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Marie-Anne de Graaff, Ph.D.

Dr. de Graaff and her daughter

Professor, Department of Biological Sciences

MS Biology Graduate Program Coordinator

Mailing Address:
Department of Biology
Boise State University
Boise, ID 83725-1515

Office Location:   Science Building, Room 209
Office Number:   208-426-1256
Fax Number: 208-426-1040

E-Mail Address:

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)

Research Interests

Collage of photos showing de Graaff's work and community outreach

Broadly our lab studies how changes in climate and land-use affect ecosystem processes that drive the global carbon cycle. We are especially interested in the question of how plant roots and soil microorganisms interact to affect soil carbon and nutrient dynamics.

Research projects

Grassy fieldAt 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.

Grassy landscape with field researchers

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 (BSU); 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 sagebrushestablishmentSage steppe

Collaborators: Marcelo Serpe (BSU); Leonora Bittleston (BSU) Funded by the ID 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

Map of Reynold's Creek

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)

Field research with soil

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: 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

PEOPLELab posing for a photoDr. de Graaff lab doing field work

Dr. de Graaff posing for photo while digging next to tree trunk

Marie-Anne de Graaff  PI of the lab



Toby Maxwell

Toby studies how legacy effects of hydroclimate impact resistance and resilience of ecosystems following a fire.

Graduate Students

Megan Kelly-Slatten portrait

Megan Kelly-SlattenPhD student

Megan studies how intra specific variation of root traits in switchgrass cultivars affects soil carbon stabilization.

Lucy Wilson Portrait

Luci WilsonMS student

Luci studies impacts of plant species diversity and biochar additions on restoration outcomes in the Sage Steppe ecosystem.

Arden Engel – MS student

Arden studies how the AMF community composition affects local adaptation and response to drought in sagebrush.

Ashley Leavell – MS student

Ashley studies how biochar addition may help sagebrush seedling establishment post-fire.


Abigail Sasso 

Abigail studies how root architecture differs among switchgrass and big bluestem cultivars and the implications for the carbon cycle.

Grace-Ann Myers

Grace Ann studies soil microbial influences on local adaptation in sagebrush.

Sami Kennel 

Sami studies soil microbial influences on local adaptation in sagebrush.

Micki Keiser (Highschool Teacher – Murdock Fellow)

Micki studies how native plant species diversity affects restoration in the sagebrush steppe.


