Chirpine dieback at Gubjithang under Punakha Dzongkhag

Pinus roxburghii (known as Chirpine) is a species of pine. It is native to the Himalayas, and was named after William Roxburgh. It generally occurs at lower altitudes than other pines in the Himalaya, from 500–2,000 m. Usually, the accumulating carpet of needles on the forest floor under these trees makes it unsuitable for many common plants and trees to grow. This could possibly be due to the relative immunity from fire that the thick bark of these species gives them. The wood of this tree is the least preferred for or local building purpose, as it is the weakest and most prone to decay when compared with other conifers. 

 
Forest types in Bhutan are Fir forests, mixed conifer forest, Bluepine forest, Chirpine forest, broad leaf mixed with conifer, upland hardwood forest, lowland hardwood forest, and tropical lowland forests. As such, more than 60 percent of the common plant species of the eastern Himalayas can be found within Bhutan. However, the disease prevention & control is concern for all plant pathologists around the world to maintain respective trait adaptable to the natural processes. Particularly, the Chirpine dieback is common sighting and recurrent case to Bhutanese forest.  

Early July 2014, we visited to Gubjithang under Punakha Dzongkhag to study on dying of Chirpine trees, which has been suspected to die-back. The forest type there is pure Chirpine stands with Eupatorium and other shrubby undergrowth. I noted that, approximately 0.50 acreage and other thicket pockets turned deep brown from top-down (die-back). The needles wilted, drooped and developed a brownish tinge, gradually turned reddish. The inner cambium of the trees are found rotten and released lots of brownish like saw dusts while peeling of the bark. Similarly, while crosscutting of pole sized Chirpine exhibited rotten pith. I concluded that, the environmental, soil and climatic factors may be contributed to the incidence of die-back. The low humidity and scanty rainfall may be another factor beside unsuitability of soil and adverse climatic conditions.  

As such, old trees which die from fire or drought, undergo some metamorphosis in their wood due to the crystallization of the resin inside the heart wood. This makes the wood become brightly colored and very aromatic with a brittle, glassy feel. Every autumn, the dried needles of this tree forms a dense carpet on the forest floor, which the locals gather in large bundles to serve as bedding for their cattle, for the year round. On distillation, the resin yields an essential oil known as turpentine and non-volatile rosin. The turpentine is chiefly used as a solvent in pharmaceutical preparations, perfume industry, in manufacture of synthetic pine oil, disinfectants, insecticides and denaturants in other countries. It is one of the most important basic raw materials for the synthesis of terpene chemicals which are used in a wide variety of industries such as adhesives, paper and rubber.