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Macroinvertebrate and fish metrics are an essential tool in freshwater biomonitoring. Yet, many well-known stream metrics do not perform well as indicators of anthropogenic stress in lakes and wetlands, and there is a need to better understand the role of potential confounding factors such as latitude or environmental variables acting at regional scales. We attempt to untangle the relationships among metrics and watershed stressors while accounting for potential confounding factors using hierarchical partitioning, and test metric consistency across time, focusing on the Laurentian Great Lakes wetland monitoring programs conducted 10 years apart. Our results show that many frequently used metrics have high temporal variability and are significantly affected by spatial factors, most notably richness-type metrics used in numerous regional monitoring studies. Only a few metrics (invasive fish species richness and relative abundance, mayfly family richness and the relative abundance of Ephemeroptera, Trichoptera, Sphaeriidae and Odonata) had slightly better and more consistent correlations with watershed land use. We suggest that explicit consideration of confounding factors is essential in the context of large-scale monitoring programs, and focus on the less general (such as habitat-specific) metrics may be a more promising approach.

We describe development anthropogenic stress indices for coastal margins of the Laurentian Great Lakes basin. Indices were derived based on the response of species assemblages to watershed-scale stress from agriculture and urbanization. Metrics were calculated for five groups of wetland biota: diatoms, wetland vegetation, aquatic invertebrates, fishes, and birds. Previously published community change points of these assemblages were used to classify each watershed as ‘least-disturbed’, ‘at-risk’, or ‘degraded’ based on community response to these stressors. The end products of this work are an on-line map utility and downloadable data that characterize the degree of agricultural land use and development in all watersheds of the US and Canadian Great Lakes basin. Discrepancies between the observed biological condition and putative anthropogenic stress can be used to determine if a site is more degraded than predicted based on watershed characteristics, or if remediation efforts are having beneficial impacts on site condition. This study provides a landscape-scale evaluation of wetland condition that is a critical first step for multi-scale assessments to help prioritize conservation or restoration efforts.

Stressor gradients and spatial narratives of the St. Louis River Estuary, a joint Minnesota and Wisconsin Sea Grant study, connected aquatic science research with spatially-explicit stories of local resource issues and place-based geo-quests to enhance spatial awareness and stewardship of the estuary. The goal of this paper is to report and reflect on an integrated study that combined environmental humanities and technology with aquatic science in a spatial context. Our study was organized into three objectives around research, outreach, and evaluation. First, we summarized anthropogenic stressors within high resolution watersheds and linked the watershed stress estimates to aquatic habitats within the estuary. Second, we designed tools to deliver place-based environmental science and technology to targeted users to increase awareness, learning, and the potential for long-term stewardship. And third, we evaluated the responses of targeted end users to their interaction with the project’s integrated science and innovative delivery methods. Finally, central to all three objectives, we created a dynamic website to facilitate regional to national coastal outreach and education goals. We found significant correlations between the stressor index and the water quality and biotic data, along with variability attributed to landscape elements. Connecting this science with the place-based experiences we collected is expected to expand the scope and reach of state, bi-national and non-governmental outreach programs. The project also has direct applications to classroom science education. Developing this integrated project contributed to our shared knowledge of environmental and cultural aspects of the estuary for place-based education, and offers several lessons for future work of this nature.

The St. Louis River drains an area of 9412 km 2 into the western arm of Lake Superior. The river's lower section, including a 48.5 km 2 estuary, was designated as a Great Lakes Area of Concern due to degradation from industrial activities. Part of the estuary is occupied by the largest port in the Great Lakes. A GIS-based stressor index was previously developed to characterize anthropogenic stress within the watershed. The components of the stressor index were road density, point-source pollution permit density, population density, and percent agricultural and developed land. Water quality sampling was conducted at 27 sites in the estuary in tributaries and associated nearshore areas during multiple flow regimes in 2010–2011. Additional data were analyzed from 34 upper watershed sites sampled in 2009–2010. Stressor scores were significantly (p 2 − /NO 3 − -N, dissolved oxygen saturation, pH, specific electrical conductivity, chloride, sulfate, and E. coli in the upper watershed. In the estuary, the index was significantly and positively correlated with NO 2 − /NO 3 − -N, NH 4 + -N, and chloride at multiple flow regime and location combinations. Soil K factor (an erosivity index from recent NRCS SSURGO soil surveys) was found to have stronger relationships with sediment related parameters than the stressor gradient. Although originally designed to help stratify sampling across a gradient of landscape stress and identify reference areas for restoration projects, the stressor index was shown to have substantial predictive power for multiple water quality parameters.

Context Green infrastructure may improve water quality and mitigate flooding in forest-urban watersheds, but reliably quantifying all benefits is challenging because most land cover maps depend on moderate- to low-resolution data. Complex and spatially heterogeneous landscapes that typify forest-urban watersheds are not fully represented with these types of data. Hence important questions concerning how green infrastructure influences water quality and quantity at different spatial scales remain unanswered. Objectives Demonstrate the feasibility of creating novel high-resolution land cover maps across entire watersheds and highlight deficiencies of standard land cover products. Methods We used object-based image analysis (OBIA) to create high-resolution (0.5 m) land cover maps and detect tree canopy overlapping impervious surfaces for a representative forest-urban watershed in Duluth, MN, USA. Unbiased estimates of accuracy and area were calculated and compared with similar metrics for the 30-m National Land Cover Database (NLCD). Results Mapping accuracies for the high-resolution land cover and canopy overlap maps were ~90 %. Error-adjusted estimates of area indicated that impervious surfaces comprised ~21 % of the watershed, tree canopy overlapped ~10 % of impervious surfaces, and that three high-resolution land cover classes differed significantly from similar NLCD classes. Conclusions OBIA can efficiently generate high-resolution land cover products of entire watersheds that are appropriate for research and inclusion in the decision-making process of managers. Metrics derived from these products will likely differ from standard land cover maps and may produce new insights, especially when considering the unprecedented opportunity to evaluate fine-scale spatial heterogeneity across watersheds.

