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At least 109 records · Page 6Linked to original sources
USGS2019

Coastal marsh bird habitat selection and responses to Hurricane Sandy

Wetlands provide numerous ecosystem functions such as water purification, nutrient cycling, and wildlife habitat. Avian populations are indicators of wetland health, and understanding their responses to extreme events can aid in targeting restoration efforts following disturbance. Here, we assessed the habitat selection of six coastal wetland bird species (American Bittern, Black-crowned Night Heron, Great Egret, Glossy Ibis, Snowy Egret, Yellow-crowned Night Heron) related to an extreme weather event, Hurricane Sandy. We used Discrete Choice Resource Selection Functions to estimate habitat selection. Results showed species probability of use increased with lower elevation and slope, and closer proximity to marsh, salt marsh, Phragmites , and protected areas. Estimates of marsh dieback from Hurricane Sandy occurred disproportionately in areas with higher probability of species use. Species were observed farther from the coast and at higher elevations in the four breeding seasons after (2013–2016) compared to before (2000–2012) Hurricane Sandy. Our results indicate that although high suitability areas were affected by the storm, these six wetland bird species may have responded by moving inland and to higher elevation. Understanding how coastal wetland birds respond to storm events is important for conservation planning, particularly as storm frequency is projected to increase in the future.

New Jersey↗
USGS2013

Environmental clustering of lakes to evaluate performance of a macrophyte index of biotic integrity

Proper classification of sites is critical for the use of biological indices that can distinguish between natural and human-induced variation in biological response. The macrophyte-based index of biotic integrity was developed to assess the condition of Minnesota lakes in relation to anthropogenic stressors, but macrophyte community composition varies naturally across the state. The goal of the study was to identify environmental characteristics that naturally influence macrophyte index response and establish a preliminary lake classification scheme for biological assessment (bioassessment). Using a comprehensive set of environmental variables, we identified similar groups of lakes by clustering using flexible beta classification. Variance partitioning analysis of IBI response indicated that evaluating similar lake clusters could improve the ability of the macrophyte index to identify community change to anthropogenic stressors, although lake groups did not fully account for the natural variation in macrophyte composition. Diagnostic capabilities of the index could be improved when evaluating lakes with similar environmental characteristics, suggesting the index has potential for accurate bioassessment provided comparable groups of lakes are evaluated.

Minnesota↗
USGS2013

An algorithmic and information-theoretic approach to multimetric index construction

The use of multimetric indices (MMIs), such as the widely used index of biological integrity (IBI), to measure, track, summarize and infer the overall impact of human disturbance on biological communities has been steadily growing in recent years. Initially, MMIs were developed for aquatic communities using pre-selected biological metrics as indicators of system integrity. As interest in these bioassessment tools has grown, so have the types of biological systems to which they are applied. For many ecosystem types the appropriate biological metrics to use as measures of biological integrity are not known a priori. As a result, a variety of ad hoc protocols for selecting metrics empirically has developed. However, the assumptions made by proposed protocols have not be explicitly described or justified, causing many investigators to call for a clear, repeatable methodology for developing empirically derived metrics and indices that can be applied to any biological system. An issue of particular importance that has not been sufficiently addressed is the way that individual metrics combine to produce an MMI that is a sensitive composite indicator of human disturbance. In this paper, we present and demonstrate an algorithm for constructing MMIs given a set of candidate metrics and a measure of human disturbance. The algorithm uses each metric to inform a candidate MMI, and then uses information-theoretic principles to select MMIs that capture the information in the multidimensional system response from among possible MMIs. Such an approach can be used to create purely empirical (data-based) MMIs or can, optionally, be influenced by expert opinion or biological theory through the use of a weighting vector to create value-weighted MMIs. We demonstrate the algorithm with simulated data to demonstrate the predictive capacity of the final MMIs and with real data from wetlands from Acadia and Rocky Mountain National Parks. For the Acadia wetland data, the algorithm identified 4 metrics that combined to produce a -0.88 correlation with the human disturbance index. When compared to other methods, we find this algorithmic approach resulted in MMIs that were more predictive and comprise fewer metrics.

