FIRST-YEAR EFFECTS OF CLEARCUTTING AN OAK-HICKORY WATERSHED ON WATER YIELD1

ABSTRACT: Two intermittent streams on oak-hickory watersheds in southern Illinois were gaged with a V-notch weir and sampled with an automatic water sampler. Baseline data was collected for a period of three years. Flow volume showed large variations between years and watersheds. Water samples were analyzed for Na, K, Ca, Mg, ortho-P, and NO₃-N. Water quality was consistently high, but there were significant differences between the watersheds during the calibration period. One watershed was clearcut in November 1979. One year of postharvest data has been analyzed. Flow volume increased 95 percent, but there was no evidence of increased sedimentation. There were significant increases in the stream water concentrations of K, Mg, and NO₃-N of 18 percent, 8 percent, and 274 percent, respectively. Nutrient budgets for the site were not adversely affected by the harvest. The clearcutting operation appears to have had a small impact on the watershed due to minimal disturbance during the logging and below normal precipitation the first year following the harvest.     

Construing of self and others at work in the early years of corporate careers

Research has examined personal change and stability in early adulthood but generally with standardized scales and without inviting explicit comparison of self with other people. The present work uses the repertory grid method to examine how graduates construe themselves and others during early career. Ninety-four graduate entrants to a multinational corporation with zero to four years' tenure completed repertory grids on two occasions one year apart. Results shed much light on the graduates' concepts of self relative to others in their work setting, and how these change over time. The graduates generally had fairly positive self concepts, though these did not become more positive with tenure. Most saw themselves much as they thought others saw them. Change in concepts of self varied greatly between graduates, as did the constructs on which those concepts were described. The results cast further doubt on whether organizational socialization affects people in uniform ways.     

Evaluating the cumulative effects of alteration on New England wetlands

In New England, patterns of glacial deposition strongly influence wetland occurrence and function. Many wetlands are associated with permeable deposits and owe their existence to groundwater discharge. Whether developed on deposits of high or low permeability, wetlands are often associated with streams and appear to play an important role in controlling and modifying streamflow. Evidence is cited showing that some wetlands operate to lessen flood peaks, and may have the seasonal effect of increasing spring discharges and depressing low flows. Wetlands overlying permeable deposits may be associated with important aquifers where they can produce slight modifications in water quality and head distribution within the aquifer. Impacts to wetlands undoubtedly will affect these functions, but the precise nature of the effect is difficult to predict. This is especially true of incremental impacts to wetlands, which may, for example, produce a change in streamflow disproportionate to wetland area in the drainage basin, i.e., a nonlinear effect as defined by Preston and Bedford (1988). Additional research is needed before hydrologic function can be reliably correlated with physical properties of wetlands and landscapes.A model is proposed to structure future research and explore relationships between hydrologic function and physical properties of wetlands and landscapes. The model considers (1) the nature of the underlying deposits (geologic type), (2) location in the drainage basin (topographic position), (3) relationship to the principal zone of saturation (hydrologic position), and (4) hydrologic character of the organic deposit.     

HYDROLOGIC MODELING USING A SIMULATION LANGUAGE BASED ON QUEUEING THEORY1

ABSTRACT: A novel approach has been developed by applying queueing theory to hydrologic modeling. A queueing situation is characterized by a flow of customers arriving randomly at one or more service facilities. In this case, the customers are represented by water and the service time is the time it takes to move through the soil and over the land. This approach has the potential to be simpler and more efficient than some previously developed models. Another important attribute of queueing theory is its ability to model almost unlimited detail. Many simulation languages based on queueing theory have been developed and tested and are available. Applications of the languages include manufacturing operations, transportation systems, computer systems, financial planning, and health care systems. A model was developed, using a simulation language, to predict runoff hydrographs from storms occurring on small homogeneous watersheds. With continued development, queueing theory could provide an effident, detailed approach to simulating many natural processes.     

