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Weekly Highlights

MEMORANDUM

From: Gabrielle Boudreaux Bodin
Subject: Weekly Highlights, USGS National Wetlands Research Center, April 11, 2013

Departmental/Bureau News - Current

  • Influence of Hummocks on Tidal Freshwater Trees: USGS NWRC contractor Jamie Duberstein (Five Rivers Services, LLC) and USGS NWRC Research Ecologist Ken Krauss, along with three Clemson University professors, co-authored a paper published in the journal Wetlands, entitled Do hummocks provide a physiological advantage to even the most flood tolerant of tidal freshwater trees? The scientists wanted to know whether or not small elevation changes have an effect on the health of baldcypress, an extremely flood-tolerant tree found in tidal freshwater swamps. In wetlands, surface elevation changes can often be measured in centimeters, with hummocks and hollows forming a dominant landscape feature of forested wetland systems. The base elevation is referred to as the hollows, while hummocks are relatively small elevated islands within the hollows. Hummocks are typically 15-20 cm tall, range between 1 and 10 m2, and generally comprise 20-30% of the landscape in tidal freshwater swamps in the southeastern United States. More trees grow atop hummocks than in hollows, suggesting that microtopography might be an important consideration when restoring tidal swamps. Hummocks influence ecosystem function by affecting nutrient availability, rates of decomposition, and herbaceous plant species distributions. Based on sapflow data used to determine the health of trees, this study was unable to conclude that mature baldcypress gained any physiological benefits from growing on hummocks when sites were flooded. Future studies may reveal whether trees other than baldcypress are able to maintain normal transpiration (sapflow) rates during short-term tidal flooding events, on or off of hummocks. These data also provide a better understanding of why hummocks might collapse during periods of greater flood depths (or chronic saltwater intrusion) within the many hectares of managed tidal swamps in the Southeast. (Ken Krauss; Lafayette, La.; 337-266-8882)

  • Earth Day Celebrations: USGS NWRC contractor (Five Rivers Services, LLC) and Coastal Wetlands Planning, Protection and Restoration Act Media Specialist, Cole Ruckstuhl, along with NWRC and CWPPRA intern, Josh Cohen, will work an exhibit booth in the University of Louisiana at Lafayette's Earth Day Celebration. ULL’s Office of Sustainability, the School of Geosciences, and the Institute for Coastal Ecology and Engineering, are hosting this year's Earth Day celebration, Fête de la Terre, on April 19. The theme is Green Education-Green Jobs, an effort to link students to government agencies that provide green jobs. Following that event, on April 21, Susan Testroet-Bergeron, USGS NWRC contractor and CWPPRA Public Outreach Coordinator, will provide an exhibit during Louisiana Earth Day 2013, an educational observance in downtown Baton Rouge that is one of the Nation's largest Earth Day celebrations. The theme for this year's festival is “Be the Change You Want in the World.” Both exhibits will share information about NWRC and the CWPPRA program. (Cole Ruckstuhl; Lafayette, La.; 337-266-8542 and Susan Testroet-Bergeron; Lafayette, La.; 337-266-8623)

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