One hot summer afternoon, my colleagues and I were walking on a well-established trail within Kalakad Mundanthurai Tiger Reserve, Tamil Nadu. Our task for the day was to crane our necks and look at trees with a pair of binoculars, to estimate what proportion of the trees had fresh leaves, old leaves, flowers, and fruits. It sounds like a silly thing to do but, it has incredible scientific importance when repeated monthly over several years. One could detect patterns in flowering periods and fruit output. Throughout the trail, we noticed fallen leaves and we could not even hear our footsteps as the leaves were soft. Many of the leaves were eaten up, but for the intact veins. None of us paid much attention to the fallen leaves, considering that they are called leaf litter.
Cover photo: The fleshy part of a fallen leaf decomposes first, leaving behind only the veins, which will soon disintegrate as well.
While walking, we passed through a patch with wild cardamom plants and we heard the calls of a bird, the little spiderhunter. The bird is smaller than a sparrow and has a long recurved beak. We ignored the calls and were estimating the percentage of leaves when I noticed something odd. There was a clump of dry leaves attached under a bunch of green leaves and appeared to be a nest of some sort. It was intricate and made of the fallen leaves upon which we walked. Interlinked with each other, the whole setup was attached to a green leaf using cobwebs.
We moved away from the nest and soon, the spiderhunter stopped its incessant calls and flew into the nest. Not wanting to disturb the nesting bird, we moved on. However, I kept wondering about the effort the small bird must have put in to construct that nest. Some of my questions had no clear answers. For example, was the nest made up of leaves from one species of a plant? If so, why? And how far away would the bird go to fetch leaves?
A few days later, I was accompanying a colleague who was writing his thesis on seed-dispersal in forests. We would spend the entire day squatting and sifting through leaf litter to find seeds. The seeds would have fallen from the tall trees or dispersed by an animal. The forest floor was replete with leaf litter and sifting through; one could notice the variety of leaves strewn around. Each leaf was dry, crisp, and would crumble with a pleasant smell. This leaf litter is how nutrients get cycled back into the environment. Devoid of leaf litter, the soil would get washed off in the rain or blown away by the wind.
Our search continued until I found a pale round thing that I excitedly picked up, thinking it to be a seed. Turns out that it was not a seed but, a large, gravid tick; ready to deposit thousands of eggs in the leaf litter. These tiny blood-suckers latch on to an unsuspecting animal and feed of their blood. They do not differentiate us humans and happily bite us in the choicest of places, especially on our legs and waist. Many a time, they carry deadly diseases like the infamous “monkey fever” or “Kyasanour forest disease”. Monkey fever is named so because monkeys are the first to die. And once the ticks bite us humans, it could be fatal. Having known of the risks of tick bites, I immediately put the gravid female back after taking a few photographs. From then on, I tend to think twice before picking up any seed-like thing from the forest floor.
The other creatures we typically encounter amongst leaf litter aren’t as scary or harmful to us. One of the common creatures we encountered in the forests of KMTR was the dainty butterfly called the white bar bush brown (Mycalesis anaxias). This species appears to be adapted to blend into leaf litter and will sit motionless until we almost step on them. However, they do have the habit of sitting in sun-specks, areas where sunlight penetrates to the ground, through the tall evergreen forests.
Perhaps the most fascinating adaptation to a life among the leaf litter that I have seen so far is a frog from the forests of Southeast Asia. The Malayan horned frog (Megophrys nasuta) lives on the forest floor and is adept at camouflage. It has a loud “toonk” call and hops around among dense leaf litter. The horn-like ridges over its eyes appear like the stalks of dry leaves, the body has ridges that look like the edges of leaves, and its colour and pattern are exactly like that of fallen dry leaves.
It is a shame that we end up calling the rich, organic, and nutrient-rich habitat clothing the forest floor as litter. It is time for us to recognise how important the fallen leaves and twigs are for supporting life. One place for us to start could be to stop the mindless collection of fallen leaves in our cities and parks where we set fire to them. The leaves could be used for decomposing or simply let be, for it supports various life forms even in urban environments. The other thing we could all do when we step out into the wilderness is to take some time to squat and appreciate the intricate beauty of the forest floor.
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