Research

The Tumber-Dávila Lab research program investigates global environmental change effects on terrestrial ecosystems, plant functional traits, and subsequent consequences for global carbon cycling. With a focus on terrestrial ecosystem ecology, our unique, interdisciplinary, approach spans regional and global scale experiments, syntheses, and modeling. The lab's research program addresses two pressing knowledge gaps in our understanding of how plants influence the global carbon cycle: 1) the above- to belowground allometry of plants, their carbon cycle implications, and their interactions with the environment, and 2) the future trajectory of forest carbon. Additionally, through our scholarship and service, we foster diversity, equity, inclusion, justice, and belonging (DEIJB) in STEM and in the academy.

Keywords: Plant Root Systems, Terrestrial Ecosystems, Long-Term Ecological Research (LTER), Forest Ecology, Carbon, Allometry, Carbon Sequestration, Forest Carbon, JDEI Scholarship

Forest Carbon Futures in New England

Estimating risk to forest carbon due to ecological disturbance
This project is the focus of my postdoc as a member of Jonathan Thompson’s Landscape Ecology Lab and as part of the Harvest Forest Long Term Ecological Research (LTER) program. I work with the lab's existing landscape modeling framework and several large datasets to examine long-term, broad-scale impacts of land use, climate change, invasive insects, and their interactions. I will be quantifying opportunities and risks associated with the use of forests in climate change mitigation. The research will build on previous work done in the Thompson Lab, especially the Massachusetts Decarbonization Land Sector Report.
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Root systems of individual plants

Which biotic and abiotic factors most influence the depth and width of coarse root systems globally?
Plant roots act as the plumbing networks that move water and nutrients from belowground upward, and move carbon from the near-surface downward. This biotic plumbing system plays a major role in the terrestrial carbon, hydrologic, and nutrient cycles. To understand the depth and distribution of plant root systems, we have expanded the Root Systems of Individual Plants Database (RSIP) to ~6000 observations. The maximum rooting extents of individual plants scales primarily allometrically with plant height and width, and are secondly affected by temperature seasonality and water availability. The RSIP Manuscript has been submitted.
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Above- & Below-Ground Volumetric Allometry

How does plant volume scale above and below-ground?
The allometric scaling of plant biomass has been well studied and recorded globally. For example, Falster et al. (2015) created the Biomass and Allometry Database (BAAD)  recording the biomass of over 21,000 plants worldwide. However, the volume taken up by plants has not been equally observed. Knowing the space taken-up by plants is critical, as the rhizospere, volume of soil dominated by roots, is the most active layer belowground, and influences many terrestrial processes. Using the Wurzelaltas plant profiles (Kutchera et al., 1960-2009); we have created measurements of plant volume across three dimensions: 1) plant tissue volume and length, 2) system volume, 3) sphere of influence (i.e. rhizospere or canopy volume). To make these measurements, we have adapted the  RIA for  ImageJ package, created by Gillaume Lobet,  edited for our study by Frankie Liu. The analyses are undergoing and the manuscript is in prep (submission expected by Fall, 2019).
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The depths of resource uptake by co-OCCURRING tree SPECieS

Do co-occuring tree species stratify the depths at which they take-up critical nutrients such as water and nitrogen?
It is well known that forest species stratify their growth in the canopy, leading to separate ecological niches across tree species (Canham et al., 2006).  Root systems similarly compete for space belowground, but these dynamics are less understood (Cadotte et al., 2011). In this study, we aim to understand the depths that plants acquire their most vital belowground resources, water and nitrogen. Furthermore, we analyze the relationship between the depths of resource acquisition and the vertical plant root system distribution. We will do this by quantifying the natural abundance of soil and plant δ15N and δD for three primary temperate forest species (Pinus strobus, Acer rubrum, and Quercus rubra), and their vertical root biomass distribution. This study is taking place at the Thompson Farm Flux tower site in Durham, NH during summer 2019. 
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Operational Language Inclusivity in EEB & STEM

How is the language we speak and the terms we use affect inclusivity in our fields?
I am an active member of the EEB Language Project, a collaborative seeking to understand the impact that language has on the inclusivity in the fields of EEB. In 2023 we published a commentary in the journal TREE, discussing the ways that scientific language can harm members of our community. Currently, we are working on a manuscript that discusses the results of our IRB approved survey where more than 1,000 EEB community members discussed their relationship with language, and gathered specific terminology that community members believed should be revisited.
 
With colleagues across STEM fields and various US institutions, I am collaborating on research regarding operational linguistic inclusion in the sciences. Our goal is to revisit the use of English as the dominant language in science, thinking about the ways to reduce linguistic injustices of knowledge, both within scientific communities and the broader society. We approach our work with an understanding that humans have internalized stigmatizations about stylistic variations in language (not just the language itself), and much of that is rooted in colonialism and the hierarchical nature of our society.
Figure 1 from Cheng et al., 2023
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other projects

  • Accounting for carbon flux to mycorrhizal fungi may resolve discrepancies in forest carbon budgets (submitted, 2019)
  • Mapping the root distribution of Southern Sierra Nevada tree species and their resilience towards drought-induced tree mortality.
  • Predicting maximum rooting depth using climatic water deficit as a proxy for plant adaptations towards drought stress.
  • Linking soil carbon and root traits with the International Soil Carbon Network (ISCN).​
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Current and past collaborators

Jonathan Thompson
PostDoc Advisor
Harvard Forest
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Rob Jackson
PhD Advisor
Professor at Stanford University

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Andrew Ouimette
Collaborator
Research Scientist at The University of New Hampshire
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Avni Malhotra
Collaborator
Researcher at Stanford University & University of Zurich
H. Jochen Schenk
PhD Committee Member
Professor at California State, Fullterton
​Alexandra Konings
phd Committee member
​Assistant Professor at Stanford University
Scott Fendorf
phd Committee member
Professor at Stanford University
Kabir Peay
Doctoral Defense chair
Professor at Stanford University
​
Enzai Du
Collaborator
Faculty of Geographical Science, Beijing Normal University
Mingzhen Lu
Collaborator
Postdoctoral Fellow at Santa Fe inst.
Matthew A. Vadeboncoeur
Collaborator
Research Scientist at The University of New Hampshire
Benjamin Stocker
Collaborator
Assistant Professor at ETH ​Zürich
Harmony Lu
Research Assistant
Former Jackson Lab Manager


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Colin Finnegan
Research assistant
​Jackson Lab Manager



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Frankie Liu
Research assistant
​Consulting Engineer at Google


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Metta Nicholson
Research assistant
​Jackson Lab Manager



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Undergraduate Technicians

Ben Baraga
Pomona College '24
Madeleine  Torio Salem​
Stanford Symbolic Systems '24
Maegan Beckage
U. of Vermont  '24
Sarah Arriaga
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Stanford Biology '22
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​Agustin Leon-Saenz
Harvard College '25
Bear Kim
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Stanford Earth Systems '21
Cher Pelesia Nomura
Stanford Earth Systems '22
Lydia Marie Villa
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Stanford Biology '22
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Vanessa Yarelli Rodriguez
Stanford Biology '23
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Selected Publications

  • Ouimette AP, Ollinger SV, Lepine LC, Stephens RB, Rowe RJ, Vadeboncoeur MA, Tumber-Dávila SJ, Hobbie EA. Accounting for carbon flux to mycorrhizal fungi may resolve discrepancies in forest carbon budgets. Ecosystems. 2019 Sep 16:1-5.                                                                       
  • Tumber‐Dávila SJ, Malhotra A. Fast plants in deep water: introducing the whole‐soil column perspective. New Phytologist. 2020 Jan;225(1):7-9.
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  • ​Stocker B, Tumber-Dávila SJ, Konings AG, Anderson MB, Hain C, Jackson RB. Global distribution of the rooting zone water storage capacity reflects plant adaptation to the environment. bioRxiv preprint doi: https://doi.org/10.1101/2021.09.17.460332 (In review) 
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Highlighted Research Talks and Presentations

  • Invited Talk, Soil and Environmental Biogeochemistry Laboratory                                                                                                         Stanford, CA, May 2020                                                                           
  • Oral Presentation, The size and shape of global plant root systems                                                                                       American Geophysical Union Fall Meeting, San Francisco, CA, Dec 2019
  • Poster Presentation, The depths of the terrestrial plumbing network:  maximum rooting depth of ecosystem-scale and individual-plant profiles                                                                                                                                                                  American Geophysical Union Fall Meeting, San Francisco, CA, Dec 2018
  • Workshop Attendee & Presenter, Global-Scale Root Trait and Soil Carbon Linkages Workshop                                                Oak Ridge, TN, Aug 2018​​
  •  American Geophysical Union Fall Meeting, New Orleans, LA                                                                 Dec 2017
  •  ISCN Data Hackathon/All-Hands Meeting, New Orleans, LA                                                                  Dec 2017
  •  Southern Sierra Critical Zone Observatory Annual Meeting, Shaver Lake, CA                                     Aug 2017
  • AGU-SEG Hydrogeophysics Workshop, Stanford, CA                                                                               Jul 2017
  • American Geophysical Union Fall Meeting, San Francisco, CA                                                                Dec 2016
  • American Geophysical Union Fall Meeting, San Francisco, CA                                                                Dec 2014
  •  Stanford Summer Research Conference, Stanford, CA                                                                             Aug 2014
  •  McNair Research Symposium, Seattle, WA                                                                                                May 2014
  • COLSA Undergraduate Research Conference, Durham, NH                                                                     Apr 2014
  •  Ivy Plus Symposium, Cambridge, MA                                                                                                           Mar 2014
  • The 50th Annual Hubbard Brook Cooperators' Meeting, North Woodstock, NH                                        Jul 2013
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