Autumn Density Research Articles

Urban form and seasonal PM2.5 dynamics: Enhancing air quality prediction using interpretable machine learning and IoT sensor data

This study investigates the critical issue of how urban form characteristics influence PM2.5 concentrations, a key concern for public health in densely populated cities. Traditional monitoring methods have faced data gaps and methodological limitations. To address this, we employed interpretable machine learning (ML) models with data from 1,069 Internet-of-Things (IoT) sensors across Seoul, South Korea (September 2020–August 2023). Over 80 urban form variables—including density, transportation, road design, building morphology, and land use—were analyzed using Recursive Feature Elimination to identify key factors affecting PM2.5 concentrations within three buffer zones (300-m, 500-m, 1-km). The random forest model demonstrated the highest accuracy, with an R² of 95 % for autumn and 96 % for spring. Our findings show higher PM2.5 levels in colder months, driven by road width and building density in autumn and traffic and industrial activity in winter. In summer, green spaces and meteorological conditions were primary factors, while spring air quality was notably impacted by localized traffic emissions around highways and bus stops. This study offers robust predictions and actionable insights for urban planning and air quality management. Future research could integrate additional environmental variables and expand sensor coverage to further refine predictive models.

Restricted recovery of Eisenia bicyclis kelp forest following sea urchin removal on the Pacific coast of Tohoku, Japan

Little information is available on the destruction of Eisenia bicyclis kelp forests (Phaeophyceae: Laminariales) due to overgrazing by sea urchins. In Shizugawa Bay, on the northeastern Pacific coast of Japan, overgrazing by the sea urchin Mesocentrotus nudus caused the destruction of E. bicyclis forests between 2014 and 2015. This study investigated the recovery of an adult kelp forest in relation to sea urchin densities through the continuous removal of sea urchins at 3 permanent experimental transects spanning 100 m2 for 3.8 yr from September 2015 to June 2019. The relationship between the densities of sea urchins and kelp juveniles was also analyzed. Estimates of the threshold density and biomass of sea urchins required to trigger the phase shift from an E. bicyclis forest to a barren were 15.5 ind. m-2 and 712.0 g m-2, respectively. The removal of sea urchins expanded the offshore kelp growth area. However, an increase in adult kelp following the return of juveniles was restricted to the nearshore half of the transects. The successful recruitment of kelp juveniles, followed by the recovery of adult kelp forest, requires reduction of the density of M. nudus of 40-50 mm diameter to 0 or 1 ind. m-2. Reducing sea urchin densities in autumn, when many move from barrens to invade kelp forests, is crucial to ensure the survival of kelp juveniles. This study highlights the presence of an intensified positive feedback mechanism of the barren state due to high grazing intensity and a weakened Oyashio Current.

Analysis of environmental factors influencing lumpy skin disease outbreak seasonality and assessment of its spread risk in the Saratovskaya oblast of Russia.

Lumpy skin disease (LSD) is a transboundary viral disease of cattle that causes serious economic losses due to a significant decrease in meat and milk productivity. This study analyzed the influence of natural and anthropogenic environmental factors on LSD spread seasonality and assessed the risk of LSD outbreaks in the Saratovskaya oblast of the Russian Federation. Data on LSD outbreaks and environmental factors during different seasons were collected for the period 2011-2020 in the Balkan Peninsula, Middle East, and Russia. Risk assessment was performed using mathematical modeling with generalized linear regression and maximum entropy. Fourteen statistically significant environmental factors influencing LSD spread were identified. The analysis of MaxEnt models built using the selected factors showed that the presence of the pathogen is mostly exerted by: the density of susceptible cattle (an increased risk is observed at a density above 10 and 20 heads/10 km2 in winter and autumn, with a permanent risk in spring and summer), the density of water bodies (the risk is increased at any density in winter and autumn, in the range of 13-23.5 m2/km2 in spring, in the ranges of 0-8 and over 14.5 m2/km2 in summer), and average monthly precipitation rate (the most risky are 105-185 mm/month in winter, 35 mm in spring, 15-105 mm in summer, and above 50 mm in autumn). LSD tends to spread during the warm season. Compared with other test zones, the Saratovskaya oblast has a negligible risk of disease spread (in winter), low risk (in spring), or medium risk (in summer and autumn). The annual risk is low to medium.

