Population Structure of Cupressus tortulosa Griffith along the Altitudinal Gradients of Tsendenanag Ridge in Punakha, Bhutan

Abstract

The Cupressus tortulosa Griffith, which had been popularly known as Cupressus corneyana Carriere and Cupressus himalaica Silba, is locally known as Tsenden. There are knowledge gaps in the ecology and population dynamics of Tsenden. Using the Vegetation Survey method, this study focused on the population structure of the Tsenden along various altitudinal gradients, including its ecology and habitat within natural stands. The study was conducted at Tsendenanag of Taewang Geog, Punakha Dzongkhag. Nine designated plots (20 x 20 m) were set up, covering altitudes ranging from 1700 to 2700 m above sea level. Tsenden was the dominant species associated with Quercus lanata, Q. glauca, Pinus wallichiana, Myrsine semiserrata, with undergrowth consisting of Eurya acuminata, Rhododendron species, and bamboo – Yushania species. Tsenden was abundant on steep rocky precipices with a slope percent ranging from 49% to 80%, occupying the aspects of northeast, southeast, east, and southwest. In undisturbed areas, Cupressus regeneration was absent; whereas, profuse regeneration was observed in disturbed (fire and landslide) sites, indicating that a certain level of disturbance is required to initiate regeneration. At higher altitudes, species dominance changes from Cupressus to Q. glauca, P. wallichiana and Rhododendron species