A Framework and Software Tool to Support Collaborative Landscape Analysis: Fitting Square Pegs into Square Holes

For landscape models to be applied successfully in management situations, models must address appropriate questions, include relevant processes and interactions, be perceived as credible and involve people affected by decisions. We propose a framework for collaborative model building that can address these issues, and has its roots in adaptive management, computer‐supported collaborative work and landscape ecology. Models built through this framework integrate a variety of information sources, address relevant questions, and are customized for the particular landscape and policy environment under study. Participants are involved in the process from the start, and because their input is incorporated, they feel ownership of the resulting models, increasing the chance of model acceptance and application. There are two requirements for success: a tool that supports rapid model prototyping and modification, that makes a clear link between a conceptual and implemented model, and that has the ability to implement a wide range of model types; and a core team with skills in communication, research and analysis, and knowledge of ecology and forestry in addition to modelling. SELES (Spatially Explicit Landscape Event Simulator) is a tool for building and running models of landscape dynamics. It combines discrete event simulation with a spatial database and a relatively simple modelling language to allow rapid development of landscape simulations, and provides a high‐level means of specifying complex model behaviours ranging from management actions to natural disturbance and succession. We have applied our framework in several forest modelling projects in British Columbia, Canada. We have found that this framework increases the interest by local experts and decision‐makers to participate actively in the model building process. The workshop process and resulting models have efficiently provided insight into the dynamics of large landscapes over long time frames. The use of SELES has facilitated this process by providing a flexible, transparent environment in which models can be rapidly implemented and refined. As a result, model findings may be more readily incorporated into decision‐support systems designed to assist resource managers in making informed decisions.     

Differences in trace metal concentrations among fluvial morphologic units and implications for sampling

 This study examines the segregation of trace metals within and between fluvial morphologic units in sand-sized and finer bed sediments in a cobble bed stream. The types of fluvial morphologic units sampled are low gradient riffles, high gradient riffles, glides, eddy drop zones, lateral scour pools, attached bars, and detached bars. Three to nine samples were collected from ten of each type of morphologic unit. All 12 metals show significantly different concentrations between some morphologic units in sediments smaller than 2 mm. Eddy drop zones and attached bars consistently have the highest metal concentrations, while low gradient riffles, high gradient riffles, and glides typically have the lowest concentrations. Metals showing the greatest between-unit variability are Al, Cr, Fe, Cu, and Ti, followed by Co, Mn, and Pb, while Mg, Mn, V, and Zn display relatively few differences between units. Lateral and longitudinal variations of metals within units are not significant, and there was no consistent, predictable variation in metal concentrations with distance downstream. Results indicate that metal studies in other gravel- and cobble-bed streams should include a reconnaissance survey to determine variations between morphologic units, stratify sampling by morphologic unit, and analyze spatial autocorrelation to determine sample spacing. Received: October 1997 · Accepted: 23 March 1998     

The detection of binary companions to subdwarf B stars

Intermediate dispersion spectroscopy of a sample of 40 hot subdwarf B stars between 5500 and 9000Å has been obtained. The sample includes a large fraction of targets which have been studied photometrically. Seven targets show strong lines arising from the infrared Ca  ii triplet, the unequivocal signature of a cool companion. The positive Ca  ii identifications include known photometric binaries and new targets; all are associated with a photometric red excess. Assuming a canonical value for the subdwarf luminosity, all of the detected companions are overluminous compared with the main sequence. The detection procedure indicates an improved and more secure method for the measurement of the binary frequency of hot subdwarfs.     

The impact of drilling fluid and well cuttings on polychaete feeding guilds from the US northeastern continental shelf

The effect of recent drilling operations (fluid and well cuttings) on polychaete feeding guilds from the continental shelf off Atlantic City, New Jersey, was examined. Although there were some adverse effects on macrobenthos from 2160 metric tons of cuttings and mud solids discharged into the marine environment, the composition of polychaete feeding guilds remained essentially unchanged. This key trophic relationship between polychaetes and the changing environment due to the drilling operation was apparently uninterrupted. This relationship remains to be examined in other natural and perturbed habitats.     

Channel constituents in beryl

The electronic absorption spectra of Fe²⁺ in non-chromium beryls are examined. Fe²⁺ in the Al-rich six-coordinate site produces absorption bands at about 820 nm and 970 nm polarizedE‖c. Fe²⁺ in the channel produces bands at 820 nm (⊥c) and 2100 nm (‖c). Some blue beryls which are more intensely colored than most aquamarines, have an absorption band at ～700 nm (‖c) which is suggested to arise from an Fe²⁺/Fe³⁺ intervalence interaction. Fe²⁺ in both the six-coordinate site and the channel is identified in the Mössbauer spectra. The Mössbauer spectra of deep blue beryls are unusual and have not been satisfactorily explained. Color changes which accompany heating and irradiation are strongly influenced by the channel iron.     

A simple pore water hydrogen diffusion syringe sampler

Molecular hydrogen (H(2)) is an important intermediate product and electron donor in microbial metabolism. Concentrations of dissolved H(2) are often diagnostic of the predominant terminal electron-accepting processes in ground water systems or aquatic sediments. H(2) concentrations are routinely measured in ground water monitoring wells but are rarely measured in saturated aquatic sediments due to a lack of simple and practical sampling methods. This report describes the design and development (including laboratory and field testing) of a simple, syringe-based H(2) sampler in (1) saturated, riparian sediments, (2) surface water bed sediments, and (3) packed intervals of a fractured bedrock borehole that are inaccessible by standard pumped methods.