Cumulative effects of offshore wind farms on common guillemots (Uria aalge) in the southern North Sea - climate versus biodiversity?

Governments are under increasing pressure to reduce greenhouse gas emissions, and large-scale wind farms are being developed in marine environments worldwide. However, top predators are strongly affected by environmental change and anthropogenic activities. Common guillemots (Uria aalge, hereafter guillemots), as one of the world’s most numerous seabird species, are prone to interference with offshore wind farms (OWFs). This study assessed the cumulative impacts of all operating OWFs on guillemots in the German North Sea. These estimates were applied to quantify the possible conflicts between guillemot occurrence and current German government plans to implement large-scale OWFs. If OWFs were implemented according to the current maritime spatial plan for the German Exclusive Economic zone, they would cover 13% of the German North Sea. Guillemot numbers peak during autumn, with German North Sea offshore waters hosting approximately 90,000 individuals. Guillemot density in autumn was significantly reduced within a radius of 19.5 km around operating OWFs. Applying this disturbance distance to current installation plans, about 70% of the German North Sea would be affected, and an estimated 68% of guillemots in the German North Sea would experience habitat loss. This highlights the possible threat to guillemots in the southern North Sea if the current German government plans are implemented. The current estimates are highly relevant to decisions regarding marine spatial planning and management recommendations. Such evaluations are essential for developing sustainable scenarios including reducing the human CO2 footprint, whilst also conserving biodiversity.

Seasonal and daily effects of the sea on the surface urban heat island intensity: A case study of cities in the Caspian Sea Plain

This study aimed to explore the effect of the sea on the spatial and temporal changes in surface urban heat island (SUHI) intensity. Therefore, 11 cities located along the Caspian Sea Plain were selected as the case studies. Firstly, the SUHI intensity of both coastal and non-coastal cities was calculated for different seasons and times of day and night. Finally, the effect of distance from the sea on the SUHI intensity was calculated by modeling the relationship between the SUHI intensity and a set of independent parameters such as urban surface biophysical properties, population density, and distance from the coastline. The results showed that by increasing the distance of cities from the sea, the daily SUHI intensity increased, while it reversed during the night. The RMSE values between the actual and simulated SUHI intensities based on population density and surface biophysical properties in spring, summer, autumn, and winter were 0.9, 1.1, 0.5, and 0.3 °C, respectively. By factoring in the distance from the sea in the modeling, the RMSE values for different seasons were obtained at 0.7, 0.8, 0.3, and 0.2 °C, respectively. The results show that distance from the sea has a significant effect on UHI intensity.

Population Fluctuations of the Deer Mouse (Peromyscus maniculatus) in Old-Field and Bunchgrass–Sagebrush Habitats: The Role of Agricultural Setting and Optimum Habitat

In semiarid regions, the deer mouse (Peromyscus maniculatus) is a major small mammal species occupying perennial grassland habitats that include old-fields, native bunchgrass–sagebrush, and some agricultural settings. We investigated population changes in deer mouse populations in perennial grasslands, both natural and old-field, from 1982 to 2003 in southern British Columbia, Canada. Hypotheses (H) predicted that P. maniculatus populations will have (H1) multiannual fluctuations in abundance driven by population increases from extended breeding in summer and winter; (H2) relaxed spring reorganization events in some years leading to higher overall recruitment and survival; and (H3) interspecific competition with montane voles that causes deer mice to be lower in density when voles are higher. P. maniculatus populations in old-field and grass–sagebrush sites had clearly defined periods of high “peak” mean numbers (32–52/ha) and other times of low mean numbers (20–22/ha). Based on mean annual peak density in autumn, deer mouse populations exhibited fluctuations of 3–4 years in both habitats, but this pattern was not always present. The greater numbers of P. maniculatus in high than low years was directly related to population increases from extended breeding seasons and an increased number of lactating females, thereby supporting H1. Spring breeding season declines occurred but were similar or less in high than low years of mean abundance and were relaxed in comparison to forest populations of deer mice in other studies. Thus, H2 was supported for recruitment with high numbers of young-of-the-year breeding and total number of juvenile recruits but for survival was equivocal. Total summer survival was consistently higher in high than low population years but juvenile productivity in all years was poor. Mean abundance of P. maniculatus and M. montanus in old-field sites were highly correlated, and hence H3 was not supported. This latter result is the first, to our knowledge, of P. maniculatus coexisting in a similar pattern of population fluctuations with a Microtus species in a mainland grassland habitat. Higher than average precipitation in the year preceding a peak population of deer mice may have enhanced herbaceous vegetation and contributed to population increases in both habitats. We conclude that the old-field habitat associated with this agricultural setting provides optimum habitat for P. maniculatus and facilitates multiannual population fluctuations in this species.