*Denotes graduate student author; ** Denotes undergraduate student author

  • Pierson D, Lohse KA, Wieder WR, Patton NR, Facer J, de Graaff MA, Georgiou,K Seyfried MS, Flerchinger G, Will R (202x) Optimizing process-based models to predict current and future soil organic carbon stocks at high-resolution. Scientific Reports (in review).
  • Szymanski LM*, McMurtry A*, Dolui M*, de Graaff MA, Berhe AA, Mason JA, Marin-Spiotta E (202x) Vulnerability of ancient carbon in buried soils to microbial decomposition with landscape disturbance. Soil Biology & Biochemistry (in review).
  • Roser A*, Enterkine J, Requena-Mullor J, Boehm A, de Graaff MA, Clark P, Pierson F, Glenn N, Caughlin T (202x) UAS flight protocols to map vegetation are transferable between dryland sites across an elevational gradient. Ecosphere (in revision).
  • 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. Genes, Genomes, Genetics.
  • 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 (Online), 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.
  • 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.
  • Adkins J**, Jastrow JD, Morris GP, de Graaff M-A (2019) Effects of fertilization, plant species, genotypic diversity on soil carbon in biofuel cropping systems. Biomass and Bioenergy, 130, 105393
  • Bennett AE, Preedy K, Golubski A, Umbanhowar J, Borrett SR, Byrne L, Apostol K, Bever JD, Biederman L, Classen AT, Cuddington K, de Graaff M-A, Garrett KA, GrossL, Hastings A, Hoeksema JD, Hrynkiv V, Karst J, Kummel M, Lee CT, Liang C, Liao W, Mack K, Miller L, Ownley B, RojasC, Simms AL, Walsh VK, Warren M, Zhu J. (2019) Beyond the Black Box: Identifying mathematical tools for elucidating interactions in soils. Ecosphere, 10(7), e02799.
  • Dashti H*, Glenn NF, Mitchell JJ, Ilangakoon NT, Spaete LP, Qi Y, Ustin S, Flores A, de Graaff M-A (2019) Empirical Methods for Remote Sensing of Nitrogen in Drylands May Lead to Unreliable Interpretation of Ecosystem Function. IEEE Transactions on Geoscience and Remote Sensing, 57(6), 3993-4004.
  • de Graaff MA, Kardol P, van Diepen L, Throop H (2019) Effects of agricultural intensification on soil biodiversity and implications for ecosystem functioning: a meta-analysis. In Advances in Agronomy. Academic Press Inc.
  • Dierks J*, Denef K, van Diepen L, de Graaff M-A (2019) Cheatgrass-associated AMF community negatively affects sagebrush root production but not C transfer to the soil. Plant and Soil, 436, 381-396.
  • Pacioretty MT*, Martinez M*, Cinto Meija E*, Reinhardt K, Barber J, de Graaff M-A, Kahaware AY, Aho K (2018) Experimental exclusion of insectivorous predators results in no responses across multiple trophic levels in a water-limited, sagebrush-steppe ecosystem. Journal of Arid Environments, DOI: 10.1016/j.jaridenv.2018.09.011.
  • Djukic I, Kepfer-Rojas S, Kappel Schmidt I, Steenberg Larsen K, Beier C, Berg B, Verheyen K, TeaComposition (including de Graaff M-A) (2018) Early stage litter decomposition across biomes. Science of the Total Environment,
  • Campos X*, Germino M, de Graaff M-A (2017) Enhanced precipitation promotes decomposition and soil C stabilization in semiarid ecosystems, but seasonal timing of wetting matters. Plant and Soil 416, 427-436.
  • Kardol P, Throop HL, Adkins J**, de Graaff M-A (2016) A hierarchical framework for studying the role of biodiversity in soil food web processes and ecosystem services. Soil Biology & Biochemistry 102, 33-36.
  • Adkins J**, Jastrow JD, Morris G, Six J, de Graaff M-A (2016) Effects of switchgrass cultivars and intraspecific differences in root morphology on soil carbon stabilization. Geoderma 262, 147-154.
  • Morris GP, Hu Z, Grabowski PP, Borevitz JO, de Graaff M-A, Miller RM, Jastrow JD (2015) Genotypic diversity effects on biomass production in native perennial bioenergy cropping systems. Global Change Biology Bioenergy (DOI: 10.1111/gcbb.12309).
  • de Graaff M-A, Adkins J**., Kardol P, Throop HL (2015) A meta-analysis of soil biodiversity impacts on the carbon cycle. Soil 1, 257-271.
  • de Graaff M-A., Throop H.L., Verburg P.S.J., Arnone J.A., Campos X.* (2014) A synthesis of climate change and vegetation cover effects on biogeochemical cycling in shrub dominated drylands. Ecosystems 5, 931-945.
