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RhizoNet-Linking roots, the rhizosphere and soil science with ecosystem ecology
Ecosystem ecologists have long understood that belowground processes play an important role mediating whole system productivity and diversity. However, due to methodological limitations it has often been difficult to directly quantify and describe connections from belowground to aboveground. With the emergence of new techniques and improvements on older methods it is now possible directly link root and fungal processes to nutrient, water, and carbon fluxes within and across ecosystems. In collaboration with Dali Guo and many others, a set of observational studies were established to track patterns of belowground activity in relation to whole-plant strategies. Furthermore, we are also able to compare observed patterns across ecosystems and biome types (temperate, subtropical, and tropical forests as well as grasslands and deserts). This work is being conducted primarily in China but has logical extensions to areas outside of China. In addition to opening new avenues of research in ecosystem and belowground ecology, this project will also served as a platform for training several graduate students and for the development of new methods and approaches in belowground ecology.
Picture. A stand of Chinese fir (Cunninghamia lanceolata) at the Qianyanzhou Research Station in Jiangxi Province.
Li F, H Hu, ML McCormack, D Feng, X Liu, W Bao. A community-level economics spectrum of fine-roots driven by nutrient limitations in subalpine forests. Journal of Ecology, 107: 1238-1249 (2019).
Li L, ML McCormack, F Chen, H Wang, Z Ma, D Guo. Different responses of absorptive roots and arbuscular mycorrhizal fungi to fertilization in Chinese fir. Forest Ecology and Management, 433: 64-7 (2019).
Wang C, ML McCormack, D Guo, J Li. Angiosperms and gymnosperms differ in patterns of root carbon allocation along environmental gradients. Journal of Biogeography, 46: 123-133 (2019).
Mao Z, Y Wang, ML McCormack , N Rowe, X Deng, X Yang, S Xia, J Nespoulous, RC Sidle, D Guo, A Stokes. Mechanical properties of fine roots as a function of topology and anatomy. Annals of Botany, mcy076 (2018).
Li H, B Liu, ML McCormack, B Zhu, Z Ma, D Guo. Diverse belowground resource strategies underlie plant species coexistence and spatial distribution. New Phytologist, 216: 1140-1150 (2017).
Lin G, ML McCormack, C Ma, D Guo. Similar soil carbon but contrasting modes of nitrogen cycling between arbuscular mycorrhizal and ectomycorrhizal forests. New Phytologist, 213: 1440-1451 (2017).
Liu R, Z Huang, ML McCormack, X Zhou, X Wan, Z Yu, M Wang, L Zheng. Plasticity of fine-root functional traits in response to nitrogen addition in a Mytilaria laosensis plantation. Plant and Soil, 415: 317-330 (2017).
Kou L, ML McCormack, W Chen, D Guo, H Wang, W Gao, H Yang, S Li. Nitrogen and variation in root distribution mediate nitrogen effects on lifespan of ectomycorrhizal roots. Plant and Soil, 411: 261 (2017).
Sun K, Li L, ML McCormack, L Li, Z Ma, D Guo. Fast-cycling unit of root turnover in seven perennial herbaceous plants:. Scientific Reports, 6: 19698 (2016).
Lin G, ML McCormack, D Guo. A meta-analysis of arbuscular mycorrhizal fungi effects on plant competition and community structure. Journal of Ecology, 103: 1224-1232 (2015).
Liao Y, ML McCormack, D Guo, H Wang, J Wu, J Tu, W Liu. Relation of fine root distribution to soil C in Cunninghamia lanceolata forest. Plant and Soil, Plant and Soil, 381: 225-234 (2014).
Picture. A stand of Chinese fir (Cunninghamia lanceolata) at the Qianyanzhou Research Station in Jiangxi Province.
Li F, H Hu, ML McCormack, D Feng, X Liu, W Bao. A community-level economics spectrum of fine-roots driven by nutrient limitations in subalpine forests. Journal of Ecology, 107: 1238-1249 (2019).
