Yaser Mohammadi1, Jahangir Mohammadi *1, HamidReza Riyahi Bakhtiyari2, Shaban Shataee Jouibary1, Ramin Rahmani1
1- Gorgan University of Agricultural Sciences and Natural Resources
2- Shahrekord University
2- Shahrekord University
Abstract: (161 Views)
Background and Objective: Transitions between developmental stages in forest stands are often accompanied by shifts in intra-stand competition and changes in key structural attributes such as Leaf Area Index (LAI), stand volume per hectare, basal area per hectare, and tree density. Understanding these structural dynamics from the initial stage through maturity to degradation is essential for restoring ecosystem functionality in disturbed forests. Evaluating these attributes across developmental stages provides insight into the ecological processes governing natural forest dynamics. Structural changes not only reflect internal stand interactions and competitive relationships but also serve as indicators of ecosystem health and resilience to stressors. Analyzing these changes within the framework of forest succession—particularly in Caspian forests like Shast-Kalateh—plays a critical role in shaping effective management and restoration strategies. Accordingly, this study aimed to assess and compare quantitative structural attributes including LAI, volume per hectare, basal area per hectare, and tree density across three developmental stages: initial, peak, and degraded.
Materials and Methods: The study was conducted in series one and two of the Shastkalateh forest management plan in Gorgan. A systematic sampling grid with a random start (200 × 150 m) was established, and data on diameter at breast height, species type, and height of selected trees were collected from each sample plot. Additionally, a litter trap (60 × 60 cm, 20 cm deep) was installed in each plot to collect leaves over one year. The collected leaves were transferred to the laboratory, where specific leaf area and dry leaf weight were calculated by species and for all species combined per plot. Furthermore, volume per hectare, basal area per hectare, and number of trees per hectare were calculated for each plot. The developmental stage of each plot was determined using the structural triangle method. The total LAI, species-specific LAI, volume per hectare, basal area per hectare, and number of trees per hectare were compared across the initial, optimal, and decay stages using analysis of variance (ANOVA) and Duncan’s test.
Findings: Descriptive statistics revealed that total LAI values for the initial, peak, and degraded stages were 6.09, 7.07, and 5.85 respectively, with the peak stage exhibiting the highest LAI. The highest species-specific LAI in the initial and degraded stages was observed in Carpinus betulus (2.44 and 2.33), while Parrotia persica showed the highest LAI in the peak stage (3.28). Standard deviations for volume, tree density, and basal area per hectare were 84.5, 33.52, and 12.41 (initial); 95.6, 40.06, and 9.59 (peak); and 102.5, 28.13, and 6.39 (degraded). LAI standard deviations were 3.52, 4.11, and 2.19 respectively. Duncan’s test indicated no significant differences (P > 0.05) in total LAI, LAI of Fagus orientalis and Parrotia persica, tree density, and basal area across stages. However, significant differences (P < 0.05) were found in LAI of Carpinus betulus, Carpinus orientalis, and stand volume.
Conclusion: The study demonstrated that structural attributes such as LAI, stand volume, basal area, and tree density undergo substantial changes across developmental stages. These variations reflect ecological dynamics including competition, mortality, and regeneration. Recognizing these patterns is vital for understanding forest ecosystem performance and for designing targeted restoration strategies, especially in degraded stands. The findings offer valuable guidance for forest managers and planners in selecting stage-specific interventions to enhance sustainability, biodiversity, and ecosystem services in semi-natural and disturbed Hyrcanian forests
Materials and Methods: The study was conducted in series one and two of the Shastkalateh forest management plan in Gorgan. A systematic sampling grid with a random start (200 × 150 m) was established, and data on diameter at breast height, species type, and height of selected trees were collected from each sample plot. Additionally, a litter trap (60 × 60 cm, 20 cm deep) was installed in each plot to collect leaves over one year. The collected leaves were transferred to the laboratory, where specific leaf area and dry leaf weight were calculated by species and for all species combined per plot. Furthermore, volume per hectare, basal area per hectare, and number of trees per hectare were calculated for each plot. The developmental stage of each plot was determined using the structural triangle method. The total LAI, species-specific LAI, volume per hectare, basal area per hectare, and number of trees per hectare were compared across the initial, optimal, and decay stages using analysis of variance (ANOVA) and Duncan’s test.
Findings: Descriptive statistics revealed that total LAI values for the initial, peak, and degraded stages were 6.09, 7.07, and 5.85 respectively, with the peak stage exhibiting the highest LAI. The highest species-specific LAI in the initial and degraded stages was observed in Carpinus betulus (2.44 and 2.33), while Parrotia persica showed the highest LAI in the peak stage (3.28). Standard deviations for volume, tree density, and basal area per hectare were 84.5, 33.52, and 12.41 (initial); 95.6, 40.06, and 9.59 (peak); and 102.5, 28.13, and 6.39 (degraded). LAI standard deviations were 3.52, 4.11, and 2.19 respectively. Duncan’s test indicated no significant differences (P > 0.05) in total LAI, LAI of Fagus orientalis and Parrotia persica, tree density, and basal area across stages. However, significant differences (P < 0.05) were found in LAI of Carpinus betulus, Carpinus orientalis, and stand volume.
Conclusion: The study demonstrated that structural attributes such as LAI, stand volume, basal area, and tree density undergo substantial changes across developmental stages. These variations reflect ecological dynamics including competition, mortality, and regeneration. Recognizing these patterns is vital for understanding forest ecosystem performance and for designing targeted restoration strategies, especially in degraded stands. The findings offer valuable guidance for forest managers and planners in selecting stage-specific interventions to enhance sustainability, biodiversity, and ecosystem services in semi-natural and disturbed Hyrcanian forests
Keywords: Initial stage, optimal stage, decay stage, volume per hectare, number of trees per hectare, basal area per hectare, Hyrcanian forests.
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