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At least 541 records · Page 30Linked to original sources

USGS2015

Population ecology of the gulf ribbed mussel across a salinity gradient: recruitment, growth and density

Benthic intertidal bivalves play an essential role in estuarine ecosystems by contributing to habitat provision, water filtration, and promoting productivity. As such, changes that impact population distributions and persistence of local bivalve populations may have large ecosystem level consequences. Recruitment, growth, mortality, population size structure and density of the gulf coast ribbed mussel, Geukensia granosissima , were examined across a salinity gradient in southeastern Louisiana. Data were collected along 100-m transects at interior and edge marsh plots located at duplicate sites in upper (salinity ~4 psu), central (salinity ~8 psu) and lower (salinity ~15 psu) Barataria Bay, Louisiana, U.S.A. Growth, mortality and recruitment were measured in established plots from April through November 2012. Mussel densities were greatest within the middle bay (salinity ~8) regardless of flooding regime, but strongly associated with highest stem densities of Juncus roemerianus vegetation. Mussel recruitment, growth, size and survival were significantly higher at mid and high salinity marsh edge sites as compared to all interior marsh and low salinity sites. The observed patterns of density, growth and mortality in Barataria Bay may reflect detrital food resource availability, host vegetation community distribution along the salinity gradient, salinity tolerance of the mussel, and reduced predation at higher salinity edge sites.

Louisiana↗

USGS1982

Acid rain, air pollution, and tree growth in southeastern New York

Whether dendroecological analyses could be used to detect changes in the relationship of tree growth to climate that might have resulted from chronic exposure to components of the acid rain-air pollution complex was determined. Tree-ring indices of white pine ( Pinus strobus L.), eastern hemlock ( Tsuga canadensis (L.) Cart.), pitch pine ( Pinus rigida Mill.), and chestnut oak ( Quercus prinus L.) were regressed against orthogonally transformed values of temperature and precipitation in order to derive a response-function relationship. Results of the regression analyses for three time periods, 1901–1920, 1926–1945, and 1954–1973 suggest that the relationship of tree growth to climate has been altered. Statistical tests of the temperature and precipitation data suggest that this change was nonclimatic. Temporally, the shift in growth response appears to correspond with the suspected increase in acid rain and air pollution in the Shawangunk Mountain area of southeastern New York in the early 1950's. This change could be the result of physiological stress induced by components of the acid rain-air pollution complex, causing climatic conditions to be more limiting to tree growth.

New York↗

USGS1991

Growth and development of thermoregulation in nestling San Miguel Island Song Sparrows

Patterns of growth (reviewed by Ricklefs 1968, 1969; O'Connor 1984) and the development of endothermy (reviewed by Dawson and Hudson 1970, Dunn 1975, Hill and Beaver 1982) have been well-studied in altricial wild birds, especially passerines. But few studies compare grown and thermogenesis in separate populations of the same species. Results of such studies with emberizids varied among species. King and Hubbard (1981), for example, found that nestlings from subarctic, subalpine, and low-altitude montane populations of White-crowned Sparrows ( Zonotrichia leucophrys gambelii ) grew at similar rates. In contrast, Rogers (1985) reported that the growth rates of nestlings in different populations of Savannah Sparrows ( Passerculus sandwichensis ) varied in response to the different environmental constraints of the localities in which they were reared. Nice (1937) and Smith et al. (1982) documented patterns of nestling growth in mainland (Ohio) and insular (Mandarte Island, British Columbia, Canada) populations of Song Sparrows ( Melospiza melodia ), respectively, and found that they were similar to those reported for most other passerines by Ricklefs (1968, 1969) and O'Connor (1984). In 1985-1986, we had the opportunity to examine the growth of nestlings from a third race of Song Sparrows, M. m. micronyx , which is endemic to San Miguel Island near Santa Barbara, California. We also studied the development of endothermy in these young birds, a process not hitherto described for nestling Song Sparrows. We report both in this paper.