Total suspended solids (TSS) and total phosphorus (TP) have been shown to be strongly correlated with turbidity in watersheds. High-frequency in situ turbidity can provide estimates of these potential pollutants over a wide range of hydrologic conditions. Concentrations and loads were estimated in four western Lake Superior trout streams from 2005 to 2010 using regression models relating continuous turbidity data to grab sample measures of TSS and TP during differing flow regimes. TSS loads estimated using the turbidity surrogate were compared with those made using FLUX software, a standard assessment technique based on discharge and grab sampling for TSS. More traditional rating curve methodology was not suitable because of the high variability in the particulates vs. discharge relationship. Stream-specific turbidity and TSS data were strongly correlated (r2 = 0.5 to 0.8; p

Non-native earthworm invasions in north-temperate North America cause substantial adverse effects to hardwood forest ecosystems. Quantification of invasions is necessary for understanding impacts and identifying remnant earthworm-free areas, but existing sampling techniques are effort-intensive and/or environmentally damaging. We: (1) developed and applied a protocol that allows rapid classification of earthworm invasion into five stages based primarily on visual assessment of the forest floor, (2) sampled earthworms to test whether the protocol's stages can predict invasion by different species, and (3) assessed relationships between individual forest floor characteristics and presence of different earthworm species. Based on differences in biomass among points assigned to different stages, the 5-stage classification protocol accurately identified the onset of invasion by Lumbricus rubellus and Lumbricus terrestris, the species of greatest management concern in the northern Midwest. Except for middens as a predictor of L. terrestris presence, no forest floor variable was useful by itself for assessing invasions. The 5-stage protocol provides an efficient approach for assessing earthworm invasions in hardwood forests of the U.S. northern Midwest, can be implemented with minimal training, and serves as a blueprint for similar protocols in other regions experiencing earthworm invasions.

Many streams along the Minnesota coast of Lake Superior have been listed as impaired from either high turbidity or high fish mercury concentrations or both. Both turbidity and total mercury have been shown to be strongly correlated to total suspended sediment in many disturbed watersheds. Turbidity and total mercury concentrations and loads were estimated in four western Lake Superior watersheds from 2005–2006 using automated in-stream turbidity measurements. Regression models were developed relating this near-continuous turbidity data to grab sample measures of mercury during differing flow regimes. Total mercury values ranged from 1 to 28 ng l−1 throughout the open water season and showed a close relationship to total suspended sediment (r2 = 0.85, n = 23; p < 0.001) and a less robust but still significant relationship with turbidity (r2 = 0.40, n = 34; p < 0.001) for all four streams. Mercury loads to Lake Superior were estimated to range from 8 to 97 g yr−1 with watershed yields ranging from 0.5 to 4.3 μg m−2 yr−1. Continuous turbidity monitoring appears to be a reasonable surrogate for both suspended sediment and total mercury concentration, providing information when manual sample collection is cost-prohibitive or logistically difficult, and across a wide range of flows.

Biological indicators can be used both to estimate ecological condition and to suggest plausible causes of ecosystem degradation across the U.S. Great Lakes coastal region. Here we use data on breeding bird, diatom, fish, invertebrate, and wetland plant communities to develop robust indicators of ecological condition of the U.S. Lake Superior coastal zone. Sites were selected as part of a larger, stratified random design for the entire U.S. Great Lakes coastal region, covering gradients of anthropogenic stress defined by over 200 stressor variables (e.g. agriculture, altered land cover, human populations, and point source pollution). A total of 89 locations in Lake Superior were sampled between 2001 and 2004 including 31 sites for stable isotope analysis of benthic macroinvertebrates, 62 sites for birds, 35 for diatoms, 32 for fish and macroinvertebrates, and 26 for wetland vegetation. A relationship between watershed disturbance metrics and 15N levels in coastal macroinvertebrates confirmed that watershed-based stressor gradients are expressed across Lake Superior's coastal ecosystems, increasing confidence in ascribing causes of biological responses to some landscape activities. Several landscape metrics in particular—agriculture, urbanization, human population density, and road density—strongly influenced the responses of indicator species assemblages. Conditions were generally good in Lake Superior, but in some areas watershed stressors produced degraded conditions that were similar to those in the southern and eastern U.S. Great Lakes. The following indicators were developed based on biotic responses to stress in Lake Superior in the context of all the Great Lakes: (1) an index of ecological condition for breeding bird communities, (2) diatom-based nutrient and solids indicators, (3) fish and macroinvertebrate indicators for coastal wetlands, and (4) a non-metric multidimensional scaling for wetland plants corresponding to a cumulative stress index. These biotic measures serve as useful indicators of the ecological condition of the Lake Superior coast; collectively, they provide a baseline assessment of selected biological conditions for the U.S. Lake Superior coastal region and prescribe a means to detect change over time.

Quantifying gradients of anthropogenic stress can inform the development of sample designs, provide an important covariate in modeling relationships of response variables, identify reference and highly-disturbed sites, and provide a baseline and guidance to restoration and remediation efforts. We describe development of SumRel, a composite index of anthropogenic stress, for the U.S. and Canadian Lake Superior basin. Key elements of the project include development of high-resolution watersheds throughout the basin, summarization of the major point and non-point stressors within these watersheds, and creation of tools for scaling the watersheds and stressor summaries. SumRel was calculated at two spatial scales: for high resolution subcatchments within the Lake Superior basin (mean watershed area = 93 ha) and for coastal watersheds of Lake Superior. An assessment of subcatchments within Minnesota's St. Louis River watershed showed a correlation between the degree of disturbance, as indicated by SumRel, and impaired water quality, as evidenced by in-stream conductivity. These data and tools allow identification and visualization of reference and highly-disturbed sites at multiple spatial scales, providing decision support for individual agency and binational monitoring, assessment and restoration initiatives across the Lake Superior basin.

We summarized landscape approaches used in the study of freshwater ecosystems, updated recent literature reviews on interactions between terrestrial and lotic ecosystems, and discussed the influence of J-NABS on developments in the field. We focused primarily on studies of freshwater ecosystems done at or above the catchment scale. Special issues of J-NABS and other journals have advanced our understanding of the effects of spatially distributed characteristics and phenomena on aquatic ecosystems. Topics that have been well covered in J-NABS include use of classification to predict biotic assemblages and impacts of human disturbance (especially urbanization) on stream structure and function. Early work focused on correlative relationships between landscape variables and various biotic components of stream systems, whereas later studies addressed causal linkages between landscape and biota, including landscape effects on hydrology, habitat at various spatial scales, and ecosystem processes. At larg...

