Emma Kay Bleakley
It's all about the poo
Re-wilding – It’s all about the poo and throwing your food around!
The re-wilding or returning wild spaces back to their natural state, especially in remote areas of the planet, has always been a tricky problem. There are many organisations that specialise in the restoration of wild spaces. Organisations like Moors for the Future who are behind the restoration of the peat and moorland in the Peak District National Park in Derbyshire. They re-seed the heather plants and replant sphagnum moss blankets to restore the moorland in the Park. To get the large quantities of heather brash, which contains the heather seed, up to the remote moorlands, they must employ teams of helicopters. That’s all well and good for treeless areas, where the ground to be seeded is clearly visible, but is an expensive method of spreading seeds around. What happens if you want to re-seed somewhere like a jungle, where the ground is hidden by dense canopy?
Re-seeding remote and out-of-the-way places has long been a problem for ecologists and conservationists. How do you successfully get seeds to these remote places? The answer is look at how Mother Nature deals with the problem. This is where the poo comes in. A lecturer during my undergrad always used to say, “It’s all about the poo!” and he was right. Finding most wild animals, especially more elusive animals, means that you must first find where they have been. The chances of just seeing them is almost impossible, but you can find out where they were by their footprints and their droppings/scat. This became the running joke throughout the course and it stuck with me.
Recently, a group of scientists wanted to look at seed dispersal in the Khao Yai National Park, in central Thailand. The Platymitra macrocarpa trees in the area are becoming scarce and are struggling to produce enough seedlings from their fruits. This means that the tropical forests in Thailand are becoming less and less diverse in the tree species that grow there. The scientists focused their research on how the fruits of the Platymitra macrocarpa trees were spread around the forest floor. The fruits are about 3” to 5” in size and hang in the canopy of the tree, just like the apples we see in orchards and are related to the Custard Apple (Annonaceae family). The scientists knew that the large animals found in the region are mainly herbivores and that these animals could be the answer. The fruits are picked and eaten in one of two ways. Either, directly from the tree, by animals like gibbons, macaques, squirrels, or local bears who pick the fruit from the branches, or by animals such as elephants, sambar deer and muntjac who forage them from the ground. These animals look along the ground and eat whatever fallen fruit they can find. Instead of trying to find the animals, which could be difficult (it’s amazing how hard it can be to find an elephant in a dense leafy jungle), the scientists looked for seedlings from the trees and for the poo from the animals that had eaten the fruits.
They found that the elephants were the best at seed scattering and were responsible for 37% of the new seedlings found by the scientists. What makes the elephants, together with the sambar deer and local bears, great at spreading these little seeds? Well, it’s all down to sloppy table manners and defecating wherever they want. A big animal like an elephant picks up an apple sized fruit and gives a quick chew and swallows it. Some of the fruit goes into the stomach and some falls out of their mouths and back onto the ground. The seeds that stay inside the elephant are not chewed up and are still whole when they pass through and out the other end. Out of approximately 70 seeds found in each elephant poo, 78% of the seeds went on to grow into seedlings.
Poo is a fantastic place for plants to begin their lives. A readymade source for the seedlings to use as food and grow into strong healthy plants. I remember my Dad running out with a bucket and spade if he saw the horses going down the road so that he could put the manure on his roses. It’s the same idea. Using Poo as a nourishment for plants.
Unfortunately, the Platymitra macrocarpa trees are their own worst enemies. Not enough new trees are growing, and in this case, the help from the elephants and the other large herbivores in the area is not enough to replace the Platymitra macrocarpa trees. Nonetheless, the scientists’ work means that they now know that “rewilding” by using nature’s own seed dispersers is a practical, cost effective and ecologically friendly way to help our more inaccessible regions.