Long-Term Community Dynamics of Small Landbirds with and Without Exposure to Extensive Disturbance from Military Training Activities

Military training activities are known to impact individual species, yet our understanding of how such activities influence animal communities is limited. In this study, we used long-term data in a case study approach to examine the extent to which the local small landbird community differed between a site in northeast Kansas that experienced intensive disturbance from military training activities (Ft. Riley Military Installation) and a similar, nearby site that experienced minimal human disturbance (Konza Prairie Biological Station). In addition, we characterized how the regional pool of potential colonizers influenced local community dynamics using Breeding Bird Survey data. From 1991 to 2001, most species of small terrestrial landbirds (73%) recorded during breeding surveys were found at both sites and the mean annual richness at Ft. Riley (39.0 ± 2.86 [SD]) was very similar to that of Konza Prairie (39.4 ± 2.01). Richness was maintained at relatively constant levels despite compositional changes because colonizations compensated local extinctions at both sites. These dynamics were driven primarily by woodland species that exhibited stochastic losses and gains and were present at a low local and regional abundance. Our results suggest that military training activities may mimic natural disturbances for some species in this area because the small landbird community did not differ markedly between sites with and sites without extensive human disturbance. Although our results suggest that military training is not associated with large changes in the avian community, additional studies are needed to determine if this pattern is found in other ecological communities.     

Agroforest’s growing role in reducing carbon losses from Jambi (Sumatra), Indonesia

This paper examines the size and intensity of changes among five land categories during the two time intervals in a region of Indonesia that is pioneering negotiations concerning reducing emissions from deforestation and forest degradation (REDD). Maps at 1973, 1993, and 2005 indicate that land-cover change is accelerating, while carbon loss is decelerating in Jambi Province, Sumatra. Land dynamics have shifted from Forest loss during 1973–1993 to Agroforest loss during 1993–2005. Forest losses account for most reductions in aboveground carbon during the both time intervals, but Agroforest plays an increasingly important role in carbon reductions during the more recent interval. These results provide motivation for future REDD policies to count carbon changes associated with all influential land categories, such as Agroforests.     

Characterization of Sonic Devices Used for Cleaning Fabric Filters

ABSTRACT

Ozone reactivity scales play an important role in selecting which chemical compounds are used in products ranging from gasoline to pesticides to hairspray in California, across the United States and around the world. The California Statewide Air Pollution Research Center (SAPRC) box model that calculates ozone reactivity uses a representative urban atmosphere to predict how much additional ozone forms for each kilogram of compound emission. This representative urban atmosphere has remained constant since 1988, even though more than 25 years of emissions controls have greatly reduced ambient ozone concentrations across the United States during this time period. Here we explore the effects of updating the representative urban atmosphere used for ozone reactivity calculations from 1988 to 2010 conditions by updating the meteorology, emission rates, concentration of initial conditions, concentration of background species, and composition of volatile organic compound (VOC) profiles. Box model scenarios are explored for 39 cities across the United States to calculate the Maximum Incremental Reactivity (MIR) scale for 1,233 individual compounds and compound-mixtures. Median MIR values across the cities decreased by approximately 20.3% when model conditions were updated. The decrease is primarily due to changes in atmospheric composition ultimately attributable to emissions control programs between 1998 and 2010. Further effects were caused by changes in meteorological variables stemming from shifting seasons for peak ozone events (summer versus early fall). Lumped model species with the highest MIR values in 1988 experienced the greatest decrease in MIR values when conditions were updated to 2010. Despite the reduction in the absolute reactivity in the updated 2010 atmosphere, the relative ranking of the VOCs according to their reactivity did not change strongly compared to the original 1988 atmosphere. These findings indicate that past decisions about ozone control programs remain valid today, and the ozone reactivity scale continues to provide relevant guidance for future policy decisions even as new products are developed.

Implications: Updating the representative urban atmosphere used for the Maximum Incremental Reactivity (MIR) scale from 1988 to 2010 conditions caused the reactivity of 1223 individual compounds and combined mixtures to decrease by an average of 20.3% but the relative ranking of the VOCs was not strongly affected. This means that previous guidance about preferred chemical formulations to reduce ozone formation in cities across the United States remain valid today, and the MIR scale continues to provide relevant guidance for future policy decisions even as new products are developed.     

Methods to summarize change among land categories across time intervals

Time-series maps have become more detailed in terms of numbers of categories and time points. Our paper proposes methods for raster datasets where detailed analysis of all categorical transitions would be initially overwhelming. We create two measurements: Incidents and States. The former is the number of times a pixel’s category changes across time intervals; the latter is the number of categories that a pixel represents across time points. The combinations of Incidents and States summarize change trajectories. We also describe categorical transitions in terms of annual flow matrices, which quantify the additional information generated by intermediate time points within the temporal extent. Our approach summarizes change at the pixel and landscape levels in ways that communicate where and how categories transition over time. These methods are useful to detect hotspots of change and to consider whether the apparent changes are real or due to map error.     

Estimation of the mean in line intercept sampling

Ratio estimation of the parametric mean for a characteristic measured on plants sampled by a line intercept method is presented and evaluated via simulation using different plant dispersion patterns (Poisson, regular cluster, and Poisson cluster), plant width variances, and numbers of lines. The results indicate that on average the estimates are close to the parametric mean under all three dispersion patterns. Given a fixed number of lines, variability of the estimates is similar across dispersion patterns with variability under the Poisson pattern slightly smaller than varia-bility under the cluster patterns. No variance estimates were negative under the Poisson pattern, but some estimates were negative under the cluster patterns for smaller numbers of lines. Variance estimates become closer to zero similarly for all spatial patterns as the number of lines increases. Ratio estimation of the parametric mean in line intercept sampling works better, from the viewpoint of approximate unbiasedness and variability of estimates, under the Poisson pattern with larger numbers of lines than other combinations of spatial patterns, plant width variances and numbers of lines.     

Rejoinder

Environmental and Ecological Statistics -     

A Comprehensive Approach to Identifying Monitoring Priorities of Small Landbirds on Military Installations

Military installations provide important native habitat for songbirds, including many species that have experienced population declines in recent decades. As part of the Land Condition Trend Analysis (LCTA) program to monitor animal populations on military lands, we surveyed small (<250 g) breeding landbirds on 60 permanent plots on the Fort Riley Military Installation in northeastern Kansas from 1991 to 2002. During this period, species richness averaged 39.0 species (SE 0.9)/year and mean species richness per plot ranged from 3.6 species (SE=0.2)/plot (1999) to 7.5 species (SE=0.3)/plot (1992). Turnover (the appearance and disappearance of species on all plots from one year to the next) ranged from 5 species (2000–2001) to 16 species (1992–1993) and was driven primarily by turnover of woodland species. We developed an index of relative difference (C) to evaluate relative trends of local populations and found that 25 species declined, 15 species increased, and 7 did not change. Based on migration assemblages, more resident species (6 of 10) and more short-distant migrants (9 of 12) decreased than long-distance migrants (10 vs. 11). Our analysis of major vegetation communities on plots showed few changes in the quantity of habitats (grassland vs. woodlands) during the study. Our results indicate that Fort Riley provides important habitats for many landbirds, particularly those that require grasslands for breeding. Several species exhibited local declines when compared to the regional Breeding Bird Survey routes. We offer an approach that evaluates population changes of small landbirds and provides objective inputs for conservation directives. These can be adopted easily for use on military installations (that use LCTA), parks, and wildlife refuges that have data from annual breeding bird surveys.