Negin Behnia, Sayed Yousef Erfanifard, Sayed Rashid Fallah Shamsi, Sayed Aliakbar Moosavi,
Volume 2, Issue 2 (3-2016)
Abstract
The aim of this study was to assess the efficiency of cokriging method in comparing to kriging to map biophysical properties of wild pistachio trees in Zagros forests. A 45 ha stand, covered with wild pistachio trees was chosen in FiroozAbad wild pistachio research site in Fars province. 87 circular plates with 800 m2 area were selected based on a 72 × 72 m2 grid. Biophysical properties (height, diameter at breast height, trees per ha, and canopy cover percent) of all wild pistachio trees were measured in each plot. Kriging and cokriging methods were then used to map each biophysical property. The results showed that mean error and root mean squared error of height, diameter at breast height, and trees per ha of cokriging method were less than kriging method. The regression coefficients of height, diameter at breast height, and trees per ha of cokriging method were also greater than the kriging method that showed the efficiency of the cokriging method in the improvement of estimation of trees’ biophysical properties. The amount of root mean squared error and regression coefficient were slightly better for canopy cover percent in kriging, though, they were not significant. In general, it was concluded that the maps of biophysical properties can be obtained with suitable accuracy and precision using Cokriging method.
Ms Elham Fazeli, Mr Asghar Fallah, Mr Morteza Shabani, Mr Mahya Tafazoli,
Volume 5, Issue 1 (9-2025)
Abstract
Extended Abstract
Background and Objectives: One of the most important factors of global warming is the phenomenon of illegal emission of greenhouse gases; The most important of which are nitrogen dioxide (NO2), carbon dioxide (CO2), and methane (CH4). However, due to the large amount of carbon dioxide accumulation in the atmosphere, this gas is one of the key gases in the phenomenon of global warming. Therefore, to reduce atmospheric carbon dioxide and balance the content of greenhouse gases, atmospheric carbon must be absorbed and deposited in various forms. Urban forests have a high capacity to absorb atmospheric carbon dioxide and provide many environmental services in urban areas. Therefore, it is necessary to obtain correct and accurate information in this regard to optimally manage these forests in increasing carbon sequestration. This research aimed to estimate the amount of carbon stock of the urban forest in Sari City, the capital of Mazandaran province.
Materials and methods: This research Using selective sampling, 150 samples were taken (50 samples in each region) and an effort was made to distribute these samples in the three regions. First, the information related to the general characteristics of each of the samples, including the height above sea level, the slope, and the direction of measurement, were recorded. In each sample plot, species type, breast diameter, height, and small and large crown diameters of all trees were measured, and the number of each tree and shrub species was counted and harvested. The center of each sample and measured tree was recorded with a GPS device and transferred to the GIS software environment. After calculating the carbon sequestration of trees, the relationship between diameter and carbon sequestration was investigated using linear regression in SPSS software version 21. Then, a carbon sequestration zoning map was prepared in all areas of Sari using the conventional kriging method and in GS+ software.
Results: The highest and lowest amount of carbon sequestration of trees was observed in areas one (60.95 ± 31.10 tons per hectare) and three (13.68 ± 3.84 tons per hectare) of Sari city, respectively. Variance analysis of diameter and carbon deposition relationships showed that linear and power regression models were significant. The evaluation results of the linear regression model (R2=0.74) and power (R2=0.97) showed that both models are highly accurate in estimating carbon deposition on the ground of trees. According to the results, the highest potential of carbon sequestration was observed in the northeastern part and located in an area of Sari.
Conclusion: In this research, a high amount of carbon sequestration was observed in the city of Sari. It can be said that the main reason for the high amount of carbon deposition in Sari city is that, most of the trees in the green space of Sari city are old plane trees The reason for the high level of carbon deposition of the plantain tree is the high density of its wood compared to other trees. In general, young trees have a higher amount and speed of carbon deposition than old trees, but old trees also deposit carbon in a larger amount and for a longer period. Obtaining the results that the trees of Sari city can absorb 200 tons of carbon per hectare is remarkable and promising. Prioritizing the preservation and growth of larger and older trees in urban environments may have significant results for carbon sequestration. At the same time, examining the temporal dynamics of carbon sequestration, combining other environmental variables, or modifying the spatial resolution of the analysis can further increase the accuracy of carbon sequestration estimation. Therefore, obtaining more information in this direction is necessary and necessary.