Ecological Indicators↗
USGS2011

Evaluating the effects of future climate change and elevated CO 2 on the water use efficiency in terrestrial ecosystems of China

Water use efficiency (WUE) is an important variable used in climate change and hydrological studies in relation to how it links ecosystem carbon cycles and hydrological cycles together. However, obtaining reliable WUE results based on site-level flux data remains a great challenge when scaling up to larger regional zones. Biophysical, process-based ecosystem models are powerful tools to study WUE at large spatial and temporal scales. The Integrated BIosphere Simulator (IBIS) was used to evaluate the effects of climate change and elevated CO 2 concentrations on ecosystem-level WUE (defined as the ratio of gross primary production (GPP) to evapotranspiration (ET)) in relation to terrestrial ecosystems in China for 2009–2099. Climate scenario data (IPCC SRES A2 and SRES B1) generated from the Third Generation Coupled Global Climate Model (CGCM3) was used in the simulations. Seven simulations were implemented according to the assemblage of different elevated CO 2 concentrations scenarios and different climate change scenarios. Analysis suggests that (1) further elevated CO 2 concentrations will significantly enhance the WUE over China by the end of the twenty-first century, especially in forest areas; (2) effects of climate change on WUE will vary for different geographical regions in China with negative effects occurring primarily in southern regions and positive effects occurring primarily in high latitude and altitude regions (Tibetan Plateau); (3) WUE will maintain the current levels for 2009–2099 under the constant climate scenario (i.e. using mean climate condition of 1951–2006 and CO 2 concentrations of the 2008 level); and (4) WUE will decrease with the increase of water resource restriction (expressed as evaporation ratio) among different ecosystems.

Ecological Modelling↗
USGS2022

Active forest management accelerates carbon storage in plantation forests in Lishui, southern China

Background China has committed to achieving peak CO 2 emissions before 2030 and carbon neutrality before 2060; therefore, accelerated efforts are needed to better understand carbon accounting in industry and energy fields as well as terrestrial ecosystems. The carbon sink capacity of plantation forests contributes to the mitigation of climate change. Plantation forests throughout the world are intensively managed, and there is an urgent need to evaluate the effects of such management on long-term carbon dynamics. Methods We assessed the carbon cycling patterns of ecosystems characterized by three typical plantation species (Chinese fir ( Cunninghamia lanceolata (Lamb.) Hook.), oak ( Cyclobalanopsis glauca (Thunb.) Oerst.), and pine ( Pinus massoniana Lamb.)) in Lishui, southern China, by using an integrated biosphere simulator (IBIS) tuned with localized parameters. Then, we used the state-and-transition simulation model (STSM) to study the effects of active forest management (AFM) on carbon storage by combining forest disturbance history and carbon cycle regimes. Results 1) The carbon stock of the oak plantation was lower at an early age (<50 years) but higher at an advanced age (>50 years) than that of the Chinese fir and pine plantations. 2) The carbon densities of the pine and Chinese fir plantations peaked at 70 years (223.36 ​Mg·ha ‒1 ) and 64 years (232.04 ​Mg·ha ‒1 ), respectively, while the carbon density in the oak plantation continued increasing (>100 years). 3) From 1989 to 2019, the total carbon pools of the three plantation ecosystems followed an upward trend (an annual increase of 0.16–0.22 ​Tg ​C), with the largest proportional increase in the aboveground biomass carbon pool. 4) AFM increased the recovery of carbon storage after 1996 and 2009 in the pine and Chinese fir plantations, respectively, but did not result in higher growth in the oak plantation. 5) The proposed harvest planning is reasonable and conducive to maximizing the carbon sequestration capacity of the forest. Conclusions This study provides an example of a carbon cycle coupling model that is potentially suitable for simulating China's plantation forest ecosystems and supporting carbon accounting to monitor peak CO 2 emissions and reach carbon neutrality.