Li L, ML McCormack, F Chen, H Wang, Z Ma, D Guo. Different responses of absorptive roots and arbuscular mycorrhizal fungi to fertilization in Chinese fir. Forest Ecology and Management, 433: 64-7 (2019).
Wang C, ML McCormack, D Guo, J Li. Angiosperms and gymnosperms differ in patterns of root carbon allocation along environmental gradients. Journal of Biogeography, 46: 123-133 (2019).
Mao Z, Y Wang, ML McCormack , N Rowe, X Deng, X Yang, S Xia, J Nespoulous, RC Sidle, D Guo, A Stokes. Mechanical properties of fine roots as a function of topology and anatomy. Annals of Botany, mcy076 (2018).
Li H, B Liu, ML McCormack, B Zhu, Z Ma, D Guo. Diverse belowground resource strategies underlie plant species coexistence and spatial distribution. New Phytologist, 216: 1140-1150 (2017).
Lin G, ML McCormack, C Ma, D Guo. Similar soil carbon but contrasting modes of nitrogen cycling between arbuscular mycorrhizal and ectomycorrhizal forests. New Phytologist, 213: 1440-1451 (2017).
Liu R, Z Huang, ML McCormack, X Zhou, X Wan, Z Yu, M Wang, L Zheng. Plasticity of fine-root functional traits in response to nitrogen addition in a Mytilaria laosensis plantation. Plant and Soil, 415: 317-330 (2017).
Kou L, ML McCormack, W Chen, D Guo, H Wang, W Gao, H Yang, S Li. Nitrogen and variation in root distribution mediate nitrogen effects on lifespan of ectomycorrhizal roots. Plant and Soil, 411: 261 (2017).
Sun K, Li L, ML McCormack, L Li, Z Ma, D Guo. Fast-cycling unit of root turnover in seven perennial herbaceous plants:. Scientific Reports, 6: 19698 (2016).
Lin G, ML McCormack, D Guo. A meta-analysis of arbuscular mycorrhizal fungi effects on plant competition and community structure. Journal of Ecology, 103: 1224-1232 (2015).
Liao Y, ML McCormack, D Guo, H Wang, J Wu, J Tu, W Liu. Relation of fine root distribution to soil C in Cunninghamia lanceolata forest. Plant and Soil, Plant and Soil, 381: 225-234 (2014).
Spatial patterns of root growth in a diverse temperate forest
Spatial patterns of root growth are poorly understood in natural systems. While it is clear that rooting density tends to decline with soil depth, the complexity of most natural systems have limited development of more robust and nuanced understanding regarding fine roots and their links to ecosystem processes. How do rates of root production and turnover vary among species and how do different species allocate their root biomass in the presence and absence of competitors? Our overall objective in this study is to develop a better understanding of the spatial distribution of roots of different species within the soil profile. Additionally, we will link the amount and distribution of coarse and fine roots belowground to the distribution and total basal area of stems aboveground. Linking measurements of aboveground biomass with detailed information on the distribution of belowground biomass will enable improved understanding of C partitioning, nutrient and water fluxes in forested ecosystems.
This work is being conducted in a diverse temperate forest of the Changbai Mountains in northeastern China. Following a spatially explicit and intensive soil coring campaign, we are utilizing DNA markers to identify all sampled tree root biomass to individual species and analyzing a suite of key soil and microbial parameters to better understand whole-forest processes. Key collaborators include Dali Guo, Jing Tian, and Jingyuan Wang.
Tian J, ML McCormack, J Wang, D Guo, X Zhang, G Yu. Linkages between the microbial metabolic functional diversity and soil organic matter fractions within a broad-leaved Korean pine forest in Changbai Mountain. European Journal of Soil Biology, 66: 57-64 (2015).
This work is being conducted in a diverse temperate forest of the Changbai Mountains in northeastern China. Following a spatially explicit and intensive soil coring campaign, we are utilizing DNA markers to identify all sampled tree root biomass to individual species and analyzing a suite of key soil and microbial parameters to better understand whole-forest processes. Key collaborators include Dali Guo, Jing Tian, and Jingyuan Wang.