We developed ecological indicators of stream macroinvertebrates in two regions of the Midwestern USA dominated by row-crop agriculture. Indicators were identified in a hierarchical fashion. Reach-scale variables related to macroinvertebrate attributes were first identified, and then catchment-scale variables related to those reach-scale variables were identified. Reach-scale indicators common to both regions were % fine sediments, number of habitats, and width:depth ratio. SD of elevation and % commercial land use were selected as catchment-scale indicators in both regions. Our analyses revealed a multi-scale mechanistic relationship between macroinvertebrate attributes associated with degraded conditions (i.e., fewer taxa of Plecoptera and Trichoptera, and a higher proportion of chironomids, burrowers, and depositional taxa) and % fine sediments in stream reaches, which, in turn, was negatively related to catchment characteristics (i.e., SD of elevation) in one region. Understanding how natural variables such as topography influence channel shape and within-channel structure can help guide management options and expectations for different regions. We suggest that developing multi-scale indicators in a mechanistic fashion will be more effective than developing indicators at only one spatial scale for protecting and restoring stream structure and function.

We used General Land Office survey data (1860–1890) and interpreted aerial photography from the 1930s, 1970s, and 1990s to quantify forest disturbance frequency and spatial patterns for four time periods in the Mixed Forest Province of Minnesota. The study region included eight subsections within the Mixed Forest Province of Minnesota’s Ecological Classification System. Presettlement disturbance and spatial pattern estimates varied across the eight subsections indicating a strong relationship to soil and landform characteristics. Land surveyors primarily recorded higher severity disturbances that resulted in significant tree mortality. The 1900–1940 era was characterized by a short-term increase in fire frequency that was relatively uniform across the study region, in contrast to the variability of the presettlement (1860–1890) landscape. In the postsettlement period (1940–1995), timber harvest replaced fire as the dominant disturbance factor. Similar management practices among subsections created similar harvest rates throughout the study region. These management practices imposed a more homogeneous pattern dominated by small (10–25 ha) patches. Management practices now have a greater influence than natural processes in the generation of landscape pattern in the Mixed Forest Province of Minnesota. Information on presettlement forest conditions and subsequent changes can be used by land managers to restore spatial pattern variability in managed forest landscapes.

Developing indicators of ecosystem condition is a priority in the Great Lakes, but little is known about appropriate spatial scales to characterize disturbance or response for most indicators. We surveyed birds, fish, amphibians, aquatic macroinvertebrates, wetland vegetation, and diatoms at 276 coastal wetland locations throughout the U.S. Great Lakes coastal region during 2002-2004. We assessed the responsiveness of 66 candidate indicators to human disturbance (agriculture, urban devel- opment, and point source contaminants) characterized at multiple spatial scales (100, 500, 1,000, and 5,000 m buffers and whole watersheds) using classification and regression tree analysis (CART). Non- stressor covariables (lake, ecosection, watershed, and wetland area) accounted for a greater proportion of variance than disturbance variables. Row-crop agriculture and urban development, especially at

The City of Duluth, the University of Minnesota-Duluth (Natural Resources Research Institute and Minnesota Sea Grant) and other regional partners collaborated to develop Lakesuperiorstreams.org, a website that utilizes real time data (temperature, flow, precipitation, turbidity, specific conductivity) in an easy to understand animated graphical format to educate the public about (1) how streams function, and (2) the impacts of human activities on water quality, habitat, and aquatic organisms. In support of the data, the website provides a comprehensive library of information on stream parameters and information on local streams and surface water issues. It covers land use impacts on streams and positive approaches to protecting water quality. For example, a site design tool kit provides information and examples of approaches to building and maintaining homes and businesses while reducing stormwater impacts. The website also serves as a repository for regionally relevant school curricula for K-12 schools and colleges. The website has been the catalyst that has brought together regional agencies and communities, who have established the Regional Stormwater Protection Team (RSPT), designed to develop one voice for surface water education and technical assistance for communities at the head of Lake Superior.

Identification of reference conditions for ecological assessments of coastal ecosystems poses a challenging problem in highly modified landscapes. A method is described for characterizing disturbance in coastal ecosystems using remotely sensed land classification and other publicly available GIS data. Within ecoregions bordering the US Great Lakes coast, aquatic habitats bordering the shoreline were classified into five ecological types: high‐energy shoreline, embayments, open‐coast, river‐influenced and protected wetlands. Degree of anthropogenic disturbance in contributing areas to these ecosystems was assessed using a watershed approach for wetland types or a moving window approach for high‐energy shorelines. Anthropogenic stress variables included proportions of agricultural or residential land use, information on population and road density, and distance from the nearest point source. Polygons (wetlands) or pixels (high‐energy shoreline) were categorized as ‘reference’ if the magnitude of the most se...

Land use and geology are two important extrinsic factors regulating the structure and function of stream ecosystems. The interactions among these two landscape-scale factors on streams are, however, poorly understood. To determine the effects of these factors on stream flow, sediment, and nutrients, we analyzed 72 ungaged, agricultural watersheds in Minnesota and Michigan using the hydrologic model SWAT (the Soil Water Assessment Tool). The watersheds differed in surficial geology (landform) and land use, but were of similar size, with streams ranging from 2nd to 3rd order. SWAT was developed for use on ungaged basins, but to improve the outputs we used US Geological Survey discharge data from sites near our study watersheds for calibration. We found seasonal and annual differences in flow and nutrient and sediment loading across different land forms and land use types. Watersheds with greater amounts of row-crop agriculture and watersheds dominated by morainal landforms were associated with more sediment and nutrients and greater flow volumes and flashiness. Multivariate analyses identified at least nine landscape variables which were related to nutrients, sediment, and flow, although the responses varied between Minnesota and Michigan. Results also indicated the possibility of a threshold effect for row crop agricultural. Increases in this land use had little additional effect on nutrients or flow when percent row crop exceeds the threshold value. At moderate to high levels of row crop agriculture, watersheds appeared to show greater sensitivity to differences in landform.

Understanding the relationship between human disturbance and ecological response is essential to the process of indicator development. For large-scale observational studies, sites should be selected across gradients of anthropogenic stress, but such gradients are often unknown for a population of sites prior to site selection. Stress data available from public sources can be used in a geographic information system (GIS) to partially characterize environmental conditions for large geographic areas without visiting the sites. We divided the U.S. Great Lakes coastal region into 762 units consisting of a shoreline reach and drainage-shed and then summarized over 200 environmental variables in seven categories for the units using a GIS. Redundancy within the categories of environmental variables was reduced using principal components analysis. Environmental strata were generated from cluster analysis using principal component scores as input. To protect against site selection bias, sites were selected in random order from clusters. The site selection process allowed us to exclude sites that were inaccessible and was shown to successfully distribute sites across the range of environmental variation in our GIS data. This design has broad applicability when the goal is to develop ecological indicators using observational data from large-scale surveys.