Lishui↗
USGS2012

Effects of future climate change, CO 2 enrichment, and vegetation structure variation on hydrological processes in China

Investigating the relationship between factors (climate change, atmospheric CO 2 concentrations enrichment, and vegetation structure) and hydrological processes is important for understanding and predicting the interaction between the hydrosphere and biosphere. The Integrated Biosphere Simulator (IBIS) was used to evaluate the effects of climate change, rising CO 2 , and vegetation structure on hydrological processes in China at the end of the 21st century. Seven simulations were implemented using the assemblage of the IPCC climate and CO 2 concentration scenarios, SRES A2 and SRES B1. Analysis results suggest that (1) climate change will have increasing effects on runoff, evapotranspiration (ET), transpiration (T), and transpiration ratio (transpiration/evapotranspiration, T/E) in most hydrological regions of China except in the southernmost regions; (2) elevated CO 2 concentrations will have increasing effects on runoff at the national scale, but at the hydrological region scale, the physiology effects induced by elevated CO 2 concentration will depend on the vegetation types, climate conditions, and geographical background information with noticeable decreasing effects shown in the arid Inland region of China; (3) leaf area index (LAI) compensation effect and stomatal closure effect are the dominant factors on runoff in the arid Inland region and southern moist hydrological regions, respectively; (4) the magnitudes of climate change (especially the changing precipitation pattern) effects on the water cycle are much larger than those of the elevated CO 2 concentration effects; however, increasing CO 2 concentration will be one of the most important modifiers to the water cycle; (5) the water resource condition will be improved in northern China but depressed in southernmost China under the IPCC climate change scenarios, SRES A2 and SRES B1.

Global and Planetary Change↗
USGS2013

Effect of heterogeneous atmospheric CO2 on simulated global carbon budget

The effects of rising atmospheric carbon dioxide (CO 2 ) on terrestrial carbon (C) sequestration have been a key focus in global change studies. As anthropological CO2 emissions substantially increase, the spatial variability of atmospheric CO 2 should be considered to reduce the potential bias on C source and sink estimations. In this study, the global spatial–temporal patterns of near surface CO 2 concentrations for the period 2003-2009 were established using the SCIAMACHY satellite observations and the GLOBALVIEW-CO 2 field observations. With this CO 2 data and the Integrated Biosphere Simulator (IBIS), our estimation of the global mean annual NPP and NEP was 0.5% and 7% respectively which differs from the traditional C sequestration assessments. The Amazon, Southeast Asia, and Tropical Africa showed higher C sequestration than the traditional assessment, and the rest of the areas around the world showed slightly lower C sequestration than the traditional assessment. We find that the variability of NEP is less intense under heterogeneous CO 2 pattern on a global scale. Further studies of the cause of CO 2 variation and the interactions between natural and anthropogenic processes of C sequestration are needed.

Global and Planetary Change↗
USGS2014

An analysis of the global spatial variability of column-averaged CO 2 from SCIAMACHY and its implications for CO 2 sources and sinks

Satellite observations of carbon dioxide (CO 2 ) are important because of their potential for improving the scientific understanding of global carbon cycle processes and budgets. We present an analysis of the column-averaged dry air mole fractions of CO 2 (denoted XCO 2 ) of the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) retrievals, which were derived from a satellite instrument with relatively long-term records (2003–2009) and with measurements sensitive to the near surface. The spatial-temporal distributions of remotely sensed XCO 2 have significant spatial heterogeneity with about 6–8% variations (367–397 ppm) during 2003–2009, challenging the traditional view that the spatial heterogeneity of atmospheric CO 2 is not significant enough (<4%) to have any large effect on terrestrial ecosystem carbon cycles. By comparison with surface measurements from the NOAA Earth System Research Laboratory (ESRL) GLOBALVIEW network, significant statistical relationships between XCO 2 and surface CO 2 were found for major ecosystems, with the exception of tropical forest. In addition, when compared with a simulated terrestrial carbon uptake from the Integrated Biosphere Simulator (IBIS) and the Emissions Database for Global Atmospheric Research (EDGAR) carbon emission inventory, the latitudinal gradient of XCO 2 seasonal amplitude was influenced by the combined effect of terrestrial carbon uptake, carbon emission, and atmospheric transport, suggesting no direct implications for terrestrial carbon sinks. From the investigation of the growth rate of XCO 2 we found that the increase of CO 2 concentration was dominated by temperature in the northern hemisphere (20–90°N) and by precipitation in the southern hemisphere (20–90°S), with the major contribution to global average occurring in the northern hemisphere. These findings indicated that the satellite measurements of atmospheric CO 2 improve not only the estimations of atmospheric inversion, but also the understanding of the terrestrial ecosystem carbon dynamics and its feedback to atmospheric CO 2 .

