Last week, I had the opportunity to teach the students of our third Bachelor in Biology a little lesson about vegetation surveys.
It was a half a day course in the framework of their course on Good Field Practices, in which we try to give them a good toolbox on how to perform ecological fieldwork.
Crucial tool in the toolbox of a plant ecologist? The vegetation survey! Especially in my branch of ecology, in which we look at the effects of global change, vegetation surveys are key. Global change has strong effects on the distribution of species, but without surveying where species are actually growing, it is impossible to conclude anything meaningful.
Going outside and establishing a basic knowledge of common plant species is thus important, even in these modern times in which many ecological questions are answered from behind a computer. Someone needs to go out in the field and record where the plants are growing, indeed. There are botanists we can trust with that task (and oh, how much credit do they deserve in todays’ ecology!), but how to understand your system if you have not gone out in the field to experience it yourself?
It is also important to know the strengths of weaknesses of different types of vegetation surveys: some are fast (just estimating a percentage cover), some are more meticulous (like the pin-frame method above). All of them have a significant amount of noise, as the students found out quickly enough when trying to repeat each-other survey. Yet despite all that noise, survey method and observer differences turned out rather robust. Some rare species might be missed with one method or the other, yet common species always emerge as common.
The students hopefully took an other important lesson home: looking at plants can be a lot of fun, but vegetation surveys are as ‘serious’ science as any other scientific approach. Another tool in the toolbox that a good plant ecologist needs to keep sharp.