Alarm bells have started ringing after mortality in shisham (Dalbergia sisoo) reached an alarming proportion in India, Pakistan, Nepal and Bangladesh.
Scientists at the prestigious Forest Research Institute (FRI) in Dehra Dun have taken the sudden wilting of trees as a challenge to stem the rot.
Following a survey, scientists found that the loss was huge in terms of the mortality of shisham, which is also known as pay-cheque in the timber business parlance. “Nearly 8 to 10 lakh trees have so far dried causing a colossal loss of Rs 800-1000 crores in India alone,” said Dr A N Shukla, the Head of the Forest Pathology Division at the FRI.
Already, multi-location trials through root-dip methods are underway at the FRI. Through these trials, scientists are trying to bring back resistance in the shisham, which is one of the biggest timbers available in India for furniture and other building materials.
The root cause of the disease plaguing shisham is a soil-borne fungus called Fusarium solani which inflicts the trunk of the sheesham following which the tree does not recoup.
As soon as the fungus strikes, the leaves of the tree starts turning pale and within one or two weeks, the whole tree dies.
Various factors like the climate change due to global warming, type of site and hydrological stress in the form of flooding and drought have been attributed to the dying of these trees, preliminary investigations revealed.
Evidences from satellite pictures showed a new phenomenon “brown haze” over Delhi and the entire stretch of lower Himalayas extending right up to West Bengal and Bangladesh and other south Asian countries.
Scientists, who studied the phenomenon as part of “India Ocean Experiment (INDOEX) for about six years from 1995 named it as “Asian Brown Haze.” The survey under the United Nations Environment Programme (UNEP) found three km deep pollution blanket disrupting climate pattern across Asia and beyond.
As the forests are natural reserves and repository of biodiversity, effect of global warming is apparent on large scale mortality of shisham trees of all age groups in India, scientists say. “There is a definite correlation between brown haze and mortality of shisham as the area of mortality is the same over which the brown haze is presently static,” said Dr Shukla.
Shisham is one of the most important timber species in India. It is widely distributed in along river-banks where it grows naturally in the sub-Himalayan tracts from the Indus to the Brahmaputra in lower Assam. It is also planted extensively on alluvial soil.
Plantations of shisham have also been raised in southern states like Tamil Nadu, Kerala and Karnataka, scientists say.