Abstract:

Plant parameters were sampled monthly at the Louisiana Universities Marine Consortium (LUMCON) saltmarsh mesocosm facility in Cocodrie, Louisiana. These twelve hydrologically-isolated, large (~3m diameter) mesocosms were planted with intact Spartina alterniflora and soil sections in January 2018. Each month from July to November 2019, 5 out of 25 possible central grids were randomly selected to be sampled within each marsh mesocosm. A 0.25m x 0.25 m quadrat was randomly placed within each grid and the following plant parameters were recorded: live stem density (stems/m2), median live stem height (cm; determined from measurements of 5 random stems per quadrat), new growth (stems < 10 cm) stem density (stems/m2), flower density (flowers/m2), and dead stem density (stems/m2). This dataset represents results for the four-month period after each mesocosm received one of 4 levels of oiling on 2019-07-08: Control (0.0 L/m2), Low (0.1 L/m2), Medium (0.5 L/m2), or High (3.0 L/m2). This is a continuation of dataset R6.x808.000:0035 (DOI: 10.7266/n7-08d3-ce43) that covers data during the June 2018–June 2019 pre-oiling period.

Suggested Citation:

Roberts, B.J., Rossi, R.. 2020. Plant parameters assessed from random quadrat sampling in marsh mesoscosms immediately after oiling: July-November 2019. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-md7w-at26

Purpose:

This work provides results of the impacts of oil exposure on basic plant parameters in all 12 marsh mesocosms during the first 4 months after initiation of a mesocosm oiling experiment that began on 2019-07-08.

Data Parameters and Units:

Year: year of sampling; Month-name: month of sampling (3 letter month abbreviation); Month-number: month of sampling (1= Jan, 2 = Feb, etc.); Date: date that sampling took place (MM/DD/YYYY); Mesocosm number: ID number assigned to marsh mesocosm that was sampled (1-12); Sampling grid: region of mesocosm sampled (1-25), with mesocosm being divided into 25 total grids (5 x 5); Oil treatment: Oiling level applied to mesocosm on 2019-07-08; Live stem density (stems/m2): density of live stems in plot; Live median stem height (cm): median height of 5 random live stems in plot; New growth (< 10cm) stem density (stems/m2): density of live stems less than 10cm in height (measurement of new growth); Flower density (flowers/m2): density of flowers in plot; Dead stem density (stems/m2): density of dead stems in plot.

Methods:

The sampling methods employed in this dataset are based on those detailed in Hill and Roberts (2017). Briefly, five out of 25 central grids were randomly selected to sample within each of 12, 3m diameter marsh mesocosms during each sampling month between July and November 2019. A 0.25m x 0.25m quadrat was randomly placed within each grid and several plant metrics were quantified, including the total number of live plant stems, the number of new growth plant stems (defined as live stems < 10cm), the median height (in cm) of 5 randomly selected live plant stems, the total number of flowers within the quadrat, and the total number of dead plant stems. All areal values were converted to units of number per square meter. The sampling took place during the first four months after the addition of oil to some of the mesocosms as part of large-scale oiling experiment initiated on 2019-07-08.

Provenance and Historical References:

Hill, T. D., & Roberts, B. J. (2017). Effects of seasonality and environmental gradients on Spartina alterniflora allometry and primary production. Ecology and Evolution 7 (22). doi:10.1002/ece3.3494

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