Camera Trap Methods and Drone Thermal Surveillance Provide Reliable, Comparable Density Estimates of Large, Free-Ranging Ungulates.

Camera traps and drone surveys both leverage advancing technologies to study dynamic wildlife populations with little disturbance. Both techniques entail strengths and weaknesses, and common camera trap methods can be confounded by unrealistic assumptions and prerequisite conditions. We compared three methods to estimate the population density of white-tailed deer (Odocoileus virgnianus) in a section of Pilot Mountain State Park, NC, USA: (1) camera trapping using mark-resight ratios or (2) N-mixture modeling and (3) aerial thermal videography from a drone platform. All three methods yielded similar density estimates, suggesting that they converged on an accurate estimate. We also included environmental covariates in the N-mixture modeling to explore spatial habitat use, and we fit models for each season to understand temporal changes in population density. Deer occurred in greater densities on warmer, south-facing slopes in the autumn and winter and on cooler north-facing slopes and in areas with flatter terrain in the summer. Seasonal density estimates over two years suggested an annual cycle of higher densities in autumn and winter than in summer, indicating that the region may function as a refuge during the hunting season.

Species Enriched Grass–Clover Pastures Show Distinct Carabid Assemblages and Enhance Endangered Species of Carabid Beetles (Coleoptera: Carabidae) Compared to Continuous Maize

There is an urgent global need for the ecological intensification of agricultural systems to reduce negative impacts on the environment while meeting the rising demand for agricultural products. Enriching grasslands with floral species is a tool to promote diversity and the associated services at higher trophic levels, and ultimately, to enhance the agricultural landscape matrix. Here, we studied an organic pastures-based dairy production system with plant species enhanced grass–clover pastures with respect to the effect on the activity density, functional traits, carabid assemblages, and species richness of carabid beetles. To understand the effect of land management on carabid beetles, we studied two types of grass–clover pastures with low and relatively high plant diversities in an integrated crop–livestock rotational grazing system (ICLS). As a comparison, organic permanent grasslands and conventionally managed maize were studied. We installed pitfall traps for three weeks in early summer, and for two weeks in autumn. In total, 11,347 carabid beetles of 66 species were caught. Grass–clover pastures did not differ in activity density, functional traits, habitat guilds, or species richness, but conventional maize did show a higher activity density in autumn and a higher proportion of eurytopic species and mobile species compared to grass–clover pastures. On grass–clover pastures, we found more endangered species, Carabus beetles, and a distinct carabid assemblage compared to maize. However, we attribute the lack of an effect of increased plant diversity of the grass–clover pastures on carabid species richness and functional traits to the intensive grazing regime, which resulted in the compositional and structural homogeneity of vegetation. Still, the presence of specialized and endangered species indicated the potential for organically managed grass–clover pastures to promote dispersal through an otherwise depleted and fragmented agricultural landscape. By increasing crop diversity in ICLS, more resources for foraging and nesting are created; therefore, organically managed grass–clover pastures add to the multi-functionality of agricultural landscapes.

People's olfactory perception potential mapping using a machine learning algorithm: A Spatio-temporal approach