International Journal of Remote Sensing↗
USGS2002

Recovery of severely compacted soils in the Mojave Desert, California, USA

Often as a result of large-scale military maneuvers in the past, many soils in the Mojave Desert are highly vulnerable to soil compaction, particularly when wet. Previous studies indicate that natural recovery of severely compacted desert soils is extremely slow, and some researchers have suggested that subsurface compaction may not recover. Poorly sorted soils, particularly those with a loamy sand texture, are most vulnerable to soil compaction, and these soils are the most common in alluvial fans of the Mojave Desert. Recovery of compacted soil is expected to vary as a function of precipitation amounts, wetting-and-drying cycles, freeze-thaw cycles, and bioturbation, particularly root growth. Compaction recovery, as estimated using penetration depth and bulk density, was measured at 19 sites with 32 site-time combinations, including the former World War II Army sites of Camps Ibis, Granite, Iron Mountain, Clipper, and Essex. Although compaction at these sites was caused by a wide variety of forces, ranging from human trampling to tank traffic, the data do not allow segregation of differences in recovery rates for different compaction forces. The recovery rate appears to be logarithmic, with the highest rate of change occurring in the first few decades following abandonment. Some higher-elevation sites have completely recovered from soil compaction after 70 years. Using a linear model of recovery, the full recovery time ranges from 92 to 100 years; using a logarithmic model, which asymptotically approaches full recovery, the time required for 85% recovery ranges from 105-124 years.

Arid Land Research and Management↗
USGS1983

Feeding habitats of nesting wading birds: Spatial use and social influences

In an effort to relate social interactions to feeding-habitat use, I observed six species of wading birds near a major colony site in coastal North Carolina. Three spatial scales of habitat use were considered: the general orientation to and from the colony (coarsest level), the habitat "patch," and (at the finest level) the microhabitat. Departure-arrival directions of Great Egrets ( Casmerodius albus ), Snowy Egrets ( Egretta thula ), Cattle Egrets ( Bubulcus ibis ), Little Blue Herons ( Egretta caerulea ), Tricolored Herons ( Egretta tricolor ), and Glossy Ibises ( Plegadis falcinellus ) were monitored at the colony site to document coarse patterns of feeding-habitat use. Added to these data were observations made at five different wetland sites to monitor between-habitat and within-habitat patterns for the five aquatic-feeding species. The results indicated a broad and variable use of feeding habitat over time. At the coarsest scale (i.e. orientation at the colony), diffuse patterns, influenced little by either inter- or intraspecific social interaction, were found for all species. At the next level (habitat "patch"), only one of five wetland sites was relatively consistent in attracting feeding birds, and its use increased from May to June. Few groups were seen at four of the five sites. At the one "attractive" site, the within-habitat patterns again were spatially variable over time, except for those of the abundant Snowy Egret, whose microhabitat preference was fairly consistent. Glossy Ibises and Snowy Egrets frequently formed mixed-species groups, Little Blue Herons were the least social, and Great Egrets and Tricolored Herons generally occurred in groups of less than 10 birds but rarely in groups larger than 30. The close association between Snowy Egrets and Glossy Ibises appeared to be based on a "beater-follower" relationship, wherein the probing, nonvisually feeding ibises make prey more available to the followers. In the study area, local enhancement appeared to play a more important role than did any "information-sharing" at the colony.

North Carolina↗
USGS2009

Effects of climate change on soil moisture over China from 1960-2006

Soil moisture is an important variable in the climate system and it has sensitive impact on the global climate. Obviously it is one of essential components in the climate change study. The Integrated Biosphere Simulator (IBIS) is used to evaluate the spatial and temporal patterns of soil moisture across China under the climate change conditions for the period 1960-2006. Results show that the model performed better in warm season than in cold season. Mean errors (ME) are within 10% for all the months and root mean squared errors (RMSE) are within 10% except winter season. The model captured the spatial variability higher than 50% in warm seasons. Trend analysis based on the Mann-Kendall method indicated that soil moisture in most area of China is decreased especially in the northern China. The areas with significant increasing trends in soil moisture mainly locate at northwestern China and small areas in southeastern China and eastern Tibet plateau. ?? 2009 IEEE.

