Are native orchids more likely to be grazed by herbivores if they are touched by humans?
It is a commonly held belief both in Tasmania and Victoria that if you touch native orchids they are more likely to be eaten by animals. Since we touch orchids frequently in the course of our orchid monitoring program, we were keen to find out experimentally if the belief was justified.
The method we used was to number 60 plants of Glossodia major and 60 plants of Caladenia carnea. We then touched every other plant of each species on two consecutive evenings and recorded whether the plants had been damaged the morning afterwards, and also a week later.
The results of this experiment indicated that the numbers of two orchid species, Glossodia major and Caladenia carnea that were damaged or destroyed were not significantly affected by human touching of the plants. This finding is a relief to those of us that touch orchids frequently in the course of identifying or measuring them.
We did, however, find that the numbers of specimens of both species that were damaged or destroyed were significantly affected by whether they were growing in an open track or amongst vegetation. Orchids growing in the open track were more vulnerable, especially to presumed damaged by mammals, e.g. by being dug up and/or eaten by herbivores travelling along the tracks.