Environment, Projects

Modeling Belowground Biomass in a Texas Salt Marsh

About the Paper: 

I graduated from the University of Texas at Austin in the spring of 2022 with a B.S.A. in honors biology. As part of the honors degree, I wrote a thesis made up of original research about modeling the mass of plant matter underground in a Texas salt marsh. Modeling this underground plant mass, or belowground biomass, is important because it can determine the salt marsh’s ability to survive flooding due to sea level rise.

Although the topic sounds technical, I went great lengths to make my thesis accessible to everyone, so feel free to read it even if you have no background in ecology!

Taking a soil sample near Port Aransas, Texas.


Salt marshes, ecosystems dominated by grasses in areas subject to frequent tidal flooding, are threatened by sea level rise. Salt marshes can survive sea level rise through a process known as vertical accretion, where marshes create soil and increase their elevation. Accretion rates can be predicted by belowground biomass, the total mass of living plant matter in the soil. Thus, belowground biomass models can be used to monitor the health of these ecosystems. In this study, I created an exploratory belowground biomass model of a salt marsh in the coastal community of Port Aransas, Texas dominated by Spartina alterniflora and Distichlis spicata, two common marsh grasses. To create the model, measured 8 ecologically important parameters and used them to create a model to look for predictors of belowground biomass in the two grasses. For Spartina, stem length and gross primary productivity were the two most important predictors of belowground biomass. For Distichlis, aboveground biomass alone predicted most of the variation in belowground biomass. I then present the models as tools for conservation planners to identify areas of the marsh with low belowground biomass that are especially vulnerable to sea level rise.

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