California↗

USGS1991

Growth rates of great egret, snowy egret and black-crowned night-heron chicks

Growth rates of Great Erget (Casmerodius albus), Snowy Erget (Egretta thula), and Black-crowned Night-Heron (Nycticorax nycticorax) chicks to 18 days-of-age were estimated from repeated measurements of chicks in broods of three young. Weight gain (g/day) or increase in length (mm/day) of forearm, tarsus, or culmen did not between Black-crowned Night-Heron chicks at a colony in Rhode Island and a colony in Texas (USA). In Black-crowned night-Herons and Great Egrets, the last chick (C-chick) to hatch had lower growth rates than the first (A-) or second (B-) hatched chick. Black-crowned Night-Heron and Great Egret A-chicks gained weight faster than Snowy Egret A-chicks; however growth rates of the forearm, tarsus, or culmen each were not different among the three species. Equations based on the growth rate of culmen, forearm, or tarsus for repeatedly measured A-chicks estimated age of Great Egret, Snowy Egret, and Black-crowned Night-Heron chicks collected elsewhere to within two days of known age.

Colonial Waterbirds↗

USGS1989

Growth and morphometrics of the box turtle, Terrapene c. carolina

Growth of box turtles in a bottomland forest in Maryland was studied over a period of years (1944-1981). A bivariate analysis of age related growth showed that between 8 and 13 yr, male turtles grew at an average rate of 6.7% per year in carapace length, whereas females grew at 5.3% per year. Both males and females grew considerably more slowly between 14 and 19 years, males at 2.3% per year and females at 3.4% per year. Growth slowed still more in the twenties. Growth in the six other dimensions that were measured provided additional comparisons. Allometric analysis of the different carapace and plastron dimensions showed that among males length increased proportionally more than either width or height and that width increased more than height. Among females, only the greater increase of length than of width was statistically significant. Fully grown males were larger than females in all dimensions except height. Differences from the normal scutal pattern occurred in 16.8% of fully grown males and 18.4% of the females

Journal of Herpetology↗

USGS1977

Interactions of nutrients, plant growth and herbivory in a mangrove ecosystem

The effect of nutrient enrichment of red mangroves ( Rhizophora mangle ) was studied by comparing two mangrove—covered islands in the Indian River at Ft. Pierce, Florida, USA, one (high nutrient) with and one (low nutrient) without a breeding colony of pelicans and egrets. Repeated measurements taken on > 100 tagged branches in each area revealed higher growth rates at the high nutrient site. Trees at the high nutrient site showed greater additions of (1) leaves; (2) reproductive parts; (3) new lateral branches; and (4) larger increments to existing stems. Growth in the fertilized stand also began earlier in the year and had a second maximum not shared by the low nutrient area. Both leaves and fruits at the high nutrient site were richer in nitrogen. More striking than the effects on plant growth, however, was the proportionately much greater stimulation of herbivory by insects in response to nutrient enrichment. Larvae of the five lepidopteran species that we observed feeding on buds or leaves were either more abundant or only present in the high nutrient area, as was the scolytid beetle that infested seedlings before they dropped from the parent tree. This difference in herbivory between sites disappeared when the birds seasonally migrated away from their nesting areas at the high nutrient site. This observation and the demonstration that the mangrove skipper Phocides pigmalion attains a higher growth efficiency on high nutrient leaves are both consistent with the hypothesis that increased nutritive value of vegetation (correlated with the increased concentration of nitrogen) is responsible for the 4x greater losses to herbivores in the high nutrient. Implications for environmental management and in more complex communities are discussed.

