Marie-Anne de Graaff, Ph.D.

Academic Degrees

• Postdoctoral Research Associate – Biosciences Division, Molecular Microbial Ecology Group, Oak Ridge National Laboratory (2008-2010)
• Ph.D. – Environmental Science, Wageningen University, the Netherlands (2007)
• M.Sc. – Nature conservation and development, Wageningen University, the Netherlands (2003)
• B.Sc. – Forestry and Nature Management, Wageningen University, the Netherlands (2001)

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Research Interests

Broadly, Marie-Anne de Graaff’s lab studies how changes in climate and land-use affect ecosystem processes that drive the global carbon cycle. de Graaff is especially interested in the question of how plant roots and soil microorganisms interact to affect soil carbon and nutrient dynamics.

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Research Projects

At the Root of Sustainable Bioenergy: Using Genetic Variation in Root Traits to Maximize Soil Carbon Sequestration and Biomass Yields

Collaborators: Julie Jastrow (ANL), Johan Six (UC-Davis), Geoff Morris (University of South Carolina). Funded by USDA-NIFA.

Land use change for bioenergy production can create substantial green house gas emissions through removal of standing vegetation and disturbance of soil carbon pools. With this project we assess: (1) whether shifting C₃-dominated nonnative perennial grasslands to C₄-dominated native perennial grasslands repay the carbon debt of land-use change by increasing soil carbon sequestration; (2) whether increased variation in root traits in species and cultivar mixes of native perennial grasses will enhance biomass production, soil carbon storage and the efficiency of nitrogen (N) cycling (i.e., decrease N losses); and (3) whether energy gain resulting from an increase in soil carbon storage and yield, along with a decrease in nutrient inputs and losses in low-input diverse mixtures of perennial grasses, is sufficient to offset energy gain from relatively greater biomass production in high input monocultures of perennial grasses.

Litter Quality Controls on the Temperature Sensitivity of Litter and Soil Organic Carbon Decomposition

Collaborators: Sindhu Jagadamma (UTK), Melanie Mayes  (ORNL). Funded by DOE.

It is uncertain which factors control the temperature sensitivity of litter decomposition. This study aims to examine how decomposition-induced changes in the quantity and quality of litter through time affect the temperature kinetics of decomposition processes.

Vulnerability of Carbon in Buried Soils to Climate Change and Landscape Disturbance

Collaborators: Dr. Erika Marin Spiotta (UW-Madison), Dr. Asmeret Berhe (UC-Merced), Dr. Joe Mason (UW-Madison). Funded by NSF Geobiology and Low Temperature Geochemistry.

This project will test the potential for deep buried soil organic matter to become a carbon source in response to changes in climate or land use that affect the connectivity of buried soils to the atmosphere. The research aims to understand (1) how soil burial contributes to the persistence of carbon in the form of soil organic matter and (2) whether exposure to surface conditions can trigger the decomposition of ancient carbon. The proposed study site is located in the U.S. Great Plains, where climate-driven loess deposition during the late Pleistocene and Holocene resulted in sequences of buried soils in thick loess deposits. The vulnerability of ancient organic matter to changing environmental conditions will be measured in two ways. First, changes in organic matter age, composition and bioavailability will be quantified along eroding and depositional field toposequences, where the paleosol exists at varying degrees of isolation from the modern landscape surface. Second, laboratory manipulations will measure the effects of carbon substrates, nitrogen availability, and microbial composition on ancient organic matter decomposition and mobilization in gaseous and dissolved forms. This study combines a geomorphic approach drawing from paleoclimatic reconstructions with advanced geochemical, spectroscopic and metagenomic techniques to generate new knowledge on environmental controls on carbon biogeochemistry.

Effects of Plant Species Diversity and Soil Biochar Amendments on Reestablishment and Performance of Native Sage Steppe Species

Collaborators: Marcelo Serpe (Boise State); Francis Kilkenny (Forest Service). Funded by the Forest Service.

Disturbance of native plant communities by invasive non-native plant species leads to reduced plant diversity, ecosystem function, and ecosystem services. In the intermountain west of North America, invasion of the winter annual cheatgrass (Bromus tectorum) has significantly altered the native Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) ecosystem. Restoring this ecosystem has proven difficult, largely due to the fact that not only the plant community has changed, but also the abiotic and biotic environment in which it resides. Thus, soil physical, chemical and biological properties need to be restored to attain successful restoration of native sage steppe plant communities. With this project, we aim to evaluate how increasing plant species diversity and amending soils with biochar affects the success of restoration treatments.

