Lee E. Frelich's research while affiliated with University of Minnesota Duluth and other places

Publications (149)

Article
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The morphological traits of seeds have a fundamental meaning for spread and regeneration of non-native zoochorous plants, as they determine the level of establishment success and the ability of native fauna to disperse the alien plant. Here we studied the size, mass and viability of acorns of the North-American northern red oak Quercus rubra in its...
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A campaign is underway to clear established forests and expand early-successional habitats—also called young forest, pre-forest, early seral, or open habitats—with the intention of benefitting specific species. Coordinated by federal and state wildlife agencies, and funded with public money, public land managers work closely with hunting and forest...
Article
Woody invaders of temperate forest understories reduce native diversity worldwide. Common buckthorn Rhamnus cathartica, is among the most widespread of such invaders in North America. Invaded communities often have seedbanks largely comprised of the dominant invader - with few native species remaining - and therefore lack the capacity to build biot...
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Under a warming climate, the southern boreal forest of North America is expected to see a doubling in fire frequency and potential for increased wind disturbance over the next century. Although boreal forests are often considered fire‐adapted, projected increases in disturbance frequency will likely result in novel combinations of disturbances with...
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Recognition of the seed crop size and the periodicity of abundant seed production is essential for the management and control of introduced tree species. Here we studied acorn production of the North American northern red oak, Quercus rubra-the most common commercially important and invasive alien tree in European forests. A four-year (2017-2020) s...
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The study area is in the Järvselja Training and Experimental Forest Centre, Estonia. The conservation of Järvselja old-growth forest started in 1924 when the area was excluded from all management activities and left to natural development. The aim of this study is to analyse the methods for calculating single tree height, tree stem lateral surface...
Article
Key messageWhite-tailed deer (Odocoileus virginiana Zimmermann) browsing reduces seedling and sapling abundance of more palatable winter woody browse such as Tsuga canadensis L. Carrière, Thuja occidentalis L., Betula alleghaniensis Britton, and Pinus strobus L. across the Lake States Region of the USA.ContextWhite-tailed deer consume buds and twig...
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In much of the central and eastern United States, tree damage is typically the most common damage indicator available to National Weather Service meteorologists estimating wind speeds from convective storms. Unfortunately, most meteorologists have little or no formal training in the susceptibility of trees to high winds, and the Enhanced Fujita sca...
Chapter
The Great Lakes-Northeastern forest region from Minnesota to New England has varied climates and site conditions that allow diverse fire regimes. In the coldest, boreal forests, infrequent high-severity fires maintain jack pine forests or birch-aspen-spruce-fir-forests. Moderately frequent, mixed-severity fires maintain red/white pine forests on si...
Article
Mixedwood forest composition, or co-dominance of hardwood and softwood species, has been interpreted as both stable and unstable. Through review of existing theory, we propose a conceptual model to understand mixedwood compositional stability in boreal and temperate forests of eastern North America. We first review the current theory that the stren...
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The southern boreal forests of North America are susceptible to large changes in composition as temperate forests or grasslands may replace them as the climate warms. A number of mechanisms for this have been shown to occur in recent years: (1) Gradual replacement of boreal trees by temperate trees through gap dynamics; (2) Sudden replacement of bo...
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Global forest area is declining rapidly, along with degradation of the ecological condition of remaining forests. Hence it is necessary to adopt forest management approaches that can achieve a balance between (1) human management designs based on homogenization of forest structure to efficiently deliver economic values and (2) naturally emerging se...
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Anthropogenic pressures alter the biodiversity, structure and organization of biological communities with severe consequences for ecosystem processes. Species invasion is such a human‐induced ecosystem change with pronounced impacts on recipient ecosystems. Around the globe, earthworms invade habitats and impact abiotic soil conditions and a wide r...
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In light of the difficulties in stand volume estimation of natural forests, we analyzed height–diameter relationships and derived a set of height estimation equations for volume estimation for naturally developing forest ecosystems, using the Järvselja old-growth and the Laeva commercial forest in Estonia as a case study. This contribution presents...
Chapter
The Ural Mountain Range spans from the arctic tundra in the north to temperate forest and steppes in the south. Between these two biomes lie vast acreages of taiga (boreal forest) at varied elevations within the mountains and across the adjacent foothills and plains. This includes large intact forest landscapes and Europe's largest remaining primev...
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Research Highlights: We modeled climate-biome envelopes at high resolution in the Western Great Lakes Region for recent and future time-periods. The projected biome shifts, in conjunction with heterogeneous distribution of protected land, may create both great challenges for conservation of particular ecosystems and novel conservation opportunities...
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In this review and synthesis paper, we review the resilience of secondary forests to climate change through the lenses of ecosystem legacies and landscape diversity. Ecosystem legacy of secondary forests was categorized as continuous forest, non-continuous forest, reassembled after conversion to other land uses, and novel reassembled forests of non...
