Dr. Heather McCarthy

EPSCoR Research Focus: 
Observatory Network
Assistant Professor
Department of Microbiology and Plant Biology
University of Oklahoma
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B.S. | Environmental Science | Oregan State University | 2000
Ph.D. | Ecology | Duke University | 2007
Research Interests: 

Oklahoma NSF EPSCoR Researchers: 
Establishing a Novel State-Wide Socio-Ecological Observatory

Broadly, research in Dr. McCarthy's lab follows from two main questions: How do trees and forests respond to environmental changes? And, conversely, How can they be managed to moderate environmental changes?

As humans exert greater influence on global cycles, it becomes increasingly important to resolve the effects of these changes on both natural and highly managed systems.  Dr. McCarthy's research uses physiological and ecosystem ecology to explore how tree and forest-scale water and carbon cycle processes respond to global change factors, including changes in water availability, extreme weather events, elevated atmospheric CO2, and urbanization. 

Her work on the Oklahoma NSF EPSCoR research project will aid in the establishment of a first-of-its-kind, statewide, socio-ecological observatory.

Other recent research projects include:

Carbon storage in forests with increased CO2 levels

Forested ecosystems are the dominant terrestrial sink for carbon, making their potential to slow the rise of atmospheric carbon dioxide (CO2) levels of great interest. Determining future carbon sinks requires accurate information on the current carbon storage capacity of forests, as well as forest responses to increased atmospheric CO2 against the background of a changing climate. For several decades studies have focused on aspects of the carbon cycle of trees, and more recently ecosystems, exposed to elevated CO2, finding on average that photosynthesis and growth are enhanced. Despite the attention given to this issue, much of the focus has been on broad averages that may not capture all of the variation inherent in a landscape with uneven nutrient and water availability. My research has focused on the spatial and temporal variation in CO2 response, building a quantitative framework allowing CO2-induced enhancement of growth or carbon storage to be considered in the context of the availability of other resources.
Tree function and ecosystem services in urban forests

As populations become more urbanized, an increasing number of people live in systems whose fundamental processes are shaped almost entirely by humans. These highly managed systems are of growing interest due to recognition that trees can have large impacts on their surroundings and may be useful for mitigating urban heat island effects, storm water runoff, atmospheric CO2 emissions and pollution, and energy expenditures. But, trees may also have environmental costs, such as high water use in water-limited regions. Urban ecosystems are not only interesting ecosystems in their own right, they also result in “common garden” scenarios in which unique assemblages of species can be studied under the same environmental conditions, and are “natural laboratories” of global change, as they already feature altered water supplies and increased CO2, temperature, nutrient supplies, and air pollutants. Thus, studying urban tree function can also give insight on future tree function, adaptability, and what competitive advantages may emerge as trees in different environments are exposed to climatic shifts. By quantifying tradeoffs between water use and carbon uptake, my research aims to understand how trees (frequently non-native) function in stressful environments, as well as improving the ability of humans to manage these systems in ways that maximize human benefits (such as mitigating pollution, energy usage and urban heat island effects).

Teaching Responsibilities: 
PBIO 6484: Plant Physiological Ecology
PBIO 3453: Principles of Plant Ecology
PBIO 3452: Methods in Plant Ecology
Research Assistants Funded by EPSCoR: 

Jonathan Giddens (Graduate Student)
Dept. of Microbiology and Plant Biology, University of Oklahoma 
Research Focus:  Obtaining field measurements, and analyzing and logging the data; training and supervising others in the field.
Email:  jongiddens@ou.edu

Key Publications: 

Access some of the publications below online at:

