By Ranil Senanayake –
Preparing for the future by looking back.
Understanding the issues and options before us.
The central mountains of Sri Lanka drain radially to the sea, through 103 distinct watersheds. A watershed of a river is that area of land whose rainfall feeds the river and begins in the mountains. As commented by the Rt. Hon. D.S. Senanayake :
“With the evidence daily accumulating of the wisdom of our forefathers, we need scarcely doubt that it was not merely the idea of making the mountain country difficult of approach by the foreign invader that caused them to preserve unfilled and uncleared the dense vegetation of their mountain slopes. We may readily believe that they deliberately left these untouched in order to provide that abundant supply of water on which they might draw for the benefit of man.”
This ‘uncleared and dense vegetation’ that evoked so much gratitude in our founding father, had been existant on the mountains of Sri Lanka for a period exceeding 20 million years and over this time built a soil that contained a treasure in organic matter. Soil organic matter is the living fraction that drives the ecosystem that lies above it. Sustainable agriculture and forestry will be an impossibility without the optimum levels of organic matter for that soil. The organic matter of soil when extracted is seen as a dark, amorphous solid mass. On closer examination this ‘solid mass’ is seen to be comprised of billions of organisms. In fact, any one acre of farmyard soil contains as much biomass as an Elephant. One gram of ordinary farmyard soil can contain over 1 billion individual bacteria, over 100 million individual actinomyctes and over 1 kilometer of fungal hyphpae, notwithstanding plants like algae and animals like collembolids, nematodes or worms. In Sri Lanka the soil ecosystem is further enhanced by presence of many genera and species of soil dwelling snakes, lizards etc; all massive predators in this ecosystem that suggest the age and the massive nature of the soil bank this nation once possessed.
A forest soil, if undisturbed will develop humic acid molecues that allow carbon to be sequestered in the soil for periods exceeding 15,000 years. These soils are deep and ‘spongy’ allowing them to soak up and retain rainwater, to feed springs and rivers below. This function of our mountain forests came to an end with the advent of the colonial adventure. Fredrick Lewis in his book Sixty Four Years in CEYLON makes this observation on the destruction of the mountain forests in the Agra Patana area;
“I know of no more awe-inspiring sight, than that of a thousand acres on fire. Sheets of flame appear to leap into the air, and yell with a sort of devilish delight at their victory over the magnificent trees they are reducing into charred masses of cinder and charcoal. It is more than impressive, it is fearful, yet grand ! After the fire has completed its work, the land is covered with .black logs, lumps of charred timber, masses, and often great fragments of stones, broken by the heat that has swept over them. A deep black covers the landscape; impressive, but depressing.
It was in a burned wilderness like this, that I found my new home. It lay at the extreme end of one of the many blocks of land that had been simultaneously burned off. My path, for road it could not be then called led over hundreds of fallen and charred logs, and followed the valley of the Agra stream……. When morning broke upon the day following the events recorded at the conclusion of the last chapter, I found myself gazing upon a scene not altogether unfamiliar to me. All around me lay hundreds of charred black logs, stumps in fantastic shapes and outlines: fallen branches, broken and distorted by fire: cinder heaps, and little rivulets of sodden ash: all indicative of the fierce, merciless fire that but a few weeks ago, had raged over a spot that so lately had been a beautiful forest land. It was now a blackened wilderness, to be changed into fields of coffee, by the labour and patience of man. A strange picture; fascinating in one respect: fearful in another and yet so full of a strange mixture of possibilities was this wild heap of ruins, this uncouth mass of slaughtered giants of an inarticulate, yet eloquent world, to be transformed by , industry in the pursuit of fleeting wealth.”
The colonial exploiters, cannot claim ignorance of their deeds Dr. Strange, an agricultural expert made this observation in 1909 with respect to the clearing of the mountain forests, but for those who benifitted from this action, the Tea, Rubber and Coconut plantations, this was not a matter for their concern.