We investigated impacts of harvesting on soil disturbance and vegetation in the aspen cover type of northern Minnesota, United States. The soil disturbance (resistance to penetration) and understory vegetation were characterized for 19 sites on five 60-m 2 plots placed along a disturbance gradient: landings (high harvesting traffic), skid trails (inter- mediate harvesting traffic), and areas off skid trails (low to no harvesting traffic). Penetration levels were quite variable, but they still indicated that within-site responses to disturbance patterns created by clear-cut harvesting were not uniform. In general, soil disturbance and understory species composition within landings were similar to those with skid trails. The soil disturbance and vegetation composition of these two levels differed from those of the low-disturbance plots (off skid trails), indicating that removing trees alone did not affect vegetation composition as much as creating an es- tablished skid trail, regardless of harvest timing. However, sites with more variable species composition (win- ter-harvested sites) and lower disturbance levels were less altered than sites with likely lower initial diversity (summer-harvested sites). The results suggest that it is important for recovery of understory plant communities to not only limit the amount and level of disturbances but also consider the spatial layout of harvesting, thus maintaining a spatially connected network of remnant forest patches large enough to contain interior forest species. Resume : Les auteurs etudie l'impact des activites de recolte sur la perturbation du sol et la vegetation dans les forets de peuplier faux-tremble du nord du Minnesota aux Etats-Unis. La perturbation du sol (resistance a la penetration) et la vegetation de sous-bois ont ete caracterisees pour 19 sites dans cinq places-echantillons de 60 m 2 etablies de long d'un

Summary 1. The impacts of elevated atmospheric CO 2 and/or O 3 have been examined over 4 years using an open-air exposure system in an aggrading northern temperate forest containing two different functional groups (the indeterminate, pioneer, O 3 -sensitive species Trembling Aspen, Populus tremuloides and Paper Birch, Betula papyrifera , and the determinate, late successional, O 3 -tolerant species Sugar Maple, Acer saccharum ). 2. The responses to these interacting greenhouse gases have been remarkably consistent in pure Aspen stands and in mixed Aspen/Birch and Aspen/Maple stands, from leaf to ecosystem level, for O 3 -tolerant as well as O 3 -sensitive genotypes and across various trophic levels. These two gases act in opposing ways, and even at low concentrations (1·5 × ambient, with ambient averaging 34‐36 nL L − 1 during the summer daylight hours), O 3 offsets or moderates the responses induced by elevated CO 2 . 3. After 3 years of exposure to 560 µ mol mol − 1 CO 2 , the above-ground volume of Aspen stands was 40% above those grown at ambient CO 2 , and there was no indication of a diminishing growth trend. In contrast, O 3 at 1·5 × ambient completely offset the growth enhancement by CO 2 , both for O 3 -sensitive and O 3 -tolerant clones. Implications of this finding for carbon sequestration, plantations to reduce excess CO 2 , and global models of forest productivity and climate change are presented.

ECOPHYS, an individual-based process model for poplar, requires a three-dimensional soil water redistribution model to simulate soil water dynamics, plant uptake, and root growth. SOILPSI is a potential-driven water redistribution model based on the RHIZOS rhizosphere simulator. It expands on RHIZOS by calculating water flux based on water potential, and has a macropore flow mode to allow rapid drainage of the soil. SOILPSI simulates water flux in three dimensions and accounts for slope. SOILPSI was evaluated by comparing model output to soil moisture data collected under bare soil conditions. AMMI analysis of a date × depth matrix of differences between simulated and observed soil moisture content showed that excluding the two shallowest soil layers resulted in a difference matrix that conformed to an additive model. The grand mean predicted values were within 2% of the observed values, and 50 of 56 predicted values were within 5% of the observed values. Better agreements between simulated and observed soil moisture content were observed deeper in the soil profile and later in the season. Agreement between SOILPSI and field conditions was consistently more accurate than RHIZOS. Improving simulation of evaporative flux at the soil surface would improve simulation accuracy in the upper horizons.  2002 Elsevier Science Ltd. All rights reserved.

To improve source–sink relationship based carbon-allocation models, the basic proportional model was extended to account for a well-known effect of individual source to sink distances: among different sinks of similar characteristics, the more distant from the source, the lower the allocation coefficient. This was achieved through multiplication of the sink strength value by a coefficient that is proportional to a decreasing, simple function of distance, f; the power form was chosen for both simplicity and theoretical reasons. The resulting model was parameterized and evaluated on the empirical allocation matrix of the ECOPHYS model, after grouping together several individual, small sinks of similar nature and close location to remove any phyllotaxy-related bias. Both goodness of fit and predictive value were significantly improved compared with the basic proportional model (f = constant). The f-extended model yielded even better results if segments of different nature or age on the source to sink pathway were assigned different weights in the expression of distance, whereas the default expression of f, with an exponent of –1 and no additive constant, was optimal with no further parameter required. Thus, only 7 parameters (3 for pathway segment weights and 4 for sink strength values) were sufficient to retrieve the original 68 independent experimental allocation coefficients with a reasonable degree of accuracy. Pathway segment weights likely reflect both intrinsic transport pathway properties and situation within the plant architecture; this is discussed in relation to the possibilities of generalization and practical use of the model.

Biological attributes of ecosystems often change nonlinearly as a function of anthropogenic and natural stress. Plant and animal communities may exhibit zones of change along a stressor gradient that are dispropor- tionate relative to the incremental change in the stressor. The ability to predict such transitions is essential for effective management intervention because they may indicate irreversible changes in ecological processes. De- spite the importance of recognizing transition zones along a stressor gradient, few, if any, investigators have examined these responses across multiple taxa, and no community threshold studies have been reported at large geographic scales. We surveyed benthic macroinvertebrate, fish, bird, diatom, and plant communities in coastal wetlands across a geospatially referenced gradient of anthropogenic stress in the Laurentian Great Lakes. We used Threshold Indicator Taxon Analysis (Baker and King 2010) to analyze each community's response to iden- tify potential zones of disproportionate change in community structure along gradients of major watershed-scale stress: agriculture and urban/suburban development. Our results show surprising congruence in community thresholds among different taxonomic groups, particularly with respect to % developed land in the watershed. We also analyzed uncertainty associated with the community-specific thresholds to understand the ability of different assemblages to predict stress. The high and congruent sensitivity of assemblages to development dem- onstrates that watershed-scale stress has discernible effects on all biological communities, with increasing poten- tial for ecosystem-scale functional changes. These findings have important implications for identifying reference- condition boundaries and for informing management and policy decisions, in particular, for selecting freshwater protected areas.

