bluuebunny/crossref_metadata_2025_split huggingface dataset:
A BEHAVIOR‐BASED MODELING APPROACH TO REDUCING SHOREBIRD–SHELLFISH CONFLICTS
Authors: Caldow Richard W. G. , Beadman Helen A. , McGrorty Selwyn , Stillman Richard A. , Goss-Custard John D. , Durell Sarah E. A. le V. dit , West Andrew D. , Kaiser Michel J. , Mould Kim , Wilson Andrew 
Published: June 2007

Bottom cultivation of mussels on intertidal flats is practiced throughout the world. This often generates conflicts between commercial interests and competing birds such as oystercatchers. At the Menai Strait, United Kingdom, the overwinter consumption of 242 tonnes (1 metric tonne = 1000 kg) of commercially harvestable mussels (>40 mm) by oystercatchers in 1999–2000 was worth £133 000 ($226 000 U.S. dollars). This represents 19% of the value of the landings. We used a behavior‐based simulation model to predict the extent to which such losses can be reduced by novel commercial management practices, and to explore the consequences for the oystercatcher population.Simulations of novel lay management practices indicated that the losses of commercially harvestable mussels to oystercatchers can be considerably reduced by altering the shore level and/or extent of the commercial lays. We propose a novel management strategy for the bottom cultivation of mussels in intertidal areas. Seed mussels (15–20 mm) should be laid relatively far upshore, where losses to oystercatchers will be minimal. As the mussels grow over the next 2–3 years, they should be moved progressively further downshore such that the largest mussels spend their last season prior to harvest in a relatively small area, lower on the shore than all mussels earlier in the cultivation cycle. Support for the effectiveness of this proposed management strategy can be found in the reports of commercial operators who have incorporated this management strategy in new management practices in the last few years. They report an increase in the ratio of the live mass of harvested to seeded mussels from the previous norm of 1:1 to 4:1. By accepting greater losses of mussels earlier in the cultivation cycle, rather than later, the feeding conditions for oystercatchers might even be improved under this system. With appropriate management, the interest of shellfish growers and competing shorebirds need not conflict.
OCEAN WARMING EFFECTS ON GROWTH, REPRODUCTION, AND SURVIVORSHIP OF SOUTHERN CALIFORNIA ABALONE
Authors: Vilchis L. Ignacio , Tegner Mia J. , Moore James D. , Friedman Carolyn S. , Riser Kristin L. , Robbins Thea T. , Dayton Paul K. 
Published: June 2007

Traditional fisheries management in southern California has failed, in part because it is based on an assumption of an unvarying environment and is focused on size limits rather than insuring the persistence of aggregations of large fecund individuals. The combined effect of low frequency climatic variability and anthropogenic perturbations can have dramatic consequences for abalone in southern California. Abalone species are tightly linked to kelp forest ecosystems that, besides furnishing habitat, also provide the main food source for abalone. In southern California, kelp canopies are very sensitive to oceanographic climate because the kelp depend upon high nutrients in the water column. Oceanic warming, in turn, results in decreased nutrients in the surface water, and this is correlated with marked reductions in giant kelp biomass.Here we address the additive effects of ocean warming on two species of California abalone (the red abalone, Haliotis rufescens; and the green abalone, H. fulgens) by subjecting them to varied environmental conditions similar to cool, normal, and warm phases of the California current in the southern California Bight. Our experimental design simultaneously tested the synergistic effects of temperature and food quantity and quality on survivorship, growth, and reproduction. For red abalone, warm temperatures increased the onset of withering syndrome, a fatal abalone disease, and halted growth and reproduction. In contrast, green abalone survivorship, growth, and reproduction were relatively robust irrespective of temperature, while their growth and reproduction were most strongly influenced by food quantity. We found clear evidence suggesting that, combined with overfishing, California abalone populations are adversely affected by ecosystem responses to ocean warming: Cool‐water red abalone suffer stronger consequences in warm water than do green abalone. Conservation, restoration, and recovery plans of remnant California abalone populations must consider these relationships when taking any action.
THE ROLES OF FISHING AND CLIMATE IN THE POPULATION DYNAMICS OF BOCACCIO ROCKFISH
Authors: Tolimieri Nick , Levin Phillip S. 
Published: June 2007

