Successive Summers Research Articles

Summer soil moisture content and the water table in a forested wetland peat

Soil samples were collected from the peat of the Beverly Swamp, at weekly intervals, over three successive summers. The samples were analyzed to determine the distribution of soil moisture within the peat above the water table. A calculation scheme for the soil mositure deficit is defined and utilized to describe the behaviour of the soil moisture regime over time. Linear regressions of soil moisture deficit against water table level are found to be statistically strong, but the slopes of the regressions change significantly from one summer to the next. Therefore, it is concluded that the position of the water table is not necessarily a consistent indicator of storage capacity in wetlands.

Spatial and temporal patterns of recuruitment of juvenile coral reef fishes to coral habitats within ?One Tree Lagoon?, great barrier reef

Recruitment of juvenile fishes to coral grids, each comprising 4 colonies of 3 species of coral (Acropora formosa, Seriatopora hystrix and Pocillopora damicornis), was examined at 4 widely separated sites within the lagoon of “One Tree Reef” over two successive summers and intervening months (November 1976–January 1978). Recruitment was highly seasonal, with most recruitment occurring during summer. For many species, numbers settling differed greatly from year to year with total numbers (over all sites) differing as much as an order of magnitude between summers. Many fish species demonstrated marked preference among the three coral species as settling sites. The distribution of each of the 20 commonest species across the 4 lagoon sites differed significantly from a random pattern. Differences of an order of magnitude were common in the numbers of a given species recruited to different sites. Each site was preferred by at least one species. In each of 5 cases examined, the pattern of settlement of the species across the 4 sites changed significantly from one summer to the next. The distribution of recruits of a number of species corresponded to the distribution of adults, but for other species there was no correspondence. It is concluded that, at the spatial scale examined, patterns of recruitment of some taxa are consistently more variable than those of other taxa. The implications of spatial variability of recruitment for the distribution of adult fish is discussed and the importance of being able to discriminate such “natural” variability from other kinds of change is stressed.

Home-Based Treatment of Severe Disruptive Behaviors

A home-based reinforcement package was implemented to decrease serious disruptive and aggressive behaviors in three groups of six pre-school and kindergarten-age children, who participated across successive summers in an intensive nine-week remedial program. For each group, the effectiveness of experimental treatment was evaluated in a multiple baseline design across three target behaviors: off-area, physical aggression, and negative statements. Results showed that the home-based package was highly effective for all target responses of all children in the first two groups, but failed to modify disruptive responses of two children in the third group. Potential explanations for the discrepant results, as well as supplementary findings on untreated variables and some individual treatment components, are discussed.

Biology of Hypogastrura tullbergi (Collembola) at a high arctic site

The life cycle, reproductive biology and growth rates of Hypogastrura tullbergi (Schäffer), one of the most abundant and widespread Collembola on Devon Island, N.W.T., were investigated.Reproductive activity was confined to a period of 2–4 wk every season, starting approximately 2 wk after snow‐melt. Individuals of H. tullbergi had the potential of breeding in at least 2 successive summers. This species had an extended, flexible life cycle with a total life span of approximately 3 yr.Growth rates of individuals of H. tullbergi maintained at field temperatures with an excess of fungal material greatly exceeded growth rates of individuals in the field population. It is suggested that in the field, growth rates are limited by food rather than directly by low temperatures. H. tullbergi was not able to grow on a diet of decomposing Dryas integrifolia leaves. Growth rates on fungal substrates were found to depend on temperature, species of fungus, and age. Maximum growth rates for adults occurred at 10°C, but juveniles showed a maximum growth rate at 15°C.The adaptive significance of aspects of the biology of H. tullbergi for long‐term survival in tundra environments is discussed.

Dye tracer tests of water movement at the glacier Austre Okstindbreen, Norway

Theakstone, W. H. & Knudsen, N. T. 1981. Dye tracer tests of water movement at the glacier Austre Okstindbreen, Norway. Norsk geogr. Tidsskr. Vol. 35, 21–28. Oslo. ISSN 0029-1951. Dye tracer tests of water movement through the glacier Austre Okstindbreen in three successive summers have shown that, whilst some water passes rapidly through the glacier from points of entry at the surface, considerable delays characterise throughflow from many points. The tests, together with other hydrological studies at the glacier, indicate that discrete but changeable drainage systems exist within Austre Okstindbreen during the summer. Observations suggest that the systems are well represented by the model derived by Stenborg (1969, 1973) for two Swedish glaciers. Relatively low ice permeability is indicated by the results of a test in which tracer injected into water entering a crevasse re-emerged in water overflowing from another crevase, and in which one water-filled crevasse remained tracer-free although the water in...

