Dylan Fischer - Academia.edu (original) (raw)

Papers by Dylan Fischer

Northwest Science, Dec 18, 2023

Plant Ecology, Jan 16, 2022

Plant and Soil, Feb 1, 2019

Aims In forest ecosystems, trees may have genetically distinct patterns in leaf decomposition. Tr... more Aims In forest ecosystems, trees may have genetically distinct patterns in leaf decomposition. Trees also can have genetically distinct canopy environments which modify temperature, moisture, and microbial communities on the forest floor. The interaction between these factors may result in underexplored interactions between microenvironment and leaf decomposition at the genotype level. Methods We compare litter decomposition rates for distinct genotypes of Fremont cottonwood (Populus fremontii) grown in a common garden environment under three different riparian conditions: 1) under a 16-tree stand of the same genotype, 2) under a 16-tree stand of another genotype, and 3) under a 16-tree stand of 16 different genotypes. Genotypes differed in canopy size and phenology. Results While genotype exerted a strong effect on decomposition, this effect was most pronounced when litter was decomposed under a self-similar (Bhome^) canopy. The strongest driver of decomposition rates across all factors (including litter quality and environmental factors) was spring (leaf-out) and fall (leaf-drop) phenology, but responses were variable by genotype. Conclusions The influence of genetics on litter decomposition, canopy environment, and tree phenology provides justification for the inclusion of stand-level traits like canopy cover into models of decomposition and complicates the results of studies that rely on litter quality traits alone.

Canadian Journal of Forest Research, 2021

Forest disturbance is usually described by effects on trees, and small disturbances to forest und... more Forest disturbance is usually described by effects on trees, and small disturbances to forest understory are seldom studied. Nevertheless, effective analyses of succession need to consider both stand-replacing and subsequent “secondary” disturbances in both the canopy and understory. We estimated the characteristics of 13 types of secondary disturbances in old-growth forest understory, as well as change in the canopy cover, after the deposition of tephra (aerially transported volcanic ejecta) in 1980 from Mount St. Helens, Washington. We sampled 100 plots (1 m2) at each of four sites for vegetation change and types of disturbance at 10 different times from 1980 to 2010; we sampled the tree canopy above each plot in 1980 and 2016. The number of canopy gaps increased by 23% and mean gap dimension increased by 68% over 36 years, mostly from the loss of Abies amabilis (Douglas ex Loudon) Douglas ex Forbes. Secondary disturbance in understory affected 1.4% of stand area per year. The are...

Journal of Ecology, 2019

Studies of succession have a long history in ecology, but rigorous tests of general, unifying pri... more Studies of succession have a long history in ecology, but rigorous tests of general, unifying principles are rare. One barrier to these tests of theory is the paucity of longitudinal studies that span the broad gradients of disturbance severity that characterize large, infrequent disturbances. The cataclysmic eruption of Mount St. Helens (Washington, USA) in 1980 produced a heterogeneous landscape of disturbance conditions, including primary to secondary successional habitats, affording a unique opportunity to explore how rates and patterns of community change relate to disturbance severity, post‐eruption site conditions and time. In this novel synthesis, we combined data from three long‐term (c. 30‐year) studies to compare rates and patterns of community change across three ‘zones’ representing a gradient of disturbance severity: primary successional blast zone, secondary successional tree blowdown/standing snag zone and secondary successional intact forest canopy/tephra deposit zo...

Botanical Journal of the Linnean Society, 2013

Canadian Journal of Forest Research, 2018

Ecological impacts of climate change in the Pacific Northwest may hinge on acclimation to drier s... more Ecological impacts of climate change in the Pacific Northwest may hinge on acclimation to drier summers, highlighting the importance of plant physiological studies in forests. Evaluating dominant forest plant species under old-growth and managed forest conditions is similarly important as timber harvest might change microclimates and alter drought effects on plants. We examined water potential and gas exchange rates of four dominant plant species in understories of subalpine forests of the Pacific Northwest region of the United States during 2015 — a year with drought conditions representative of future climate projections. We examined two conifer species (Abies amabilis Douglas ex J. Forbes and Tsuga heterophylla (Raf.) Sarg.) and two huckleberry species (Vaccinium membranaceum Douglas ex Torr. and Vaccinium ovalifolium Sm.) in old-growth and formerly clear-cut forests at two elevations. Contrary to expectations, we found no evidence of hydraulic stress, and there were no significa...

