Trees Of Death

MEENA SUBRAMANIAM Artist and gardener, Western Ghats

HIGH ELEVATION grasslands are characterised by grasses, long and short, meadows dotted with wild flowers, occasional rhododendron trees, water pools and marshlands. Through the wet months, thick clouds of mist gather and swirl in incredible patterns interspersed sometimes by saaral or thin rain.

Today, exotics are a vast expanse, self-seeding and expanding beyond manageable proportions. With the grasses gone, most of the natural wetland or swamp-dependent life forms and precious stored water are under stress.

The artificiality of working the ‘wasteland’ has drastically altered the ecosystem. Plantation-cutting and sunlight-intrusion has allowed pesky invasives like exotic Eupatorium (a flowering shrub) and indigenous Rubus ellipticus (Himalayan raspberry) along with some dominant grasses, to explode. A small, indigenous Rubus ellipticus, usually found on the fringes of shola forests, is today thriving in massive thickets across the high ranges.

The cost-benefit ratios of cutting plantation soon outran the cost of imports. Today, we have resumed importing exotic pulp and the ‘working forest’ stands testimony to myopic vision. In South Africa, this ‘working forest’ mindset cost an estimated 82 percent inflow in some watersheds: a loss of at least 3.3 billion cubic metres per year.

Mountain catchments occupy roughly 10 to 20 percent of land area but contribute roughly 50 percent of water inflow. However, exotics don’t just reduce stream inflows compared to natural vegetation; stream flow reduction is drastic in high rainfall zones and worsens in drier zones. Evaporation rates can exceed rainfall by as much as 100 percent. Exotics counter water limitations by consuming all available water, much like drinking with a straw on a hot day. A three-year-old Eucalyptus extracts water across eight metres of soil. Young exotics possess more leaf surface area, enhancing evaporation. Natural recharge is virtually impossible when soil moisture is thus exhausted.

The molecules of natural resins and aromatic oils found in some exotics bind with soil particles. Their nature is oily; therefore, when these oils bind with soil molecules, the soil becomes impervious to water penetration (like a plastic raincoat). Such impervious soil molecules are called ‘hydrophobic’. When burnt, the heat from fire releases aromatic compounds and the soil is again free to absorb moisture. You may have smelt it in hill stations where they make eucalyptus oil, and a lot of the aromatic oil escapes into the atmosphere.

An important source of fuel wood, wattle’s water consumption is an estimated 2,555 mm per annum. The Palni Hills receive an estimated yearly rainfall of 1,655 mm. The trees often reach an average height of nearly 30 metres, although in their native Australia they only grow to five metres. Again, residual soil moisture is the compensatory mechanism. The result: dried-out highland marshes and entire trees dying in competition for water. Shallow root systems, useless for soil stability, result in soil erosion and downstream silting when uprooted. Traditional coppicing, a method of sustainable fuel wood cutting whereby stems are cut to the ground and freshly emerging shoots provide the subsequent harvest, is being replaced by dead-wood collection. The sponge effect of absorb-and-release that grasslands provided has all but disappeared, as have reservoir recharges for the dry plains.

Only timely intervention and prudent forest policy can save the small towns in the foothills, currently undergoing rampant urbanisation. Despite stupendous restorative costs, the rapid loss of water, biodiversity and fuel wood could soon be a thing of the past if forest officials initiate restoration of highland marshes, culling exotics and replacing them with indigenous species, acting on the premise that Water is Life.