Use of Deterministic and Empirical Models to Predict Potential Evapotranspiration in an Advective Environment1

AbstractA field experiment was conducted for three successive summers in the arid southwestern United States to determine the applicability of traditional empirical and deterministic potential evapotranspiration formulas for predicting water loss under extreme advective conditions. Five models for predicting potential evapotranspiration were compared to hydrologic balance estimates of water loss from a cowpea (Vigna unguiculata L. Walp) crop over two summer seasons and to each other during a third summer season. Of the five methods, pan evaporation was the least reliable indicator of full‐cover crop water use whether considered on a weekly or seasonal basis. The Priestley‐Taylor correlation, which required local calibration could not describe extreme changes in sensible heat advection from year to year with a single calibration. A form of the solar radiation correlation which contains parameters that are functions of humidity and wind run, worked adequately in all years as did an advection‐modified Priestley‐Taylor equation which requires a single calibration and vapor pressure deficit values. The Penman combination equation, which did not require local calibration, corresponded most closely to measured values. All models which contained some facility for recalibration or correction in response to changes in vapor deficit worked adequately under changing advective conditions during the entire experiment.

Caste-biased Polyethism in a Mound-building Ant Species

Formica obscuripes Forel, the western thatching ant, a mound-building species found at Illinois Beach State Nature Preserve, has three morphological castes (major, media and minor, in order of decreasing size). Observations on the activities of each caste were made from May to September 1975, June 1976, and September 1976. Behaviors were categorized and frequencies of the three castes exhibiting each behavior type were calculated. Caste strongly influenced occupational repertoires of the ants. Repairing the nest, carrying dead conspecifics and bringing in prey were performed primarily by majors, whereas medias carried brood and foraged on vegetation for honeydew from aphids or plant sap. Minors were seen outside the nest too infrequently to allow a detailed analysis of their activities. I NTRODUCTION Colonies of social insect populations are intriguing for behaviorists because of their high degree of organization. The performance of numerous tasks is required for successful colony maintenance, and division of duties among individuals has been demonstrated for bees (Brian, 1952; Free, 1965), wasps (Akre et al., 1976; Potter, 1964) and ants (Weir, 1958; Wallis, 1965). Oftentimes, workers assume certain duties as a result of morphological specialization. For example, army ant soldiers with huge heads and jaws serve primarily for defense while smaller individuals assume the domestic chores of brood rearing, nest cleaning and so forth (Schneirla, 1971). However, a generalized relationship between polymorphism and the division of labor, or polyethism, cannot be defined for those groups displaying continuous size-frequency distributions (Wilson, 1971). This paper reports a morphology-behavior association for the western thatching ant (Formica obscuripes Forel) at Illinois Beach State Nature Preserve in Lake County, Illinois. METHODS Workers collected from colonies at Illinois Beach were examined in the laboratory. Morphological measurements were made with the use of an ocular micrometer mounted in a dissecting microscope. Head width across the eyes, head length from back to mandible base, and alitrunk length from head to petiole were recorded in micrometer units and subsequently converted to millimeters. A total of 241 individuals were measured and then assigned to castes according to a decision function using both size and coloration: majors, the largest-sized group, have red heads and thoraxes; the smaller medias have reddish streaks on the heads and rarely on the thoraxes; minors, the smallest worker group, are uniformly black. Data on division of labor were collected in the field during 2 successive summers. Data from 1975 were compiled from incidental observations throughout the season. Over 2-7 days in both June and September 1976 each of the nests was watched for 5-10 min during mornings and late afternoons when overall activity was high. Workers were assigned to a caste as outlined above. Records of nest location, caste designation and behavioral activities were tallied throughout the observation periods. CASTE MORPHOLOGY Workers of Formica obscuripes exhibit continuous size variation; nonetheless, 'Present address: Department of Biological Sciences, Stanford University, Stanford, California 94305.