Climate is an important force influencing the dynamics of populations and communities in many terrestrial, aquatic, and marine systems. The precipitous decline of stocks of bocaccio (Sebastes paucispinis) since the mid‐1970s has been attributed to a combination of a shift in the climate regime in the eastern Pacific Ocean during the winter of 1976–1977 (leading to lower productivity) and overfishing. We used a bocaccio recruitment time series (1959–1997) and indices of climate and ocean condition (e.g., sea surface temperature, Northern Oscillation Index, El Niño–Southern Oscillation Index, and upwelling indices) to examine the relationship between bocaccio productivity (recruits per spawning output, R/S) and both interannual (e.g., ENSO) and interdecadal (regime shifts) scale variation in climate and ocean conditions.We did not detect an effect of the 1976 climate regime shift on bocaccio productivity. Mean log R/S and the frequency of “good” recruitment years (log R/S > 1 sd above the long‐term mean) were the same before and after the 1976 regime shift. Good recruitment years occurred about 13% of the time in both regimes. At an interannual time scale, cooler ocean temperatures during the period spanning egg production to the end of the larval stage correlated with higher log R/S both before and after the regime shift. Prior to the 1976 shift, high log R/S values were more likely when upwelling was low during the settlement period, but there was no relationship after the regime shift. A matrix population model suggested that in the absence of fishing a “good” recruitment year needs to occur 15% of the time to achieve a nonnegative population growth rate of (λ ≥ 1.0), similar to the observed frequency of good recruitment events. Good recruitment years needed to occur >90% of the time under historic levels of fishing mortality to achieve a population growth rate ≥1.0. Taken together, these results suggest that the 1976 regime shift did not contribute to the decline in bocaccio stocks through processes affecting recruitment, and that the degree to which populations of bocaccio can withstand fishing depends on the frequency of climatic conditions that promote strong recruitment.
NOTHOFAGUS REGENERATION DYNAMICS IN SOUTH‐CENTRAL CHILE: A TEST OF A GENERAL MODEL
Authors: Pollmann William , Veblen Thomas T. 
Published: June 2007

Studies in Southern Hemisphere temperate forests have yielded a general model of how the successional status of shade‐intolerant Nothofagus is related to site conditions and disturbance. According to model predictions, regeneration of most Nothofagus species is dependent on coarse‐scale disturbance at favorable sites where shade‐tolerant rain forest species co‐occur. In contrast, at suboptimal sites where tree species richness is low, regeneration is not dependent on coarse‐scale disturbance. We used variation in forest composition and structure as well as disturbance patterns in the forests of Puyehue National Park, Chile, to test several predictions from this general model. The study area presents a complex mosaic of disturbance patterns, including the effects of the strong 1960 earthquake as well as fire and wind disturbance. We reconstructed stand development on sites affected by these disturbances, and compared these patterns with the structure of old‐growth forests along an elevation gradient from species‐rich montane rain forest to monotypic subalpine Nothofagus forests.Tree age data indicate that both the Nothofagus and many of the rain forest tree species are long‐lived, often reaching ages greater than 600 years. Regeneration of Nothofagus was abundant in stands recently disturbed by landslides, fire, or blowdown across the entire elevation gradient, and Nothofagus also regenerated in old‐growth high‐elevation forests. In contrast, regeneration of Nothofagus was scarce or absent in undisturbed stands and at lower elevation. In comparison with the rain forest species, Nothofagus species are more tolerant of the unfavorable site conditions associated with increasing elevation. Thus, there is a gradient of decreasing interspecific tree competition with increasing elevation, so that the dependence of regeneration of Nothofagus on coarse‐scale disturbance is much less at higher elevation. This study confirms that changes in forest composition may be explained by simple processes occurring in accordance with the main predictions of the general model of Nothofagus forest dynamics: At low elevations, coarse‐scale disturbance is required for Nothofagus regeneration; at higher elevations under decreasing competition the regeneration of Nothofagus is less dependent on coarse‐scale disturbance. Thus, for the Puyehue landscape, patterns of forest structure and disturbance history are congruent with the major features of the general model of Nothofagus dynamics.
AVIAN COMMUNITY DYNAMICS IN A FRAGMENTED TROPICAL LANDSCAPE
Authors: Borgella René , Gavin Thomas A. 
Published: June 2007

