Forests are one of the most significant carbon pools in terrestrial ecosystems. Forests store carbon not only in the tree biomass that composes them but also in pools such as dead wood, litter, and soil. Similarly, vegetation elements, which are components of forest ecosystems and are referred to as understory in forestry practice, are also constituents of the forest ecosystems' primary living biomass pool. On the carbon accumulation in forest ecosystems in Türkiye a substantial number of studies have been or are being conducted but this is still insufficient. However, the vast majority of these studies involve tree biomass (particularly above-ground biomass). Some subsequent studies have focused on carbon in litter and soil. But as stated previously, studies attempting to ascertain the amount of carbon stored in the understory biomass, which is a component of the living biomass pool and a part of the forest vegetation, are almost nonexistent. Consequently, the aim of this study is to determine the carbon concentrations of the shrub part of the vegetation on a coastal dune (Durusu (Terkos) Sand Dune) that had zero carbon stock prior to 60 years ago afforestation. During the biomass inventory of the maritime pine and stone pine plantations in Durusu Sand Dune, the carbon content of the shrub species was determined by collecting samples from a total of 18 sample plots. Both the above- and below-ground portions of the plants were sampled independently for shrubs. During the inventory investigations, the following species of shrubs were identified: arbutus (Arbutus unedo), heather (Erica arborea), cistus (Cistus creticus), laurel (Laurus nobilis) and broom (Sarathommus scoparius). Using the LECO TruSpec 2000 C/N Analyzer, the carbon concentrations of the leaves, branch/stem wood and root organs of these shrub species were determined via the dry burning method. The carbon contents of the leaf, branch/stem wood, and root components of arbutus species were measured and found to be 48.37%, 47.77%, and 47.47%, respectively. The carbon contents in heather species were found to be 51.62%, 50.26%, and 50.64%, while in laurel species, they were revealed to be 51.27%, 48.43%, and 48.28%. The carbon factors of the three biomass components in the broom species are 48.59%, 47.54%, and 48.98%, respectively. The present study investigated the biomass components of the cistus species, specifically classifying them into above-ground and below-ground categories. Additionally, carbon ratios were found for these components. The carbon ratio of the above-ground organs of the cistus species was found to be 48.96%, whereas the carbon ratio of the below-ground organs was determined to be 47.97%.