<i>Acacia trotilis</i> and <i>Calotropis procera</i>: Do They Substantially Promote Soil Carbon Sequestration?

Abstract

Very little is known about the type and mix of desert plant species and their management to optimize carbon sequestration in desert ecosystems. Overgrazing is one important practice that affects soil carbon cycling and therefore sequestration. Improving soil carbon in desert ecosystems may be best through the use of native trees and shrubs. Acacia tortilis and calotropis procera are two important species in the United Arab Emirates (UAE). The former is a native species that improves biodiversity and the latter is not native and has been reported to be an indicator of overgrazing. The average soil organic matter (SOM) content was higher in soils dominated by A. tortilis when compared to those dominated by C. procera; 2.98 and 1.34; respectively (P < 0.05). Moreover, A. tortilis leaves had a higher OM content than C. procera leaves (94.1% and 90.6%; respectively). The higher OM content of A. tortilis leaves explains the higher contribution of this species to the overall soil organic matter inputs. There was also a significant effect of shrub species on total SOC (P < 0.05). A total of about 14.7 tons of SOC were added per hectare in the areas dominated by A. tortilis. While only about 6.6 tons of SOC were added to the areas dominated by C. procera. In short, it is believed that both species substantially promote soil carbon sequestration. Some significant superiority of the native A. tortilis has been shown. But much has to be done to investigate the mix of plant species that promote the best soil carbon sequestration in the desert areas. Further studies are required in order to assess temporal as well as spatial variations in soil carbon sequestration in the UAE deserts. This will certainly help, in addition to other practices, in mitigating CO 2 emission.