As humans alter habitats worldwide, developing reliable methods of assessing biodiversity and community attributes of interest (e.g., species richness, turnover, and extinction rates) is important. Frequently, estimates of community‐level attributes are biased because the estimators make assumptions of the data that are violated; many published studies assume equal detectability across species, sites, or time. The accuracy of estimators of species richness and community‐level vital rates (e.g., extinction and colonization) can be increased by using probabilistic estimation methods, which do not assume that all species are detected, or that the data assume a particular statistical distribution.Using these estimation methods, we examined avian community dynamics in a fragmented tropical landscape using data from five years of a mark–release–recapture study. For the resident understory avifauna in each of five small (∼0.3–20 ha), isolated forest fragments in southern Costa Rica, we estimated species richness, rate of change in species richness, extinction and turnover rates of species, and the number of colonizing species over temporal scales of one month, one year, and two years. We expected that community dynamics would be higher in smaller fragments than in larger fragments, reflecting greater temporal variability of avian communities in relatively small habitat patches. Additionally, a selective logging operation was conducted at one of our sites during the midpoint of this study, which gave us the opportunity to examine how community‐level vital rates may reflect the effects of that perturbation.Our results demonstrate that avian communities in the larger fragments were more stable than those in the smaller fragments, and that the selectively logged fragment was the most unstable of all. We found that extinction rates were more similar across our sites than were colonization rates, and that the higher instability of the small fragments was due primarily to higher levels of colonization. Although our sample size (n = 5) precludes strong inference, our findings are consistent with the prediction of higher local dynamics within small fragments and after logging. Taken together, these findings suggest that smaller fragments are more dynamic over time, and that ecological processes and multitrophic relationships at these dynamic sites may be in a constant state of flux.
MODIFYING DAM OPERATIONS TO RESTORE RIVERS: ECOLOGICAL RESPONSES TO TENNESSEE RIVER DAM MITIGATION
Authors: Bednarek Angela T. , Hart David D. 
Published: June 2007

The Tennessee Valley Authority (TVA) initiated a Reservoir Releases Improvement Program in 1991 to increase minimum flows and improve water quality by modifying its dam operations. We compiled a comprehensive data set from ecological monitoring below nine dams to evaluate the effects of these modifications on physicochemical conditions and benthic macroinvertebrate assemblages. Abiotic and biotic data were collected in tailwaters by the TVA for three dam operation “treatments” (i.e., before any modifications, following flow modifications, and following both flow and dissolved oxygen [DO] modifications) at three different stations (Upper, Middle, and Lower) located at increasing longitudinal distances below each dam. Analysis of variance was used to test for differences in ecological conditions among treatments and stations.Dam modifications had significant effects on both abiotic and biotic variables, and macroinvertebrate assemblages exhibited significant longitudinal differences. Yearly mean DO and mean minimum velocity increased following dam modifications. Across all sampling stations, macroinvertebrate family richness increased and the percentage of pollution‐tolerant macroinvertebrates (% Tolerant) decreased after dam modifications. Family richness also increased, and % Tolerant decreased, with increasing distance below the dams. Total abundance of macroinvertebrates increased after flow modifications and then decreased following changes in DO. The percentage of individuals belonging to the orders Ephemeroptera, Plecoptera, and Trichoptera (% EPT) increased following flow and DO modifications, but only at the Upper station. EPT family richness was unaffected by increased flow alone but increased following increases in both flow and DO. The design of the re‐operation “experiment” made it difficult to ascertain the relative contributions of flow and DO changes to the observed biotic responses, but flow alone appeared to have a smaller beneficial effect than the combined effects of flow and DO.
REGIONAL LEGACIES OF LOGGING: DEPARTURE FROM PRESETTLEMENT FOREST CONDITIONS IN NORTHERN MINNESOTA
Authors: Friedman Steven K. , Reich Peter B. 
Published: June 2007