Conference Paper↗
USGS2007

Influences of watershed, riparian-corridor, and reach-scale characteristics on aquatic biota in agricultural watersheds

Multivariate analyses and correlations revealed strong relations between watershed and riparian-corridor land cover, and reach-scale habitat versus fish and macroinvertebrate assemblages in 38 warmwater streams in eastern Wisconsin. Watersheds were dominated by agricultural use, and ranged in size from 9 to 71 km 2 Watershed land cover was summarized from satellite-derived data for the area outside a 30-m buffer. Riparian land cover was interpreted from digital orthophotos within 10-, 10-to 20-, and 20-to 30-m buffers. Reach-scale habitat, fish, and macroinvertebrates were collected in 1998 and biotic indices calculated. Correlations between land cover, habitat, and stream-quality indicators revealed significant relations at the watershed, riparian-corridor, and reach scales. At the watershed scale, fish diversity, intolerant fish and EPT species increased, and Hilsenhoff biotic index (HBI) decreased as percent forest increased. At the riparian-corridor scale, EPT species decreased and HBI increased as riparian vegetation became more fragmented. For the reach, EPT species decreased with embeddedness. Multivariate analyses further indicated that riparian (percent agriculture, grassland, urban and forest, and fragmentation of vegetation), watershed (percent forest) and reach-scale characteristics (embeddedness) were the most important variables influencing fish (IBI, density, diversity, number, and percent tolerant and insectivorous species) and macroinvertebrate (HBI and EPT) communities.

Wisconsin↗
USGS2004

Stream salamanders as indicators of stream quality in Maryland, USA

Biological indicators are critical to the protection of small, headwater streams and the ecological values they provide. Maryland and other state monitoring programs have determined that fish indicators are ineffective in small streams, where stream salamanders may replace fish as top predators. Because of their life history, physiology, abundance, and ubiquity, stream salamanders are likely representative of biological integrity in these streams. The goal of this study was to determine whether stream salamanders are effective indicators of ecological conditions across biogeographic regions and gradients of human disturbance. During the summers of 2001 and 2002, we intensively surveyed for stream salamanders at 76 stream sites located west of the Maryland Coastal Plain, sites also monitored by the Maryland Biological Stream Survey (MBSS) and City of Gaithersburg. We found 1,584 stream salamanders, including all eight species known in Maryland, using two 15 ? 2 m transects and two 4 m2 quadrats that spanned both stream bank and channel. We performed removal sampling on transects to estimate salamander species detection probabilities, which ranged from 0.67-0.85. Stepwise regressions identified 15 of 52 non-salamander variables, representing water quality, physical habitat, land use, and biological conditions, which best predicted salamander metrics. Indicator development involved (1) identifying reference (non-degraded) and degraded sites (using percent forest, shading, riparian buffer width, aesthetic rating, and benthic macroinvertebrate and fish indices of biotic integrity); (2) testing 12 candidate salamander metrics (representing species richness and composition, abundance, species tolerance, and reproductive function) for their ability to distinguish reference from degraded sites; and (3) combining metrics into an index that effectively discriminated sites according to known stream conditions. Final indices for Highlands, Piedmont, and Non-Coastal Plain regions comprised four metrics: number of species, number of salamanders, number of intolerant salamanders, and number of adult salamanders, producing classification efficiencies between 87% and 90%. Partial validation of these indices was obtained when a test of the number of salamanders metric produced an 82% correct classification of 618 MBSS sites surveyed in 1995-97. This study supports the use of stream salamander monitoring and a composite stream salamander index of biotic integrity (SS-IBI) to determine stream quality in Maryland.

Applied Herpetology↗
USGS2014

Physiological condition of juvenile wading birds in relation to multiple landscape stressors in the Florida Everglades: effects of hydrology, prey availability, and mercury bioaccumulation

The physiological condition of juvenile birds can be influenced by multiple ecological stressors, and few studies have concurrently considered the effects of environmental contaminants in combination with ecological attributes that can influence foraging conditions and prey availability. Using three temporally distinct indices of physiological condition, we compared the physiological response of nestling great egrets ( Ardea alba ) and white ibises ( Eudocimus albus ) to changing prey availability, hydrology (water depth, recession rate), and mercury exposure in the Florida Everglades. We found that the physiological response of chicks varied between species and among environmental variables. Chick body condition (short-term index) and fecal corticosterone levels (medium-term) were influenced by wetland water depth, prey availability, region, and age, but not by mercury contamination. However, mercury exposure did influence heat shock protein 70 (HSP70) in egret chicks, indicating a longer-term physiological response to contamination. Our results indicate that the physiological condition of egret and ibis chicks were influenced by several environmental stressors, and the time frame of the effect may depend on the specialized foraging behavior of the adults provisioning the chicks.

