmission, in planta biodiversity and fitness benefits conferred to hosts. Using this framework, we contrast the life histories, interactions with hosts and potential roles in plant ecophysiology of C- and NC-endophytes, and highlight several key questions for future work in endophyte biology.

New Phytologist↗
USGS2018

UZIG research: Measurement and characterization of unsaturated zone processes under wide-ranging climates and changing conditions

Unsaturated zone properties and processes are central to understanding the interacting effects of land-use change, contamination, and hydroclimate on our ability to grow food, sustain clean water supplies, and minimize loss of life and property. Advances in unsaturated zone science are being achieved through collaborations across traditional boundaries where information from biological, physical, and chemical disciplines is combined for new insights. The Unsaturated Zone Interest Group (UZIG) is an organization that exists principally to promote multidisciplinary collaborations and the sharing of ideas, expertise, and technical assets. Here we summarize key findings from 14 papers, several of which originated from a meeting convened by UZIG in 2017 at the University of Florida in Gainesville titled “Land-Use Change, Climate Change, and Hydrologic Extremes: Unsaturated Zone Responses and Feedbacks.” This special section of Vadose Zone Journal contains multidisciplinary research in three general categories relevant to measuring and understanding unsaturated zone responses to changing land uses and climate: (i) unsaturated zone properties and processes; (ii) soil–plant–atmosphere interactions; and (iii) novel field sampling devices. A strong cross-cutting theme in these papers is the value of continuous monitoring data and ways of utilizing them to discover novel hydrologic, biologic, and pedologic information. As climatic and land-use conditions change and demands for resources and stresses on ecosystems continue to intensify, it is vital to improve our fundamental understanding of the processes at work in the unsaturated zone. Toward that goal, we discuss the need for improved ground-based unsaturated zone monitoring networks.

Vadose Zone Journal↗
USGS2007

Role of burning season on initial understory vegetation response to prescribed fire in a mixed conifer forest

Although the majority of fires in the western United States historically occurred during the late summer or early fall when fuels were dry and plants were dormant or nearly so, early-season prescribed burns are often ignited when fuels are still moist and plants are actively growing. The purpose of this study was to determine if burn season influences postfire vegetation recovery. Replicated early-season burn, late-season burn, and unburned control units were established in a mixed conifer forest, and understory vegetation was evaluated before and after treatment. Vegetation generally recovered rapidly after prescribed burning. However, late-season burns resulted in a temporary but significant drop in cover and a decline in species richness at the 1 m 2 scale in the following year. For two of the several taxa that were negatively affected by burning, the reduction in frequency was greater after late-season than early-season burns. Early-season burns may have moderated the effect of fire by consuming less fuel and lessening the amount of soil heating. Our results suggest that, when burned under high fuel loading conditions, many plant species respond more strongly to differences in fire intensity and severity than to timing of the burn relative to stage of plant growth. ?? 2007 NRC.

Canadian Journal of Forest Research↗
USGS1975

Phosphate fertilizer materials in Colombia; imports, uses, and domestic supplies

The distribution of potentially economic phosphate deposits and the locations of major users of phosphate products in Colombia are some of the economic factors that indicate the capability of the deposits to supply domestic demands. Much research is required to determine the types of processing plants needed and to outline changes from standard procedures, but there is little doubt that with proper planning a phosphate chemical industry could be developed that would supply domestic demands for the forseeable future.

Journal of Research of the U.S. Geological Survey↗
USGS1976

The Placer River Silt — An intertidal deposit caused by the 1964 Alaska earthquake

At the head of Turnagain Arm near Anchorage, the major lasting geologic consequence of the Alaska earthquake of 1964 was deposition of the Placer River Silt, an intertidal deposit covering an area of more than 18 km 2 and containing more than 20X10 6 m 3 of sediment. This formation, which was derived from erosion of intertidal bars in Turnagain Arm, averages 1.5 m thick seaward of the Seward Highway and 0.9 m thick landward. Its distribution is controlled both, by the arrangement of the major streams that enter tidewater and by manmade features such as the highway and railroad embankments. The Placer River Silt is still being deposited. The contemporary lowland sedimentation system of the Portage area includes a number of depositional settings: (1) In the Placer River Silt upper tidal flats, levees, and channelway fans, (2) elsewhere in the intertidal zone tidal stream channels, lower tidal flats, and saltwater marsh, and (3) in the supratidal zone gravel levees, freshwater marsh, bogs, and lakes. Since 1964, the critical environmental results of the earthquake-caused deposition have been abandonment of the settlement of Portage, formation of an unsightly blanket of silt, destruction of natural plant communities, localized erosion, and creation of quicksand hazards.

Alaska↗
USGS2010

Vulnerability of white spruce tree growth in interior Alaska in response to climate variability: Dendrochronological, demographic, and experimental perspectives

This paper integrates dendrochronological, demographic, and experimental perspectives to improve understanding of the response of white spruce ( Picea glauca (Moench) Voss) tree growth to climatic variability in interior Alaska. The dendrochronological analyses indicate that climate warming has led to widespread declines in white spruce growth throughout interior Alaska that have become more prevalent during the 20th century. Similarly, demographic studies show that white spruce tree growth is substantially limited by soil moisture availability in both mid- and late-successional stands. Interannual variability in tree growth among stands within a landscape exhibits greater synchrony than does growth of trees that occupy different landscapes, which agrees with dendrochronological findings that the responses depend on landscape position and prevailing climate. In contrast, the results from 18 years of a summer moisture limitation experiment showed that growth in midsuccessional upland stands was unaffected by moisture limitation and that moisture limitation decreased white spruce growth in floodplain stands where it was expected that growth would be less vulnerable because of tree access to river water. Taken together, the evidence from the different perspectives analyzed in this study clearly indicates that white spruce tree growth in interior Alaska is vulnerable to the effects of warming on plant water balance.

Alaska↗
USGS2000

Growth and nutrition of baldcypress families planted under varying salinity regimes in Louisiana, USA

Saltwater intrusion from the Gulf of Mexico is one important factor in the destruction of baldcypress (Taxodium distichum (L.) Rich.) swamps along the Louisiana Gulf Coast, USA. Recent restoration efforts have focused on identification of baldcypress genotypes with greater tolerance to saline conditions than previously reported. To date, salt tolerance investigations have not been conducted under saline field conditions. In 1996, therefore, three plantations were established with 10 half-sib genotype collections of baldcypress in mesohaline wetlands. Tree survival and growth were measured at the end of two growing seasons, and foliar ion concentrations of Na, Cl, K, and Ca and available soil nutrients were measured during the 1996 growing season. In general, soil nutrient concentrations exceeded averages found in other baldcypress stands in the southeastern United States. Seedlings differed among sites in all parameters measured, with height, diameter, foliar biomass, and survival decreasing as site salinity increased. Average seedling height at the end of two years, for example, was 196.4 cm on the lowest salinity site and 121.6 cm on the highest. Several half-sib families maintained greater height growth increments (ranging from 25.5 to 54.5 cm on the highest salinity site), as well as lower foliar ion concentrations of K, Cl, and Ca. Results indicate that genotypic screening of baldcypress may improve growth and vigor of seedlings planted within wetlands impacted by saltwater intrusion.

Louisiana↗
USGS2023

Integrated rangeland fire management strategy actionable science plan completion assessment: Invasives topic, 2015–20

