Fieldwork and measuring biodiversity

Ten years ago, this area was a forest teeming with life. Then, the forest was cut down, and most of the local wildlife and plant species disappeared. For the past year, however, local communities have made an effort to preserve the area. Deforestation has stopped, and new trees have been planted. Now, it’s time for conservation biologist Ayanna to see whether these efforts were successful!

Ayanna needs to find out how many different species of plants and animals live there now. She will measure biodiversity by performing a field experiment! When she gets to the site, Ayanna records the time, temperature, and weather conditions. This is important, because these factors can have a big impact on her findings. For example, she’s not very likely to observe flying insects on a very windy or rainy day, even if they are otherwise present in the area.

Ayanna sketches out the site in her notebook. Then, using sticks and tape, she divides the ground into smaller sections. This way, she'll be able to keep track of what’s been done and make sure she investigates the whole area. Afterwards, she observes and counts birds that fly through the area, noting the species. She continues making these observations throughout the day.

She also writes down all the species of plants that she can identify, and takes photos and samples of the ones she doesn’t recognise, to look up later. It’s time to take measurements! Ayanna outlines the sample area of 1 metre by 1 metre by laying down a square frame — a quadrat. First, she counts the number of plants by species, inside the quadrat area. Within this quadrat, there are quite a few young trees — saplings.

Ayanna tags them and measures their height. She will return to the site at a later date, to see how many of them survived and how much they’ve grown. Next, she counts the number of insects inside the quadrat by species. Finally, she notes any other animals inside the quadrat — just one snail, in this particular one. This counting method is very common for determining the amount of plants or wildlife per square metre.

But it’s not enough to do it once, as that may not be representative of the whole site. For her sampling to be valid, Ayanna needs to repeat the process several times. So, she picks up her quadrat, closes her eyes, spins round, opens her eyes and walks 10 steps in that direction. This way, she’s picked a random area. By picking randomly, she can avoid bias, and her results will be more truthful to the actual population size.

Ayanna places the quadrat on the ground, notes the time, temperature, weather, and starts counting all over again. This time, Ayanna’s job is to assess general biodiversity in the regenerating forest. But sometimes, her job is to study just one specific species in an area. In that case, she wouldn’t be counting everything she sees. Instead, she would focus on that one species.

She would still have to log the other plants or wildlife, because that can give her an idea of how good the environment is, and how likely a species is to survive there. So, to run a field experiment successfully, it is important to have a goal and a plan before starting, to be highly observant of your surroundings, to measure things consistently but at random sites, and to make sure everything is written down. Now you’re ready to try your own field experiment!