Predicting ozone-induced reduction of carbon sequestration of forests under elevated tropospheric ozone concentrations requires robust mechanistic leaf-level models, scaled up to whole tree and stand level. As ozone effects depend on genotype, the ability to predict these effects on forest carbon cycling via competitive response between genotypes will also be required. This study tests a process-based model that predicts the relative effects of ozone on the photosynthetic rate and growth of an ozone-sensitive aspen clone, as a first step in simulating the competitive response of genotypes to atmospheric and climate change. The resulting composite model simulated the relative above ground growth response of ozone-sensitive aspen clone 259 exposed to square wave variation in ozone concentration. This included a greater effect on stem diameter than on stem height, earlier leaf abscission, and reduced stem and leaf dry matter production at the end of the growing season. Further development of the model to reduce predictive uncertainty is discussed.

The interaction between physical environment and land ownership in creating spatial heterogeneity was studied in largely forested landscapes of northern Wisconsin, USA. A stratified random approach was used in which 2500-ha plots representing two ownerships (National Forest and private non-industrial) were located within two regional ecosystems (extremely well-drained outwash sands and moderately well-drained moraines). Sixteen plots were established, four within each combination of ownership and ecosystem, and the land cover on the plots was classified from aerial photographs using a modified form of the Anderson (U.S. Geological Survey) land use and land cover classification system. Upland deciduous forests dominated by northern hardwoods were common on the moraines for both ownerships. On the outwash, the National Forest was dominated by pine plantations, upland deciduous forests, and upland regenerating forests (as defined by

Quantitative structure-activity relationship (QSAR) models are routinely used in predicting toxicologic and ecotoxi- cologic effects of untested chemicals. One critical factor in QSAR-based risk assessment is the proper assignment of a chemical to a mode of action and associated QSAR. In this paper, we used molecular similarity, neural networks, and discriminant analysis methods to predict acute toxic modes of action for a set of 283 chemicals. The majority of these molecules had been previously determined through toxicodynamic studies in fish to be narcotics (two classes), electrophiles/proelectrophiles, uncouplers of oxidative phosphorylation, acetylcholinesterase inhibitors, and neurotoxicants. Nonempirical parameters, such as topological indices and atom pairs, were used as structural descriptors for the development of similarity-based, statistical, and neural network models. Rates of correct classification ranged from 65 to 95% for these 283 chemicals. Keywords—Toxic mode prediction Topological indices Molecular similarity Neural network Discriminant func- tion analysis

1. Landscape characteristics of sixty-two subcatchments within the Saginaw Bay Catchment of central Michigan were examined to identify relationships with stream water chemistry. Land use, land cover and elevation were quantified for both entire catchments and the upland–river ecotone (100 m stream buffer strip). Catchment and ecotone data were then empirically compared with stream water chemistry using multivariate and regression analyses. Redundancy analysis was used to partition variance among land use, geology, and the shared influence of land use and geology. 2. Major catchments dominated by rowcrop agriculture had the highest alkalinity, total dissolved solids and nitrate + nitrite concentrations. 3. Strong seasonal differences were observed in total nitrogen and nitrite + nitrate, but not in total phosphorus or suspended solids. Land use and landscape structure factors such as slope and patch density (number of land use patches per km2) accounted for most of the observed variance in summer. 4. In both autumn and summer, landscape factors accounted for much of the observed variation in total dissolved solids and alkalinity. During autumn, geological factors and the shared influence of geology/landscape structure plus land use exerted more influence than did land use alone. 5. Total phosphorus and total suspended solids were much better explained by land use within the stream ecotone in summer than in other seasons. However, total nitrogen, nitrate, orthophosphate and alkalinity were equally well explained by land use within the ecotone and throughout the whole catchment. Only total dissolved solids in summer and ammonium in autumn were explained better by the whole catchment than the ecotone. 6. Our results show that relatively coarse spatial databases can provide useful descriptors of regional water quality.

1. We used catchment and reach-scale physical properties to predict the occurrence of specific species life history and behaviour traits of aquatic insects across fifty-eight catchments in a mixed land use basin. Catchment-scale attributes were derived using a geographical information system (GIS). Logistic regression techniques were used to model the relationships. 2. The reach-scale properties were highly predictive of species traits. Fourteen of the fifteen traits had significant models with concordance values greater than 68%. Cross-sectional area at bank full discharge, % shallow, slow-water habitats, and % fines were the most important variables. 3. Life history and behavioural attributes were best related to reach-scale physical features. This suggests that species traits exhibit strong relationships to local environmental conditions. 4. Catchment-scale variables had fewer significant models with species traits (four of fifteen), however these variables may have direct or indirect influence on reach-scale properties. 5. Catchment features, in particular surficial geology, influence macroinvertebrate assemblages through their control over channel morphology and hydrologic patterns. 6. The effects of land use were masked by geology (i.e. lacustrine clay geology and rowcrop agriculture were correlated), lack of detail in land use data and the aggregation of the species data. 7. These models reflect the coupling of local environmental conditions and the set of adaptations among the local taxa. These observations underscore the idea that habitat plays a major role in organizing stream assemblages. 8. Using these approaches, predictions can be made about the ability of various taxonomic groupings to track environmental change through time, or for projecting the impact of alternative land management scenarios. Identifying fundamental life history and other traits can improve the selection and evaluation of such indicators.