  • Avolio ML, Pataki DE, Pincetl S, Gillespie T, Jenerette GD, McCarthy HR. Understanding preferences for tree attributes: the relative effects of socio-economic and local environmental factors. Proceedings of the National Academy of Science, in review.
  • Ummenhofer CC, Xu H, Twine TE, Girvetz E, McCarthy HR, Chhetri N, Nicholas KA. How climate change affects extremes in maize and wheat yield in two cropping regions. Journal of Climate, in review.
  • Wang H, Zhao P, Zou LL, McCarthy HR, Zeng XP, Ni GY, Rao XQ. CO2 uptake of mature Acacia mangium plantation from sap flow measurements and stable carbon isotope discrimination. Biogeosciences, in review.
  • Liang X, Luo X, McCarthy HR. VIC+ for Arid Conditions: A Study of Biological and Hydrological Processes and Their Interactions in Soil-Plant-Atmosphere Continuum. Water Resources Research, in review.
  • Oishi AC, Palmroth S, Johnsen KH, McCarthy HR, Oren R. Effects of atmospheric [CO2], nitrogen availability and soil moisture on the spatial and temporal variation of forest soil CO2 flux. Global Change Biology, in review.
  • Ward EJ, Oren R, Bell DM, Clark JS, McCarthy HR, Kim H-S, Domec J-C (2013). The effects of long-term elevated CO2 and nitrogen fertilization on stomatal conductance estimated from scaled sap flux measurements at Duke FACE. Tree Physiology, 33, 135-151. Link
  • Battipaglia G, Saurer M, Cherubini P, Calfapietra C, McCarthy HR, Norby RJ, M. Cotrufo MF. (2013). Elevated CO2 increases tree-level intrinsic water use efficiency: insights from carbon and oxygen isotope analyses across three forest FACE sites. New Phytologist, 197, 544-554. Link
  • McCarthy HR, Luo Y, Wullschleger SD (2012). Integrating empirical-modeling approaches to improve understanding of terrestrial ecology processes. New Phytologist, 195, 523-525. Link
  • Novick KA, Katul GG, McCarthy HR, Oren R. (2012). Increased resin flow in mature pine trees growing under elevated CO2 and moderate soil fertility. Tree Physiology, 32, 752-763. Link
  • Litvak E, McCarthy HR, Pataki DE. (2012). Transpiration sensitivity of urban trees in a semi-arid climate is constrained by xylem vulnerability to cavitation. Tree Physiology, 32, 373-388. Link
  • Bijoor NS, McCarthy HR, Zhang D, Pataki DE. (2012). Water sources of urban trees in the Los Angeles metropolitan area. Urban Ecosystems, 15, 194-214. Link
  • McCarthy HR, Pataki, DE, Jenerette GD (2011). Plant water use efficiency as a metric of urban ecosystem services. Ecological Applications, 21, 3115-3127. Link
  • Hofmockel KS, Gallet-Budynek A, McCarthy HR, Currie WS, Jackson RB, Finzi AC (2011). Sources of increased N uptake in forest trees growing under elevated CO2: results of a large-scale 15N study. Global Change Biology, 17, 3338-3350. Link
  • Litvak E, McCarthy HR, Pataki DE (2011). Water relations of coast redwood planted in the semi-arid climate of southern California. Plant, Cell & Environment, 34, 1384-1400. Link
  • Pataki DE, McCarthy HR, Litvak E, Pincetl S. (2011). Transpiration of urban forests in the Los Angeles metropolitan area. Ecological Applications, 21, 661-677. Link
  • Drake JE, Gallet-Budynek A, Hofmockel KS, Bernhardt ES, Billings SA, Jackson RB, Johnsen KS, Lichter J, McCarthy HR, McCormack ML, Moore DJP, Oren R, Palmroth S, Phillips RP, Pippen JS, Pritchard SG,Treseder KK, Schlesinger WH, DeLucia EH, Finzi AC. (2011). Increases in the flux of carbon belowground stimulates nitrogen uptake and sustains the long-term enhancement of forest productivity under elevated CO2. Ecology Letters, 14, 349-357. Link
  • Domec J-C, Schäfer, K, Oren R, Kim H-S, McCarthy HR. (2010). Variable conductivity and embolism in roots and branches of four contrasting tree species and their impacts on whole-plant hydraulic performance under future atmospheric CO2 concentration. Tree Physiology, 30, 1001-1015. Link
  • Palmroth S, Katul GG, Hui D, McCarthy HR, Jackson RB, Oren R. (2010). Estimation of long-term basin-scale evapotranspiration from streamflow time series. Water Resources Research, 46, W10512, doi:10.1029/2009WR008838. Link
  • McCarthy HR, Pataki, DE (2010). Drivers of variability in water use of native and non-native urban trees in the greater Los Angeles area. Urban Ecosystems, 13, 393-414. Link
  • Way DA, LaDeau SL, McCarthy HR, Clark JS, Oren R, Finzi AC, Jackson RB (2010). Greater seed production in elevated CO2 is not accompanied by reduced seed quality in Pinus taeda L. Global Change Biology, 16, 1046-1056. Link
  • McCarthy HR, Oren R, Johnsen KH, Gallet-Budynek A, Pritchard SG, Cook CW, LaDeau SL, Jackson RB, Finzi AC (2010). Reassessment of plant carbon dynamics at the Duke free air CO2 enrichment site: interactions of atmospheric [CO2] with nitrogen and water availability over stand development. New Phytologist, 185, 514-528. Link
  • Song C, Katul G, Oren R, Band LE, Tague CL, Stoy PC, McCarthy HR (2009). Energy, water and carbon fluxes in a loblolly pine stand: results from uniform and gappy canopy models with comparisons to eddy flux data. Journal of Geophysical Research – Biogeosciences, 114, G04021, doi:10.1029/2009JG000951. Link