Changes in Mycorrhizal Communities in Sage-Steppe Ecosystems, and Consequences for Sagebrush Establishment

Collaborators: Marcelo Serpe (Boise State); Leonora Bittleston (Boise State). Funded by the Idaho National Guard

Sagebrush is an obligate mycorrhizal species. Cheatgrass invasion may reduce mycorrhizal abundance and change their communities, thereby complicating sagebrush restoration success. With this study we aim to investigate how arbuscular mycorrhizal fungi (AMF) communities and abundance differ between sagebrush and cheatgrass dominated ecosystems, and how invasion by cheatgrass affects plant performance and carbon allocation to AMF in sagebrush seedlings.

Pre-fire Hydroclimate and Plant-Community Composition Influence Post-Fire Soil Resource Availability and Resistance and Resilience in the Sagebrush Steppe

Collaborators: Dr. Matt Germino (USGS). Funded by NSF.

The exotic-annual grass and fire cycle is degrading ecosystem structure and function across millions of acres of semiarid landscapes in the Western US, and our understanding of the factors that impact native plant community recovery following fire remains limited. This study addresses several key knowledge gaps by experimentally separating pre-fire hydroclimate, plant community composition, and soil depth, and testing for their control over post-fire recovery. With this study we ask (1) how legacy effects of hydroclimate and community composition impact soil resource availability after fire, and (2) how differences in soil water and nutrient availability affect resistance to invasion and resilience of desirable plant communities following wildfire. This work leverages a 25-year manipulative ecohydrological experiment in the sagebrush-steppe of Eastern Idaho, that burned in a 2019 megafire, to identify mechanisms that govern resistance and resilience in the sagebrush steppe. Our results are based on pre- and post-fire plant community surveys, demographic measurements, monitoring of soil nitrogen and moisture content, and stable isotope tracer studies of nitrogen and deuterium.

Reynold’s Creek Critical Zone Observatory

Funded by NSF.

Reynolds Creek Critical Zone Observatory (RC CZO) is focused on the quantification of soil carbon and the critical zone processes governing it. Most of the world’s terrestrial carbon is found in the critical zone, where it is predominantly stored as soil carbon and sensitive to climate change and land management. Despite its importance, soil carbon remains a large source of uncertainty in both carbon cycling and global climate models. The RC CZO will address the grand challenges of improving prediction of soil carbon storage and flux from the pedon to landscape scale.

Detrital Input and Removal Treatment experiment (Desert-DIRT)

Despite the critical role played by litter in the global carbon cycle, and in the Earth’s climate system, its control on soil organic matter dynamics remains poorly understood. The DIRT (Detrital Input and Removal Treatments: dirtnet.wordpress.com) experiments were started in 1956 at the University of Wisconsin Arboretum by Dr. Francis Hole, a soil scientist who wanted to examine the effects of changing litter inputs on soil organic matter dynamics. This launched the international DIRT network which aims to assess how rates and sources of plant litter inputs control the long-term stability, accumulation, and chemical nature of soil organic matter in ecosystems over decadal time scales. Originally, the majority of DIRT sites in the US were established in mesic forests. To increase the diversity of ecosystems included in the network, I established a desert (D-) DIRT experiment in Idaho in 2013, at the Reynold’s Creek Experimental Watershed (RCEW). A sister D-DIRT site is located in the Santa Rita Experimental Range, AZ (in collaboration with ASU). For more information on DIRT and to find out how you can collaborate visit: The Detrital Input and Removal Experiment (DIRT) network.

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Students

Graduate students

• Yas Jafari, Ph.D.
• Abigail Sasso, MS student
• Naomi Shapiro, MS student

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Recent Publications

*Denotes graduate student author
** Denotes undergraduate student author

• Belnap J, Throop H, de Graaff MA (202x) Location, location, location: How spatial heterogeneity in plant litter accumulation affects carbon fluxes in dryland ecosystem. In review-PNAS.
• Lu Y, Eisenhauer N, Patoine G, Chen Y, Heintz-Buschart A, Küsel K, Wegner C-E, Buscot F, Liu X, Araujo ASF, Frey B, Maestre FT, Vadeboncoeur M, van den Brink L, Ponette Q, Didion M, Wohlfahrt G, Gaxiola A, Branquinho C, Meesenburg H, Fukuzawa K, Adair C, Andrić A, Barna M, Bei Q, Bruelheide H, Caliman A, Canessa R, Carbognani M, Gatti RC, Chen C, Christiansen CT, Danger M, Davydov EA, de Graaff MA, Delire C, Di Cecco V, Di Martino D, Djukic I, Drollinger S, Enoki T, Fekete I, Fransson P, Freitag M, Frenzel M, Gavilán R, Glatzel S, Glushkova M, Gonzalez G, Gripp AR, Haase P, Hamer U, Hishi T,  Hiura T, Hornung E, Hoshizaki K, Jäger H, Jiménez J-J, Kelly-Slatten MJ, Kepfer-Rojas S, Kotroczó Z, Kriiska K, Kurokawa H, Lajtha K, Loehr J, Löfgren F, Maire V, Martins R, Maunoury-Danger F, Melece I, Ochoa V, Ostonen I, Paquette A, Parker WC, Peri PB, Peters R, Petraglia A, Petřík P, Pușcaș M, Rebmann C, Rillig MC, Schaub M, Schmidt A, Seeber J, Serrano HC, Sousa AI, Stefan S, Stefanski A, Tomaselli M, Tóth Z, Trevathan-Tackett SM, Trogisch S, Turtureanu PD, Ursu TM, Venn SE, Verstraeten A, Vijayanathan J, Vujanović D, Wagner M, Weih M, Zehetner F, Guerra CA (202x). Landscape effects on global soil pathogenic fungal diversity across spatial scales. In review – Nature.
• Maxwell M, Germino M, de Graaff MA (202x) High pre-fire sagebrush cover enriches post-fire soil inorganic nitrogen and diminishes resistance to invasive annual plants in the burned sagebrush steppe. In revision – Ecosystems. 
• Malhotra A, Moore JAM, Weintraub-Leff S, Georgiou K, Berhe AA, Billings SA, de Graaff MA, Fraterrigo JM, Grandy SA, Kyker-Snowman E, Lu M, Meier C, Pierson D, Tumber-Dávila SJ, Lajtha K, Wiede WR, Jackson RB (2025). Contrasting continental scale covariation in soil and root carbon in grasslands and forests. Communications Earth & Environment, 6(1), 497.
• Richter DD, Gaillardet J, Brantley SL, Schlesinger WH, Amundson RG, Bales R, Billings SA, Binkley D, Brecheisen ZS, de Graaff MA, Calvo-Alvarado J, Cassar N, Clark JS, Eppes MC, Fergusson TA, Handelsman J, Hartemink AE, Jobbagy E, Krishnaswamy J, Kumar P, Li W, Lohse K, Markewiitz D, McDowell WH, Oh N, Reinfelder YF, Richardson CJ, Richardson JB, Schroeder PA, Seok H, Siebe CD, Thompson A, Whitlock CL, Wall DH (2024) The earth sciences are the model sciences for the Anthropocene. Perspectives of Earth and Space Scientists. 5(1), e2024CN000237.
• Engel A*, Simler-Williamson A, Ravenscraft A, Bittleston L, de Graaff MA (2024). Interactive effects of fungal community structure and soil moisture on Wyoming big sagebrush performance. Plant and Soil, 1-23.
• Katz S*, Maxwell T, de Graaff MA, Germino M (2024) Invasion of perennial sagebrush steppe by shallow-rooted exotic cheatgrass reduces stable forms of soil carbon in a warmer but not cooler ecoregion. Environmental Research Communication, 7 (3) https://doi.org/10.1088/2515-7620/adb93f.
• McMurtry AR*, Kasmerchak CS*, Vaughan EA*, Dolui M*, Szymanski LM*, Mueller CW, Pett-Ridge J, Mason JA, Marín-Spiotta E, de Graaff MA (2024) Getting at the root of the problem: Disentangling interactions between modern root inputs, microbial activity, and carbon destabilization in buried paleosols. Soil Biology and Biochemistry, 198, 109549.
• Lazarus B, Germino M, de Graaff MA (2024) Nontarget effects of pre-emergent herbicides and a bioherbicide on soil resources, processes, and communities. Restoration Ecology, 32(5), e14140, https://doi.org/10.1111/rec.14140.
• Kelly-Slatten M*, Stewart C, Tfaily M, Jastrow JD, Sasso A**, de Graaff MA (2023) Root traits of perennial C4 grasses contribute to cultivar variations in soil chemistry and species patterns in particulate and mineral-associated carbon pool formation. Global Change Biology – Bioenergy, https://doi.org/10.1111/gcbb.13041.
• Melton A, Child A, Beard Jr. R, Dumaguit CD*, Forbey J, Germino MJ, de Graaff MA, Kliskey A, Leitch I, Martinez M, Novak S, Pellicer J, Richardson B, Self D, Serpe M, Buerki S (2022) A haploid pseudo-chromosome genome for a keystone sagebrush species of western North American rangelands. G3, 12, 122.
• Pierson D, Lohse KA, Wieder WR, Patton NR, Facer J, de Graaff MA, Georgiou,K Seyfried MS, Flerchinger G, Will R (2022) Optimizing process-based models to predict current and future soil organic carbon stocks at high-resolution. Scientific Reports, 12, 10824.
• Roser A*, Enterkine J, Requena-Mullor J, Boehm A, de Graaff MA, Clark P, Pierson F, Glenn N, Caughlin T (2022) UAS flight protocols to map vegetation are transferable between dryland sites across an elevational gradient. Ecosphere 13, e4330.
• Kwon T, Shibata H, Kepfer-Rojas S, Schmidt IK, Larsen KS, Beier C, Berg B, Verheyen K, Lamarque JF, Hagedorn F, Eisenhauer N, Tea Composition Initiative (including de Graaff MA) (2021) Effects of climate and atmospheric nitrogen deposition on early to mid-term stage litter decomposition across biomes. Frontiers in Forests and Global Change, p.90.
• Jansson C, Faiola C, Wingler A, Xin-Guang Z, Kravchenko A, de Graaff MA, Ogden A, Handakumbura PP, Werner C, Beckles M (2021). Crops for Carbon Farming. Frontiers in Plant Science, doi: 10.3389/fpls.2021.636709.
• Nichols L*, Schinneman DJ, Mclroy SK, de Graaff MA (2021) Fire frequency impacts soil properties and processes in sagebrush steppe ecosystems of the Columbia Basin. Applied Soil Ecology, 165, 103967.
• Wieder WR, Pierson D, Earl SR, Lajtha K, Baer S, Ballantyne F, Berhe A, Billings S, Brigham LM, Chacon SS, Fraterrigo J, Frey SD, Georgiou K, de Graaff  MA, Grandy AS, Hartman MD, Hobbie SE, Johnson C, Kaye J, Snowman E, Litvak ME, Mack MC, Malhotra A, Moore JAM, Nadelhoffer K, Rasmussen C, Silver WL, Sulman BN, Walker S, Weintraub S (2021) SOils DAta Harmonization database (SoDaH): an open-source synthesis of soil data from research networks ver 1. Earth System Science Data, 13(LLNL-JRNL-821943.
• Dashti H*, Pandit K, Glenn NF, Shinneman DJ, Flerchinger GN, Hudak AA, de Graaf MA, Flores A, Ustin S, Ilangakoon N, Fellows AW (2021) Performance of the Ecosystem Demography model (EDv2.2) in simulating gross primary production capacity and activity along an elevation gradient in a dryland study area – Agricultural and Forest Meteorology, 297, 108270-1 – 108270-10. https://dx.doi.org/10.1016/j.agrformet.2020.108270. 
• Shinneman DJ, McIlroy SK, de Graaff MA (2020) Disentangling the effects of multiple fires on spatially interspersed sagebrush (Artemisia spp.) communities. Journal of Vegetation Science, 32(1), e12937.
• Billings AS, Lajtha K, Malhotra A, Berhe AA, de Graaff MA, Earl S, Fraterrigo J, Georgiou K, Grandy S, Hobbie SE, Moore J, Nadelhoffer K, Pierson D, Rasmussen C, Silver W, Sulman B, Weintraub S, Wieder W (2020) Soil organic carbon is not just for soil scientists: Measurement recommendations for diverse practitioners. Ecological Applications. https://doi.org/10.1002/eap.2290