Florida↗

USGS1998

Thermally induced chronic developmental stress in coho salmon: Integrating measures of mortality, early growth and fluctuating asymmetry

Developmental stability, or homeostasis, facilitates the production of consistent phenotypes by buffering against stress. Fluctuating asymmetry is produced by developmental instability and is manifested as small random departures from bilateral symmetry. Increased fluctuating asymmetry is thought to parallel compromised fitness, in part, because stress promotes energy dissipation. Compensatory energy expenditures within the organism are required to complete development, thus promoting instability through reductions in homeostasis. Increased heterozygosity may enhance developmental stability by reducing energy dissipation from stress through increased metabolic efficiency, possibly by providing greater flexibility in metabolic pathways. Traditionally, fluctuating asymmetry has been used as a bioindicator of chronic stress, provided that selective mortality of less fit individuals did not reduce stress-mediated increases in fluctuating asymmetry to background levels produced by natural developmental error, or create data inconsistencies such as higher asymmetry in groups exposed to lower stress. Unfortunately, absence of selective mortality and its effects, while often assumed, can be difficult to substantiate. We integrated measures of early growth, mortality, fluctuating asymmetry (mandibular pores, pectoral finrays, pelvic finrays, and gillrakers on the upper and lower arms of the first branchial arch) and directional asymmetry (branchiostegal rays) to assess chronic thermal stress (fluctuating temperatures as opposed to ambient temperatures) in developing eggs from two different coho salmon (Oncorhynchus kisutch) stocks and their reciprocal hybrids. Hybridization provided insight on the capacity of heterozygosity to reduce stress during development. Although egg losses were consistently higher in crosses exposed to fluctuating temperatures, egg mortality was predominantly a function of maternal stock of origin. Post-hatch losses were higher in crosses exposed to ambient temperatures than in crosses exposed to fluctuating temperatures during embryogenesis. Observed patterns of early growth revealed no heterosis, but instead reflected maternal effects, with some crosses slowing growth and yolk utilization when exposed to fluctuating temperatures. Analyses of fluctuating asymmetry also showed no effects from heterosis. While analyses of composite asymmetry scores and branchiostegal rays were inconclusive, analyses of individual characters showed significantly higher fluctuating asymmetry in pelvic finray counts and a marginal change in the numbers of fish asymmetric for this character in crosses exposed to chronic thermal stress. In contrast, the fluctuating asymmetry in lower gillraker counts was significantly higher in crosses exposed to ambient temperatures and there were significantly more fish asymmetric for this character. Data on mortalities and fluctuating asymmetry indicate pelvic finray development was thermally stressed, while the heightened fluctuating asymmetry in lower gillraker counts under ambient temperatures was due to a greater frequency of less fit fish that had not been culled by thermal stress. Changes in early growth patterns in response to developmental stress yielded no parallel responses in meristic characters. We conclude that chronic thermal stress produced both selectively lethal and sublethal effects that directly shaped fluctuating asymmetry and fitness profiles in these crosses. Implicit in this conclusion is that developmental instability analyses can detect more than just chronic sublethal stress, thus providing substantial credence for using instability studies as proactive bioassessment methodologies.

Oikos↗

USGS1986

Shrinkage and growth compensation in common sunflowers: refining estimates of damage

Shrinkage and growth compensation of artificially damaged common sunflowers ( Helianthus annuus ) were studied in central North Dakota during 1981-1982 in an effort to increase accuracy of estimates of blackbird damage to sunflowers. In both years, as plants matured damaged areas on seedheads shrank at a greater rate than the sunflower heads themselves. This differential shrinkage resulted in an underestimation of the area damaged. Sunflower head and damaged-area shrinkage varied widely by time and degree of damage and by size of the seedhead damaged. Because variation in shrinkage by time of damage was so large, predicting when blackbird damage occurs may be the most important factor in estimating seed loss. Yield'occupied seed area was greater ( P < 0.05) for damaged than undamaged heads and tended to increase as degree of damage inflicted increased, indicating growth compensation was occurring in response to lost seeds. Yields of undamaged seeds in seedheads damaged during early seed development were higher than those of heads damaged later. This suggested that there was a period of maximal response to damage when plants were best able to redirect growth to seeds remaining in the head. Sunflowers appear to be able to compensate for damage of ≤ 15% of the total hear area. Estimates of damage can be improved by applying empirical results of differential shrinkage and growth compensations.