  • Smith A.P.*, Marin-Spiotta E., de Graaff M-A., Balser T.C. (2014) Microbial community structure varies across soil organic matter aggregate pools during tropical land cover change. Soil Biology & Biochemistry 77, 292-303.
  • De Graaff M-A., Jastrow J.D., Gillette S., Johns A.**, Wullschleger S.D.  (2014) Differential priming of soil carbon driven by soil depth and root impacts on carbon availability. Soil Biology & Biochemistry 69, 147-156.
  • De Graaff M-A., Six J., Jastrow J.D., Schadt C.W., Wullschleger S.D.  (2013) Variation in root architecture among switchgrass cultivars impacts root decomposition rates. Soil Biology & Biochemistry 58, 198-206.
  • De Graaff M-A., Schadt C.W., Six J., Schweitzer J.S., Rula K.**, Classen A.T. (2011) Elevated CO2 and plant species diversity interact to slow root decomposition. Soil Biology & Biochemistry, 43, 2347-2354.
  • De Graaff M-A., Castro H., Classen A.T., Garten C.T. Schadt C.W. (2010) Root exudates mediate plant residue decomposition rates by regulating the microbial community structure. New Phytologist, 188, 1055-1064.
  • De Graaff M-A., Six J., van Kessel C. (2009) Rhizodeposition-induced decomposition increases N availability to wild and cultivated wheat genotypes. Soil Biology & Biochemistry, 41, 1094-1103.
  • Hungate B.A., van Groenigen K.J., Six J., Jastrow J.D., Luo Y., de Graaff M-A., van Kessel C., Osenberg C.W. (2009) Assessing the effect of elevated CO2 on soil carbon: a comparison of four meta-analyses. Global Change Biology, 15, 2020-2034.
  • De Graaff M-A., Six J., van Kessel C. (2008) The impact of long-term elevated CO2 on C and N retention in stable SOM pools. Plant and Soil, 303, 311-321.
  • De Graaff M-A., Six J., van Kessel C. (2007) Elevated CO2 increases rhizodeposition and microbial immobilization of root-derived nitrogen. New Phytologist, 173, 778–786.
  • de Graaff M-A., van Groenigen K.J., Six J., Hungate B., van Kessel C. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a Meta-Analysis. Global Change Biology, 12, 1-15.
  • Van Kessel C., Boots B., de Graaff M-A., Six J. (2006) Soil C and N sequestration in a grassland following 10 years of Free Air CO2 Enrichment. Global Change Biology, 12, 1-13.
  • Van Groenigen K.J., Six J., Hungate B., de Graaff M-A., van Breemen N., van Kessel C. (2006) Element interactions limit soil carbon storage. Proceedings of the National Academy of Sciences, 103, 6571-6574.
  • De Graaff M-A., Six J., van Kessel C. (2006) Prolonged elevated atmospheric CO2 does not affect decomposition of plant material. Soil Biology & Biochemistry, 38, 187-190.
  • Van Groenigen, K.J., de Graaff M-A., Six J., Harris D., Kuikman P., van Kessel C. (2005) The impact of elevated [CO2] on soil C and N dynamics: a meta-analysis. In: Nösberger J, Long SP, Norby RJ, Stitt M, Hendrey GR, Blum H, eds. Managed Ecosystems and CO2 Case Studies, Processes and Perspectives. Berlin Heidelberg, Germany: Springer-Verlag, 373-388.
  • De Graaff M-A., Six J., Harris D., van Kessel C. (2004) Decomposition of soil and plant carbon from pasture systems after 9 years of exposure to elevated CO2: impact on C cycling and modeling. Global Change Biology, 10, 1922-1935.


  • General Biology II (BIOL 192)
  • Ecosystem Ecology (BIOL 497/ 597)
  • Conservation Biology (BIOL 422/ 522)
  • Global Change Biology (BIOL 197)
  • General Ecology (Biol 323)
  • Graduate seminar: “Plant-Soil Relations and Ecosystem Processes under Climate Change” (Biol 597)
  • Graduate seminar: “Global Climate Change and Solutions: ecological, social and economic perspectives” (Biol 597)
  • Graduate seminar: “Agricultural Challenges in the 21st Century: How to Feed 9 Billion People Without Destroying the Earth?” (Biol 597)

Prospective graduate students

I’m happy to receive applications for graduate school. If you like to apply, please write me a short letter outlining why you are interested to work in my lab, how your interests would contribute to the research (see descriptions above) in the ecosystem ecology lab and why you want to go to graduate school. Thanks for your interest!