Forests

Forest tree canopies have a critical influence on water cycles through the interception of precip... more Forest tree canopies have a critical influence on water cycles through the interception of precipitation. Nevertheless, radial patterns of canopy interception may vary interspecifically. We analyzed canopy interception using catchments along radial transects underneath four common forest tree species (Acer macrophyllum, Alnus rubra, Pseudotsuga menziesii, and Thuja plicata) in the Pacific Northwest over two years. Near the center of the canopy in the leaf-off season, interception was 51.6%–67.2% in conifer species and only 20.1%–40.1% in broadleaf species, and interception declined to 19.9–29.9 for all species near the edge of the canopy. One deciduous species (A. rubra) showed spatially uniform interception during the leaf-off period (19.9%–20.96%), while another varied from 23.1%–40.1%. Patterns were more pronounced in the leaf-on period (under high vapor pressure deficit conditions), where conifers intercepted 36.5%–95.9% of precipitation, depending on the species and position un...

Airborne volcanic ejecta (tephra) can strongly in uence forest ecosystems through initial disturb... more Airborne volcanic ejecta (tephra) can strongly in uence forest ecosystems through initial disturbance processes and subsequent ecological response. Within a tephra-disturbed forest, large trees may promote plant growth and create favorable sites for colonization. Three primary ways trees can in uence post-eruption vegetation response include: 1) amelioration of volcanic substrates, 2) as source propagules from the tree or from associated epiphytes, and 3) by sheltering understory vegetation, thereby increasing rate of recovery near tree bases. Here, we evaluate Valdivian temperate rainforest understory vegetation response and soil characteristics in close proximity to large trees that survived the 2015 eruption of Calbuco Volcano. Understory vegetative cover was higher near the base of trees for mosses, many epiphytes, and some herbaceous, shrub, and trees species. However, signi cant interactions with year of measurement, and individualistic responses by many species made generalizations more di cult. Small shrubs and trees in particular demonstrated patterns of recovery that were frequently independent of distance. In some cases, percent cover of colonizing vegetation actually increased far from trees by 2019. The soil surface was similarly variable where bare soil cover was associated with locations proximal to tree bases, but material shed from living and dead standing vegetation increased wood and litter abundances on the soil surface away from the base of trees. Soils near trees had lower pH, elevated organic matter, and higher nitrogen and carbon. Our results support the assertion that in this temperate rainforest ecosystem, large trees can modify edaphic conditions and provide important early refugia for vegetative regrowth following a tephra fall event. Nevertheless, complex interactions through time with species and growth form, suggest the in uence of large trees on plant establishment and growth with close proximity tree boles is more complex than a simple facilitative model might suggest.

Plant Ecology

Airborne volcanic ejecta (tephra) can strongly influence forest ecosystems through initial distur... more Airborne volcanic ejecta (tephra) can strongly influence forest ecosystems through initial disturbance processes and subsequent ecological response. Within a tephra-disturbed forest, large trees may promote plant growth and create favorable sites for colonization. Three primary ways trees can influence posteruption vegetation response include: (1) amelioration of volcanic substrates, (2) providing source propagules from the tree or from associated epiphytes, and (3) sheltering understory vegetation, thereby increasing the rate of recovery near tree bases. Here, we evaluate Valdivian temperate rainforest understory vegetation responses in close proximity to large trees that survived the 2015 eruption of Calbuco Volcano. Understory vegetative cover was higher near the base of trees for mosses, many epiphytes, and some herbaceous, shrub, and trees species. However, significant interactions with year of measurement, and individualistic responses by many species made generalizations more difficult. Shrubs and trees in particular demonstrated patterns of recovery that were frequently independent of distance. In some cases, percent cover of colonizing vegetation actually increased away from trees by 2019. The soil surface was similarly variable where bare soil cover was associated with locations proximal to tree bases, but material shed from living and dead standing vegetation increased wood and litter abundances on the soil surface away from the base of trees. Soils near trees had lower pH, elevated organic matter, and higher nitrogen and carbon. Our results support the assertion that in this temperate rainforest ecosystem large trees may provide important early refugia for vegetative regrowth following a tephra-fall event with altered edaphic conditions. Nevertheless, individualistic dynamics of different species and growth forms suggest the influence of large trees on nearby understory plants is more complex than a simple facilitative model might suggest.