The relative influence of geologic versus anthropogenic attributes of catchments on stream ecosystems was examined in 45 catchments of a river basin in central Michigan. Each catchment was characterized by land use, surficial geology, elevation, and hydrography, and summaries of these data were related to physical habitat characteristics that had the greatest influence on macroinvertebrate assemblages. Partial redundancy analysis revealed that geologic and land-use variables had similar magnitudes of influence on stream habitats. Of the geologic variables, catchment area, proportion of lacustrine clays, and glacial outwash materials had the strongest influence on physical habitat, particularly on channel dimensions. Row-crop agriculture and the presence of wetlands were the most important land-use variables, particularly influencing amounts of woody debris. Stream buffers (100 m) were more important than whole catchment data for predicting sediment-related habitat variables; however, channel morphology was more strongly related to whole catchments. Results suggest that catchment-wide geology and land-use characteristics may be more important than stream buffers for maintaining or restoring stream ecosystems. These techniques can be used to develop biologic signatures of catchment condition that discriminate causal factors influencing the biodiversity and health of stream ecosystems. Resume : Nous avons examine les influences respectives sur les ecosystemes des cours d'eau des attributs geologiques des bassins-versants en regard de leurs attributs anthropiques dans 45 aires d'alimentation d'un bassin fluvial du centre du Michigan (Etats-Unis). Nous avons caracterise chaque aire d'alimentation par l'utilisation du sol, la geologie de subsurface, l'elevation et l'hydrographie et nous avons rattache les sommaires des donnees ainsi obtenues aux caracteristiques de l'habitat physique qui exercaient la plus forte influence sur les communautes de macro-invertebres. L'analyse par redondance partielle a revele que les variables geologiques et les variables d'utilisation du sol exercaient sur les habitats une influence du meme ordre de grandeur. Pour ce qui est des variables geologiques, ce sont l'aire du bassin-versant ainsi que la proportion d'argiles lacustres et de materiaux stratifies fluvio-glaciaires qui ont agi le plus sur l'habitat physique, particulierement sur les dimensions du chenal. Les cultures en lignes et la presence de terres humides consituaient les plus importantes variables en matiere d'utilisation du sol, variables qui ont agi tout particulierement sur la quantite de debris ligneux. Les zones tampons (100 m) ont joue un plus grand role que les donnees sur les bassins-versants tout entiers dans la prevision des variables d'habitat relatives aux sediments; par contre, la morphologie du chenal se rattachait plus fortement aux bassins-versants tout entiers. Les resultats permettent de penser que la geologie du bassin-versant et les caracteristiques d'utilisation du sol font peut-etre plus que les zones tampons pour maintenir ou retablir les ecosystemes des cours d'eau. On peut recourir a ces techniques pour elaborer, au sujet de l'etat des bassins-versants, des signatures biologiques qui distinguent les facteurs causaux de la biodiversite et de la sante des ecosystemes des cours d'eau. (Traduit par la Redaction)

A simulation model is described that grows stands of aspen of given age, site quality, and stocking from establishment to breakup. Specifying mean July air temperature allows custom application to most aspen growing regions in North America and Scandinavia. The program predicts total yields in number of trees, basal area, and biomass; and merchantable yields in cubic feet and cords for user-specified utilization standards, and in board feet, Scribner. North. J. Appl. For. 13(4):164-170.

A generic bioenergetics model for chinook salmon was modified to estimate solid wastes from a commercial net-pen aquaculture operation in a Minnesota mine-pit lake. The model was calibrated using data from the operation on growth, ration, and temperature. Multiple simulations were run to form three-dimensional response surfaces for consumption, egestion, excretion and respiration as a function of fish size and water temperature. These formed the basis for the Fish Simulation Culture (FIS-C) Model. Predictions for food consumption and solids load were compared with actual ration levels and sedimentation within the mine-pit lake from 1989 to 1992, and compared well with the general trends of the observed data. However, the actual predictive power of FIS-C was very sensitive to our initial model assumption that aquaculture operations are predicated on maximizing the growth of their stock. FIS-C currently does not account for management decisions electing sub-optimal stock growth, but under these conditions does estimate a worst case loading scenario for the system. The annual phosphorus load to the system predicted by FIS-C was not significantly different from that of the mean of 17 values of annual P-load estimated empirically from the literature. However, FIS-C's estimate of P-loading shows a pronounced seasonal pattern to the annual loading. FIS-C offers substantial benefits to users by estimating seasonal and shorter term food wastage and wasteloads to receiving waters under particular operating conditions. Then, other operational scenarios can be created to examine the effects of changing fish inventory, feeding schedule, food composition, etc., in order to examine the impacts on production, environmental and/or regulatory requirements, prior to costly implementation.

Ecological land classification systems have recently been developed at continental, regional, state, and landscape scales. In most cases, the map units of these systems result from subjectively drawn boundaries, often derived by consensus and with unclear choice and weighting of input data. Such classifications are of variable accuracy and are not reliably repeatable. We combined geographic information systems (GIS) with multivariate statistical analyses to integrate climatic, physiographic, and edaphic databases and produce a classification of regional landscape ecosystems on a 29 340-km2 quadrangle of northwestern Wisconsin. Climatic regions were identified from a high-resolution climatic database consisting of 30-yr mean monthly temperature and precipitation values interpolated over a 1-km2 grid across the study area. Principal component analysis (PCA) coupled with an isodata clustering algorithm was used to identify regions of similar seasonal climatic trends. Maps of Pleistocene geology and major soil morphosequences were sued to identify the major physiographic and soil regions within the landscape. Climatic and physiographic coverages were integrated to identify regional landscape ecosystems, which potentially differ in characteristic forest composition, successional dynamics, potential productivity, and other ecosystem-level processes. Validation analysis indicated strong correspondence between forest cover classes from an independently derived Landsat Thematic Mapper classification and ecological region. The development of more standardized data sets and analytical methods for ecoregional classification provides a basis for sound interpretations of forest management at multiple spatial scales.

A strategy for process modelling of short-rotation Salix coppice plantations is presented. To integrate effectively both large- and small-scale processes, this model must simulate critical processes at scales ranging from the individual leaf to the plantation. This multiscale modelling strategy extrapolates the detail of mechanistic physiological models to the patch and plantation scales. To accomplish this scaling, regional climatic and soil databases are used to generate model inputs; i.e. site and climatic information is passed from the regional scale to drive models operating at the stand or tree level. Key input variables at the individual tree level include genetically determined factors such as leaf morphology and branch architecture, as well as phenological and physiological parameters. Outputs such as carbon fixation, leaf area index, biomass by component, and yields per hectare are then passed back up to address regional questions. This strategy requires a parallel programme of modelling and experimentation. While this strategy focuses on Salix , the approach should also be applicable to species with similar life history attributes, such as Betula and Populus .

In order to effectively deploy short-rotation woody crop plantations for energy and fiber production at regional scales, biologically sound-field-level models of plant growth are required. Individual tree growth process models have proven effective at predicting growth based on environmental driving variables, but in the past these models have been too complex to use at the plantation scale. In this paper we describe an object-oriented strategy for scaling ECOPHYS, an individual tree growth process model for hybrid poplar, to a plantation. Included in this strategy are methods of scaling from an individual shoot to a tree, from individual trees to a patch, and from patches to a plantation. In describing interactions among trees, both above- and below-ground processes are considered. Finally, we describe methods for integrating the plantation level ECOPHYS with EPIC, a field scale model of soil productivity and erosion used in regional assessment.

