Remember:

Fire, used alone or in combination with an herbicide, aids in the control of unwanted competitive vegetation. If used alone, most of the existing plant community will remain intact. Some woody plants may be eliminated and desirable grasses and forbs enhanced by the fire. Selective herbicides will invariably  kill some desirables, but may be used to improve survival and growth.

 

Remember:

The choice of chemical should be matched to the vegetation to be controlled, but also to the vegetation desired to be retained.

Preparing the Site for Restoration - Situation #1: Cutover Land

In general, even inexperienced foresters or landowners should be successful planting longleaf pine on cutover sites.  Planting longleaf pine in these situations does not require extraordinary site preparation and herbaceous release.

We have found that a chemical site preparation is a good first step. A chemical site preparation has three main advantages over a mechanical site preparation.

  1. A chemical site preparation tends to yield better and longer-lasting control of woody and shrubby competition on most sites. While we want to maintain as much of herbaceous community as possible, it is to our advantage to control oaks, gums, hollies, and other unwanted hardwood species. Mechanical site preparation may give you a site that looks clean, but subsequent sprouting and competition will typically be more severe when compared to a good chemical site preparation.
  2. Chemical site preparations tend to retain more of the native perennial herbaceous community that is especially valuable for wildlife food and diversity. For instance, most native legumes are tolerant of two of the three most commonly used chemicals: hexazinone and imazapyr.  Following a chemical site preparation, legume rootstocks often remain intact and viable, and will frequently bloom profusely one to two years after the site preparation was applied. On the other hand, an intensive mechanical site preparation will generally eliminate many of these root systems, and many of the species that invade the site will be weedy annuals.
  3. A chemical site preparation causes less soil movement. Less soil movement means more consistent planting depth and seedling placement. Since incorrect planting depth or seedling placement frequently causes planting failures, the decreased soil movement associated with a chemical site preparation is a major advantage.

A consistent formula for artificially establishing longleaf pines on cutover sites is:

  1. apply chemical site prep in late spring,
  2. burn in early fall, and 
  3. plant by winter.

In areas where maximizing growth of longleaf pine is not the driving management force and retention of key native groundcover species is important, fire remains the least destructive and most viable option for site preparation. In other areas where target groundcover species are already in place (such as wiregrass) and more emphasis is placed on tree survival and growth, the judicious use of herbicides is a useful tool in the restoration and management toolbox. 

Some herbicides can be used surgically to remove certain competition while maintaining key components of the understory. For example, one study in a Florida sandhill community found that 1 - 2 lbs / acre broadcast application of hexazinone removed some plants that are of ecological importance to targeted species, e.g., gopher apple. However, spot application at the aforementioned rates resulted in fewer effects on forbs cover, species richness, and diversity.

Note:  other studies have shown that two passes of a drum chopper in similar dry, wiregrass sandhills (a typical site preparation technique) will nearly eliminate wiregrass from a site.

For more information on planting longleaf on cutover sites, click here for Longleaf Note #6.