نوع مقاله : مقاله پژوهشی
نویسندگان
عضو هیات علمی مرکز تحقیقات کشاورزی و منابع طبیعی مازندران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The inadequate production of existing poplar cultivations can be due to unfavorable planting, maintenance and harvesting operations. In order to clarify the defects in the above operations, in the 30 stands of poplar trees, the diameter, height, wood volume and wood volume growth per hectare and year were measured and calculated. Then some information including primary planting spacing, existing tree number per hectare, etc. were determined by field survey. In path analysis, the causal and noncausal relationships between the independent variables and the volume growth were determined and demonstrated the direct effects of each component on growth, along with their indirect effects on the growth. Results showed, the area of the stands varied from 0.3 to 4 hectares. In more than 60 percent of the stands, the planting spacing was less than 2 by 2 meters. In most of the stands the percentage of survival was less than 50%. Only 10% of the stands had more than 25 m3 wood per year and per hectare. Principle component analysis showed that decreasing the planting distance had the most important effect in reducing the annual growth. Irrigation intensity showed the highest positive correlation with annual growth. Also, initial density showed the highest negative correlation with diameter and height. In path analysis, initial density showed the most direct negative effect on annual growth. Irrigation intensity has the highest positive indirect effect on annual growth. According to the results, the main defects of poplar farming are low spacing and more irrigation intervals, respectively.
کلیدواژهها [English]
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