SURVIVAL TIME AND EFFECTIVENESS OF GIRDLING AND HERBICIDE METHODS IN THE CONTROL OF Pinus elliotti: A CASE STUDY IN SECONDARY ATLANTIC FOREST IN SOUTHEASTERN BRAZIL

Pinus elliottii is a notorious invasive exotic species in grassland ecosystems; however, it can also establish itself in forest ecosystems during secondary succession. In this case, killing invasive standing trees is preferable to cutting, as it reduces damage to surrounding native vegetation. This study evaluates the survival time and effectiveness of two methods for killing standing Pinus elliottii trees in a regenerating forest ecosystem: girdling (a 50 cm wide ring, followed by scarification of the wound surface) and herbicide (a 30% glyphosate solution injected into three perforations in the stem). The application times of the treatments were recorded for each tree individually. Tree survival times and rates were monitored over 24 months and eight days and compared using survival analysis models and binomial test, respectively. Girdling resulted in longer survival times, but survival rates did not differ significantly between the two methods. All trees in the control group remained alive during the monitoring period. The average time per tree for girdling application was 2.3 minutes longer, resulting in a higher labor cost. However, this additional cost was less than the cost of purchasing the herbicide. Our data indicate that girdling, although resulting in longer survival time, is more effective than herbicide in killing invasive Pinus elliottii trees under the soil and climate conditions of this experiment.