Tian J, ML McCormack, J Wang, D Guo, X Zhang, G Yu. Linkages between the microbial metabolic functional diversity and soil organic matter fractions within a broad-leaved Korean pine forest in Changbai Mountain. European Journal of Soil Biology, 66: 57-64 (2015).
Measuring and modeling fine root dynamics in temperate forests
Project Goals: Using a multifaceted approach we aim to determine controls and constraints on fine root lifespan as well as identify consistent patterns of fine root lifespan across temperate tree species. The project contains many parts operating under three specific research areas which are highlighted below. This research combines field observations, physiological and ecological manipulations, laboratory experiments, and modeling in an effort to shed light on what has for decades remained a poorly understood, though critical, part of ecosystem functioning and biogeochemistry. This research is conducted primarily in collaboration with David Eissenstat. Erica Smithwick. and Tom Adams and was funded by a grant from the National Science Foundation (to D. Eissenstat) and the Department of Energy Graduate Research Environmental Fellowship (to M.L. McCormack).
1. Variation in fine root lifespan across a range of root traits and tree species. Using a common garden in central Pennsylvania, we are investigating how fine root lifespan varies across 12 temperate tree species. Importantly, these 12 species span a wide range of several root traits and life history traits. Furthermore, the species represent a diverse phylogeny and include three direct congeneric contrasts with three Acer species, two Quercus, and two Pinus species. The common garden plot is pictured above as the photograph expanded from the US map.
2. Estimating current and future fine root turnover at landscape scales. This study combines species-specific estimates of fine root turnover with known distributions of common temperate trees across the eastern half of the United States. Using this paired information we can estimate fine root turnover rates in forested areas. Our species-specific turnover rates are derived primarily from direct field observations of fine root lifespan while the tree distributions were obtained using the DISTRIB model developed by Louis Iverson and Anantha Prasad. The map above gives a coarse representation of fine root turnover across the landscape with warmer colors having slower turnover and cooler colors having faster turnover.
3. Climate and soil impacts on fine root lifespan. While differences between species are likely to account for a large portion of the variation in observed fine root lifespan, we have observed that climate and soil factors also impact fine root physiology and turnover. However, it has been difficult to identify which environmental factors have the strongest impacts on root lifespan and what qualitative effect (increased or decreased lifespan) each factor has. Here we will use a multi-site analysis eastern US spanning from Maine to Georgia to address these uncertainties. Each site is identified on the US map above.
McCormack ML, KP Gaines, MP Pastore, DM Eissenstat. Early season root production in relation to leaf production among six diverse temperate tree species. Plant and Soil, 389: 121-129 (2015).
McCormack ML, DM Eissenstat, EAH Smithwick. Sensitivity of four ecological models to adjustments in fine root turnover in temperate forests. Ecological Modelling, 297: 107-117 (2015).
Smithwick EAH, ML McCormack, G Sivandran, MS Lucash. Improving the representation of roots in terrestrial models. Ecological Modelling, 291: 193-204 (2014).
McCormack ML, TS Adams, EAH Smithwick, DM Eissenstat. Variability in root production and root turnover alter estimates of fine root turnover rate. Ecology 95: 2224-2235 (2014).
Adams TS, ML McCormack, DM Eissenstat. Foraging strategies in trees of different root morphology: the role of root lifespan. Tree Physiology 33: 940-948 (2013).
McCormack ML, DM Eissenstat, AM Prasad, EAH Smithwick. Regional scale patterns of fine root lifespan and turnover under current and future climate. Global Change Biology, 19: 1697-1708 (2013).
McCormack ML, TS Adams, EAH Smithwick, DM Eissenstat. Predicting fine root lifespan from plant functional traits in temperate trees. New Phytologist, 195: 823-831 (2012).
1. Variation in fine root lifespan across a range of root traits and tree species. Using a common garden in central Pennsylvania, we are investigating how fine root lifespan varies across 12 temperate tree species. Importantly, these 12 species span a wide range of several root traits and life history traits. Furthermore, the species represent a diverse phylogeny and include three direct congeneric contrasts with three Acer species, two Quercus, and two Pinus species. The common garden plot is pictured above as the photograph expanded from the US map.
2. Estimating current and future fine root turnover at landscape scales. This study combines species-specific estimates of fine root turnover with known distributions of common temperate trees across the eastern half of the United States. Using this paired information we can estimate fine root turnover rates in forested areas. Our species-specific turnover rates are derived primarily from direct field observations of fine root lifespan while the tree distributions were obtained using the DISTRIB model developed by Louis Iverson and Anantha Prasad. The map above gives a coarse representation of fine root turnover across the landscape with warmer colors having slower turnover and cooler colors having faster turnover.
3. Climate and soil impacts on fine root lifespan. While differences between species are likely to account for a large portion of the variation in observed fine root lifespan, we have observed that climate and soil factors also impact fine root physiology and turnover. However, it has been difficult to identify which environmental factors have the strongest impacts on root lifespan and what qualitative effect (increased or decreased lifespan) each factor has. Here we will use a multi-site analysis eastern US spanning from Maine to Georgia to address these uncertainties. Each site is identified on the US map above.
McCormack ML, KP Gaines, MP Pastore, DM Eissenstat. Early season root production in relation to leaf production among six diverse temperate tree species. Plant and Soil, 389: 121-129 (2015).
McCormack ML, DM Eissenstat, EAH Smithwick. Sensitivity of four ecological models to adjustments in fine root turnover in temperate forests. Ecological Modelling, 297: 107-117 (2015).
Smithwick EAH, ML McCormack, G Sivandran, MS Lucash. Improving the representation of roots in terrestrial models. Ecological Modelling, 291: 193-204 (2014).
McCormack ML, TS Adams, EAH Smithwick, DM Eissenstat. Variability in root production and root turnover alter estimates of fine root turnover rate. Ecology 95: 2224-2235 (2014).
Adams TS, ML McCormack, DM Eissenstat. Foraging strategies in trees of different root morphology: the role of root lifespan. Tree Physiology 33: 940-948 (2013).
McCormack ML, DM Eissenstat, AM Prasad, EAH Smithwick. Regional scale patterns of fine root lifespan and turnover under current and future climate. Global Change Biology, 19: 1697-1708 (2013).
McCormack ML, TS Adams, EAH Smithwick, DM Eissenstat. Predicting fine root lifespan from plant functional traits in temperate trees. New Phytologist, 195: 823-831 (2012).
The mysterious Cenococcum
Ectomycorrhizal fungi (EMF) are symbiotic fungi that associate with many of our forest tree species and are especially common in temperate and boreal regions. While receiving carbon from their plant host, EMF ostensibly mine the soil environment for nutrients to supply the plant. Cenococcum geophilum is one of the most commonly occurring species of EMF yet little is known about its physiology or ontogeny. While it is increasingly appreciated as a cryptic species complex, Cenococcum is often identified as a single species in field samples based on its characteristic black mantle and wiry black hairs. Collaborating with Christopher Fernandez and Seth Pritchard, we are studying field collected samples of Cenococcum and other EMF as well as analyzing a 12 year dataset of minirhizotron images to determine basic patterns of Cenococcum production, longevity, and vitality in an effort to better understand factors contributing to the apparent dominance of this fungus in many temperate forests.
McCormack ML, CW Fernandez, H Brooks, SG Pritchard. Production dynamics of Cenococcum geophilum in response to elevated CO2 and N fertilization. Fungal Ecology, 26: 11-19 (2017).
Fernandez CW, ML McCormack, JM Hill, SG Pritchard, RT Koide. On the persistence of Cenococcum geophilum and its implications for forest C and nutrient cycles. Soil Biology and Biochemistry 65: 141-143 (2013).