This research aimed to conduct Spatio-temporal modeling of people's olfactory perception in the Tehran city using a machine learning-based approach considering the importance of people's perception of the urban environment and the effect of the sense of smell in strengthening or weakening the environmental and urban spaces. Therefore, a spatial database containing dependent and independent data was established to model and prepare a potential map of people's olfactory perception in Tehran. The dependent data were collected through a questionnaire among 687 people, which contains three states of sense of smell, including neutral (350 cases), pleasant (247 cases), and unpleasant (90 cases). The independent data consisted of distance to public transport stations, livestock and poultry production centers, streets, fuel stations, fruit and vegetable fields, restaurants, industrial areas, garbage volume, traffic volume, population density, normalized difference vegetation index (NDVI), meteorological data (wind speed and direction, and humidity), and air quality index (AQI). The last three criteria were provided temporarily in four seasons. A random forest (RF) algorithm was utilized to model and prepare the potential map of people's olfactory perception in four seasons. Generally, 70% of the information was dedicated to modeling, and the remained 30% was applied for validation. Results of the Gini index revealed the more significant impact of the criteria of distance from fruit and vegetable fields and distance from restaurants in neutral smells, distance from streets and distance from restaurants in pleasant smells, and distance from livestock and poultry production centers and garbage volume in unpleasant smells among spatial criteria. One of the essential spatial-temporal criteria was wind direction in all seasons for neutral smells, in summer, fall, and winter for pleasant smells, and in fall for unpleasant smells. The RF algorithm modeling results indicated the greater effect of distance to public transport stations in spring, garbage volume in summer and winter, and population density in autumn on the sense of smell. The potential maps of olfactory perception were evaluated using the receiver operating characteristic (ROC) curve and area under the curve (AUC). AUC values were calculated for the spring, summer, autumn, and winter seasons as much as 0.956, 0.955, 0.957, and 0.958 for neutral, 0.944, 0.928, 0.946, and 0.942 for pleasant, and 0.922, 0.931, 0.963, and 0.981 for unpleasant states, respectively. The potential maps of this study help present a more pleasant olfactory space to urban users by urban planners and managers.

Spatial distribution of Munida gregaria (Decapoda, Munididae) larvae in the silled Beagle Channel: Insights from spring and autumn surveys

The squat lobster Munida gregaria is an ecologically relevant species in southern South American waters. Nonetheless, fundamental topics regarding its larval ecology remain poorly studied, especially at the southern limit of its distribution area. Here, we investigated the abundance, size, and spatial distribution of M. gregaria larval stages (zoeae I-V and megalopa) in the Beagle Channel, during spring and autumn, and explored their relationships with variations in bathymetry and seawater physico-chemical properties at both sides of the Mackinlay pass sill. Plankton samples were collected from the inner sector of the channel, a fresh water-influenced and semi-enclosed system, to its mouth towards the Atlantic Ocean during four oceanographic cruises (springs of 2014 and 2015 and autumns of 2016 and 2017). Zoeae occurred throughout the study area in both seasons, with lower densities in autumn, whereas megalopae were detected exclusively in spring. The highest larval abundances and all developmental stages were found in the outer sector, where juveniles and adults also occurred. These spatial patterns were consistently observed across the different sampling dates. Contrary to previous reports, the coexistence of zoeae I-V during autumn would indicate that, at least in the outer sector, larvae that hatch late in the summer are able to reach advanced developmental stages. However, it remains unknown whether they fully develop in subsequent months. Significant associations among larval distribution patterns and environmental variables were detected, especially for late stages, which occurred mainly in the westernmost and shallowest part of the outer sector, characterized by highly stratified waters with the warmest bottom temperatures. All together, these results may reflect the effects of variations in local environmental conditions along the channel, related to bottom topography and degree of freshwater/oceanic influence, on larval cohort dynamics, adult reproduction, or both. Larvae hatched in spring were larger than those hatched in summer/autumn for all zoeal stages. Possible explanations for this finding are discussed. This study contributes to our knowledge of M. gregaria larval ecology, which is essential to understand its complex population dynamics in an environmentally complex geographical area, and to better predict its responses to climate change. • Zoeal stages I-V occurred in both spring and autumn. • Larval abundance and stage structure differed west and east of the Mackinlay sill. • Higher larval abundances and all larval stages occurred in the outer sector. • Advanced stages occurred mainly in shallow and highly stratified waters. • Larvae hatched in spring were larger than those hatched in summer-autumn.