Journal of Wildlife Management↗

USGS1999

Bat activity in thinned, unthinned, and old-growth forests in western Oregon

Many aspects of the influences of forest management activities on bats (Chiroptera) in the Pacific Northwest are poorly known. We compared thinned and unthinned forest stands of the same age and old-growth forest stands to determine potential differences in structure and amount of use by bats. We hypothesized that activity levels of bats would differ in stands differing in structure as a result of management history and that activity of bats would be similar in stands of similar structure. We used automated ultrasonic detectors (Anabat II) to record calls of bats in 50-100-year-old thinned and unthinned stands, and in old-growth (a?Y200 yr old) stands in the Oregon Coast Range during the summers of 1994 and 1995. Our median index of bat activity was higher in old-growth than in unthinned stands and higher in thinned than in unthinned stands. We were not able to detect a significant difference between the index of median bat activity for old-growth and thinned stands. More than 90% of identifiable passes were identified as calls from Myotis species. The 3 stand types we examined differed in certain structural characteristics such as density and size of trees, and amount of overstory and understory cover. We concluded that the structural changes caused by thinning may benefit bats by creating habitat structure in young stands that bats are able to use more effectively.

Journal of Wildlife Management↗

USGS2023

CGS: Coupled growth and survival model with cohort fairness

Fish modeling in complex environments is critical for understanding drivers of population dynamics in aquatic systems. This paper proposes a Bayesian network method for modeling fish survival and growth over multiple connected rivers. Traditional fish survival models capture the effect of multiple environmental drivers (e.g., stream temperature, stream flow) by adding different variables, which increases model complexity and results in very long and impractical run times (i.e., weeks). We propose a coupled survival-growth model that leverages the observations from both sources simultaneously. It also integrates the Bayesian process into the neural network model to efficiently capture complex variable relationships in the system while also conforming to known survival processes used in existing fish models. To further reduce the performance disparity of fish body length across cohorts, we propose two approaches for enforcing fairness by the adjustment of training priorities and data augmentation. The results based on a real-world fish dataset collected in Massachusetts, US demonstrate that the proposed method can greatly improve prediction accuracy in modeling survival and body length compared to independent models on survival and growth, and effectively reduce the performance disparity across cohorts. The fish growth and movement patterns discovered by the proposed model are also consistent with prior studies in the same region, while vastly reducing run times and memory requirements.

Conference Paper↗

USGS2008

Geologic controls on the growth of petroleum reserves

The geologic characteristics of selected siliciclastic (largely sandstone) and carbonate (limestone and dolomite) reservoirs in North America (largely the continental United States) were investigated to improve our understanding of the role of geology in the growth of petroleum reserves. Reservoirs studied were deposited in (1) eolian environments (Jurassic Norphlet Formation of the Gulf Coast and Pennsylvanian-Permian Minnelusa Formation of the Powder River Basin), (2) interconnected fluvial, deltaic, and shallow marine environments (Oligocene Frio Formation of the Gulf Coast and the Pennsylvanian Morrow Formation of the Anadarko and Denver Basins), (3) deeper marine environments (Mississippian Barnett Shale of the Fort Worth Basin and Devonian-Mississippian Bakken Formation of the Williston Basin), (4) marine carbonate environments (Ordovician Ellenburger Group of the Permian Basin and Jurassic Smackover Formation of the Gulf of Mexico Basin), (5) a submarine fan environment (Permian Spraberry Formation of the Midland Basin), and (6) a fluvial environment (Paleocene-Eocene Wasatch Formation of the Uinta-Piceance Basin). The connection between an oil reservoir's production history and geology was also evaluated by studying production histories of wells in disparate reservoir categories and wells in a single formation containing two reservoir categories. This effort was undertaken to determine, in general, if different reservoir production heterogeneities could be quantified on the basis of gross geologic differences. It appears that reserve growth in existing fields is most predictable for those in which reservoir heterogeneity is low and thus production differs little between wells, probably owing to relatively homogeneous fluid flow. In fields in which reservoirs are highly heterogeneous, prediction of future growth from infill drilling is notably more difficult. In any case, success at linking heterogeneity to reserve growth depends on factors in addition to geology, such as engineering and technological advances and political or cultural or economic influences.