Geographic Information Systems (GIS) were used to assess the relationships between land use patterns and the physical habitat and macroinvertebrate fauna of streams within similar sized watersheds. Eleven second or third order watersheds ranging from highly urbanized to heavily forested were selected along Lake Superior's North Shore. Land use patterns within the watersheds were quantified using readily available digital land use/land cover information, with a minimum mapping resolution of 16 ha. Physical habitat features, describing substrate characteristics and stream morphology, were characterized at sample points within each stream. Principle component and correlation analyses were used to identify relationships between macroinvertebrates and stream physical habitat, and between habitat and land use patterns. Substrate characteristics and presence of coarse woody debris were found to have the strongest correlations with macreinvertebrate assemblage richness and composition. Agricultural and urban land use was correlated with substrate characteristics. Algal abundance, associated with macroinvertebrate compositional differences, was correlated with housing density and non-forest land covers. The use of readily available spatial data, even at this relatively coarse scale, provides a means to detect the primary relationships between land use and stream habitat quality; finer-resolution GIS databases are needed to assess more subtle influences, such as those due to riparian conditions.

SUMMARY 1 Patterns of macroinvertebrate community composition were examined in streams within a 40000-km2 catchment in central Michigan, U.S.A., to identify the major environmental gradients influencing community variation. Agriculture and associated clay and sandy soils predominated in much of the region. 2 Eighty macroinvertebrate taxa were collected from stream surveys conducted during May and August 1990. Community composition varied primarily by the proportions of Plecoptera and Ephemeroptera. Benthic communities from the heaviest agricultural zones were most different from those at other sites. 3 Chemical composition among the sites varied most in relation to nutrients (NH3, NO3, PO4). Other parameters were relatively similar. Physical characteristics of the sites were scored in six habitat categories: (i) substrate characteristics, (ii) instream cover, (iii) channel morphology, (iv) riparian zone and stream-bank conditions, (v) riffle/run quality, (vi) pool quality. Most physical habitat scores were lowest in the intense agriculture zones. 4 The relative importance of physical and chemical variables in explaining variation in macroinvertebrate communities was quantified using canonical correspondence analysis. Substrate characteristics were most important in both surveys. Significant correlations (P

Ground-flora and overstory composition and abundance patterns in 76 upland forest stands were related to the glacial geomorphology of a five-county area in northwestern lower Michigan. Nine classes of landforms were identified based on parent material and surface configuration. Chi-squared analyses of standardized residuals indicated that spatial distribution patterns of the ground flora were significantly associated with glacial landform. Detrended correspondence analyses showed that specific overstory–ground flora assemblages recur in characteristic landscape positions. The Interlobate Moraine, a predominant landform in the northeastern portion of the study area, was characterized by a northern hardwood canopy, primarily sugar maple (Acersaccharum Marsh.), basswood (Tiliaamericana L.), and red oak (Quercusrubra L.), with herbaceous annuals, perennials, and ephemerals forming the ground flora. Other morainal and glaciofluvial landforms supported oak (Quercus spp.) overstories with a woody ericaceous or graminoid ground flora. Ground-flora and overstory composition were highly correlated, indicating that they respond similarly to variation in environmental and historical factors. Moisture availability, as evidenced by soil texture and the presence of subsurface textural discontinuities, appeared to be a predominant factor influencing species distribution patterns. Since moisture availability and related nutrient dynamics are functions of depositional and postglacial history, regional-scale geomorphic patterns constrain forest composition in a probabilistic manner.

In this paper we present the proposed conceptual approach and essential subsystems of SYLVATICA, a landscape-based simulation model which will integrate several resource-management technologies in a visual interactive environment. We believe this approach incorporates several critical technologies which should be common to any integrated landscape-based simulation and visualization environment.

The balance of mechanistic detail with mathematical simplicity contributes to the broad use of the Farquhar, von Caemmerer and Berry (FvCB) photosynthetic rate model. Here the FvCB model was coupled with a stomatal conductance model to form an [A,g(s)] model, and parameterized for mature Populus tremuloides leaves under varying CO(2) and temperature levels. Data were selected to be within typical forest light, CO(2) and temperature ranges, reducing artifacts associated with data collected at extreme values. The error between model-predicted photosynthetic rate (A) and A data was measured in three ways and found to be up to three times greater for each of two independent data sets than for a base-line evaluation using parameterization data. The evaluation methods used here apply to comparisons of model validation results among data sets varying in number and distribution of data, as well as to performance comparisons of [A,g(s)] models differing in internal-process components.

Multivariate classification and ordination methods were used to develop ecological species groups for upland forest ecosystems of northwestern Lower Michigan. Species groups were based on similarities in ground-flora composition and abundance patterns among 76 sample stands. Nine ecological species groups were identified using 48 herbaceous, woody and moss species. The divisive classification produced six classes of stands: two dominated by northern hardwoods and four dominated by oaks. The distribution patterns typified by Deschampsia flexuosa, Vaccinium angustifolium, Viburnum acerifolium, and Desmodium spp. were important in discriminating among oak stands, whereas patterns typical of Osmorhiza claytonii and Maianthemum canadense distinguished northern hardwood stands. The species groups exhibited a wide range of ecological amplitudes, from highly specific associations with individual ecosystems to broad distributions across a range of site conditions. Within the geographic limits imposed by macroclimate and regional physiography, ecological species groups act to integrate site attributes and can simplify the process of mapping ecological land units.

Functional–structural plant models (FSPMs) typically integrate suites of detailed physiological and phenological processes to simulate the growth of individual plants. Recent advances in high-performance computing have allowed FSPMs to be extended to patches of interacting trees. Here, we describe a parallel modelling strategy to run simultaneous individual tree models across an 8 × 8 patch of trees. The 64 ‘core’ trees are surrounded by multiple rings of neighbour trees to remove edge effects. A sensitivity analysis of the patch model demonstrates that computational factors such as the number of independently simulated trees (9 v. 36) or number of neighbour rings (3 v. 6) did not significantly influence model estimates of tree volume growth. Updated submodels for phenology and redistribution of overwinter carbohydrate storage allow the simulation to be more responsive to above ground competition among trees in a patch over multiple growing seasons. An 8-year patch-scale simulation of aspen clones 216 and 259 was conducted using high-resolution environmental data from the Aspen FACE Experiment, a long-term free-air carbon dioxide enrichment (FACE) study. Tree heights and volumes were comparable to 8-year growth measurements made at the Aspen FACE site.

A model of photosynthate production is the central component of a larger whole-tree ecophysiological growth process model for Populus (ECOPHYS). This photosynthesis model was validated by comparing predicted photosynthate production values for individual leaves and the total tree with hourly field measurements collected on four days spaced throughout a growing season. Simulated trees had identical numbers of leaves and leaf areas as the sample trees studied in the field, and hourly weather data collected on the plantation site were supplied as a model input. Total production for the four sample days ranged between 200 and 4900 mg CO(2) tree(-1) day(-1). Model predictions of total daily photosynthate production were within 12% of the observed rates for three of the four sampling days. Diurnal variations in stomatal conductance and ambient CO(2) concentrations and seasonal variations in area leaf weight were the primary sources of error. Total leaf area, proportion of sunlit leaf area, and photosynthetic efficiency were the most important factors influencing carbon dioxide exchange rates.