Lucerne survival in relation to grass management on a brigalow land in south-east Queensland

Lucerne, Medicago sativa cv. Hunter River, was planted on a 90 cm x 90 cm grid on a fertile brigalow clay soil in south-east Queensland in November 1971. The lucerne was either cut regularly or cut annually. Volunteer species, principally grasses, were either mown regularly, 2-3 times as often as the lucerne during periods of active growth, or were also cut annually in late summer. Changes in lucerne vigour and survival were recorded about four times a year through to 1977. A few lucerne plants died between most samplings in each treatment. More substantial losses due to individual treatments were superimposed on the continuing small losses in successive summers. The first two summers following establishment were wetter than average, and as many as 41% of the original population died when volunteer species were cut annually. Where volunteer species were mown regularly from between lucerne plants, survival was good until the very dry 1974-75 summer when 35% of the original plants died. Our results thus suggest that lucerne plants were lost through their incompatibility with vigorous tropical grass growth, through drought effects, and also through the continuous slow erosion of the population : they emphasise the importance of managing vigorous grass growth if lucerne survival is to be prolonged in fertile sub-tropical environments. Vigour declined markedly only where4wzerne was regularly cut from within the annually cut volunteer species, but there were large seasonal fluctuations. The relative size of plants decreased over some 4 to 9 months before death, although there was an indication that those dying in summer were more representative of the population mean size. This suggests that summer deaths rapidly follow the occurrence of predisposing factors. In summer, management should aim mainly to prevent plant deaths, whereas at other times there may be additional scope for alleviating losses in productivity.

The Dynamics of an Entomopoxvirus in a Field Population of Larval Midges of the Chironomus decorus1 Complex 3

The incidence of entomopoxvirus infections in larval midge populations of an undescribed species in the Chironomus decorus complex from 2 southern California flood-control channels was monitored during 2 successive summers. The population densities and prevalence of disease were inversely related to the rate of water flow at each sampling site. Results from laboratory rearings of field-collected larvae suggested that the impact of the virus on the midge populations was greater than that indicated by infection rates alone and that the virus may play an important role in population regulation. Studies with field collected egg masses suggested that the virus is introduced to the channels by transovum transmission.

Structures and Dynamics of Populations of the Salamader Desmognathus Ochrophaeus Cope in Different Habitats

Two populations of Desmognathus ochrophaeus, one inhabiting a wet rockface created during the construction of a tunnel portal on the Blue Ridge Parkway and the other a wooded cover 145 m away, were compared with respect to size at maturity, growth rates, age structure, and fecundity. Woodland animals are larger at maturity than rockface animals. This is because of their faster juvenile growth rates, not delayed maturity as previously believed. Woodland juveniles then continue to grow faster than rockface individuals after they mature, possibly because food resources are more extensive and dependable in leaf litter than on wet rockfaces. In the rockface population, growth rates appear to vary slightly from year to year. Body sizes and egg production are positively correlated in both populations, and the larger body sizes of woodland females enables them to achieve a mean clutch size nearly 50% greater than that of the rockface population. Body—size variation among populations of D. ochrophaeus is a complex phenomenon, possibly involving genetic differentiation of populations at different elevatons as well as non—evolutionary differences in growth rates between populations in different habitats. Further studies will be required to show whether other differences among rockface populations and between rockface and woodland populations have genetic bases. In the rockface population, proportions of second—summer juveniles and males in their 1st yr of sexual maturity appear to decrease during the summer. The cause of this phenomenon is unknown, and there is no evidence for it in the woodland population. Both populations have similar age structures in the early summer, before changes in the structure of the rockface population have occurred. Continued sampling of the rockface population over four successive summers resulted in a decline in the ratio of adult males to 1st yr juveniles, especially after the summer of 1971 when collecting was particularly intense. Estimates of the normal number of adult males in the population and the amount of yearly recruitment were made from capture—release—recapture data on another rockface population of similar density. Sustained collecting, which should have resulted in a greater decline in mean number of testis lobes per male than was observed, showed that older males may have been underrepresented in samples because of their more secretive habits.

