The term litter conjures up in one’s mind a messy affair, such as the town park strewn with the remnants of schoolchildren’s lunchablesin the ditch along our favourite scenic drive, its beauty tarnished by unsightly coffee cups, napkins and cigarette butts discarded by irresponsible drivers. Litter! Yuk! Its presence acts as one of those ugly reminders of what our throw-away culture can make the landscape look like.
However, an altogether different type of litter exists, one that is not only beneficial (nay, essential) for nature and all of its inhabitants. To the knowing eye it offers an enchanting beauty all of its own. You should count your blessings, my friend, if you witness this litter in your local park. Should the litter that I refer to here fill all of the ditches of the world, we would be a lucky bunch.
Granted, this better sort of litter is, like cigarette butts and coffee cups, still discarded by living organisms. But, the litter that I am speaking of has one fundamental difference that distinguishes it in every way from litter of human origin — it is 100% biodegradable. Plant litter (e.g., leaves fallen from autumn branches onto the forest floor and dead grasses slowly withering away into the prairie soil) is a type of refuse without which the world would be a very different place.
Above-ground plant matter (i.e., the green, living stuff we see every day) is chock full of goodness sucked up by below-ground root systems. As they gather moisture from the soil, roots bring to the above-ground plant parts essential nutrients. But, greedily hoarding these nutrients would be counterproductive, both for the ecosystem as a whole and for the plant itself. With a limited supply of plant food available, it is essential that plant matter fall back to the ground to release that which helped the flora grow and mature, thereby contributing to the nutrient cycle that we all learned about back in grade nine.
So when leaves fall or plants die, a type of litter accumulates on the surface of the soil. But, rather than being a scourge on the landscape, plant litter is really like an infusion of nutrients back into the soil in preparation for reuse at a later time. Tiny microflora and microfauna in the soil (little creatures from both the plant and animal kingdoms) break down that matter and convert the component nutrients back into a chemical form that can once again be used by other organisms, including the tree that just donated its leaves to the cause.
Hmmm, you may say, I know all about what accumulates means. Those leaves we have to clean each fall (or spring, if we prefer to leave our gardens and the organisms they harbour a protective blanket for the winter) are proof positive of how like litter plant refuse really is — in a word, messy.
Well, messy in a sense, I suppose. However, I must defend that tree’s presence by your house, as the extent of accumulation is only in part due to the amount of litter produced by any plant’s above-ground parts. Equally important in determining how much you will have to rake when the season shifts are factors such as temperature and moisture.
As anyone who has tried and failed to produce a prize-winning garden will attest to, plants need relatively warm, moist conditions in which to grow and be productive. But microorganisms, so essential to nutrient cycling, depend on these factors to an even greater extent. They simply cannot do their work of breaking down plant litter if it is too dry or too cold. Therefore, in areas where it is cold and dry (think Arctic tundra), dead vegetation will accumulate because the conditions are just not right for those wee microorganisms to carry-out their ecological duties. However, in the tropics, where moisture and temperature present no such limitations, plant litter never has the chance to build up because the microorganisms beneath the soil’s surface are breaking down the litter more efficiently than it can even be produced.
So don’t despair! Your tree is not trying to drive you mad by littering all over your yard. It is just trying to do its best to give back and to share the nutrients that allowed it to grow to such towering heights with the rest of its kith and kin. If you must blame something for the eternal back-breaking labour of yard cleaning, blame the weather, as we Canadians love to do anyway. Those leaves that just will not stop falling, year after year, could have been happily tucked away into the soil long ago by productive little microorganisms if it had just been a little warmer, if only it hadn’t been such a long winter, if the summer hadn’t been so scorchingly dry, if fall hadn’t come so early, if only….