Watersheds represent spatially explicit areas within which terrestrial stressors can be quantified and linked to measures of aquatic ecosystem condition. We delineated thousands of Great Lakes watersheds using previously proven and new watershed delineation techniques. These were used to provide summaries for a variety of anthropogenic stressors within the Great Lakes. All delineation techniques proved useful, but each had applications for which they were most appropriate. A set of watershed delineations and stressor summaries was developed for sampling site identification, providing relatively coarse strata for selecting sites along the U.S. Great Lakes coastline. Subsequent watershed delineations were used for high-resolution site characterization of specific sites and characterizing the full coastal stressor gradient. For these delineations we used three general approaches: 1) segmentation of the shoreline at points midway between adjacent streams and delineation of a watershed for each segment; 2) specific watershed delineations for sampled sites; and 3) a Great Lakes basin-wide, high-resolution approach wherein sub-basins can be agglomerated into larger basins for specific portions of the coast. The third approach is unique in that it provides a nested framework based on hierarchies of catchments with associated stressor data. This hierarchical framework was used to derive additional watershed delineations, and their associated stressor summaries, at four different scales. Providing anthropogenic stressor metrics in such a format that can quickly be summarized for the entire basin at multiple scales, or specifically for particular areas, establishes a strong foundation for quantifying and understanding stressor-response relationships in these coastal environments.

15.1 INTRODUCTION Riparian zones are the ecotones or transition areas between upland and aquatic ecosystems, located at the margins of rivers, lakes, ponds and wetlands. Their boundaries are defined by changes in soil, moisture, and vegetation (Naiman 2000, Decamps 1996, Gregory et al. 1991). Although these ecosystems may be small relative to the aquatic systems they abut, they perform many important ecosystem services, including shading (thus buffering air and water temperature), retaining nutrients and/or sediments, stabilizing stream banks and littoral zones, and providing organic material (leaves, wood) and critical habitat for a diverse community of plant and animal species (Malanson 1993). Riparian zones are highly variable systems whose structure and composition are shaped by geomorphology, vegetation patterns, disturbance regimes (Decamps 1996), as well as current (Erickson and DeYoung 1993) and perhaps historic land use practices (Foster et al. 2003). Processes that operate over a large range of temporal and spatial scales control these structuring factors. At one end of the time/space continuum are processes such as tectonics, volcanism, glaciation, and climate change. At intermediate spatial and temporal scales are historic land use practices (e.g., burning regimes implemented by native peoples, permanent land cover conversion) and catastrophic flooding. At small scales, localized flooding and land management practices influence the structure and function of riparian zones. Some processes occur over multiple scales and their effects may also vary by scale. The fine-scale variation of vegetative cover resulting from moisture and soil gradients around streams and wetlands has posed a challenge to research scientists and land managers (Muller 1997, Congalton et al. 2002). One of the current

Integrated, quantitative expressions of anthropogenic stress over large geographic regions can be valuable tools in environmental research and management. Despite the fundamental appeal of a regional approach, development of regional stress measures remains one of the most important current challenges in environmental science. Using publicly available, pre-existing spatial datasets, we developed a geographic information system database of 86 variables related to five classes of anthropogenic stress in the U.S. Great Lakes basin: agriculture, atmospheric deposition, human population, land cover, and point source pollution. The original variables were quantified by a variety of data types over a broad range of spatial and classification resolutions. We summarized the original data for 762 watershed-based units that comprise the U.S. portion of the basin and then used principal components analysis to develop overall stress measures within each stress category. We developed a cumulative stress index by combining the first principal component from each of the five stress categories. Maps of the stress measures illustrate strong spatial patterns across the basin, with the greatest amount of stress occurring on the western shore of Lake Michigan, southwest Lake Erie, and southeastern Lake Ontario. We found strong relationships between the stress measures and characteristics of bird communities, fish communities, and water chemistry measurements from the coastal region. The stress measures are taken to represent the major threats to coastal ecosystems in the U.S. Great Lakes. Such regional-scale efforts are critical for understanding relationships between human disturbance and ecosystem response, and can be used to guide environmental decision-making at both regional and local scales.

Predicting ozone-induced reduction of carbon sequestration of forests under elevated tropospheric ozone concentrations requires robust mechanistic leaf-level models, scaled up to whole tree and stand level. As ozone effects depend on genotype, the ability to predict these effects on forest carbon cycling via competitive response between genotypes will also be required. This study tests a process-based model that predicts the relative effects of ozone on the photosynthetic rate and growth of an ozone-sensitive aspen clone, as a first step in simulating the competitive response of genotypes to atmospheric and climate change. The resulting composite model simulated the relative above ground growth response of ozone-sensitive aspen clone 259 exposed to square wave variation in ozone concentration. This included a greater effect on stem diameter than on stem height, earlier leaf abscission, and reduced stem and leaf dry matter production at the end of the growing season. Further development of the model to reduce predictive uncertainty is discussed.

Field data from poplar plantations in Michigan, Washington, and Wisconsin were used to validate ECOPHYS, a whole-tree growth process model for juvenile poplar. Five clones representing a range of morphological, phenological, and physiological characteristics were planted on the same date at the three sites. Height and diameter measurements were made monthly on 20 trees per clone, and intensive morphological measurements were made every two weeks on two trees per clone. Hourly solar radiation and temperature data were recorded at each site over the growing season. The model was run for each clone x site combination with the weather data and clonal parameters as inputs. A repeated measures ANOVA indicated that there were significant differences in height growth patterns among both clones and sites, as well as significant clone x site interactions. The model generally predicted height growth within a standard deviation of the field plantation means; three of the 15 clone x site simulations were significantly different from the plantation means. The median error between predicted and observed values was 5%. Evaluation of the clonal parameters showed that differences in photosynthetic rates, morphological attributes such as specific leaf area, and timing of budset are primary factors leading to differences in growth.

Reports that both forest floor removal and soil compaction significantly reduced biomass and height of 2-year-old aspen suckers in plots in northern Minnesota.

Presents technical documentation for development of an Ecological Classification System for the Manistee National Forest in northwest Lower Michigan, and suggests procedures applicable to other ecological land classification projects. Includes discussion of sampling design, field data collection, data summarization and analyses, development of classification units, and validation.