Biological features of an aestival pond in Western Canada

The seasonal changes in flora and fauna in an aestival pond in central Alberta, Canada, were studied through a complete annual cycle during which an exceptional decrease in water volume occurred in response to lower than normal rainfall. Substantial changes took place between successive summers in the species composition of the phytoplankton, Rotifera, Oligochaeta, Copepoda and Zygoptera. Some of the incoming species, particularly Chaetogaster diaphanus (Oligochaeta) and three species of Lestes (Zygoptera) are often associated with more temporary habitats of the region. The instability of species composition and productivity of the community is discussed in terms of the trophic position of aestival lakes and ponds.

Seasonal trichorrhexis nodosa. Role of cumulative damage in frayed hair.

A young man acquired trichorrhexis nodosa during two successive summers. Clinical evidence and scanning electron microscopy of the hairs indicated that shampooing, brushing and combing, saltwater bathing and ultraviolet exposure, as additive traumas, accounted for the unusual recurrences. The underlying cause is removal of the hair cuticle. Damage present between clinical appearances of the disorder could be visualized in newly grown hair, but only with the aid of the scanning electron microscope. Severe cuticular damage was reproduced by in vitro methods which simulated the physical and chemical factors involved in this case. The relationships between acquired and congenital trichorrhexis nodosa and split ends of hair are discussed.

Quelques données sur les Lézards (Lacerta viridis et L. agilis) marques à la pointe d’Arçay (Vendée)

In a tidal marsh along the Vendee coast, a programme of rodent trapping enabled the study of a Lizard community comprising two species : Lacerta viridis and L. agilis. Individuals were weighed, marked and released. The two species were active from April to August. They shared, without apparent competition, a common hunting area ; this seems referable to a slight difference in activity hours and preferential activity zones. A narrow barrier beach, always above sea-level, is used as a wintering area and, at least by L. viridis, for night resting places during summer. There is a tendency among recaptured individuals to use a restricted (20-30 m diameter) activity range. Some individuals of the two species have been recaptured in two successive summers.

Der Verlauf desynchronisierter, circadianer Periodik einer Waldmaus (Apodemus flavicollis) in Nordfinnland

1. A free running circadian periodicity in the locomotive activity of a wood mouse (Apodemus flavicollisMelch.) was recorded 172 km south of the arctic circle for two successive summers during natural day. 2 The sensitivity of the animal to the pacemaker varied with age under the same experimental conditions. The same mouse was desynchronized for 48 days in 1967, in 1968, 77 days. 3. The time of desynchronization coincides exactly with the time during which the midpoint of the sun is not more than 6° below the horizon (Civil Twilight). 4. Despite free running periodicity, day and night were perceived as variations in the conditions of continuous lighting. An activity period including a night was shortened, and lengthened when it included a day.

Reproductive Potential, Activity, and Cycles in the Painted Turtle, Chrysemys Picta

Reproductive cycles, reproductive potential and activity were determined for populations of the painted turtle, Chrysemys picta. The male reproductive cycle is divisible into three phases. From late March to early May (the mating season) the testes are small but the sperm ducts are filled with sperm. Spermatogenesis occurs from July to October. This results in an increase in testis size. The winter phase is characterized by small testes. Most of the sperm are contained in the epididymis at this time. Transitional periods occur between each of these phases. Courtship behavior occurs in spring and fall, but effective mating probably does not occur in the fall. Ovarian follicles begin to increase in size in September. By March the largest follicles are around 16 mm in diameter. Immediately before ovulation these increases to about 18 mm in diameter. Ovulation occurs around the middle of May and enlarged follicles, as well as the oviducal eggs, are invariably present at this time. Presumably a second clutch is laid. The second ovulation probably occurs in middle June. Mean clutch size is about 6.5 eggs and the annual reproductive potential for an individual is around 13 eggs. Adults become active in early spring when water temperatures reach the minimum tolerance limits. Reproduction is believed to be the incentive for this early activity. Distances traveled by mature males are greatest in the spring. Travel is limited throughout the summer. Juveniles and mature males are found in the same general area in successive summers whereas mature females have often traveled long distances. This is attributed to females leaving the water in one area for nesting purposes and returning to the water in another area.

The Nudist Camp: Way of Life and Social Structure

The purpose of this paper is to describe the modes of behavior, demographic composition, social structure, and paths of mobility that characterize organized nudism. The data come from three sources : ( 1 ) two successive summers of participant observation in camps in the United States and Europe, (2) interviews with 101 nudists from the Chicago area, and (3) mailed questionnaires completed by 617 nudists located throughout the United States and Canada.

