Bioindication of air pollution effects has received considerable attention in recent years. It has been almost entirely focused on individual species and relatively little notice has been given to ecosystem level process and function monitors. Longterm research projects in the Niepolomice Forest in southern Poland and the Colstrip area in southeast Montana, U.S.A., were analyzed for both organismic and system level indicators and monitors for SO, trace elements, and fluoride pollution originating in nearby coal-fired industrial processes. Species of lichens exhibited changes in morphology and survival and pine species exhibited pollutant accumulation in needles at both sites. Declines in Scotch pine growth in Poland of up to 20% were compared with declines in western wheatgrass rhizone biomass in Montana to illustrate system wide effects on primary productivity. Directly observable declines in decomposition rate were noted for both sites at higher pollution levels and tied to system wide occurrences of nutrient deficiency and toxicant buildup in soil pools. Pollutant increases in deer antler composition, changes in grasshopper dietary patterns, and lichen density and health were postulated to have system level implications as well.

Species and ecosystem level bioindicators of airborne pollution: an analysis of two major studies

The Effects of SO2 on a Grassland

We describe the design and performance of two replicate field exposure systems for evaluating the ecological effects of chronic SO2 exposure on 0.5 ha plots of native Montana grassland. The SO2 was supplied at a constant rate to each plot through a network of 2.5-cm inside diameter aluminum pipes set parallel to and approximately 0.7 m above the ground with 0.8-mm SO2 release holes at 3-m intervals. The resulting SO2 concentrations on the plots varied with micrometeorological conditions. Fumigations were essentially continuous from April through October for 5 yr on one set of four plots and for 4 yr on another set of four plots. Frequency distributions of SO2 concentrations were approximately log-normal and qualitatively similar to those from various area and point sources. The diurnal pattern of SO2 concentrations was strongly correlated with the reciprocal of windspeed. Nighttime concentrations averaged almost double daytime concentrations. The diurnal concentration pattern resembled an area source more closely than a point source, a direct result of using constant SO2 source strength. Plume strikes could be simulated by turning the system on only during pre-specified meteorological conditions. Similarly, seasonal variations in area source concentrations could be simulated by varying source strength on the plots. The data from 5 years use of the system indicate that the fine-scale behavior of SO2 concentrations would be realistic.

Design and performance of a field exposure system for evaluation of the ecological effects of SO2 on native grassland.

The dynamics of S02 exposure concentrations at any point are unique, determined by distance from various sources, source strengths, wind speed and direction, topography, stack height, and a variety of lesser influences. Nevertheless, in the simplest analysis, distinction can be made between exposure patterns in the vicinity of point (single) sources and those influenced by area (multiple) sources.

The Field Exposure System

Mathematical modeling is a long-standing tool for the analysis of ecological systems (Lotka, 1925). Before the elaboration of systems engineering, beginning during World War II, applications of mathematical models in ecology were limited to small systems (few equations). The widespread availability of computers in the late 1950s and the 1960s made it possible for ecologists to explore the potential of systems analysis to contribute to the study of ecological systems. This period of experimenting with systems analysis techniques coincided with a period during which many ecologists were switching their interests from the study of populations and communities to ecosystems (Odum, 1957; Margalef, 1963). Systems analysis, computers, and ecological systems were merged into systems ecology in the mid- 1960s (Odum, 1960; Olson, 1963; Patten and Witkamp, 1967; Van Dyne, 1969; Watt, 1966).

K.B. Olsen

Papers

Air quality measurements in the coal fired power plant environment of Colstrip, Montana☆