Botany

Responses in bryophyte communities following volcanic disturbance are not well understood. The er... more Responses in bryophyte communities following volcanic disturbance are not well understood. The eruption of Mount St. Helens on 18 May 1980 deposited large amounts of tephra (aerially transported volcanic ejecta) on nearby forests in southwestern Washington and presented an opportunity to examine bryophyte succession, with a focus on mosses. We examined changes in moss community over 36 years following this disturbance, using permanent plots located in old-growth conifer forests. We used an experimental design where we removed the tephra from some of the plots shortly after the eruption. Initial dramatic decreases in total bryophyte cover, moss species richness, and diversity in plots with intact tephra were followed by increases by 2016. Community profiles also shifted through time but were somewhat site-specific. Moss community change was related to changes in vascular plant species and was driven by changes in a few key moss species with distinct growth strategies. Bryophyte chang...

Botany

Forest understory herbs exhibit a large range of variation in morphology and life history. Here, ... more Forest understory herbs exhibit a large range of variation in morphology and life history. Here, we expand the reported range of variation by describing the belowground structures of two very different species, Xerophyllum tenax (Pursh) Nutt. and Chimaphila umbellata (L.) Nutt. We excavated individuals in forests of the Cascade Mountains in the Pacific Northwest of the United States. Xerophyllum tenax has short rhizomes but an extensive root system that is exceptionally large among forest understory species. The roots reach 4 m in length and may occupy an area 50 times that of the aboveground canopy. In contrast, C. umbellata has very small roots but an extensive rhizome system. The largest plant we excavated had 57 m of connected rhizomes and still had a seedling source. Both species have long-lived individuals but differ in response to disturbance. On the basis of monitoring 151 permanent 1 m2 plots in an old-growth forest, X. tenax increased only minimally in density over 40 year...

Forest Ecology and Management, 2016

Canadian Journal of Fisheries and Aquatic Sciences, 2015

Biodiversity at many scales (functional group, species, genetic) can result in emergent ecologica... more Biodiversity at many scales (functional group, species, genetic) can result in emergent ecological patterns. Here we explore the influence of tree genotypic variation and diversity on in-stream ecosystem processes and aquatic communities. We test whether genetically diverse inputs of leaf litter interact with a keystone organism, anadromous salmon, to influence in-stream ecosystem function. We used reach-level manipulation of salmon carcasses and leaf litter bags to examine how nutrient inputs interact with genetic variation in leaf litter decomposition. Genotypic variation in black cottonwood (Populus balsamifera ssp. trichocarpa) significantly influenced leaf litter chemistry, litter mass loss, and fungal biomass, but these variables were only weakly influenced by salmon carcass presence or a genotype × salmon (G × E) interaction. Mixtures of genotypes tended to demonstrate antagonistic effects (slower than expected decomposition) in the absence of salmon, but synergistic effects ...

Philosophical Transactions of the Royal Society B: Biological Sciences, 2009

Using two genetic approaches and seven different plant systems, we present findings from a meta-a... more Using two genetic approaches and seven different plant systems, we present findings from a meta-analysis examining the strength of the effects of plant genetic introgression and genotypic diversity across individual, community and ecosystem levels with the goal of synthesizing the patterns to date. We found that (i) the strength of plant genetic effects can be quite high; however, the overall strength of genetic effects on most response variables declined as the levels of organization increased. (ii) Plant genetic effects varied such that introgression had a greater impact on individual phenotypes than extended effects on arthropods or microbes/fungi. By contrast, the greatest effects of genotypic diversity were on arthropods. (iii) Plant genetic effects were greater on above-ground versus below-ground processes, but there was no difference between terrestrial and aquatic environments. (iv) The strength of the effects of intraspecific genotypic diversity tended to be weaker than int...