Florida↗
USGS2015

Linking dynamic habitat selection with wading bird foraging distributions across resource gradients

Species distribution models (SDM) link species occurrence with a suite of environmental predictors and provide an estimate of habitat quality when the variable set captures the biological requirements of the species. SDMs are inherently more complex when they include components of a species' ecology such as conspecific attraction and behavioral flexibility to exploit resources that vary across time and space. Wading birds are highly mobile, demonstrate flexible habitat selection, and respond quickly to changes in habitat quality; thus serving as important indicator species for wetland systems. We developed a spatio-temporal, multi-SDM framework using Great Egret ( Ardea alba ), White Ibis ( Eudocimus albus ), and Wood Stork ( Mycteria Americana ) distributions over a decadal gradient of environmental conditions to predict species-specific abundance across space and locations used on the landscape over time. In models of temporal dynamics, species demonstrated conditional preferences for resources based on resource levels linked to differing temporal scales. Wading bird abundance was highest when prey production from optimal periods of inundation was concentrated in shallow depths. Similar responses were observed in models predicting locations used over time, accounting for spatial autocorrelation. Species clustered in response to differing habitat conditions, indicating that social attraction can co-vary with foraging strategy, water-level changes, and habitat quality. This modeling framework can be applied to evaluate the multi-annual resource pulses occurring in real-time, climate change scenarios, or restorative hydrological regimes by tracking changing seasonal and annual distribution and abundance of high quality foraging patches.

PLoS ONE↗
USGS2023

A comparison of direct & indirect survey methods for estimating colonial nesting waterbird populations

Population estimates derived from monitoring efforts can be sensitive to the survey method selected, potentially leading to biased estimates and low precision relative to true population size. While small unmanned aerial systems (UAS) present a unique opportunity to survey avian populations while limiting disturbance, relatively little is known about how this method compares with more traditional approaches. In this study we compared population estimates of Snowy ( Egretta thula ) and Cattle Egrets ( Bubulcus ibis ) in a mixed-species colony in the Chesapeake Bay (Maryland, USA) derived from UAS photo counts, flush counts, flight-line surveys, and in-colony nest counts along with the time required to derive an estimate via each approach. We found that UAS counts and flush counts produced lower pair estimates than nest counts and flight-line surveys ( P < 0.05), and required dramatically less time (x̄ = 6, 8, 84 and 90 min, respectively). These results suggest that while UAS have the potential to collect valuable survey data from breeding colonies that are hard to reach or are especially sensitive to the disturbance inherent in other methods, inherent biases should be considered and caution should be used when comparing results between survey types.

Maryland↗
USGS2011

Use of the superpopulation approach to estimate breeding population size: An example in asynchronously breeding birds

Many populations of animals are fluid in both space and time, making estimation of numbers difficult. Much attention has been devoted to estimation of bias in detection of animals that are present at the time of survey. However, an equally important problem is estimation of population size when all animals are not present on all survey occasions. Here, we showcase use of the superpopulation approach to capture–recapture modeling for estimating populations where group membership is asynchronous, and where considerable overlap in group membership among sampling occasions may occur. We estimate total population size of long‐legged wading bird (Great Egret and White Ibis) breeding colonies from aerial observations of individually identifiable nests at various times in the nesting season. Initiation and termination of nests were analogous to entry and departure from a population. Estimates using the superpopulation approach were 47–382% larger than peak aerial counts of the same colonies. Our results indicate that the use of the superpopulation approach to model nesting asynchrony provides a considerably less biased and more efficient estimate of nesting activity than traditional methods. We suggest that this approach may also be used to derive population estimates in a variety of situations where group membership is fluid.

Florida↗