McCormack ML, CW Fernandez, H Brooks, SG Pritchard. Production dynamics of Cenococcum geophilum in response to elevated CO2 and N fertilization. Fungal Ecology, 26: 11-19 (2017).
Fernandez CW, ML McCormack, JM Hill, SG Pritchard, RT Koide. On the persistence of Cenococcum geophilum and its implications for forest C and nutrient cycles. Soil Biology and Biochemistry 65: 141-143 (2013).
More past research topics
Effect of free-air-CO2-enrichment (FACE) on fine root and mycorrhizal dynamics in a loblolly pine forest
Meier IC, SG Pritchard, ER Brzostek, ML McCormack, RP Phillips. Rhizosphere and hyphosphere differ in their impacts on C and N cycling in forests exposed to FACE. New Phytologist, 205: 1164-1174 (2015).
Pritchard SG, BN Taylor, ER Cooper, KV Beidler, AE Strand, ML McCormack, S Zhang. Long-term dynamics of mycorrhizal tips in a loblolly pine forest with FACE and fertilization. GCB, 20: 1313-1326 (2014).
McCormack ML, SG Pritchard, et al. Soil Fungi respond more strongly than fine roots to elevated CO2 in longleaf pine-wiregrass ecosystem. Ecosystems, 13: 901-916 (2010).
Pritchard SG, AE Strand, ML McCormack, MA Davis, and R Oren. Mycorrhizal and rhizomorph dynamics in a loblolly pine forest during five years of FACE. GCB, 14: 1252-1265 (2008).
Pritchard SG, AE Strand, ML McCormack, MA Davis, AC Finzi, RB Jackson, R Matamala, HH Rogers, and R Oren. Fine root dynamics in a loblolly pine forest are influenced by FACE. GCB, 14: 1-15 (2008).
Strand AE, SG Pritchard, ML McCormack, MA Davis, and R Oren. Irreconcilable differences: fine root lifespans and soil carbon persistence. Science, 319: 456-458 (2008).
Effect of Nickel on root dynamics of known hyperaccumulator Streptanthus polygaloides and non-hyperaccumulater Streptanthus insignus (2005)
Renewable Portfolio Standard: A Mindful Analysis of a Policy for Progress (Bachelor’s thesis, 2004-2005)
Meier IC, SG Pritchard, ER Brzostek, ML McCormack, RP Phillips. Rhizosphere and hyphosphere differ in their impacts on C and N cycling in forests exposed to FACE. New Phytologist, 205: 1164-1174 (2015).
Pritchard SG, BN Taylor, ER Cooper, KV Beidler, AE Strand, ML McCormack, S Zhang. Long-term dynamics of mycorrhizal tips in a loblolly pine forest with FACE and fertilization. GCB, 20: 1313-1326 (2014).
McCormack ML, SG Pritchard, et al. Soil Fungi respond more strongly than fine roots to elevated CO2 in longleaf pine-wiregrass ecosystem. Ecosystems, 13: 901-916 (2010).
Pritchard SG, AE Strand, ML McCormack, MA Davis, and R Oren. Mycorrhizal and rhizomorph dynamics in a loblolly pine forest during five years of FACE. GCB, 14: 1252-1265 (2008).
Pritchard SG, AE Strand, ML McCormack, MA Davis, AC Finzi, RB Jackson, R Matamala, HH Rogers, and R Oren. Fine root dynamics in a loblolly pine forest are influenced by FACE. GCB, 14: 1-15 (2008).
Strand AE, SG Pritchard, ML McCormack, MA Davis, and R Oren. Irreconcilable differences: fine root lifespans and soil carbon persistence. Science, 319: 456-458 (2008).
Effect of Nickel on root dynamics of known hyperaccumulator Streptanthus polygaloides and non-hyperaccumulater Streptanthus insignus (2005)
Renewable Portfolio Standard: A Mindful Analysis of a Policy for Progress (Bachelor’s thesis, 2004-2005)