Nature Reviews Genetics, 2006

Ecosystems, 2008

Research that connects ecosystem processes to genetic mechanisms has recently gained significant ... more Research that connects ecosystem processes to genetic mechanisms has recently gained significant ground, yet actual studies that span the levels of organization from genes to ecosystems are extraordinarily rare. Utilizing foundation species from the genus Populus, in which the role of condensed tannins (CT) has been investigated aboveground, belowground, and in adjacent streams, we examine the diverse mechanisms for the expression of CT and the ecological consequences of CT for forests and streams. The wealth of data from this genus highlights the importance of form and function of CT in large-scale and long-term ecosystem processes and demonstrates the following four patterns: (1) plant

Northwest Science, Dec 18, 2023

Plant Ecology, Jan 16, 2022

Plant and Soil, Feb 1, 2019

Aims In forest ecosystems, trees may have genetically distinct patterns in leaf decomposition. Tr... more Aims In forest ecosystems, trees may have genetically distinct patterns in leaf decomposition. Trees also can have genetically distinct canopy environments which modify temperature, moisture, and microbial communities on the forest floor. The interaction between these factors may result in underexplored interactions between microenvironment and leaf decomposition at the genotype level. Methods We compare litter decomposition rates for distinct genotypes of Fremont cottonwood (Populus fremontii) grown in a common garden environment under three different riparian conditions: 1) under a 16-tree stand of the same genotype, 2) under a 16-tree stand of another genotype, and 3) under a 16-tree stand of 16 different genotypes. Genotypes differed in canopy size and phenology. Results While genotype exerted a strong effect on decomposition, this effect was most pronounced when litter was decomposed under a self-similar (Bhome^) canopy. The strongest driver of decomposition rates across all factors (including litter quality and environmental factors) was spring (leaf-out) and fall (leaf-drop) phenology, but responses were variable by genotype. Conclusions The influence of genetics on litter decomposition, canopy environment, and tree phenology provides justification for the inclusion of stand-level traits like canopy cover into models of decomposition and complicates the results of studies that rely on litter quality traits alone.

Canadian Journal of Forest Research, 2021

Forest disturbance is usually described by effects on trees, and small disturbances to forest und... more Forest disturbance is usually described by effects on trees, and small disturbances to forest understory are seldom studied. Nevertheless, effective analyses of succession need to consider both stand-replacing and subsequent “secondary” disturbances in both the canopy and understory. We estimated the characteristics of 13 types of secondary disturbances in old-growth forest understory, as well as change in the canopy cover, after the deposition of tephra (aerially transported volcanic ejecta) in 1980 from Mount St. Helens, Washington. We sampled 100 plots (1 m2) at each of four sites for vegetation change and types of disturbance at 10 different times from 1980 to 2010; we sampled the tree canopy above each plot in 1980 and 2016. The number of canopy gaps increased by 23% and mean gap dimension increased by 68% over 36 years, mostly from the loss of Abies amabilis (Douglas ex Loudon) Douglas ex Forbes. Secondary disturbance in understory affected 1.4% of stand area per year. The are...

Journal of Ecology, 2019

Studies of succession have a long history in ecology, but rigorous tests of general, unifying pri... more Studies of succession have a long history in ecology, but rigorous tests of general, unifying principles are rare. One barrier to these tests of theory is the paucity of longitudinal studies that span the broad gradients of disturbance severity that characterize large, infrequent disturbances. The cataclysmic eruption of Mount St. Helens (Washington, USA) in 1980 produced a heterogeneous landscape of disturbance conditions, including primary to secondary successional habitats, affording a unique opportunity to explore how rates and patterns of community change relate to disturbance severity, post‐eruption site conditions and time. In this novel synthesis, we combined data from three long‐term (c. 30‐year) studies to compare rates and patterns of community change across three ‘zones’ representing a gradient of disturbance severity: primary successional blast zone, secondary successional tree blowdown/standing snag zone and secondary successional intact forest canopy/tephra deposit zo...

Botanical Journal of the Linnean Society, 2013

Canadian Journal of Forest Research, 2018

Ecological impacts of climate change in the Pacific Northwest may hinge on acclimation to drier s... more Ecological impacts of climate change in the Pacific Northwest may hinge on acclimation to drier summers, highlighting the importance of plant physiological studies in forests. Evaluating dominant forest plant species under old-growth and managed forest conditions is similarly important as timber harvest might change microclimates and alter drought effects on plants. We examined water potential and gas exchange rates of four dominant plant species in understories of subalpine forests of the Pacific Northwest region of the United States during 2015 — a year with drought conditions representative of future climate projections. We examined two conifer species (Abies amabilis Douglas ex J. Forbes and Tsuga heterophylla (Raf.) Sarg.) and two huckleberry species (Vaccinium membranaceum Douglas ex Torr. and Vaccinium ovalifolium Sm.) in old-growth and formerly clear-cut forests at two elevations. Contrary to expectations, we found no evidence of hydraulic stress, and there were no significa...

