Perceived environmental quality of neighborhoods: Development of assessment scales and their relation to age and gender

The relation of age to perceived quality of neighborhoods is examined. For a large sample of persons age 18 and older (N: 1520), 15 factor scales of perceived quality of neighborhoods were developed and confirmed on a second sample (N: 1021). The scales are reliable (internally consistent and cross-validated) and ‘age fair’ in the sense that the internal structure of the set of scales is constant across age groups. The hypothesis of a positive, linear relationship between age and perceived quality of the neighborhood is supported in both exploratory and confirmatory samples. Some gender differences in scale level are also observed and cross-validated. No evidence of age-gender interaction is found for the age range: 21–69.     

Migration of pollutants in groundwater. III. Numerical dispersion reduction with cartesian coordinates

The partial differential equation governing the movement of a decomposing pollutant undergoing 2-dimensional flow in a saturated aquifer is examined. The analytical solution of the equation is usually not possible, and use of mesh numerical integration techniques causes excessive numerical dispersion to arise from the advection term. We apply two asymmetrical upwind formulas to approximate the advection term. These markedly reduce numerical dispersion without requiring the use of coordinate systems obtained by conformal mapping. Flow within a right angle and flow toward a sink in an otherwise uniform field are analyzed to illustrate the methods.     

A STUDY OF THE SURFACE SYNOPTIC CIRCULATION PATTERNS IN ASSOCIATION WITH THE DROUGHT OF THE 1960's IN THE NORTHEASTERN UNITED STATES1

A comparative evaluation is made of the frequency of air mass and frontal types during a 4-year representative portion of the drought as opposed to an equivalent non-drought period. Selection of the non-drought period is based on the Palmer Drought Index. Results indicate a statistically significant increase in the occurrence of continental polar air during the drought. Other conclusions concerning conditions during the drought, not statistically significant but worth further study, are: lower frequency of maritime tropical air in the summer months, more occurrences of cold and occluded fronts, and fewer occurrences of stationary fronts.     

Social discrimination tuning in ants: template formation and chemical similarity

To investigate the role of template plasticity in shaping nest-mate recognition processes in ants, we constructed experimental mixed-species groups of Manica rubida with either Myrmica rubra, Tetramorium bicarinatum or Formica selysi. Selecting Ma. rubida as the focal species, we observed the behaviour within mixed-species groups and the transfer rates of cuticular hydrocarbons (CHC) onto the focal ants, and we also tested the aggression of the focal species reared either alone or in association with each of the three different species. We show that Ma. rubida workers were always amicable towards their mixed group members, as towards members of the respective parental colonies, irrespective of the associated species. They did, however, express different levels of aggression towards single-species groups of the other species tested, depending on the species with which they were reared. The study suggests that similarity in CHC profiles in two species leads to a narrow template in mixed groups, while dissimilarity is followed by lower levels of aggression (a broader template), at least against species with similar CHC compound compositions (i.e. both a broader template in the focal ants and familiarity with the compound groups of the tested individuals operate together). This refutes the hypothesis that ants reared in mixed-species groups are systematically more tolerant. It also demonstrates that heterospecific information is not treated equally during development. We suggest that post-imaginal learning, template reforming and decision making are more precisely tuned when the two species' chemical complexes are similar.     

Regulation of worker reproduction in bumblebees (Bombus terrestris): workers eavesdrop on a queen signal

In the annual bumblebee Bombus terrestris, the onset of queen-worker conflict over male production is seasonally and socially constrained. Workers will do better if they start to reproduce (the so-called competition phase) only after ascertaining that larvae are committed to gyne development but before the season ends because they gain more by rearing sister-gynes than their own sons. Here, we tested two nonmutually exclusive hypotheses as to what triggers the onset of worker reproduction: Workers can directly monitor larval development and/or workers eavesdrop on the queen signal that directs gyne development. Exposing workers to gyne larvae through a double mesh did not advance the competition phase compared to control colonies. However, when workers, but not the queen, were allowed contact with gyne larvae, both the competition phase and gyne production were advanced. Thus, while larvae do not emit a volatile pheromone that discloses their developmental route, the physical contact of workers with such larvae triggers early competition phase. However, workers exclusively exposed to worker larvae (colonies prevented from producing gyne larvae) started to reproduce at the same time as control colonies. Replacing the resident queen with an older queen (from gyne-rearing colonies) advanced the competition phase, irrespective of worker age. The results are consistent with the hypothesis that workers eavesdrop on the queen pheromones. This is adaptive because it allows workers a broader time-window for reproduction and thus to gain fitness from rearing both sister-gynes and sons before the season ends without affecting colony development.     

