مجله جنگل ایران (Nov 2020)
Spatial variability of carbon storage and sequestration in leaf litter and layers of soil in the forest area of Jahannama Park
Abstract
This study was carried out to investigate the spatial variability of litter carbon storage and its sequestration in the soil layers in the forested area of Jahannama Park. First, 115 soil samples were taken from 0-15, 15-30, and 30-50 cm depths using the grid-transect sampling method. After the determination of the percentage of organic carbon, the geostatistical methods (simple kriging, ordinary kriging and inverse distance weighting methods) were used to investigate the spatial variability of carbon percentage in the non-sampled locations. The cross-validation method was used to evaluate the accuracy of the results using MARE, MBE, and RMSE statistical criteria. The results showed that the carbon content in the first two depths had a Gaussian variogram model and, in the third depth, was exponential. Nugget effect and spatial structure of carbon percentage in the first, second and third depths were 0.001%, 0.999%, 0.0045%, 0.966%, 0.0058%, and 0.956%, respectively, which shows the less nugget effect and good spatial structure of carbon in both the surface and the deep layers. Low estimation error showed that ordinary kriging was able to make the correct estimation for all of the depths. Considering the objectives of this study, in an area, about 36 hectares with a dense sampling network (115 soil profiles) with different tree stands, on average, 68.5 tons carbon sequestration per hectare has been estimated to a depth of 50 cm which is a total of 2470 tons of carbon sequestration in this area. The sampling strategy in this study to estimate the soil carbon sequestration in afforestation can be a good model for other similar areas.