Bone structure of some marine vertebrates

Bone tissue and bone organ densities, and major components of bone (i.e., ash, organic+CO₂, water and fat) of sperm whale, fin whale, sea lion, albacore, mackerel, rattail and guitarfish were measured. Mammalian vertebrae have higher tissue densities and lower organ densities than fishes. This is because of the high ash and organic content of the bone tissue and the large interstitial volume of the bone organ of mammals. Only albacore and mackerel vertebrae, which had the highest organ densities, and fin whale rib, which had the lowest organ density, contained appreciable quantities of fats. Hydrated tissue densities of all the vertebrates studies are directly correlated with ash content and inversely correlated with water content. Bone structure as related to buoyancy and locomotion is also discussed.     

The evolution of marmot sociality: I. Why disperse late?

Summary Prolonged toleration of offspring in marmots was hypothesized to be (1) a means of preventing dispersal of undersized young (Barash 1974 a) or more generally (2) continued parental investment, increasing the probability of descendant survival and reproduction (Armitage 1981, 1987). These hypotheses are tested in this paper for one of the most social of marmot species, the alpine marmot. The animals studied lived in groups within territories defended by a dominant male and female, or as floaters lacking a well-defined home range. Offspring did not disperse before sexual maturity at age 2 (Fig. 1). Only territorial females bred, whereas territorial males were not able to monopolize reproduction likewise (Table 2). Dispersers had similar spring mass to nondispersers (Table 4). Hence, hypothesis 1 is not supported, at least not for adult-sized, > 2 years old animals. During their residency, 19% of subordinates obtained their natal territory or a neighboring one (Fig. 2). Long distance dispersal bore a high mortality risk. Thus, toleration of mature offspring could well represent parental investment. Other results, however, suggest additional influences on the timing of dispersal. (i) Males dispersed later than females (Fig. 3), possibly because of mate sharing by territorial males (see Emlen 1982). (ii) The higher mass loss of dispersers during the previous winter indicates that weak animals were forced to leave (Table 5) despite presumably lower chances of becoming territorial (Table 3). (iii) Subordinate animals which could not be the offspring of both territorials present were not more likely to disperse (Fig. 3). (iv) Lower dispersal rates when immatures lived in the group (Fig. 3) may indicate benefits from the subordinates' presence for rearing young.     

Shadow cinematography of fish larvae

A simple system of shadow cinematography, consisting of a small tungsten halogen lamp, 2 large biconvex lenses and a 16 mm camera, is described for recording the swimming and feeding behaviour of larval fish. The system can be used either with infra-red film to record swimming behaviour independently of ambient light intensity, or with high-resolution film to record food organisms and feeding behaviour. Small plankton organisms of 0.2 mm width can be resolved using high-resolution film. The technique has been used to record the behaviour of plaice larvae (Pleuronectes platessa L.) feeding on the nauplii of Artemia salina L. The perceptive field of the larvae extends to approximately ±60° in azimuth, ±40° in elevation and 1.5 body lengths in range.     

Effect of El Nĩno on demographic,morphological, and chemical parameters in turtle-grass (Thalassia testudinum): an unexpected test of indicators

We examined the response of demographic, morphological, and chemical parameters of turtle grass (Thalassia testudinum), to much-higher-than-normal rainfall associated with an El Niño event in the winter of 1997–1998. Up to 20 inches of added rain fell between December 1997 and March 1998, triggering widespread and persistent phytoplankton blooms along the west coast of Florida. Water-column chlorophyll concentrations estimated from serial SeaWiFS imagery were much higher during the El Niño event than in the previous or following years, although the timing and magnitude of phytoplankton blooms varied among sites. Seagrass samples collected in 1997, 1998, and 1999 provided an excellent opportunity to test the responsiveness of Thalassia to decline and subsequent improvement of water quality and clarity in four estuaries. Using a scoring technique based on temporal responsiveness, spatial consistency, and statistical strength of indicators, we found that several morphological parameters (Thalassia shoot density, blade width, blade number, and shoot-specific leaf area) were responsive and consistent measures of light stress. Some morphological parameters, such as rhizome apex density, responded to declines and subsequent improvement in water clarity, but lacked the statistical discriminating power necessary to be useful indicators. However, rhizome sugar, starch, and the total carbohydrate concentrations also exhibited spatially and temporally consistent variation as well as statistical strength. Because changes in shoot density, as well as water clarity, affect rhizome carbohydrate levels, a composite metric based on Thalassia shoot density and rhizome carbohydrate levels together is probably more useful than either parameter alone as an indicator of seagrass health.