Forests in the Great Lakes region of Canada and the United States have been important timber producing resources for more than 100 years. Logging and fire suppression have caused major, but unquantified change in those forests, which includes both the magnitude of compositional change and its spatial patterns. Hence, a spatially explicit regional‐scale change analysis was conducted using General Land Office Survey records from the late 1800s and the 1990 U.S. Forest Service Inventory and Analysis Survey, for a 3.2 million hectare study area in northeastern Minnesota, USA. These data document altered species abundance, proportional basal area, and spatial distribution patterns. Regionally, the proportionally most abundant species shifted from the presettlement period (spruce, 21%; larch, 15%; and paper birch, 15%) to aspen (30%), spruce (16%), and balsam fir (16%) in 1990. In terms of proportional basal area dominance, white pine declined from 20% to 5%, birch from 16% to 13%, spruce from 14% to 9%, and larch from 12% to 2%, while aspen increased from 8% to 35%. Based on ordination of species abundance and proportional basal area, physiographic zones varying in geology and hydrology were characterized by different species composition in the 19th century and experienced largely parallel rather than convergent shifts in community composition since that time.Maps were developed for the regional study area using a 10 × 10 km spatial resolution to document spatial patterns of species proportional basal area. White pine co‐dominated (was ranked first or second in proportion of basal area) 45% of the 253 100‐km2 presettlement zones, but none of the 1990 zones. Forest zones co‐dominated by red pine, jack pine, and larch also largely disappeared. These forests were largely supplanted by aspen co‐dominated communities, which accounted for 82% of the 1990 forest zones and represent diminished regional landscape diversity. Although the same 11 species made up the 1990 as well as the 19th century forest, change in their relative abundance and dominance was profound such that 85% of the 253 zones now contain community types (i.e., dominant species pairs) that did not dominate anywhere in the presettlement era.
LAND USE, WATER CHEMISTRY, AQUATIC VEGETATION, AND ZOOPLANKTON COMMUNITY STRUCTURE OF SHALLOW LAKES
Authors: Dodson Stanley I. , Lillie Richard A. , Will-Wolf Susan 
Published: June 2007

Landscape–lake interactions, including anthropogenic effects in modern human‐dominated landscapes, are essential elements of our understanding of aquatic community ecology. This study links land use (six categories) to the aquatic environment (30 water chemistry, lake morphology, and vegetation variables) and to zooplankton community richness (32 common taxa) and composition in 73 small and shallow lakes of southeastern Wisconsin, USA. The sites differed most according to two environmental variables (principal components analysis [PCA] ordination): the presence/absence of riparian vegetation and the water source (whether ground or atmospheric). Shallow lakes in different land use categories (reference, urban, and agricultural) differed significantly in terms of the two major environmental variables, especially presence of riparian and aquatic vegetation.Reference sites were characterized by the most vegetation and the highest zooplankton richness. Agricultural sites with wide riparian vegetative buffer strips (>30 m) had significantly more zooplankton taxa than agricultural lakes with narrow buffer strips. A nonmetric multidimensional scaling (NMS) ordination of zooplankton community composition suggested a single community among land use categories, with some variation related to vegetation and the water source. The first NMS axis was correlated with PCA1 axis (vegetation) and with zooplankton taxon richness, and the second axis was correlated with PCA2 (water source). The third axis was not strongly correlated with any of the measured environmental factors, suggesting that an unmeasured factor related to disturbance was also important in determining taxon composition. Our analysis supports the hypothesis that zooplankton community structure (taxon richness and composition) is indirectly associated with land use, via the effect of land use on vegetation and the hydrological continuum.
EARLIER RECRUITMENT OR EARLIER DEATH? ON THE ASSUMPTION OF EQUAL SURVIVAL IN RECRUITMENT STUDIES
Authors: Cam Emmanuelle , Cooch Evan G. , Monnat Jean-Yves 
Published: June 2007