Chemistry of the postpharyngeal gland secretion and its implication for the phylogeny of IberianCataglyphis species (Hymenoptera: Formicidae)

Summary A comparative morphological and chemical study of six endemic species ofCataglyphis from the Iberian Peninsula:C. ibericus, C. rosenhaueri, C. hispanicus, C. humeya, C. velox andC. floricola and the Moroccan speciesC. bombycinus is described. The morphological study relied primarily on genitalia characteristics, whereas the chemical study concentrated on the postpharyngeal gland constituents. Cladograms based on the morphological and chemical data were performed using Ward's method. The dendrogram based on morphological features revealed that the IberianCataglyphis can be classified into three species groupsalbicans, altisquamis andemmae. The same pattern occurred when the dimethylalkanes constituents of the postpharyngeal gland were utilised as character states, with a slight displacement of species within thealtisquamis group. However, when the complete hydrocarbon blend was utilised major discrepancies in the dendrograms occurred.Cataglyphis velox proved to be very similar toC. bombycinus, whereasC. floricola clustered with the other two species of thealtisquamis group. Based on the geographical distribution and paleontological data (Tinaut 1993) it is assumed thatC. floricola recently invaded the Iberian Peninsula. Based on the chemical findings we postulate that chemical character displacement occurred inC. floricola as a result of its sympatry withC. velox after the former colonized the Iberian Peninsula. We further discuss the possible reason for the different dendrograms obtained when only the dimethylalkanes are considered and its implication for the communicative role of the postpharyngeal gland secretion in these ants.     

Economics of additionality for environmental services from agriculture

We present a model of additionality for offsets sold from agriculture to industrial sector sources regulated by cap-and-trade. We consider a potential policy where agricultural sources would not be covered by cap-and-trade requirements but would be eligible to receive offsets whenever their emissions fall below a policy-specified baseline, and would not be penalized for emissions above their baseline. Major results are: (1) The optimal baseline should be set above the average counterfactual emissions of participating farms, an unexpected result that has been missing from the literature. (2) The optimal trading ratio should be greater than one (a ton of offsets counts for less than a ton of covered emissions) even under emissions certainty. Previous research has justified such trading ratios by emissions uncertainty. (3) Emissions uncertainty does not justify a change in the baseline if the accompanying emissions model is unbiased. (4) An optimal combination of policies is to subsidize offsets and tighten the baseline relative to the no-subsidy case.     

Global warming and flowering times in Thoreau's Concord: a community perspective

As a result of climate change, many plants are now flowering measurably earlier than they did in the past. However, some species' flowering times have changed much more than others. Data at the community level can clarify the variation in flowering responses to climate change. In order to determine how North American species' flowering times respond to climate, we analyzed a series of previously unstudied records of the dates of first flowering for over 500 plant taxa in Concord, Massachusetts, USA. These records began with six years of observations by the famous naturalist Henry David Thoreau from 1852 to 1858, continued with 16 years of observations by the botanist Alfred Hosmer in 1878 and 1888-1902, and concluded with our own observations in 2004, 2005, and 2006. From 1852 through 2006, Concord warmed by 2.4 degrees C due to global climate change and urbanization. Using a subset of 43 common species, we determined that plants are now flowering seven days earlier on average than they did in Thoreau's times. Plant flowering times were most correlated with mean temperatures in the one or two months just before flowering and were also correlated with January temperatures. Summer-flowering species showed more interannual variation in flowering time than did spring-flowering species, but the flowering times of spring-flowering species correlated more strongly to mean monthly temperatures. In many cases, such as within the genera Betula and Solidago, closely related, co-occurring species responded to climate very differently from one another. The differences in flowering responses to warming could affect relationships in plant communities as warming continues. Common St. John's wort (Hypericum perforatum) and highbush blueberry (Vaccinium corymbosum) are particularly responsive to changes in climate, are common across much of the United States, and could serve as indicators of biological responses to climate change. We discuss the need for researchers to be aware, when using data sets involving multiple observers, of how varying methodologies, sample sizes, and sampling intensities affect the results. Finally, we emphasize the importance of using historical observations, like those of Thoreau and Hosmer, as sources of long-term data and to increase public awareness of biological responses to climate change.     

Park isolation in anthropogenic landscapes: land change and livelihoods at park boundaries in the African Albertine Rift

Regional Environmental Change - Landscapes are changing rapidly in regions where rural people live adjacent to protected parks and reserves. This is the case in highland East Africa, where many...     

In-nest environment modulates nestmate recognition in the ant<Emphasis Type="Italic"> Camponotus fellah</Emphasis>

Multiple behavioral and chemical studies indicate that ant nestmate recognition cues are low-volatile substances, in particular hydrocarbons (HCs) located on the cuticular surface. We tested the hypothesis that in the ant Camponotus fellah, nest environment, in particular nest volatile odors, can modulate nestmate-recognition-mediated aggression. Workers were individually confined within their own nest in small cages having either a single mesh (SM = limited physical contact permitted) or a double mesh (DM = exposed to nest volatiles only) screen. Individual workers completely isolated outside their nest (CI) served as control. When reintroduced into a group of 50 nestmates, the CI workers were attacked as alien ants after only 2 weeks of separation, whereas the SM workers were treated as nestmates even after 2 months of separation. Aggression towards DM ants depended on the period of isolation. Only DM workers isolated for over 2 months were aggressed by their nestmates, which did not significantly differ from the CI nestmates. Cuticular HC analyses revealed that the profile of the non-isolated ants (NI) was clearly distinct from that of CI, SM and DM ants. Profile differences matched the aggressive response in the case of CI ants but were uncorrelated in the case of SM or DM ants. This suggests that keeping the ants within the nest environment affected nestmate recognition in additional ways than merely altering their HC profile. Nest environment thus appears to affect label–template mismatch by modulating aggressive behavior, as well as the direction at which cuticular HCs diverged during the separation period.