Tree planting is a staple of efforts to make environments 'greener'. People expect tree planting to be a part of normal environmental activities. It's simple and the results are instantly visible: dig a hole, put a tree in and add some water. What could be easier?
As with all simple and stupid questions, answering this one leads us down some very interesting solutions. What if we try something even lazier and easier than planting trees? Why don't we just stop cutting grass? We tend to think of grass as a useless nuisance, something that should be replaced by a more productive use of land, like a car park.
Truth be told, grass plays a very important ecological role. It provides shelter and resources to small animals. Grass seeds are eaten by grain eating birds. Dry grass provides materials for birds to build nests (Notice how birds need to collect straws and bits of plastic on campus?) Thick growths provides shelter for reptiles and amphibians. Aquatic grasses like reeds make good habitat for young fish.
Not that we should advocate uncontrolled growth of grass. As in all of ecology there needs to be balance. Grass tends to require a lot of water to grow, and in hot weather dry grass can become a fire hazard. Grasses can spread very fast if allowed, so it may suffocate and compete with other types of plants. Also, there is the cultural problem of people considering unattended overgrown grassland to be 'unproductive'.
But biodiversity requires more than just creating a single type of habitat. If we keep planting trees as some nature lovers propose we will just have a lot of tree cover - something that doesn't even occur in natural forests. In rainforests, trees collapse all the time, often smashing or dragging smaller trees down with them. This destruction creates small gaps in the forest where 'gap' species such as grasses grow. That is one of the reasons why rainforests are so diverse in terms of life, not because they are permanent, but because they cycle through many different stages of life, death and regrowth.
So think about grass once in while. Or at the very least you have an excuse to put off cutting the grass for another week.
T.G. Goh is an entomologist based in the Museum of Zoology. He can frequently be seen walking around campus, ruminating on the state of biodiversity; it is from his shortcuts through untarred territories that he gets the inspiration for his columns. You can contact him at email@example.com.