In species with deferred breeding, the population can be viewed as composed of phenotypes with different underlying age of first breeding defined at birth. The distribution of underlying age of first breeding within cohorts and the realized distribution of age of recruitment in individuals that survived from birth to first breeding (assessed in the breeding segment of the population) may differ. Realized age of recruitment is governed by the product of two demographic components: [local survival probability from birth to age i − 1] × [transition probability from the “prebreeder” state to the “breeder” state between age i − 1 and i]. The usual approach to gain insight into selective pressures shaping age of recruitment is to address covariation of realized age of first breeding with population size or social and environmental factors. Ideally, one should also conduct comparisons among groups of individuals encountering different conditions at a given age as prebreeders. However, in many species with deferred breeding, individuals are not encountered between birth and first breeding. Consequently, approaches to estimating recruitment probability in the absence of data from prebreeders have been developed. Some of these measures of recruitment ignore variation in the size of the pool of prebreeders among groups (as opposed to transition probability). Unless survival before full recruitment is known to be identical in the groups, inferences about the causes of variation in realized age of first breeding among groups are difficult: such differences may result from differences in survival probability before all the individuals make the transition between states.We assessed the consequences of differences in prebreeding survival among groups on realized age‐specific recruitment probability using numerical simulations. Depending on the specific scenario, realized age‐specific breeding proportions were delayed or advanced compared to those expected according to the true underlying age‐specific transition probabilities. We consider an example of this problem using data from a population of a seabird species, the kittiwake (Rissa tridactyla), where data from prebreeders and breeders were available. Consistent with results from our numerical simulations, we show that transition probabilities directly estimated (the underlying local recruitment probabilities) and those derived from analysis of data from the breeding segment of the population are different.
MICROBE‐MEDIATED PLANT–SOIL FEEDBACK CAUSES HISTORICAL CONTINGENCY EFFECTS IN PLANT COMMUNITY ASSEMBLY
Authors: Kardol Paul , Cornips Nelleke J. , van Kempen Monique M. L. , Bakx-Schotman J. M. Tanja , van der Putten Wim H. 
Published: June 2007

Plant–soil feedback affects performance and competitive ability of individual plants. However, the importance of plant–soil feedback in historical contingency processes and plant community dynamics is largely unknown. In microcosms, we tested how six early‐successional plant species of secondary succession on ex‐arable land induced plant‐specific changes in soil community composition. Following one growth cycle of conditioning the soil community, soil feedback effects were assessed as plant performance in soil of their own as compared to soil from a mixture of the other five early‐successional species. Performance was tested in monocultures and in mixed communities with heterospecific competition from mid‐successional species. The role of soil microorganisms was determined by isolating the microbial component from the soil community, re‐inoculating microorganisms into sterilized substrate, and analyzing plant biomass responses of the early‐ and mid‐successional species.Plant–soil feedback responses of the early‐successional species were negative and significantly increased when the plants were grown in a competitive environment with heterospecifics. In monocultures, three early‐successional species experienced negative feedback in soil with a history of conspecifics, while all early‐successional species experienced negative feedback when grown with interspecific competition. Interestingly, the nonnative forb Conyza canadensis showed the weakest soil feedback effect. Biomass production of the early‐successional plant species was profoundly reduced by the microbial inocula, most strongly when exposed to inocula of conspecific origin. Molecular characterization of the fungal and bacterial rhizosphere communities revealed a relationship between plant biomass production and the composition of the dominant fungal species. Furthermore, our results show that, in early secondary succession, the early‐successional plant species induce changes in the soil microbial community composition that cause historical contingency effects in dominance patterns of mid‐succession plant communities.We conclude that feedback between early‐successional plant species and soil microorganisms can play a crucial role in breaking dominance of early‐successional plant communities. Moreover the influences on soil microorganism community composition influenced plant community dynamics in the mid‐successional plant communities. These results shed new light on how feedback effects between plants and soil organisms in one successional stage result in a biotic legacy effect, which influences plant community processes in subsequent successional stages.