It looks like there are two issues here. One is physical disturbance. When sampling the population, do you step on and destroy the plants? Since the size of the plants is not given, I'm guessing this might be the case. Perhaps the best way to deal with it is to develop a frame that is suspended over the survey site (perhaps a boardwalk or a ladder on supports) so that the surveyors do not touch the ground. Or place rocks or other stepping stones in strategic places in the off-season, so that the surveyors have places to step where they will not step on plants. Granted this will prevent plants from coming up under the steps, but if destruction of plants is an issue, steps can be a solution. Basically, if areas are being surveyed repeatedly, work out a way to access the area without touching it. I've improvised these kinds of methods in plant surveys myself, mostly by standing on rocks on a slope while using a long walking stick to balance on as I leaned over the area to be surveyed.
Another issue is whether the plant is growing from a seed bank or not. If it is, then the real question for persistence is not how many plants are coming up, but the state of the seed bank at each site. It's unclear from the original question which of these apply, but hopefully these ideas help a bit. Frank Landis