Loss and degradation of sagebrush rangelands due to an accelerated invasive annual grass-wildfire cycle and other stressors are significant management, conservation, and economic issues in the western United States. These sagebrush rangelands comprise a unique biome spanning 11 states, support over 350 wildlife species, and provide important ecosystem services that include stabilizing the economies of western communities. Impacts to sagebrush ecosystem processes over large areas due to the annual grass-wildfire cycle necessitated the development of a coordinated, science-based strategy for improving efforts to achieve long-term protection, conservation, and restoration of sagebrush rangelands, which was framed in 2015 under the Integrated Rangeland Fire Management Strategy (IRFMS). Central to this effort was the development of an Actionable Science Plan (Plan) that identified 37 priority science needs (Needs) for informing the actions proposed under the 5 topics (Fire, Invasives, Restoration, Sagebrush and Sage-Grouse, Climate and Weather) that were part of the collective focus of the IRFMS. Notable keys to this effort were identification of the Needs co-produced by managers and researchers, and a focus on resulting science being “actionable.” Substantial investments aimed at fulfilling the Needs identified in the Plan have been made since its release in 2016. While the state of the science has advanced considerably, the extent to which knowledge gaps remain relative to identified Needs is relatively unknown. Moreover, new Needs have likely emerged since the original strategy as results from actionable science reveal new questions and possible (yet untested) solutions. A quantifiable assessment of the progress made on the original science Needs can identify unresolved gaps and new information that can help inform prioritization of future research efforts. This report details a systematic literature review that evaluated how well peer-reviewed journal articles and formal technical reports published between January 1, 2015, and December 31, 2020, addressed six needs (hereinafter “Needs”) identified under the Invasives topic in the Plan. The topic outlined research Needs related to the control of invasive plant species in sagebrush rangelands, with a special emphasis on invasive annual grasses. We established the level of progress towards addressing each Need following a standardized set of criteria, and developed summaries detailing how research objectives nested within Needs identified in the Plan (“Next Steps”) were either addressed well, partially addressed, or remain outstanding (that is, addressed poorly) in the literature through 2020. Our searches resulted in the inclusion of 198 science products that at least partially addressed a Need identified in the Invasives topic. The Needs that were well and partially addressed included: studies of natural and anthropogenic factors influencing the distribution and spread; methods of preventing, eradicating and controlling invasive plant species; development of mapping techniques that provide regularly updated annual grass and fine fuel projections; and assessment of the efficacy of potential cheatgrass biocontrol agents. Needs that were addressed poorly included (1) investigations of livestock grazing as a tool for managing invasive plants and (2) investigations of cheatgrass die-offs and identification and subsequent study of potential biocontrol agents associated with those die-offs. The information provided in this assessment will assist updating the Plan along with other science strategies.

western United States↗
USGS1976

Geology of the Brysch uranium mine, Karnes County, Texas

Approximately 13,700 tons (12,400 tonnes) of oxidized uranium ore, averaging about 0.1 percent U 2 O 8 , was mined during 1966 and 1967 from the lower unit of the Deweesville Sandstone Member of the upper Eocene Whitsett Formation, from depths of 75 to 90 feet (23-27 m). The mine is in the Karnes County uranium area, 3 miles (5 km) east of Falls City, Tex. Meta-autunite, Ca(UO 2 ) 2 (PO 4 ) 2 2-6H 2 O, and meta-tyuyamunite, Ca(UO 2 ) 2 (PO 4 ) 2 3-5H 2 O, were identified in samples of the ore. The host rock is light-colored, medium-grained, well-sorted feldspathic sandstone that contains fossil wood and Ophiomorpha . It also contains clinoptilolite, cristobalite, and montmorillonite that probably formed as alteration products of volcanic grains in the original sediment. The host rock was deposited in a beach environment near or on a delta formed at the mouth of a stream channel oriented roughly normal to the beach. The Deweesville can be traced for many miles on the surface and represents in general the point of maximum transgression in a transgressive-regressive cycle. The upper unit of the Deweesville, which overlies the host rock, is now exposed in the mine and contains, in ascending order, storm-beach, shoreface, beach, and tidal-flat facies. The shape of the ore body suggests that it originated as an unoxidized ore roll. The ore-bearing fluids may have entered through porous fluvial rock extending updip. Plant material, abundant in the original host sediment, probably supplied reductant necessary for the roll formation.

Texas↗
USGS1965

Movements of hatchery-reared lake trout in Lake Superior

The history of stocking of lake trout (Salvelinus namaycush) in the Great Lakes is reviewed. The study of movements is based on capture of 24,275 fin-clipped lake trout taken in experimental gill nets and trawls and commercial gill nets. Yearling lake trout planted from shore dispersed to 15-fath (27-m) depths in 3A? hr. Most fish remained within 2 miles (3.2 km) of the planting site 2 months, but within 4 months some fish had moved as much as 17 miles (27 km). The highest abundance of planted lake trout was in areas 2-4 miles (3.2-6.4 km) from the planting site even 3 years after release. Distance moved and size of fish were not correlated. Dispersal of lake trout begins at planting and probably continues until the fish are mature. Most movement was eastward in southern Lake Superior and followed the counterclockwise surface currents. Movement is most rapid in areas of strong currents and slowest in areas of weak currents or eddies. Movement to areas west of the Keweenaw Peninsula was insignificant from plantings in Keweenaw Bay and nil from other plantings farther east. Lake trout planted in the eastern third of the lake dispersed more randomly than those planted farther west. Few fish moved farther offshore than the 50-fath (91-m) contour. Lake trout planted in Canadian waters made insignificant contributions to populations in US waters.

Journal of the Fisheries Research Board of Canada↗
USGS1976

Relations among surficial materials, light intensity, and sycamore-seed germination along the Potomac River near Washington, D.C.

Seed of sycamore, a common tree on river flood plains, germinate in mineral soil exposed to high light intensities. Germination rates are low on surfaces covered with leaf litter, and seedlings die when shaded by closely spaced herbaceous plants. All germination rates were higher when seed were kept moist. Surflcial materials and light values in this study are similar to those on flood plains. Results were derived from counting seedlings after planting 1,000 seeds in each of several flats filled with different kinds of flood-plain and upland soils.

District of Columbia, Virginia↗
USGS1999

Regeneration alternatives for upland white spruce after burning and logging in interior Alaska

Site-preparation and regeneration methods for white spruce (Picea glauca (Moench) Voss) were tested near Fairbanks, Alaska, on two upland sites which had been burned in a wildfire and salvage logged. After 5 and 10 years, white spruce regeneration did not differ among the four scarification methods but tended to be lower without scarification. Survival of container-grown planted seedlings stabilized after 3 years at 93% with scarification and at 76% without scarification. Broadcast seeding was also successful, with one or more seedlings on 80% of the scarified 6-m2 subplots and on 60% of the unscarified subplots after 12 years. Natural regeneration after 12 years exceeded expectations, with seedlings on 50% of the 6-m2 subplots 150 m from a seed source and on 28% of the subplots 230 m from a seed source. After 5 years, 37% of the scarified unsheltered seed spots and 52% of the scarified seed spots with cone shelters had one or more seedlings, but only 16% of the unscarified seed spots had seedlings, with and without funnel shelters. Growth rates for all seedlings were higher than on similar unburned sites. The results show positive effects of burning in interior Alaska, and suggest planting seedlings, broadcast seeding, and natural seedfall, alone or in combination, as viable options for similar sites.

Canadian Journal of Forest Research↗
USGS1973

Archaeocycas and Phasmatocycas - new genera of Permian cycads

The generic names Archaeocycas and Phasmatocycas are introduced for two previously announced but unnamed new genera of Early Permian plants; these taxa are regarded as early stages in the cycadean lineage. The names arc formalized with diagnoses, illustrations, and type designations.

Journal of Research of the U.S. Geological Survey↗
USGS2015

Plant phenolics and absorption features in vegetation reflectance spectra near 1.66 μm

Past laboratory and field studies have quantified phenolic substances in vegetative matter from reflectance measurements for understanding plant response to herbivores and insect predation. Past remote sensing studies on phenolics have evaluated crop quality and vegetation patterns caused by bedrock geology and associated variations in soil geochemistry. We examined spectra of pure phenolic compounds, common plant biochemical constituents, dry leaves, fresh leaves, and plant canopies for direct evidence of absorption features attributable to plant phenolics. Using spectral feature analysis with continuum removal, we observed that a narrow feature at 1.66 μm is persistent in spectra of manzanita, sumac, red maple, sugar maple, tea, and other species. This feature was consistent with absorption caused by aromatic C- H bonds in the chemical structure of phenolic compounds and non-hydroxylated aromatics. Because of overlapping absorption by water, the feature was weaker in fresh leaf and canopy spectra compared to dry leaf measurements. Simple linear regressions of feature depth and feature area with polyphenol concentration in tea resulted in high correlations and low errors (% phenol by dry weight) at the dry leaf ( r 2 = 0.95, RMSE = 1.0%, n = 56), fresh leaf ( r 2 = 0.79, RMSE = 2.1%, n = 56), and canopy ( r 2 = 0.78, RMSE = 1.0%, n = 13) levels of measurement. Spectra of leaves, needles, and canopies of big sagebrush and evergreens exhibited a weak absorption feature centered near 1.63 μm, short ward of the phenolic compounds, possibly consistent with terpenes. This study demonstrates that subtle variation in vegetation spectra in the shortwave infrared can directly indicate biochemical constituents and be used to quantify them. Phenolics are of lesser abundance compared to the major plant constituents but, nonetheless, have important plant functions and ecological significance. Additional research is needed to advance our understanding of the spectral influences of plant phenolics and terpenes relative to dominant leaf biochemistry (water, chlorophyll, protein/nitrogen, cellulose, and lignin).

International Journal of Applied Earth Observation↗