Climate is the prime factor that influences forest growth, composition and distribution. There are many ways to determine forest productivity in terms of climatic factors like temperature, precipitation, length of growing season, effective sun hour etc. When edaphic and topographic factors remain constant, climatic factors become more prominent for forest growth and productivity. Among many methods of assessment of forest productivity, Paterson's Climate Vegetation Productivity (CVP) index-requires less efforts and fieldwork to determine productive potential of any forest land. The index is not stand and species specific, hence, it can be put in use for overall assessment of the forest and vegetation productivity in any country, region and continent or even for the globe. This index may be used for comparison of forest lands, even non-forested lands with higher index value that may be established as a productive forest.

Elevated temperature has positive and/or negative effects on seedlings of forest trees. Aim of the study was to compare the impact of three higher temperature conditions with control temperature to Gmelina arborea Roxb. (family: Verbenaceae) seedlings growing in a plant growth chamber. Similar sized seedlings randomly selected from same origin were treated with three elevated temperature (30/20, 32/22 and 34/24°C) and compared with control temperature (26.31/16.54°C) at a day/night combinations. Measurements were made for height, collar diameter and increase or decrease of leaf number of the studied seedlings during the observation period. Seedlings height growth was found positive for the examination period rather favourable to elevated temperature conditions than control. Seedlings grown at three successive elevated temperatures showed significantly (p#0.05) higher growth than control temperature. However, collar diameter growth was found insignificant with respect to temperature treatment and days. Number of leaves development was found negatively responded to elevated temperatures. With successive elevated temperature, leaf shedding increased significantly which might be due to maximum thermal entropy given to plants. Thus, elevated temperature might increase seedlings shoot height significantly, where, leaf number might negatively react; leading them to a long seedling with less leaves.