Tanglehead Seed Germination

Tanglehead has expanded across the South Texas Sand Sheet over the past 15 years, resulting in reduced quality of wildlife habitat and livestock grazing value due to its formation of dense, single-species stands. The East Foundation is committed to developing solutions for such threats to the productivity of our native rangelands.

Many landowners practice disking or plowing in strips to break-up dense tanglehead stands. These practices are usually successful in the short-term, but have the potential to prolong the problem in the long-term by burying seeds that could germinate at a later date. With its partners, the East Foundation embarked on a study aimed at determining the viability of buried tanglehead seeds and the persistence of seedbanks that could cause future problems for landowners.

To address these questions, we recorded and analyzed tanglehead seed viability and germination over 25 months at 3 locations. Specifically, we:

  • Determined the effects of burying seeds at 1.5 and 3.5 inches, common depths for seed burial with mechanical treatments
  • Determined seed viability through a period from 3 to 25 months
  • Compared viability of seeds that were freshly-collected to those that were 2-years old

We found:

  • Buried tanglehead seeds to have drastically reduced germination, regardless of depth buried
  • Tanglehead seed germination decline from ~80% (at 3 months) to ~20% (at 25 months)
  • No differences between freshly-collected and 2-year old tanglehead seeds

This study indicates that buried tanglehead seeds have reduced germination, an outcome that was not related to burial depth. Also, that the formation of persistent tanglehead seedbanks are unlikely due
to the loss of seed viability. Thus, disking, plowing, or other mechanical treatments that result in buried tanglehead seeds should not prolong or promote the tanglehead problem. Landowners should consider
such treatments as viable options for wildlife habitat management in tanglehead-dominated regions of the South Texas Sand Sheet.

Partners: Caesar Kleberg Wildlife Research Institute, The Nature Conservancy, and USDA Natural Resources Conservation Service

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