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Understanding the long‐term success of ecosystem restoration following invasive plant removal is challenging. Long‐term experiments are costly and slow to yield results, whereas management decisions must often be made immediately. Alternatively, retrospective studies can leverage contrasting historical management strategies to provide insight into...
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Forest ecosystems are shaped by disturbances and functional features of vegetation recovery after disturbances. There is considerable variation in basic disturbance characteristics, magnitude, severity, and intensity. Disturbance legacies provide possible explanations for ecosystem resilience. The impact (length and strength) of the pool of ecosyst...
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The vast boreal biome plays an important role in the global carbon cycle but is experiencing particularly rapid climate warming, threatening the integrity of valued ecosystems and their component species. We developed a framework and taxonomy to identify climate‐change refugia potential in the North American boreal region, summarizing current knowl...
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Key Message We develop analytical methods and explore trends in disturbance interval via systematic forest inventory observations at a bioregional scale. Context Our study spans the dynamic ecotone at the intersection of southern boreal forest, mixed hardwood forest, and tall-grass prairie ecosystems in Minnesota, USA. Disturbance-related tree mor...
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Large-scale metal mining operations are planned or underway in many locations across the boreal forest biome in North America, Europe, and Asia. Although many published analyses of mining impacts on water quality in boreal landscapes are available, there is little guidance regarding terrestrial impacts. Scoping of potential impacts of Cu-Ni explora...
Article
Non‐native, invasive earthworms are altering soils throughout the world. Ecological cascades emanating from these invasions stem from rapid consumption of leaf litter by earthworms. This occurs at a midpoint in the trophic pyramid, unlike the more familiar bottom‐up or top‐down cascades. These cascades cause fundamental changes (“microcascade effec...
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In the Baltic States region, anthropogenic disturbances at different temporal and spatial scales mostly determine dynamics and development phases of forest ecosystems. We reviewed the state and condition of hemiboreal forests of the Baltic States region and analyzed species composition of recently established and permanent forest (PF). Agricultural...
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Increasing evidence indicates that forest disturbances are changing in response to global change, yet local variability in disturbance remains high. We quantified this considerable variability and analyzed whether recent disturbance episodes around the globe were consistently driven by climate, and if human influence modulates patterns of forest di...
Article
Although numerous species distribution models have been developed, most were based on insufficient distribution data or used older climate change scenarios. We aimed to quantify changes in projected ranges and threat level by the years 2061-2080, for 12 European forest tree species under three climate change scenarios. We combined tree distribution...
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Elevated population levels of white-tailed deer (Odocoileus virginianus Zimmerman) can drastically alter forest ecosystems and negatively impact society through human interactions such as deer vehicle collisions. It is currently difficult to estimate deer populations at multiple scales ranging from stand, county, state, and regional levels. This pr...
Data
Summary of browse score by county for the Lake States (US). (PDF)
Article
Gradient studies of wetland forests have inferred that competition from upland tree species confines waterlogging-tolerant tree species to hydric environments. Little is known, however, about competition effects on individual-tree growth along stress gradients in wetland forests. We investigated tree growth and competition in mixed-species stands r...
Article
Declines in the diversity of herbaceous and woody plant species in the understory of eastern North American hardwood forests are increasingly common. Forest managers are tasked with maintaining and/or promoting species diversity and resilience; however, the success of these efforts depends on a robust understanding of past and future system dynamic...
Chapter
The main tenets of forest health management are to simultaneously maintain productivity and all native species over time, which will in turn maintain ecosystem services provided by the forest. Natural disturbances oppose the stable flow of materials, while removals of timber short-circuit the flow of organic materials to the deadwood pool and reduc...
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Purpose of Review The goal was to synthesize the literature on wildland fires, how they create resilient landscape mosaics that affect ecosystem function and maintenance of biodiversity, and how the fires themselves are affected by wilderness edge effects and climate change. The emphasis is on cold-temperate and boreal forests. Recent Findings The...
Data
Data S3. Cravenetal_Earthworms_PlantFunctionalGroups.csv Data file containing effect sizes of relationships between introduced earthworm communities and cover of plant functional groups of forest understory communities in North America.
Data
Data S2. Cravenetal_Earthworms_PlantDiversity.csv Data file containing effect sizes of relationships between introduced earthworm communities and plant species diversity, evennness, and richness of forest understory communities in North America.
Data
Data S1. Appendix S1. PRISMA diagram Appendix S2. References of studies included in meta‐analysis Appendix S3. Metadata of ‘Cravenetal_Earthworms_PlantDiversity.csv’ Appendix S4. Metadata of ‘Cravenetal_EffectSizes_Earthworms_PlantFunctGroups.csv’ Table S1. Studies included in meta‐analysis and additional information about each study Table S2...
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The condition of forest ecosystems depends on the temporal and spatial pattern of management interventions and natural disturbances. Remnants of previous conditions persisting after disturbances, or ecosystem legacies, collectively comprise ecosystem memory. Ecosystem memory in turn contributes to resilience and possibilities of ecosystem reorganiz...
Article
Historically, oak forests and woodlands intergraded with southern boreal forest, temperate mesic forest, and grassland biomes, forming complex fire-mediated relationships in the Great Lakes region of Minnesota, Wisconsin and Michigan, USA. Variability in fire recurrence intervals allowed oaks to mix with grasses or with mesic forest species in area...
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Globally, biological invasions can have strong impacts on biodiversity as well as ecosystem functioning. While less conspicuous than introduced aboveground organisms, introduced belowground organisms may have similarly strong effects. Here, we synthesize for the first time the impacts of introduced earthworms on plant diversity and community compos...
Article
Ecological memory is central to how ecosystems respond to disturbance and is maintained by two types of legacies – information and material. Species life-history traits represent an adaptive response to disturbance and are an information legacy; in contrast, the abiotic and biotic structures (such as seeds or nutrients) produced by single disturban...
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Forest dynamics encompass changes in stand structure, species composition, and species interactions with disturbance and environment over a range of spatial and temporal scales. For convenience, spatial scale is defined as individual tree, neighborhood, stand, and landscape. Whether a given canopy-leveling disturbance will initiate a sequence of de...
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Plant growth and survival near range limits are likely sensitive to small changes in environmental conditions. Warming temperatures are causing range shifts and thus changes in species composition within range-edge ecotones; however, it is often not clear how temperature alters performance. Through an observational field study, we assessed temperat...
Technical Report
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We reviewed the literature to synthesize what is known about the use of fire to maintain and restore oak forests, woodlands, and savannas of the upper Midwestern United States, with emphasis on Minnesota, Wisconsin, and Michigan. Included are (1) known physical and ecological effects of fire on oaks from acorn through seedling, established sapling,...
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Common buckthorn (Rhamnus cathartica L.) is one of the most abundant and ecologically harmful non-native plants in forests of the Upper Midwest United States. At the same time, European earthworms are invading previously glaciated areas in this region, with largely anecdotal evidence suggesting they compound the negative effects of buckthorn and in...
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Theoretical predictions and empirical studies suggest that resident species diversity is an important driver of community invasibility. Through trait-based processes, plants in communities with high resident species diversity occupy a wider range of ecological niches and are more productive than low diversity communities, potentially reducing the o...
Conference Paper
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Background / Purpose: In two separate studies, using field data collected at 139 sites, we examined the influence of two global change agents: overabundant deer and nonnative earthworms. On the understory of mixed temperate-boreal forests across the upper Great Lakes region in central North America. Main conclusion: Study results indicate tha...
Conference Paper
Background/Question/Methods Conceptual frameworks of disturbance and ecosystem response will be presented, grounded with empirical field data on disturbance interactions in northern hardwood-hemlock and southern boreal forests of the western Great Lakes region. Questions considered include: Under what conditions do disturbances initiate episodes o...
Article
QuestionsTwo alternative mechanisms of abrupt vegetation change across ecological boundaries have been proposed: (1) concomitantly abrupt gradients in physical environmental variables and vegetation across the boundary, and (2) gradual environmental gradients that vegetation responds to in a non-linear or threshold manner. Here, we evaluate spatial...
Conference Paper
Background/Question/Methods In this work we were interested in investigating tree and seedling composition of hardwood communities dominated by sugar maple in the Upper Great Lakes region (Minnesota, Wisconsin, and Michigan). We divided this region into three distinctive zones spanning from southwest to northeast: the Prairie-Forest Border (PFB)...
Conference Paper
Background/Question/Methods Storm events increase heterogeneity in the range of potential tree establishment sites. This heterogeneity does not, however, guarantee survival. Many studies on post-disturbance stand development are limited to only the first few years after disturbance. In this investigation, we analyse regeneration height and mortali...
Conference Paper
Background/Question/Methods Changes in regional or global biological diversity or spatial distribution reflect the reactions of organisms in these ecological systems to modified environment conditions. Changes in the behavior of any single species, taxon or geographic region have a number of possible explanations including not only climate change...
Conference Paper
Background/Question/Methods Common buckthorn (Rhamnus cathartica L.) and European earthworms have been posited to facilitate each other’s invasion into deciduous forests of the Midwest United States. Both have been shown to cause changes in belowground processes and can negatively affect herbaceous and woody plant species abundance and richness....
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Temperate and boreal forests are forecast to change in composition and shift spatially in response to climate change. Local-scale expansions and contractions are most likely observable near species range limits, and as trees are long-lived, initial shifts are likely to be detected in the understory regeneration layers. We examined understory relati...
Article
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...
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As the climate warms, boreal tree species are expected to be gradually replaced by temperate species within the southern boreal forest. Warming will be accompanied by changes in above- and below-ground consumers: large moose (Alces alces) replaced by smaller deer (Odocoileus virginianus) above-ground, and small detritivores replaced by larger exoti...
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Rising temperatures are predicted to cause temperate tree species to expand north into currently boreal dominated forests. Other factors, such as overabundant deer, may hinder temperate expansion. We examined how interactions among temperature, browse pressure, light availability, and initial size impact height and radial growth of naturally regene...
Article
Parergodrilus heideri Reisinger, 1925 is one of two species of the family Parergodrilidae (together with the marine litoral, interstitial species Stygocapitella subterranea Knöllner, 1934) and one of only two truly soil-dwelling “polychaetes” (the other being Hrabeiella periglandulata Pižl and Chalupský, 1984) that are predominantly known from terr...
Article
Earthworm invasion in North American temperate forest reduces forest floor mass, yet the interactions between litter composition, invasive earthworm community composition, and forest floor structure and composition are not well understood. For 2 years, we compared disappearance of leaf litter in field mesocosms in which we manipulated litter compos...
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Ahistorical drivers such as nonnative invasive earthworms and high deer densities can have substantial impacts on ecosystem processes and plant community composition in temperate and boreal forests of North America. To assess the roles of earthworm disturbance, deer, and environmental factors in the understory, we sampled 125 mixed temperate-boreal...
Article
1. Understanding the relationship between species diversity and productivity is central to linking compositional and functional aspects of terrestrial ecosystems, and little is known about such issues in boreal forests. We used structural equation modelling (SEM) to test several hypotheses about direct and indirect influences of productivity, its c...
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Forest compositional shifts in response to climate change are likely to be initially detectable in the understory tree regeneration layer near species range limits. Because many factors in addition to climate, such as seedbed and soil characteristics, overstory composition, and interactions with other understory biota, drive tree regeneration trend...
Article
The spread of exotic earthworms (‘worming’) and rising temperatures are expected to alter the biological, chemical and physical properties of many ecosystems, yet little is known about their potential interactive effects. We performed a laboratory microcosm experiment to investigate the effects of earthworms (anecic, endogeic, epigeic, or all three...
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Earthworms are ecosystem engineers that cause a long cascade of ecological effects when they invade previously earthworm-free forests. However, the consequences of earthworm invasion for soil microbial functions are poorly understood. Here, we used two well-studied invasion fronts of European earthworms in northern North American hardwood forests p...
Conference Paper
Background/Question/Methods Forest composition and tree species range limits are predicted to shift in response to climate change, although current empirical knowledge of the interrelated roles of climatic, environmental, and biotic drivers shaping forest change is minimal. Initial forest shifts should be detectable along ecotonal boundaries wher...
Article
1. We hypothesize that flowering phenology correlates with plant height growth pattern and that the pattern is associated with functional traits including maximum plant height (Hmax), RGR, stem tissue mass density (SD), hollow ratio (proportion of central hollow of stem cross-sectional area) and leaf mass per area (LMA) in grassland herbaceous spec...
Article
1. It is well known that climate change alters abiotic factors (temperature and water availability) that directly affect ecosystem properties. However, less is known about the indirect impacts of climate change on ecosystem structure and function. Here, we show that experimental warming may deteriorate ecosystems via trophic interactions. 2. In a T...
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Wildfire can create a mosaic of impacts of varying severity across the landscape. Although widely recognized, this feature and its causes are little understood or studied in ecology. We studied a 1,200-ha wildfire in the southern boreal forest of the Boundary Waters Canoe Area Wilderness (BWCAW) in northeastern Minnesota, USA, using 275 ground plot...
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Anthropogenic factors such as elevated deer populations, invasive earthworms or climate change may alter old-growth forests of the Upper Midwest region of the United States. We examined demographic trends of woody species across all size classes over 35 years in a late-successional forest dominated by hemlock (Tsuga canadensis), sugar maple (Acer s...
Article
Ecological boundaries are critical landscape regions of transition between adjacent ecological systems. While environmental controls of boundaries may operate in a scale-dependent manner, multiple-scale comparisons of vegetation–environment relationships have been characterized for few boundary systems. We used approximately 250 000 point records o...
Article
Three red pine (Pinusresinosa Ait.) plantations were located at each of five sites across the precipitation-chemistry gradient in Wisconsin (loadings of H ion, SO42−, and NO3− generally decrease from southeast to northwest). The plantations were selected to be as similar as possible in stand characteristics, including age, initial stocking, number...