  • Juang J-Y, Katul GG, Siqueira MBS, Stoy PC, McCarthy HR (2008). Investigating a hierarchy of Eulerian closure models for scalar transfer inside forested canopies. Boundary-Layer Meteorology, 128, 1–32, doi: 10.1007/s10546-008-9273-2. Link
  • Stoy PC, Katul GG, Siqueira MBS, Juang J-Y, Novick KA, McCarthy HR, Oishi AC, Oren R (2008). Role of vegetation in determining carbon sequestration along ecological succession in the southeastern United States.  Global Change Biology, 14, 1409–1427. Link
  • McCarthy HR, Oren R, Finzi AC, Ellsworth DS, Kim H-S, Johnsen KH, Millar, B (2007). Temporal dynamics and spatial variability in the enhancement of canopy leaf area under elevated atmospheric CO2. Global Change Biology, 13, 2479-2497. Link
  • McCarthy HR, Oren R, Finzi AC, Johnsen KH  (2006). Canopy leaf area constrains [CO2]-induced enhancement of productivity and partitioning among aboveground carbon pools. Proceedings of the National Academy of Sciences, 103, 19356-19361. Link
  • Palmroth S, Oren R, McCarthy HR, Johnsen KH, Finzi AC, Butnor JR, Ryan MG, Schlesinger WH (2006). Aboveground sink strength in forests controls the allocation of carbon belowground and its CO2-induced enhancement. Proceedings of the National Academy of Sciences, 103, 19362-19367. Link
  • Stoy PC, Katul GG, Siqueira MBS, Juang J-Y, McCarthy HR, Oishi AC, Uebelherr JM, Kim H-S, Oren R (2006). Separating the effects of climate and vegetation on evapotranspiration along a successional chronosequence in the southeastern U.S. Global Change Biology, 12, 2115-2135. Link
  • McCarthy HR, Oren R, Kim H-S, Johnsen KH, Maier C, Pritchard SG, Davis MA (2006) Interaction of ice storms and management practices on current carbon sequestration in forests with potential mitigation under future CO2 atmosphere. Journal of Geophysical Research - Atmospheres, 111, D15103, doi: 10.1029/2005JD006428. Link
  • Siqueira MBS, Katul GG, Sampson DA, Stoy PC, Juang J-Y, McCarthy HR, and Oren R (2006) Multi-scale model intercomparisons of CO2 and H2O exchange rates in a maturing southeastern US pine forest. Global Change Biology, 12, 1189-1207. Link
  • Oren R, Hsieh C-I, Stoy P, Albertson J, McCarthy HR, Harrell P, Katul GG (2006) Estimating the uncertainty in annual net ecosystem carbon exchange: spatial variation in turbulent fluxes and sampling errors in eddy-covariance measurements. Global Change Biology, 12(5), 883-896. Link
  • Juang J-Y, Katul GG, Siqueira MBS, Stoy PC, Palmroth S, McCarthy HR, Kim H-S, Oren R (2006) Modeling nighttime ecosystem respiration from measured CO2 concentration and air temperature profiles using inverse methods. Journal of Geophysical Research - Atmospheres, 111, D08S05, doi:10.1029/2005JD005976. Link
  • Finzi AC, Moore DJP, DeLucia, EH, Lichter J, Hofmockel KS, Jackson RB, Kim H-S, McCarthy HR, Oren R, Pippen JS, Schlesinger WH (2006) Progressive N limitation of ecosystem processes under elevated CO2 in a warm-temperature forest. Ecology, 87(1), 15-25. Link
  • Norby RJ, DeLucia EH, Gielen B, Calfapietra C, Giardina CP, King JS, Ledford J, McCarthy HR, Moore DJP, Ceulemans R, De Angelis P, Finzi AC, Karnosky DF, Kubiske ME, Lukac M, Pregitzer KS, Scarascia-Mugnozza GE, Schlesinger WH, Oren R (2005) Forest response to elevated CO2 is conserved across a broad range of productivity. Proceedings of the National Academy of Sciences, 102, 18052-18056. Link
  • Stoy PC, Katul GG, Siqueira MBS, Juang J-Y, McCarthy HR, Kim H-S, Oishi AC, Oren R (2005) Variability in net ecosystem exchange from hourly to inter-annual time scales at adjacent pine and hardwood forests: a wavelet analysis. Tree Physiology, 25, 887-902. Link
  • Katul G, Oren R, McCarthy H, Novick K (2005) Plant hydraulic properties limit photosynthetic capacity and regeneration potential. Water and the Environment, 12, 115. Link
  • Palmroth S, Maier CA, McCarthy HR, Oishi AC, Kim H-K, Johnsen K, Katul GG, Oren R (2005) Contrasting responses to drought of forest floor CO2 efflux in a loblolly pine plantation and a nearby oak-hickory forest. Global Change Biology, 11, 421-434. Link
  • Oren R, Ellsworth DS, Johnsen KH, Phillips N, Ewers BE, Maier C, Schäfer KVR, McCarthy H, Hendrey G, McNulty SG, Katul GG (2001) Soil fertility limits carbon sequestration by forest ecosystems in a CO2- enriched atmosphere. Nature, 411, 469-472. Link

Publications (book chapters):  

  • Johnsen, KH, Keyser TL, Butnor JR, Gonzalez-Benecke CA, Kaczmarek DJ, Maier CA, McCarthy HR and Sun G. Forest productivity and carbon sequestration of forests in the southern United States, in Climate change adaptation, mitigation and management options. CRC Press, in press.
  • Katul GG, CG Williams, Siqueira M, Poggi D, Porporato A, McCarthy H, and Oren R (2006). Dispersal of Transgenic Conifer Pollen, in Landscapes, Genomics, and Transgenic Conifers, ed. Williams CG, Springer Series on Managing Forest Ecosystems, Vol. 9, Chapter 8, pp. 121-146. Link
Curriculum Vitae: