I graduated last year and would like to do a PhD next year, preferably in ecology. Since it will have been two years since I graduated, will potential supervisors worry that I'll have forgotten everything? I'm worried the 2 years will count against me and I won't be able to compete against the fresh graduates.

I've considered doing lab or environmental work in the mean time. Will this help? The only problem is it tends to be very poorly paid and I'm happy with my current job so would prefer to stay where I am.

Ecology is a very popular subject for PhD research. It is most used seach term on FindAPhD and compared to medically related topics is very poorly funded (ie there's less studentships), so competition will be intense. Because demand is high careers in ecology tend not to be very well paid, so if you're worried about earning less now a career in ecology may not be the best idea.

If you haven't worked in ecology since graduation and have no record of relevant volutary work then finding a place may be difficult (even finding a low paid job may not be that easy). If you're not prepared to give up your job try getting some relevant volutary work. You may find that the most important thing you need is a good academic reference and the only way to get that is to be woring in the field.