LTERN Data Portal

Data were collected from four 1 m x 1 m permanent survey plots situated on the 80 m transect on each of our 34 sites. Plots on each transect were set at least 20 m apart. At each plot, a 1m x 1m frame was placed over the vegetation.

The full treatment regime for the control of Bitou Bush in BNP is a combination of sequential sub-treatments. A key sub-treatment is spraying of Ultra Low Volume (ULV) glyphosate either aerially by helicopter or on the ground. The concentration of glyphosate varies by method of application, due to the size of droplets and the coverage provided by the applicator. Aerial spraying uses a concentration of 15% glyphosate, the splatter method from a hose connected to a tank on a 4WD vehicle uses 10% glyphosate, and the spot-spray method from a knapsack uses 5% glyphosate. Spraying takes place in winter (when native plants are relatively metabolically inactive but Bitou Bush remains metabolically active; Toth, Milham & Nazer 1993). After the first application of herbicide, treated Bitou Bush plants cure for >1 year before being burned in a prescribed fire. The fire triggers germination of Bitou Bush seed in the soil and a year later, a follow-up spray of ULV glyphosate kills fire-triggered seedlings. Prescribed fires are applied to 15-85 ha compartment units of treated vegetation in any given year.

Percentage cover measurements were collected for live Bitou Bush, dead Bitou Bush, all native vegetation, crown cover (by observation above the plot to an area of approximately 10 m x 10 m). In addition, we completed counts of the number of individual live Bitou Bush plants, dead Bitou Bush plants, other exotic plant species, and native plant species. We also derived a list of species in each 1 m x 1 m survey plot, from which we generated data for the number of exotic and native plant species. A single observer completed all vegetation surveys four times annually from 2007 to 2013.