Annual and Semiannual Variation in the Ionospheric F2-Layer Electron Density over the Indian Zone and Effect of Solar Activity on It

In situ measurement carried out by the Retarding potential Analyzer (RPA) on board SROSS C2 and ROCSAT during 1995 to 2003 covering ascending and descending periods of solar cycle 23 over Indian equatorial and low latitude were used to study the annual and semiannual variation of electron density at the topside F region. The ‘Semiannual anomaly’ which represent the electron density in equinox (March, April, September and October) is greater than that at solstice (May, June, July, August, November, December, January and February). The ‘annual anomaly’ which represents the electron density in winter (November, December, January, February) is higher than that in summer (May, June, July, August). The analysis has been carried out for the geomagnetic equator and ±10o magnetic latitudes. Observations reveal the existence of an equatorial asymmetry during daytime (10:00 – 14:00 hrs.) with higher electron density in spring (March, April) than in autumn (September, October) for both ascending and descending leg of the solar cycle. At the peak of the solar cycle, the density becomes equal for both equinoxes. Nighttime (22:00 – 00:00 hrs.) density in autumn is higher than that in spring for the ascending half of the solar cycle, becomes equal for both the equinoxes around the peak of the solar cycle. In the descending half the vernal density becomes higher than the autumnal density. The periodograms obtained from a Fourier analysis of the daytime average density shows that the annual variation is dominant over the semiannual variations for low to moderate solar activity whereas the semiannual peak becomes dominant over annual peak for high solar activity irrespective of the latitudes. At night, however, latitudinal differences have been observed. The annual variation is stronger than the semiannual variation at 10o N for low to moderate solar activity while for high solar activity the situation reverses. At 10o S and the magnetic equator, the annual variation is dominant for all levels of solar activity. Amplitude of the annual variation is higher in winter compared to that in summer. The physical and dynamical processes responsible for the observed annual and semi-annual trends in topside density will be identified and discussed.

Irrigation and Nitrogen Application Promote Population Density through Altered Bud Bank Size and Components in Leymus chinensis

The bud bank of perennial grasses is a controlling factor in population dynamics and is estrongly affected by soil water and nitrogen status. To explore how the bud bank size and its components affect shoot population density under different soil moisture and nitrogen contents in spring and autumn. A three-full-factorial field experiment with factors of treatment timing (spring and autumn), nitrogen rate (control and 10 g N m−2 yr−1) and irrigation rate (control and +40 mm rainfall) was conducted in Leymus chinensis (a C3 plant) in the northeast of China. The number of two types of buds (axillary shoot bud and rhizome bud), shoot population density, soil properties and rhizome traits (rhizome length and rhizome number) were determined to explore what and how changes in bud bank composition influences shoot population density in spring and autumn. The results showed that: (1) Regardless of the irrigation and nitrogen application timing, the simultaneous irrigation and nitrogen application significantly increased the number of two types of buds and promoted the shoot population density in spring and autumn by 56.75% and 47.74%, respectively. (2) The bud bank was dominated by rhizome buds in spring under control and dominated by axillary shoot buds under the combined irrigation and nitrogen treatment in autumn. Axillary shoot bud was the determining component in the population density increases in both spring and autumn, which were significantly associated with soil available phosphorus, available nitrogen and rhizome length and number. In summary, the number of different buds was strongly impacted by irrigation and nitrogen application at the crucial bud-bank formation stage. Agronomically, the forage yield could be largely increased through the increase in the axillary shoot bud density by using irrigation and nitrogen application in L. chinensis and other rhizomatous perennial grasses.

Why Did Brown Hare Lepus europaeus Disappear from Some Areas in Central Poland?

Brown hares originated in the open steppe grasslands of Eurasia and have adapted very successfully to a mixed, arable agriculture environment. In the last decades of the 20th century, a decline in brown hare populations has been observed in many European countries. In this study, we documented a long-term (1965–2018) decline in the hare population in a field and forest mosaic in central Poland (from over 30 ind./100 ha in the mid-1960s to 1–2 ind./100 ha in the past decade). We showed that the recent autumn densities were the same as compared to the preceding spring densities (suggesting a low recruitment rate) and that the recent densities recorded in the fields were no longer higher than in the forests (probably due to a decrease in the habitat quality of arable lands). We also showed that the share of hares in a red fox diet was now very low (0.1% vs. 13% in the past). We compared the recent (2004–2018) population estimates to another area that was located 70 km east (with a similar habitat structure, a community of predators and climate conditions, but with less intense agriculture), where the hare population was increasing. We suggested that the farming practices were the most important factor for the hare population decrease in our study area.

Thermospheric density responses to Martian dust storm in autumn based on MAVEN data

The unique seasonal surface dust storms on Mars have a significant impact on the Martian atmosphere. However, due to the lack of observations, semi-empirical models are difficult to simulate the density changes in the thermosphere with the existence of dust storms in detail. Data from multiple Mars probes now offer new opportunities to study the detailed response of Martian dust storms to the upper atmosphere. In this paper, we use MAVEN accelerometer and mass spectrometer to study the variations of the Martian thermosphere density in autumn between MY 32 and MY34 (The corresponding Earth dates: February 11, 2015 to February 28, 2019), and use the seasonal model with dust storm index to fit the annual data of the above three Martian years. The results show that the thermosphere density has a clear response to the surface dust storm activity. Furthermore, the spatial distribution of measured data in autumn (northern hemisphere) is compared with the atmospheric density distribution simulated by the general circulation model (GCM) under specific initial conditions. The model simulation results agree well with the thermospheric density distribution characteristics of each Martian year under the initial strong dust storm conditions. It proves the important role of global dust storm in changing the structure of the Martian thermospheric atmosphere.

Features of Structural Changes in the Plankton Community of an Alpine Lake with Increasing Fish Density in Summer and Autumn

Features of Structural Changes in the Plankton Community of an Alpine Lake with Increasing Fish Density in Summer and Autumn

Vendace (Coregonus albula) Disperse Their Eggs Widely during Spawning

Depending on their reproductive strategy, different fish species either aggregate or disperse eggs and larvae in their reproductive habitat. Because yolk-sac larvae of vendace (Coregonus albula) disperse widely across the littoral and pelagic zones of boreal lakes, it is unclear where the exact spawning and egg incubation locations are. Vendace egg and larvae densities were studied in Lake Southern Konnevesi to clarify its spawning strategy. In autumn 2019, 1–2 weeks prior to spawning, 500 egg samplers were installed in five depth zones in 20 sampling plots. Fertilized eggs were found in 18 plots. The mean density of eggs was 74 eggs m–2 and the mean fertilization rate 85%. During spawning, vendace dispersed their offspring throughout the lake. The sampling-plot-specific egg density in autumn 2019 did not correlate with larval density in the spring next year. The reproduction strategy of vendace reduces the effects of high spatial and temporal fluctuation in their reproduction and nursery habitats.

High irradiation and low discharge promote the dominant role of phytoplankton in riverine nutrient dynamics

AbstractRivers play a relevant role in the nutrient turnover during the transport from land to ocean. Here, highly dynamic planktonic processes are more important compared to streams making it necessary to link the dynamics of nutrient turnover to control mechanisms of phytoplankton. We investigated the basic conditions leading to high phytoplankton biomass and corresponding nutrient dynamics in eutrophic, 8th order River Elbe (Germany). In a first step, we performed six Lagrangian sampling campaigns in the lower river section at different hydrological conditions. While nutrient concentrations remained high at low algal densities in autumn and at moderate discharge in summer, high algal concentrations occurred at low discharge in summer. Under these conditions, concentrations of silica and nitrate decreased and rates of nitrate assimilation were high. Soluble reactive phosphorus was depleted and particulate phosphorus increased inversely. Rising molar C:P ratios of seston indicated a phosphorus limitation of phytoplankton, so far rarely observed in eutrophic large rivers. Global radiation combined with mixing depth had a strong predictive power to explain maximum chlorophyll concentration. In a second step, we estimated nutrient turnover exemplarily for N during the campaign with the lowest discharge based on mass balances and metabolism‐based process measurements. Mass balance calculations revealed a total nitrate uptake of 423 mg N m−2d−1. Increasing phytoplankton density dominantly explained whole river gross primary production and related assimilatory nutrient uptake. In conclusion, riverine nutrient uptake strongly depends on the growth conditions for phytoplankton, which are favored at high irradiation and low discharge.

