Remote sensing and GIS-based suitability modeling of medicinal plant (Taxus baccata Linn.) in Tawang district, Arunachal Pradesh, India

Taxus baccata is a valuable plant for taxol extraction used in preparation of anti-cancer drugs, Kaposi's sarcoma and over 20 such other indications. It is a slow-growing evergreen tree found in the altitudinal range 1500-3000 m. Around 2-3 million kg of biomass is harvested annually, whereas the sustainable rate of harvesting is estimated to be 0.6 million kg/year. Linear transect recorded 118 Taxus plants, out of which 99 were live and 19 were dead. The importance value index was calculated for Taxus baccata and five associated plants. Tsuga mertensiana recorded the highest with 78.32 and Taxus baccata lowest with 34.22 out of 300. The MaxEnt and SMCE models were used for suitability modeling of Taxus. The occurrence points and environmental layers - current global climate, altitude, slope and aspect were used for the MaxEnt. The results show 5.31% of the area under highly suitable and suitable and 80.14% not suitable. For SMCE, the digital elevation model from USGS website, LISS 3, IRS-P6 (Resourcesat), row/path 110/052 (25 November 2011), the annual average rainfall, temperature and humidity were used. The results show 61.66% of the area under highly suitable and suitable and only 2.8% under not suitable category. The MaxEnt results are specific and target-oriented, whereas the SMCE results appear more generalized. The region is potential area for occurrence of Taxus baccata in natural stand as well as suitable area for regeneration.