Effect of Gap size on the survival and growth of forest species (Case study: Researching Forest of the UPM University)

This study was carried out in the researching forest of the UPM University of Malaysia. In order to enrichment the forest artificially and in four different ways, make artificial gap in four 1 ha (100×100) plot. 9 micro plots 10m×10m made in 2 plots and 5 micro plots 10m×10m and 20m×20m in 2 other plots, totally 28 micro plots. In these micro plots was planted far from others in 2.5m×2.5m, seedlings of 3 species of Shorea assamica, Shorea platyclados, and Mersava anisoptera, (totally 812 seedlings). Species, number, diameter, length of stem with out branches, length, diameters of crown, survival percentage of seedlings and light intensity in each micro plot was recorded. The light intensity classified in 3 classes (Class 3: 17% - 23%, Class 2: 10% - 17%, and Class 1: 4% - 10%). Results showed that seedlings which are in Class 2 of light have more Height and Diameter growth and have more Chances of survival. M. anisoptera had the highest survival rate, and S. assamic had the less. M. anisoptera had the highest diameter growth and S. platyclados had the less. In Class 2 and 3 the diameter growth was more than in Class 1. S. platyclados had the highest growth rate in Class 2, and S. assamic had the fewer rates in Class 1. The S. platyclados had the highest crown diameter, and the S. assamica had the less. Crown diameter in Class 2 and 3 are the same and was the maximum rate, and in Class 1 had the minimum rate. M. anisoptera had maximum stem length and S. assamica had minimum and in different Light Classes had non-significant. Interaction between species and Light class had non-significant effect on height and diameter growth and had significant effect on crown diameter and stem length.