DEVELOPMENT AND EVALUATION OF MULTIPLE‐OBJECTIVE DECISION‐MAKING METHODS FOR WATERSHED MANAGEMENT PLANNING1

ABSTRACT: Making decisions for environmental management is a complex task due to the multiplicity and diversity of technological choices. Furthermore, the exploitation of natural resources and the preservation of the natural environment imply objectives that are often in conflict within a sustainable development paradigm. Managers and other decision makers require techniques to assist them in understanding strategic decision making. This paper illustrates the use of a multiple‐objective decision‐making methodology and an integrative geographical information system‐based decision‐making tool developed to help watershed councils prioritize and evaluate restoration activities at the watershed level. Both were developed through a multidisciplinary approach. The decision‐making tool is being applied in two watersheds of Oregon's Willamette River Basin. The results suggest that multiple‐objective methods can provide a valuable tool in analyzing complex watershed management issues.     

Macroinvertebrate Colonization of Woody Debris in Canadian Shield Lakes following Riparian Clearcutting

Deployment of litterfall traps revealed that clearcut logging of boreal riparian forests in northwestern Ontario, Canada resulted in a dramatic shift from once dominant conifers to regrowth composed largely of deciduous trees and reduced the allochthonous inputs of small woody debris to lake littoral zones by over 90%. Due to the rarity of macrophytes in these oligotrophic lakes, littoral macroinvertebrates were found to actively colonize woody debris placed within mesh litter bags. The recalcitrant nature of small woody debris in these lakes (average median persistence time of about 5 years estimated from mass loss data) indicates, however, that this important habitat resource will probably never completely disappear in relation to its projected rate of resupply during post-disturbance forest regeneration. Colonization rates of twigs and bark contained within the litter bags were not found to differ between coniferous and deciduous species. This indicates that macroinvertebrates in these boreal lakes are merely opportunistic colonizers of woody debris, probably for its use as either a biofilm substrate or a predation refuge. As a result, shifts in tree species composition following riparian clearcutting should not detrimentally affect the taxa richness or organism abundance of aquatic macroinvertebrates in these lakes.     

Predictive Model of the Effects on Lake Metabolism of Decreased Airborne Litterfall through Riparian Deforestation

The importance of airborne allochthonous litter to the carbon and nutrient budgets of lakes has been seldom studied. We complied data on the input of terrestrial litter to develop a simple and speculative model to predict the potential consequences of riparian deforestation on one aspect of lake metabolism, specifically the balance between phytoplankton production and plankton respiration. During the autumn of 1992, 56 litter traps were deployed around the littoral zones of four oligotrophic lakes in a densely forested region of northwestern Ontario, Canada. The airborne litter input was estimated to be 32 g dry weight per meter of forested shoreline per year. Allochthonous litter input per unit offshore distance was related to the size of riparian trees, their proximity to the shoreline, and the elevation of their canopy. Combining our data with those from other studies suggests that terrestrial litter can contribute up to 15% of the total carbon supply to oligotrophic lakes and up to 10% of the total phosphorus supply to lakes with a large surface area relative to that of their drainage basin. These results were incorporated into a simple model that predicts that removal of shoreline trees could increase the ratio of plankton production to respiration in oligotrophic lakes situated within small drainage basins. Such lakes may therefore shift from allotrophy to increasing autotropy (energy self-sustenance) following riparian deforestation.     

How do people select plants for use? Matching the Ecological Apparency Hypothesis with Optimal Foraging Theory

The present study aimed to understand human plant resource usage strategies in the context of the Ecological Apparency Hypothesis and Optimal Foraging Theory. The relationship between plant resource knowledge and availability was tested in a rural community (Palmital) in a dry Atlantic Forest fragment in the state of Minas Gerais, Southeastern Brazil, using data from phytosociological studies and interviews. We considered both total use and separate use categories. Use Value (UV) was significantly associated with all of the analyzed ecological variables, but there was an association with relative dominance and a weak relationship with relative density. When the UVs were separately analyzed for each category, we found that some, i.e., fuel and construction, corroborate the Ecological Apparency Hypothesis, while others do not, particularly the medicinal and food categories. In addition, we found large differences with respect to the ecological variables that best correlated with UV. The data suggest that the cost/benefit relationship predicted by Optimal Foraging Theory can explain the Ecological Apparency Hypothesis when the following factors are considered: (a) resource acquisition optimization and security; (b) a higher probability of acquiring more abundant species during random collection events; and (c) differential utilization patterns (distinct requirements for a specific use) for each use category. Some implications for conservation are also discussed.     

Exposure pathways of anticoagulant rodenticides to nontarget wildlife

Second-generation anticoagulant rodenticides are widely reported to contaminate and poison nontarget wildlife, primarily predatory birds and mammals. Exposure pathways, however, have not been well defined. Here, we examined potential movement of rodenticides from deployment of bait to exposure of small mammals and other biota. At two adjacent working farms, we placed baits containing either brodifacoum or bromadiolone. We monitored movement of those compounds to the surrounding environment by collecting small mammals, birds, and invertebrates. Similar collections were made at a third agricultural setting without active bait deployment, but located among intensive livestock production and regular rodenticide use by farmers. Livers and whole invertebrate samples were analyzed for rodenticides using a sensitive LC-MSMS method. Norway rats (Rattus norvegicus) from both baited and non-baited farms had residues of brodifacoum or bromadiolone, implicating rats as an important exposure pathway to wildlife. Among 35 analyzed nontarget small mammals, a single vole had high hepatic residues (18.6 μ/g), providing some indication of a small mammal pathway. One song sparrow (Melospiza melodia) sample from a baited farm contained 0.073 μg/g of brodifacoum in liver, while 0.39 μg/g of diphacinone was measured in a pool of carrion beetles (Dermestes spp.) from the non-baited farm area, implicating avian and invertebrate components in exposure pathways. Regurgitated pellets of barn owl (Tyto alba) selected randomly from baited farms contained no detectable rodenticide residues, while 90 % of owl pellets collected from a variety of farms, and selected for the presence of rat fur, contained detectable anticoagulant residues. We recorded behavior of a captive sample of a representative songbird, the house sparrow (Passer domesticus); they readily entered bait stations and fed on (unloaded) bait.     

Extirpation of Crayfish in a Lake Affected by Long-Range Anthropogenic Acidification

Plastic Lake, Ontario, remote from any point sources of pollutants, is the most thoroughly investigated anthropogenically acidifying lake in North America. As the lake pH decreased from 5.8 to 5.6 over a period of six years, a resident population of the crayfish Orconectes virilis , which had previously exhibited abundances typical of those of nearby Canadian Shield lakes, became extinct. This is one of only half a dozen documented examples of biotic impoverishment due to the long-range aerial transport of strong acids. The loss of crayfish could not be explained by changes in the predaceous fish community. However, the pH range over which extinction occurred matched that of experimentally acidified Lake 223 where O. virilis began to decline dramatically due to recruitment failures, calcium imbalances, and possibly parasite infection. O. virilis appears to be the third component of the benthic invertebrate fauna of Plastic Lake that has been extirpated by anthropogenic acidification.     

Use of sequential sampling of amphipod abundance to classify the biotic integrity of acid-sensitive lakes

A sequential sampling program using previously published zoobenthos data is described for ubiquitous, cost-effective biomonitoring of the effects of lake acidification. Spring densities of the littoral amphipodHyalella azteca are quantitatively sorted into five abundance catagories. An essential step in the a priori definition of decision criteria is the stratification of proportional densities per unit macrophyte biomass in relation to aqueous total phosphorus concentrations. Density rankings were related to lake acidity and to detailed lake-specific information on patterns ofHyalella life history and acid tolerance. Incorporation ofHyalella abundance as a potential metric for the assessment of the biological integrity of acid-sensitive waters is recommended. The temporal integration of transient changes in spring meltwater chemistry is an important rationale for the development of such biomonitoring procedures.     

Decreased carbon and nutrient input to boreal lakes from particulate organic matter following riparian clear-cutting

The plankton communities of oligotrophic Canadian Shield lakes are strongly regulated by the allochthonous supply of total phosphorus (TP) and dissolved organic carbon (DOC), a proportion of both of which originate from particulate organic matter. Although decreased inputs of allochthonous leaf litter have been documented for small streams whose riparian forests have been removed, no such data exist for boreal lakes. Through estimates of airborne litter input from forested and clear-cut shorelines and laboratory measurements of concentrations released from leaf leachate, we determined that riparian deforestation resulted in reductions of DOC from 17.8 to 0.4 g/m shoreline/yr and of TP from 2.9 to 0.3 g/m shoreline/yr. Previous predictive models indicate that such reductions may be substantial enough to decrease basic metabolic processes of lake plankton communities by as much as 9% in primary production and 17% in respiration.     

CASA DEL AGUA: WATER CONSERVATION DEMONSTRATION HOUSE 1986 THROUGH 19981

ABSTRACT: Casa del Agua (Casa) in suburban Tucson, Arizona, was designed as a residential water conservation facility for applied research, demonstration of operational results, and transfer of technology to the general public. Starting in 1983, an existing residence was located, modified and retrofitted to acquire operational data on residential water use. Modifications included retrofitting existing landscapes and enlarging the rooftop to collect and harvest rainwater; separating blackwater and graywater lines; installing meters, low‐water‐use appliances and fixtures, and underground storage tanks for rainwater and graywater; and creating a public information center. Over the 13‐plus years of actual operation, both the interior and exterior water use research results indicate large reductions in water use can be effected using water‐saving devices andlor harvesting and reusing rainwater and graywater. Casa achieved over a 24 percent reduction in total water use and a 47 percent reduction in municipal water used compared to the typical Tucson residence. Overall water used was comprised of harvested rainwater (10 percent), recycled graywater (20 percent), and municipal water (70 percent). Casa's Information Center was visited by approximately 13,000 people from September 1985 through April 1999 and the research has been featured in local, national, and international media.