Allometric equations for estimating above and below-ground carbon storage of four broadleaved and coniferous trees

Considering the climate change and global warming topics, importance of tree biomass and its measurement is increasing. Direct biomass measurement, especially for root section, is very costly, time consuming and difficult to implement. Usually, in such cases biomass can be estimated, using allometric equation. The aim of this research was to establish equations for estimating carbon content at above and below ground and whole tree biomass for four species, including Mulberry (Morus alba), Black Locust (Robinia pseudoacacia), Eldar Pine (Pinus eldarica) and Arizona cypress (Cupressus arizonica) planted around Mobarakeh Steel complex. For this purpose, 15 trees for each species (totally 60 trees) with appropriate diameter and height distribution, selected randomly and fell down and cut to different segments. Then the different components were separated and total fresh weight was measured at the field. Also roots of 20 trees fully excavated and after fresh weight measurement, some samples for dry weight determination were taken. Dry weight and carbon content of each sample were measured at laboratory. Allometric relationships between independent variables and carbon storage of different components and whole tree were established by nonlinear regression analysis. Overall, 96 models were derived for the four species and only eight of them were not statistically significant. The results showed that for Pine and Cypress, DBH (Diameter at Breast Height) and for Mulberry diameter at 0.3 m established models with highest coefficient of determination at all cases. For Black Locust, there was not special variable which can establish model with high coefficient of determination in all cases. For estimating the whole above- and below ground carbon storage of different organs, tree height had the highest coefficient of determination. Generally, concerning the both above and below ground biomass, modeling allometric relationships resulted in higher coefficient of determination of modeling for coniferous rather than for broadleaved species.