Document Type : Research Paper
Authors
Department of Forestry and Forest Economics, Faculty of Natural resources, University of Tehran, Karaj, Iran
Abstract
Natural restoration of forest after harvesting operations is one of the most important goals in forest sustainability. Forestry machine traffic by considering weight, speed, and intensity have significant impact on forest regeneration and consequently, biodiversity indices such as dominance, and equitability in the plant communities of forest floor drastically influenced. The current study has been carried out in the watershed no. 45 in the Hyrcanian forest and aim to study the skidding operation effect on diversity and tree species regeneration over a long-term period. Hence, four compartments with time since harvest of 7, 10, 15, 20 year in the Kheyrud forest (compartments no. 316, 317, 220, and 221) were selected and sampled. Also, the effect of soil physical properties (porosity and peneteration resistance), pH, litter (C, N, N/N), and light under different traffic intensity (landing, low, medium, high), and its influence on biodiversity indexes using dominance, Shannon, Simpson, Margalef, and equitability were assessed. Results revealed that skidding operations had drastic effect on forest regeneration and change species composition as well as plants quantitate. Velvet maple as light-demanding species increased by 8 percent and shade-tolerant species such as beech diminished by 68 percentages, which can be considered as ecological alarm in the Hyrcanian forest. Results demonstrated that traffic intensity and time since harvest significantly influenced on forest regeneration, and also all on the environmental factors were influenced by these parameters. PCA analyses showed that soil properties including soil penetration resistance and biodiversity indexes significantly influenced by skidding operations. There was a positive correlation between litter properties, light and porosity.
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