Bulletin↗

USGS2001

Geologic constraints on the upper limits of reserve growth

For many oil and gas fields, estimates of ultimate recovery (the sum of cumulative production plus estimated reserves) tend to increase from one year to the next, and the gain is called reserve growth. Forecasts of reserve growth by the U.S. Geological Survey rely on statistical analyses of historical records of oil and gas production and estimated reserves. The preproposal in this Open-File Report suggests that this traditional petroleum–engineering approach to reserve growth might be supplemented, or at least better understood, by using geological data from individual oil and gas fields, 3–D modeling software, and standard volumetric techniques to estimate in–place volumes of oil and gas. Such estimates, in turn, can be used to constrain the upper limits of reserve growth and ultimate recovery from those fields.

California↗

USGS2017

Inter-annual variability in apparent relative production, survival, and growth of juvenile Lost River and shortnose suckers in Upper Klamath Lake, Oregon, 2001–15

Executive Summary Populations of the once abundant Lost River ( Deltistes luxatus ) and shortnose suckers ( Chasmistes brevirostris ) of the Upper Klamath Basin, decreased so substantially throughout the 20th century that they were listed under the Endangered Species Act in 1988. Major landscape alterations, deterioration of water quality, and competition with and predation by exotic species are listed as primary causes of the decreases in populations. Upper Klamath Lake populations are decreasing because fish lost due to adult mortality, which is relatively low for adult Lost River suckers and variable for adult shortnose suckers, are not replaced by new young adult suckers recruiting into known adult spawning aggregations. Catch-at-age and size data indicate that most adult suckers presently in Upper Klamath Lake spawning populations were hatched around 1991. While, a lack of egg production and emigration of young fish (especially larvae) may contribute, catch-at-length and age data indicate high mortality during the first summer or winter of life may be the primary limitation to the recruitment of young adults. The causes of juvenile sucker mortality are unknown. We compiled and analyzed catch, length, age, and species data on juvenile suckers from Upper Klamath Lake from eight prior studies conducted from 2001 to 2015 to examine annual variation in apparent production, survival, and growth of young suckers. We used a combination of qualitative assessments, general linear models, and linear regression to make inferences about annual differences in juvenile sucker dynamics. The intent of this exercise is to provide information that can be compared to annual variability in environmental conditions with the hopes of understanding what drives juvenile sucker population dynamics. Age-0 Lost River suckers generally grew faster than age-0 shortnose suckers, but the difference in growth rates between the two species varied among years. This unsynchronized annual variation in daily growth may be an indication that environmental conditions are affecting growth rates of these species in different ways. The combined evidence outlined in this report and in Simon and others (2012) indicates that years of relatively high age-0 sucker production occurred in the late 1990s through at least 2000, in 2006, and in 2011. Our analysis of annual age-0 sucker catch per unit effort (CPUE), which accounted for zero inflated data and annual variation in sampling gears and locations, indicated that 2006 had the greatest apparent relative production of age-0 suckers ≥ 45 mm standard length (SL) during the time period examined. Midsummer trap net effort by the U.S. Geological Survey (USGS) was too sparse to examine age-0 sucker CPUE from 2011 to 2013. Relatively frequent catches of age-1 suckers in 2001, 2007, and 2012 corroborated relatively high CPUE for age-0 suckers during 1999–2000, 2006, and 2011, as reported by USGS or Simon and others (2012). There were several indications in the data that juvenile sucker survival is low from at least midsummer of the first year of life through mid-September of the second year of life. Our estimated index of relative apparent age-0 sucker late-summer survival, which accounted for zero inflated data and variations in sampling gears and locations, was higher in 2009 than in 2004. Our index of apparent age-0 sucker mortality for all other years from 2001 to 2015 was similar among years. Seventy-five percent of age-1 suckers were captured prior to July 17 each year. In 2007, the one year with substantial age-1 sucker summertime catches, the proportion of nets to capture age-1 suckers decreased from July to mid-September. Maximum annual age-2+ sucker CPUE was 0.02 fish per net, 10,000 times less than the maximum annual age-0 sucker CPUE. Analysis of species data indicated that juvenile Lost River suckers may have greater apparent mortality than shortnose suckers. Lost River suckers made up a smaller proportion of age-0 suckers captured in July each year than would be expected, based on the abundance of adult Lost River suckers relative to shortnose suckers, and higher Lost River than shortnose sucker fecundity. The proportion of age-0 suckers captured that were Lost River suckers decreased from July to September in several years. Only 14 percent of age-1 or older juvenile suckers identified to species over the 15-year time period were Lost River suckers.

