Getting rid of dead or decaying things in the bush is very important to keeping an ecosystem clean and healthy. Usually when people think about this, they think about carcasses lying around, being fed on by hyenas and vultures. These two are very important in breaking down the ‘meats’, but there are also two things that are great in breaking down the ‘salad’. Vegetation also needs to be broken down, and this is broken down by fungus and termites.
When people hear fungus, they immediately think about mushrooms. Although mushrooms certainly are fungi, there are many different types of fungi that help break down plant matter. Much is the same with termites. As soon as you mention termites, people think of the little pests that eat their houses or furniture. This is because they are breaking down the dead wood. Not all species of termites do this, though, with some species even working hand in hand with fungi to decompose the vegetation.
The hard things
When it comes to decomposing the stems of plants (grasses and woods), the hardier part, it mainly comes down to fungi. This is by no means a speedy process and can take a lot longer to do so than if insects had to do it. The reason being is these parts of the plants are also a lot harder than something like the leaves are. Cellulose, which is what is found in plant cell walls, making them very tough and strong, is usually broken down by brown rots. White rots, on the other hand, help break down the lignin, which is also found in plant cell walls, causing them to be rigid.
The structure
When we look at where most termites live, termite mounds pop into mind immediately. This is the case with a few species, but most species actually live underground without even making a mound. The mounds themselves are well known, though, as they stick out like sore thumbs all over the savanna. The mounds themselves in fact act like huge air conditioners, with the chimneys on the mound used to regulate the temperature inside. This is an act that we as humans have continually tried and failed at, yet here is a small insect opening and closing chimneys to keep a constant temperature, regardless of day or night, or even season.
These mounds penetrate the earth all the way down to ground water. This is where the mound gets its humidity from. On a cool, dry winter morning, you can see steam coming out of open chimneys, almost looking like a volcano. Birds and other small creatures will often sit over these openings, using them to warm themselves.
When looking at some areas, there is an average of one termite mound per hectare (2.2 acres). In some areas, depending on groundwater, there may be fewer or sometimes even more. Some of these large mounds may house close to a million termites, but on average you’d be looking at closer to two hundred thousand. These average mounds can be responsible for getting rid of up to 65% of dead wood and about 5 – 10% of grass and leaf litter around their mound every year. This is a very important role in the nutrient cycle, recycling so much back into the system.
Digestion
When it comes to the digestive tract of termites, they have not got the best in the animal kingdom. They have had to come up with mutualistic relationships to benefit both parties to help with their own digestion. The first group of termites uses protozoa. Protozoa are tiny organisms that are able to move around and feed. These protozoa are found within the termite’s hindgut and help break down the bits of vegetation that the termite has ingested. Even these little organisms struggle with parts of the vegetation, and these termites will often have to feed on their own faeces, giving it a second chance to try to break it down again.
Then termites that create mounds have a different way of doing it, though. Within the mound itself, they farm their own fungi. This fungus grows well because of the constant temperature and humidity that we mentioned earlier on. Within the fungal chambers, they grow their fungi. The termites collect their plant matter and take it down to the fungal chambers, where the fungi break down the vegetation for the termites. Once the fungi have broken down the cellulose and lignin, the termites are able to feed on and digest their food.
Uses for other species
Termites themselves are a massive food source for many birds, mammals and reptiles. Certain species of birds will migrate right across the globe to get to Africa for the termites in the summer months. Aarvarks and aardwolfs can feed on up to fifty thousand termites in a single night. This is where the queen termite replenishes the number, laying up to thirty thousand eggs a day and replenishing the numbers of the colony.
Some animals will use the mounds as homes, moving in as they create the perfect cover and safety from larger creatures. The mounds used are usually inactive, but sometimes active mounds are used as well. Even animals like hyenas and wild dogs will turn mounds into den sites for their young. Youngsters themselves will dig extra tunnels and cavities away from the main chambers. Large snakes, like black mambas and pythons, will use the mounds for refuge as well, often using them for nesting sites as well.
Often large trees can be seen growing out of the mounds. When people first see this, they think that the mound was built around the tree, when it is the complete opposite. With temperature and humidity in the mounds, they are the perfect greenhouse for growth. Often the vegetation growth around the mounds is far better than that of the vegetation in the adjacent areas. Even with certain grass species, grazers will completely ignore them unless they are growing on or around a termite mound where they are then readily grazed.
When people find out how these termite mounds work, how old they are and what they bring to the ecosystem, they are regarded as natural monuments. Breaking down the old vegetation is not as easy as one would think, but with the help of termites and fungi, it makes it possible.