Forests

Forest tree canopies have a critical influence on water cycles through the interception of precip... more Forest tree canopies have a critical influence on water cycles through the interception of precipitation. Nevertheless, radial patterns of canopy interception may vary interspecifically. We analyzed canopy interception using catchments along radial transects underneath four common forest tree species (Acer macrophyllum, Alnus rubra, Pseudotsuga menziesii, and Thuja plicata) in the Pacific Northwest over two years. Near the center of the canopy in the leaf-off season, interception was 51.6%–67.2% in conifer species and only 20.1%–40.1% in broadleaf species, and interception declined to 19.9–29.9 for all species near the edge of the canopy. One deciduous species (A. rubra) showed spatially uniform interception during the leaf-off period (19.9%–20.96%), while another varied from 23.1%–40.1%. Patterns were more pronounced in the leaf-on period (under high vapor pressure deficit conditions), where conifers intercepted 36.5%–95.9% of precipitation, depending on the species and position un...

Airborne volcanic ejecta (tephra) can strongly in uence forest ecosystems through initial disturb... more Airborne volcanic ejecta (tephra) can strongly in uence forest ecosystems through initial disturbance processes and subsequent ecological response. Within a tephra-disturbed forest, large trees may promote plant growth and create favorable sites for colonization. Three primary ways trees can in uence post-eruption vegetation response include: 1) amelioration of volcanic substrates, 2) as source propagules from the tree or from associated epiphytes, and 3) by sheltering understory vegetation, thereby increasing rate of recovery near tree bases. Here, we evaluate Valdivian temperate rainforest understory vegetation response and soil characteristics in close proximity to large trees that survived the 2015 eruption of Calbuco Volcano. Understory vegetative cover was higher near the base of trees for mosses, many epiphytes, and some herbaceous, shrub, and trees species. However, signi cant interactions with year of measurement, and individualistic responses by many species made generalizations more di cult. Small shrubs and trees in particular demonstrated patterns of recovery that were frequently independent of distance. In some cases, percent cover of colonizing vegetation actually increased far from trees by 2019. The soil surface was similarly variable where bare soil cover was associated with locations proximal to tree bases, but material shed from living and dead standing vegetation increased wood and litter abundances on the soil surface away from the base of trees. Soils near trees had lower pH, elevated organic matter, and higher nitrogen and carbon. Our results support the assertion that in this temperate rainforest ecosystem, large trees can modify edaphic conditions and provide important early refugia for vegetative regrowth following a tephra fall event. Nevertheless, complex interactions through time with species and growth form, suggest the in uence of large trees on plant establishment and growth with close proximity tree boles is more complex than a simple facilitative model might suggest.

Plant Ecology

Airborne volcanic ejecta (tephra) can strongly influence forest ecosystems through initial distur... more Airborne volcanic ejecta (tephra) can strongly influence forest ecosystems through initial disturbance processes and subsequent ecological response. Within a tephra-disturbed forest, large trees may promote plant growth and create favorable sites for colonization. Three primary ways trees can influence posteruption vegetation response include: (1) amelioration of volcanic substrates, (2) providing source propagules from the tree or from associated epiphytes, and (3) sheltering understory vegetation, thereby increasing the rate of recovery near tree bases. Here, we evaluate Valdivian temperate rainforest understory vegetation responses in close proximity to large trees that survived the 2015 eruption of Calbuco Volcano. Understory vegetative cover was higher near the base of trees for mosses, many epiphytes, and some herbaceous, shrub, and trees species. However, significant interactions with year of measurement, and individualistic responses by many species made generalizations more difficult. Shrubs and trees in particular demonstrated patterns of recovery that were frequently independent of distance. In some cases, percent cover of colonizing vegetation actually increased away from trees by 2019. The soil surface was similarly variable where bare soil cover was associated with locations proximal to tree bases, but material shed from living and dead standing vegetation increased wood and litter abundances on the soil surface away from the base of trees. Soils near trees had lower pH, elevated organic matter, and higher nitrogen and carbon. Our results support the assertion that in this temperate rainforest ecosystem large trees may provide important early refugia for vegetative regrowth following a tephra-fall event with altered edaphic conditions. Nevertheless, individualistic dynamics of different species and growth forms suggest the influence of large trees on nearby understory plants is more complex than a simple facilitative model might suggest.