“It would not have been necessary to notice here the matter of soil denudation, did it not affect irrigation and water supply. The result of stripping the soil is to make the springs on tea estates dry up quickly; to diminish the fair-weather flow of streams and to increase their storm flow (whereby temporary irrigation weirs are carried away) and to choke with silt the beds of the streams and the irrigation channels led from them. It is also said to reduce the fertilizing property of the water, as there is now less leaf mould in solution. Even paddy fields have been ruined by sandy deposits laid on them. When tanks lie in the course of streams thus affected, the rate of their silting-up will rapidly increase and their storage capacity will greatly diminish. Even the large rivers, such as the Kelani, have had their section diminished by soil debris, so that for this reason, as well as on account of the greater run-off produced by the clearance of the forest entailed by the establishment of estate plantations, the flood waters cannot be contained in the river channel, but are spread over the riparian land and do much damage. If such damage affected only a small area it would not, of course, matter much, but it has to be remembered that the tea and rubber estates are on the hills, and uplands, which are the principal sources of supply to rivers draining two-thirds of the Island; the effect of denudation it thus widespread.”
By this activity the incredible resource that we had in out mountains was lost. The saying that the ‘pillars of Whitehall was built on the topsoil of its colonies’ attains maore meaning with this knowledge.
Thus forest denudation and soil erosion seem to go side by side. While we have begun to address the questions of forest and tree loss there is also much to be done with the question of soil.
Soil, is one of the most important components of terrestrial ecosystems, yet its value has been overlooked by most modern approaches to land development, agriculture and forestry. To most of us soil is the stuff that holds trees up. We see it as a solid surface for us to walk, ride or construct upon. Our perception of its usefulness in our daily lives does not exceed much beyond providing a medium to grow our crops. In fact modern agriculture has discounted the value of soil in providing nutrients for plants. by enhancing the role of artificial fertilizer to the detriment of good soil management. In Sri Lanka most texts on soil only address the physical or chemical nature of soil, a view that has allowed our farmers to be pushed into reliance on ‘high input chemical agriculture’.
In 1938 Dr, William. Albrecht made the following observation for US agriculture ;
“Soil organic matter is one of our most important national resources; its unwise exploitation has been devastating; and it must be given its proper rank in any conservation policy as one of the major factors affecting the levels of crop production in the future… The Nation should be made aware of the rapid rate at which the organic matter in the soil is being exhausted. Farm-management practices should be adopted that will at least maintain, and in as many cases as possible even increase, the supply of this natural resource in the soil. The maintenance of soil organic matter might well be considered a national responsibility.”
In 2016 in Sri Lanka , we still have to appreciate this fact. The colonial experience robbed us of that precious organic matter, leaving plantations that cling to the subsoil and yield only with artificial fertilizer that we have to import. But, today a new threat has sprung up. Irresponsible land use decisions, sanctioned by the officials concerned, are rooting out the tea plants that gave some stability to the degraded mountains and replacing it with annual vegetable cultivation that bleeds away the remnant bits and poisons our water sources.
Perhaps we should look at our worn and degraded mountains, in the way that our forefathers did. Clothed with dense vegetation on their upper slopes, providing water and ecosystem services for the whole country. Forests are essential to building such a soil as tree roots provide up to 20% of their total root weight as exudates into the surrounding soil each year, to maintain their soil ecosystem. Each Species of tree provides differing chemical compounds into the soil and many species of trees have distinct species of associated soil organisms. If clothing our mountains with forest becomes a goal of adapting to the oncoming changes the gain in living soils will fit in well with any national strategy.
In the emerging modern economies, where Carbon Taxes and Ecosystem Services direct value, the mountains of the nation can be looked to providing income. If they are designed to enhance the activity of reforestation in order to optimize that water functions of that watershed, the river systems of this nation are assured of a sustainable flow and the tank system can be revitalized.
To be continued…
Adaptation – Part I