Edge density affects demography of an exploited grassland bird

AbstractHumans modify landscapes for a variety of reasons including agriculture, urbanization, and to facilitate recreation. Landscape modifications can lead to complete loss of existing cover types and/or fragmentation of remaining cover types. Grasslands are one of the ecosystems most heavily impacted by human modifications; however, for many species, an understanding of how fragmentation affects population parameters is lacking. We investigated the influence of landscape fragmentation on survival, reproduction, and density using the northern bobwhite (Colinus virginianus), a facultative grassland species, as our case study. We experimentally manipulated the level of edge density (none, low, and high) of bobwhite management units and estimated seasonal survival, productivity, and autumn densities. Winter survival was lower in edge density treatments, relative to the control. An increase in migratory raptor density during the winter, along with a decrease in thermal refugia, may be contributing to lower winter survival in edge density treatments. Fecundity was higher in the edge density treatments, relative to the control, and was negatively related to winter survival. Similarly, breeding season survival was higher in more fragmented sites. This indicated a density‐dependent relationship, where lower bird densities at the beginning of the breeding season possibly led to greater resource availability, and thus survival and productivity, of the birds that remained. However, a density‐dependent response in breeding season survival and productivity was not enough to offset the negative impact of edges in the low edge density sites. Consequently, autumn density was lower relative to both control and high edge density treatments. Our study demonstrates the importance of capturing the entire life cycle when exploring the relationship between landscape pattern and population parameters.

The Effects of Landscape Characteristics on Northern Bobwhite Density

ABSTRACTThe northern bobwhite (Colinus virginianus) is an ecologically and economically valuable species in the United States. Managers rely on autumn density estimates to set harvest regulations, balancing the interests of hunters and long‐term bobwhite population viability. Spatial capture‐recapture (SCR) is a useful framework for estimating population size and modeling spatial variation in density. We used SCR to quantify the effect of landscape structure on spatial variation in density for a population of bobwhites on the Di‐Lane Wildlife Management Area in Waynesboro, Georgia, USA. Without additional telemetry or nesting data, we were also able to estimate a spatially explicit metric of productivity. To sample the population, we deployed a fixed array of 395, 262, and 268 funnel traps in 2016, 2017, and 2018, respectively. We estimated age structure, with the highest density of juveniles (0.32 birds/ha, 95% CI = 0.28–0.37) and adults (0.10 birds/ha, 95% CI = 0.08–0.12) estimated in 2016. In our top model, density was negatively related to the proportion of closed canopy hardwoods. To increase bobwhite density on the landscape, managers should reduce the amount of closed canopy hardwood forest. Furthermore, the spatially explicit age ratio we estimated could be used to target management towards increasing the recruitment of chicks into the autumn population. An SCR approach may require additional logistical and financial resources relative to other data collection methods, but it makes modeling spatial variation in density straightforward and can be used to gather data to simultaneously understand population structure, vital rates, and movement. © 2021 The Wildlife Society.

Changing Distributions of Zooplankton Communities in a Coastal Lagoon in Response to Rainfall Seasonality

Choi, J.-Y.; Kim, J.-C., and Kim, S.-K, 2020. Changing distributions of zooplankton communities in a coastal lagoon in response to rainfall seasonality. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Geospatial Research of Coastal Environments. Journal of Coastal Research, Special Issue No. 102, pp. 69-74. Coconut Creek (Florida), ISSN 0749-0208.Coastal lagoons are unique and complex ecosystems which exhibit very high primary and secondary production rate, and their productivity is underpinned by plankton communities. Empirical studies suggest that summer rainfall determines the spatial and temporal pattern of not only physicochemical variables but also zooplankton communities in coastal regions. It was hypothesized that drier or wetter than average summer rainfall years would change the environmental variables (e.g., salinity, dissolve oxygen, and nutrients) in coastal lagoons, thereby disrupting the spring growth trend of zooplankton communities. Long-term (2014–2017) monitoring data (rainfall, environmental variables, and zooplankton) were divided into two groups: Rainy and Dry years, corresponding to years with an annual rainfall that was higher or lower than the total annual average, respectively. The results showed that summer and autumn densities of zooplankton fell sharply in Rainy years but increased steadily in Dry years. The highest density of rotifers was mainly observed in sites adjacent to the inflow of tributary streams, while copepods were abundant near the outlet to the ocean. The differing spatial distribution of rotifers and copepods is attributed to the salinity gradient in the study site, and changed with freshwater inflows. Based on these findings, it is suggested that summer rainfall variations play an important role in driving the spatial and temporal distribution of zooplankton.