当前世界环境

A study was carried out on “Impact of micro-climatic variations on forest ecosystem in mid hills of Himachal Pradesh” during winter and summer seasons of 2015-16. Comparisons of below forest canopy and open sites were carried out for abiotic and biotic factors under five forest ecosystems (chir pine forest, mixed forest, ban oak forest, agriculture field and bare area) and analysed the forest influence on local winter and summer climate according to forest type, soil type, slope orientation, tree height and diameter at breast height by using RBD design. Seasonal and diurnal variations in microclimatic variables viz., air temperature, soil temperature, relative humidity, wind speed and wind direction were measured with Portable weather station (Delta T) at afternoon 2:00-4:00 PM fortnightly in each forest ecosystem and bare area during winter and summer season. Solar radiation and albedo were measured with Pyranometer (Kipp and Zonen)at 1.35 m height. A significant decrease was attained in below forest canopy and bare area data for ambient temperature (2.5-5.0^oC),土壤温度erature (1.5-3.6^oC) solar radiation (13.2-47.4 Wm^-2), albedo (0.15-0.21) and increased relative humidity (7-18%), soil moisture (8.0-15.2%). Among different forest ecosystem, the diurnal trends in microclimatic parameters showed large variations. The ambient air temperature ranged from 02.2-16.3^oC and 14.2- 30.7^oC where as soil temperature ranged from 07.4- 16.5^oC and 15.4-32.7^oC, however relative humidity ranged from 37- 88 per cent and 14-60 per cent among different forest ecosystem during winter and summer seasons, respectively. Mico-climatic variables under Ban-Oak forest revealed significant lowest air temperature, highest relative humidity and less wind speed.