Oregon↗

USGS2023

Forest structure and residual tree growth at the Northwest Gateway project area, Lassen Volcanic National Park, California

Mechanical thinning and prescribed fire are common mitigation treatments to reduce fire hazards. However, these treatments are infrequently applied together within national parks. The Northwest Gateway project at Lassen Volcanic National Park is an exception to this pattern. Various thinning prescriptions were applied to the project area in 2014, with a subset of the area prescribed burned in 2018 and 2019. To determine responses to these treatments, we analyzed forest structure and fuels data across a network of long-term monitoring plots measured before treatments and in multiple years following treatments. Additionally, we assessed patterns in individual tree growth from cores taken from 101 individual yellow pines (ponderosa pine, Pinus ponderosa Douglas ex Lawson & C. Lawson, and Jeffery pine, P. jeffreyi Grev. & Balf.) within the project unit. Basal area and stem density were reduced following thinning treatments for pole-sized (≤15-centimeter diameter at base height) and overstory trees (>15-centimeter diameter at base height), with sharper reductions in pole-sized trees. Proportional change in live basal area after thinning was highest for pole-size Abies , with more than 80-percent basal area and stem density removed on average. There were large reductions in pole-sized Pinus and Populus . However, Populus trees were not targeted for removal, suggesting that these trees died via other mechanisms. Thinning treatments also resulted in reductions in stand density index values and in surface fuel loading when followed by prescribed fire, particularly for small fuels size classes (such as litter/duff, 1-hour, and 10-hour fuels). Growth of individual residual yellow pine, measured in terms of annual basal area increment, indicated a strong growth release in the years following thinning treatments. Taken together, these results indicate that forest restoration treatments at the Northwest Gateway project area were effective at reducing stand density and encouraging growth of residual Pinus . Interestingly, our results also indicated that although thinning followed by prescribed fire was most effective at reducing surface fuel loads, harvest techniques such as whole tree yarding may effectively reduce the accumulation of post-treatment residual fuels, especially when combined with hand piling and other targeted treatments.

California↗

USGS2023

Age-0 sablefish size and growth indices from seabird diets at Middleton Island, Gulf of Alaska

Sablefish ( Anoplopoma fimbria ) is a commercially valuable groundfish species in Alaska, with the population assessed annually by the National Oceanic and Atmospheric Administration Alaska Fisheries Science Center. Sablefish recruit into the commercially fished population at 2 years old and are poorly sampled by most surveys before that age. However, information on the abundance, distribution, and size of pre-recruitment age fish is valuable as an ecosystem indicator for older fish. Size and an index of growth rate of age-0 sablefish were quantified using samples from seabird diets at Middleton Island, Alaska, an island in the northern Gulf of Alaska. Age-0 sablefish information may serve as an indicator for potential recruitment into older age populations. This report (1) provides information on the data collection for age-0 sablefish from seabird diets at Middleton Island, Alaska from 1978 to 2022, (2) describes a method for quantifying age-0 sablefish size and growth rate, and (3) describes the size and growth rate of sablefish sampled over time. An annual release of age-0 sablefish size and growth data by U.S. Geological Survey based on continued collections on Middleton Island, Alaska, may be used to assess ecosystem status and as a recruitment indicator for sablefish.