EVAPOTRANSPIRATION BY IRRIGATED ALFALFA AS RELATED TO SEASON AND GROWTH STAGE

The results of a plot experiment wherein three levels of irrigation were applied during three successive summers showed that the average daily rates of evapotranspiration by alfalfa ranged from 0.05 to 0.36 in. per day. The maximum evapotranspiration rate was associated with complete ground cover and at this stage equalled potential evapotranspiration. Except for early in the season the conversion factor for estimating evapotranspiration from evaporation for irrigation scheduling by the budget method or soil moisture balance sheet should approximate the potential evapotranspiration–evaporation ratio.

Seasonal changes in the gonads and accessory reproductive organs of the vole ( Microtus agrestis)

Gonads and accessory reproductive organs of 161 voles ( Microtus agrestis) caught in summer and winter have been studied. The large summer testes produced abundant sperm and had conspicuous interstitial cells. In the small winter testes the epithelium of seminiferous tubules was composed chiefly of Sertoli cells and spermatogonia. Interstitial cells were generally inconspicuous in winter males. All summer females were pregnant or lactating. Summer ovaries possessed fresh corpora lutea as well as Graafian follicles. Some winter ovaries had Graafian follicles, but none had fresh corpora lutea. Seminal vesicles and ventral prostates weighed much less in winter than in summer. However, the ventral prostatic epithelium remained in winter almost as high as in summer glands. Winter males and females were divisible into 2 classes, consisting of those animals which did and did not become sexually mature in the previous summer. Voles in one winter were far more developed sexually than in others. There were also differences in the reproductive state of males in two successive summers. No obvious climatic differences could explain this variation.

The Social Organization of Some Science Research Apprentices in Scientific, Recreational, and Routine-Work Activities

The activity of the Jackson Memorial Laboratory in promoting basic research includes an effort to provide an opportunity for young people to come in contact with research problems, techniques, and programs. An attempt is made to encourage and assist students of promise to explore the possibilities of research as a career by serving as apprentices to laboratory staff members who are engaged in full time research within the fields of experimental biology, psychology, or -medicine. Each year the Laboratory maintains a Summer Apprenticeship Program for collegiate students and one for precollegiate students. In the collegiate program, each accepted applicant works as a science apprentice under the direction of his staff sponsor throughout a 10-week period. At the end of the summer each apprentice presents an oral report on the results of his experimental work and files a written dissertation in the Laboratory's library. In addition to the specific apprentice training, each apprentice is exposed to a daily colloquium on research problems, theory, and methods. Also, each is exposed to most of the Laboratory's scientific conferences, evening seminars, and special demonstrations. The apprentices room and board at the Summer Student Colony, which is near the Main Laboratory building and is admirably located for a wide variety of individual and group scientific, recreational, and routinework activities. The purpose of this investigation was to study the social organization of some science students in the Summer Apprenticeship Program for collegiate students during three successive summers. This investigation was conducted as a portion of a larger study in which the science apprenticeship programs at the Laboratory are being evaluated, and in which preliminary information concerning the psychological characteristics and abilities of young potential research scientists is being collected. A description of the particular social organization believed to be conducive for effective apprentice training in the biological sciences has not been reported, so it was hoped that progress towards this long'A portion of this paper was presented at a panel on Group Structure at the Annual

Helminth Infections in Relation to Restricted Feeding on Range

THE following experiment was initiated to provide additional information on the factors affecting the growth of replacement stock on range. Parker and McSpadden (1944) revealed that lots of pullets raised on pasture were heavier, had lower mortality rates, consumed less feed, and utilized their feed more efficiently than those on bare range. Todd and McSpadden (1947) concluded that the supplemental green feed of pasture did not prevent parasitism, but it did apparently enable birds to withstand greater parasitic burdens. Todd (1948) examined four groups of birds, one group on a bare lot and the other three on variations of pasture. The present work considered standardized pastures in conjunction with degrees of restricted mash intake. PROCEDUREIn each of the four successive summers (1951, 1952, 1953, and 1954), prospective replacement stock was divided into four groups and placed on range as follows: Group 1 had access to an all mash ration …