Abstract
Mangrove forests in southern Iran are of high ecological and economic importance.These forests are being threatened because of uncontrolled harvesting to provide fodder for livestock.The objective of this study is to provide recommendations for appropriate harvesting intensities by quantifying the effect of different harvesting intensities on vegetative and vigor characteristics of mangrove trees.This study was conducted using a randomized complete block design comprising four treatments(10.00％,20.00％,and 30.00％trimming,along with a control)replicated three times.Vegetative characteristics were measured before and after trimming(five-year period)and analyzed using generalized linear model statistical analysis.The growths of the average diameter of canopy,canopy area,canopy volume,canopy height,tree height,and collar diameter in the control treatment were all significantly higher than those in the trimming treatments.In addition,there was a decreasing trend in leaf fresh and dry mass,leaf area index,total area of canopy leaves,and health status of tree in the trimming treatments.For example,the percentage change in fresh and dry leaf mass in the control treatment was positive(29.87％and 38.31％,respectively),whereas the trimming treatments of 10.00％,20.00％and 30.00％had negative effects(-7.01％and-4.79％,-11.32％and-14.30％,and-15.84％and-17.29％,respectively).In addition,the changes in leaf area index in the control(4.95％)and 30.00％trimming(-24.57％)treatments were the highest and lowest,respectively.The percentage change in soil organic matter in the control,10.00％,20.00％,and 30.00％treatments were 22.94％,-9.90％,-16.91％,and-18.68％,respectively.The study demonstrated that gray mangrove trees were highly sensitive to canopy trimming,with even minimal trimming intensities negatively affecting vegetative growth and soil organic matter.Therefore,it is recommended that cutting and trimming of mangrove trees should be prevented even at low intensity to preserve mangrove ecosystem health and resilience against environmental stressors.
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