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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.

Impacts of fire frequency on plant-soil feedbacks in the Columbia Basin

Collaborators: Dr. Doug Schinneman (USGS), Dr. Susan McLroy (USGS). Funded by USGS and BLM

Sagebrush steppe occurs widely across the Western United States covering nearly 500,000 km2 across the western US and Canada. Much of the sagebrush steppe of the northern Columbia Basin of Washington is degraded and fragmented.  In addition, fire frequency has increased from between 50 to more than 300 years to less than 10 years.  Fire can contribute to changes in soil structure which can alter soil microbial communities and the processes they control, such as nutrient cycling.  These changes alter plant-soil feedbacks, and can transition the system into a new state comprised of a drastically different plant community that cannot sustain the native community of organisms that was once supported by sagebrush. With this study we set out to evaluate how fire recurrence in sagebrush ecosystems of the northern Columbia Basin affects soil structural and functional properties (i.e. enzyme activities, soil nutrient cycling) that are critical to plant communities.

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:

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

Graduate Students

Leslie Nichols portrait

Leslie Nichols – MS student

Leslie studies how fire impacts plant-soil relationships in the Sage Steppe ecosystem.

Abby McMurtry selfie

Abby McMurtry – MS student

Abby studies the vulnerability of deep soil carbon to decomposition.

Jenn Butt Portrait

Jenn Butt – MS student

Jenn studies how aboveground biodiversity in bioenergy cropping systems affects belowground ecosystem biodiversity and functioning.

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 WilsonPhD student

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

Sabrina with mountains in the background

Sabrina SchulerMS student

Sabrina studies interactions between the mycorrhizal community and native species in the Sage Steppe ecosystem.



Aubrion Churchfield – VIP student

Aubrion studies how DIRT treatments affect decomposition processes

Skylar Benson – VIP student

Skylar studies how DIRT treatments affect soil C in a variety of soil organic matter pools

Tori Tripoli – VIP student

Tori studies how fire and changes in plant communities affects organic matter and char contents in soils of the Sage Steppe ecosystem.

Lola Klamm – supported by HERC and the Boise Cascade Foundation

Lola studies how microbial functioning differs among switchgrass and big bluestem cultivars.

Ashley Leavell – supported by HERC

Ashley studies how fire and changes in plant communities affect soil properties in the Sage Steppe ecosystem.

Abigail Sasso – VIP student

Abigail studies how root architecture differs among switchgrass and big bluestem cultivars.


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

  • 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!