Alaska↗

USGS2021

Crater growth and lava-lake dynamics revealed through multitemporal terrestrial lidar scanning at Kīlauea Volcano, Hawaiʻi

Lava lake surfaces display the tops of active magma columns and respond to eruption variables such as magmatic pressure, convection, degassing, and cooling, as well as interactions with the craters that contain them. However, they are challenging to study owing to the numerous hazards that accompany these eruptions, and they are typically difficult to observe because the emitted gas plumes obscure the lava lake surfaces. The 2008–2018 Overlook crater and lava lake at Kīlauea Volcano, Hawaiʻi, provided a remarkable opportunity to study several high-resolution data streams of eruption variables that impacted the lava lake. To investigate how the crater and associated lava lake responded to changes in these eruption variables, we acquired terrestrial light detection and ranging (lidar) surveys of the Overlook crater and lava lake surface from February 2012 through December 2013, supplemented with several earlier terrestrial and airborne lidar datasets, to quantitatively track changes in the shape of the lava lake surface and the crater walls. Lidar captures high-resolution data even when the lake is completely obscured by thick gas plumes. We used a novel “unrolling technique” to map volumetric changes in crater shape, because standard elevation differencing fails to capture all topographic changes on the nearly vertical, and sometimes overhanging, crater walls. We measured crater perimeter growth rates of approximately 52 meters per year from 2009 to 2013, with the greatest growth occurring along a line linking areas of persistent upwelling and downwelling. We suggest that the development of an oblong crater with a perimeter that grows linearly is best explained by a model where degradation is favored at the sites of persistent upwelling and downwelling and where growth is controlled by a lithology that varies little with respect to rock strength. We also found that most of the Overlook crater growth occurred during a relatively small number of significant rockfall events (~16) over this period. Additional lidar datasets revealed that the lava lake surface has a measurable slope from the areas of persistent upwelling to downwelling, although rockfalls from the crater walls temporarily changed the direction of crustal plate movement along with the magnitude and direction of the lava lake surface slope. Our study demonstrates that lidar is an effective tool for tracking the topography of an active volcanic crater when heavy outgassing renders other tools, such as structure from motion, ineffective.

Hawaii↗

USGS2006

Growth-Form Characteristics of Ancient Rocky Mountain Bristlecone Pines (Pinus aristata), Colorado

This report describes and illustrates growth-form characteristics of Rocky Mountain bristlecone pines (Pinus aristata) at several sites in the Rocky Mountains in Colorado. Most of this study concentrates on 1,000- to 2,500-year-old bristlecone pines; however, the report also describes some of the growth-form characteristics of younger trees (about 20 to less than 1,000 years old) in order to show the continuous changes in tree form from youth to old age. To better describe the trees in this study, some tree-structure nomenclature is introduced and a growth-form classification system is provided. Other topics include the relationship of the trees to their substrate and the potential changes in the growth forms of some bristlecone pines due to damage caused by fire, porcupines, impacts from tumbling boulders, and lightning strikes.

Scientific Investigations Report↗

USGS2013

Reserve growth of oil and gas fields—Investigations and applications

The reserve growth of fields has been a topic for ongoing discussion for over half a century and will continue to be studied well into the future. This is due to the expected size of the volumetric contribution of reserve growth to the future supply of oil and natural gas. Understanding past methods of estimating future volumes based on the data assembly methods that have been used can lead to a better understanding of their applicability. The statistical nature of past methods and the (1) possible high level of dependency on a limited number of fields, (2) assumption of an age-based correlation with effective reserve growth, and (3) assumption of long-lived and more common than not reserve growth, may be improved by employing a more geologically based approach.

Scientific Investigations Report↗