Botany

Responses in bryophyte communities following volcanic disturbance are not well understood. The er... more Responses in bryophyte communities following volcanic disturbance are not well understood. The eruption of Mount St. Helens on 18 May 1980 deposited large amounts of tephra (aerially transported volcanic ejecta) on nearby forests in southwestern Washington and presented an opportunity to examine bryophyte succession, with a focus on mosses. We examined changes in moss community over 36 years following this disturbance, using permanent plots located in old-growth conifer forests. We used an experimental design where we removed the tephra from some of the plots shortly after the eruption. Initial dramatic decreases in total bryophyte cover, moss species richness, and diversity in plots with intact tephra were followed by increases by 2016. Community profiles also shifted through time but were somewhat site-specific. Moss community change was related to changes in vascular plant species and was driven by changes in a few key moss species with distinct growth strategies. Bryophyte chang...

Botany

Forest understory herbs exhibit a large range of variation in morphology and life history. Here, ... more Forest understory herbs exhibit a large range of variation in morphology and life history. Here, we expand the reported range of variation by describing the belowground structures of two very different species, Xerophyllum tenax (Pursh) Nutt. and Chimaphila umbellata (L.) Nutt. We excavated individuals in forests of the Cascade Mountains in the Pacific Northwest of the United States. Xerophyllum tenax has short rhizomes but an extensive root system that is exceptionally large among forest understory species. The roots reach 4 m in length and may occupy an area 50 times that of the aboveground canopy. In contrast, C. umbellata has very small roots but an extensive rhizome system. The largest plant we excavated had 57 m of connected rhizomes and still had a seedling source. Both species have long-lived individuals but differ in response to disturbance. On the basis of monitoring 151 permanent 1 m2 plots in an old-growth forest, X. tenax increased only minimally in density over 40 year...

Forest Ecology and Management, 2016

Canadian Journal of Fisheries and Aquatic Sciences, 2015

Biodiversity at many scales (functional group, species, genetic) can result in emergent ecologica... more Biodiversity at many scales (functional group, species, genetic) can result in emergent ecological patterns. Here we explore the influence of tree genotypic variation and diversity on in-stream ecosystem processes and aquatic communities. We test whether genetically diverse inputs of leaf litter interact with a keystone organism, anadromous salmon, to influence in-stream ecosystem function. We used reach-level manipulation of salmon carcasses and leaf litter bags to examine how nutrient inputs interact with genetic variation in leaf litter decomposition. Genotypic variation in black cottonwood (Populus balsamifera ssp. trichocarpa) significantly influenced leaf litter chemistry, litter mass loss, and fungal biomass, but these variables were only weakly influenced by salmon carcass presence or a genotype × salmon (G × E) interaction. Mixtures of genotypes tended to demonstrate antagonistic effects (slower than expected decomposition) in the absence of salmon, but synergistic effects ...

Philosophical Transactions of the Royal Society B: Biological Sciences, 2009

Using two genetic approaches and seven different plant systems, we present findings from a meta-a... more Using two genetic approaches and seven different plant systems, we present findings from a meta-analysis examining the strength of the effects of plant genetic introgression and genotypic diversity across individual, community and ecosystem levels with the goal of synthesizing the patterns to date. We found that (i) the strength of plant genetic effects can be quite high; however, the overall strength of genetic effects on most response variables declined as the levels of organization increased. (ii) Plant genetic effects varied such that introgression had a greater impact on individual phenotypes than extended effects on arthropods or microbes/fungi. By contrast, the greatest effects of genotypic diversity were on arthropods. (iii) Plant genetic effects were greater on above-ground versus below-ground processes, but there was no difference between terrestrial and aquatic environments. (iv) The strength of the effects of intraspecific genotypic diversity tended to be weaker than int...

Nature Reviews Genetics, 2006

Ecosystems, 2008

Research that connects ecosystem processes to genetic mechanisms has recently gained significant ... more Research that connects ecosystem processes to genetic mechanisms has recently gained significant ground, yet actual studies that span the levels of organization from genes to ecosystems are extraordinarily rare. Utilizing foundation species from the genus Populus, in which the role of condensed tannins (CT) has been investigated aboveground, belowground, and in adjacent streams, we examine the diverse mechanisms for the expression of CT and the ecological consequences of CT for forests and streams. The wealth of data from this genus highlights the importance of form and function of CT in large-scale and long-term ecosystem processes and demonstrates the following four patterns: (1) plant