Effect of Thinning on the Quantitative and Qualitative Variables of Acer Velutinum Bioss (Case study: Berenjestanak Seri, Mazandaran Province)

Tending Operation is one of the most important methods to improve equality and quantity of forest stands. In this study, two stands including non-managed (in parcel No.2) and managed stands (in parcel No.13) at the second series of "Berenjestanak" are selected to investigate the structural followed by tending operation. Thirty hectare of each parcel was selected, the statistic method was systematic and random, the netdimensions were 100×100 m and area of each sampling plot was 4000 m. The quantitative and qualitative variables of Acer Velutinum were measured in both stands. Age plantation was 20 years old and distances of each planted trees were 2 × 2 m. Thinning method was positive selection and rotation and thinning also was 3 to5 years. Thinning intensity in each rotation was14% approximately.Thinning operations was createda suitable atmosphereto select the trees. Results of this study show that the mean number in one hectare in sample stand was1365and in managed stand were 977.The average diameter of trees increased from 13.45 cm in sample stand up to 16.40 cmin managed stand. Also the volume average in one hectare increased from non-managed (164.2 m3) up to 188.5m3 in managed stand. The stability coefficient of control stand and managed stand were estimated 105.5 and 99.4 respectively. The statistical tests showed that there was a reasonable difference between the averages of quantitative parameters of two stands in 95% confidence level and equality of averages (zero hypothesis) are rejected regarding to quality, the managed parcel trees are in better conditions comparing tosample stand trees. It is concluded that tending operation had great effects on quantity, quality and stability of stand.