Advances in research of reclaimed water irrigation in China

In Bhutan the Persian Walnut (Juglans regia L.) is highly valued for its timber and is listed under special class in Royalty on Forest Products of Bhutan. Possessing high timber and other medicinal values, the ecology of the species in the country was poorly understood. The study aimed to understand the ecological requirements and habitat modeling of the species in Bhutan. A purposive non-probability sampling was adopted in natural habitats of the species in four districts (Gasa, Punakha, Wangdue Phodrang, and Dagana) of the country. Plot size of 20 m X 20 m (major plot) for tree and understory and 2 m X 2 m for ground cover were used to collect vegetation data. Soil samples were collected from the center of the major plot at a depth of 25 - 30 cm. A total of 163 plant species belonging to 74 families were recorded from the study plots. Pearson and Kendal correlation of CCA Ordination showed moderate influence of slope (r = .66) followed by altitude (r =.55). Annual mean temperature and rainfall showed moderately negative correlation with the growth and distribution of J. regia (r =. -54 and -.64) in the study area. Despite, scattered distribution of J. regia in the country an area of 7146.53 km2 which accounts for 18.61% of the country’s total area was found to be suitable for the growth and development of the species which can be used for protection and management of species in future.

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Ecology of Persian Walnut (Juglans regia L.) in Western Bhutan

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.

Kaka

Papers

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