Influence of Sediment Exposure and Water Depth on Torpedograss Invasion of Lake Okeechobee, Florida

Use of this dissertation is restricted to the UNT Community. Off-campus users must log in to read.

Description

Torpedograss (Panicum repens) was first observed in Lake Okeechobee in the 1970s and appears to have displaced an estimated 6,400 ha of native plants, such as spikerush (Eleocharis cellulosa), where inundation depths are often less than 50 cm. Two series of studies evaluated substrate exposure and water depth influences on torpedograss establishment and competitiveness. Results revealed that fragments remain buoyant for extended periods and so facilitate dispersal. Once anchored to exposed substrate fragments can readily root and establish. Subsequently, torpedograss thrives when subjected to inundations to 75 cm and survives prolonged exposure to depths greater than 1 m. These findings ... continued below

Creation Information

Smith, Dian H. December 2006.

Context

This dissertation is part of the collection entitled: UNT Theses and Dissertations and was provided by UNT Libraries to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 140 times . More information about this dissertation can be viewed below.

Who

People and organizations associated with either the creation of this dissertation or its content.

Chairs

Committee Members

Publisher

Rights Holder

For guidance see Citations, Rights, Re-Use.

  • Smith, Dian H.

Provided By

UNT Libraries

With locations on the Denton campus of the University of North Texas and one in Dallas, UNT Libraries serves the school and the community by providing access to physical and online collections; The Portal to Texas History and UNT Digital Libraries; academic research, and much, much more.

Contact Us

What

Descriptive information to help identify this dissertation. Follow the links below to find similar items on the Digital Library.

Description

Torpedograss (Panicum repens) was first observed in Lake Okeechobee in the 1970s and appears to have displaced an estimated 6,400 ha of native plants, such as spikerush (Eleocharis cellulosa), where inundation depths are often less than 50 cm. Two series of studies evaluated substrate exposure and water depth influences on torpedograss establishment and competitiveness. Results revealed that fragments remain buoyant for extended periods and so facilitate dispersal. Once anchored to exposed substrate fragments can readily root and establish. Subsequently, torpedograss thrives when subjected to inundations to 75 cm and survives prolonged exposure to depths greater than 1 m. These findings suggest that fluctuating water levels contribute to torpedograss dispersal and colonization patterns and that low water levels increase marsh area susceptible to invasion. The competition study found that spikerush grown in monoculture produces significantly more biomass when continually inundated to shallow depths (10 to 20 cm) than when subjected to drier conditions (-25 cm) or greater inundations (80 cm). In contrast, torpedograss establishes more readily on exposed substrate (-25 to 0 cm) compared to inundate substrates. During the first growing season biomass production increases as substrate exposure interval increases. However, during the second year, established torpedograss produces more biomass when grown on intermittently wet (0 cm) compared to permanently dry (-25 cm) or intermittently inundated (10 cm) substrates. No difference in production was observed between substrates permanently inundated (10 cm) and any other regime tested. During the first two years of torpedograss invasion, regardless of treatment, spikerush suppresses invasion and torpedograss had little effect on established spikerush, indicating that spikerush-dominated areas are capable of resisting torpedograss invasion. Even so, disturbances that might cause mortality of long hydroperiod species, such as spikerush, may create open gaps in the native vegetation and thus facilitate torpedograss establishment and expansion.

Language

Identifier

Unique identifying numbers for this dissertation in the Digital Library or other systems.

Collections

This dissertation is part of the following collection of related materials.

UNT Theses and Dissertations

Theses and dissertations represent a wealth of scholarly and artistic content created by masters and doctoral students in the degree-seeking process. Some ETDs in this collection are restricted to use by the UNT community.

What responsibilities do I have when using this dissertation?

When

Dates and time periods associated with this dissertation.

Creation Date

  • December 2006

Added to The UNT Digital Library

  • May 14, 2008, 9:19 p.m.

Description Last Updated

  • March 22, 2010, 2 p.m.

Usage Statistics

When was this dissertation last used?

Yesterday: 0
Past 30 days: 1
Total Uses: 140

Interact With This Dissertation

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Smith, Dian H. Influence of Sediment Exposure and Water Depth on Torpedograss Invasion of Lake Okeechobee, Florida, dissertation, December 2006; Denton, Texas. (digital.library.unt.edu/ark:/67531/metadc5607/: accessed July 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .