Soil properties of mangroves in contrasting geomorphic settings within the Zambezi River Delta, Mozambique
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Mangroves are well-known for their numerous ecosystem services, including sequestering a significant carbon stock, with soils accounting for the largest pool. The soil carbon pool is dependent on the carbon content and bulk density. Our objective was to assess the spatial variability of mangrove soil physical and chemical properties within the Zambezi River Delta and determine whether it may be associated with geomorphic setting. Plots were classified as one of four geomorphic settings: seaward fringe, creek, riverine, and interior. Additionally, we attempted to determine the source(s) of organic matter contributing to the soil carbon pool and any associated spatial variability therein. Many statistically significant differences were shown with depth and setting. However, variability of the measured characteristics was low when compared to other mangrove settings. Mean carbon concentrations ranged from 1.38 to 2.38 % C and mean bulk density values ranged from 0.75 to 1.02 g cm−3. Stable isotopic signatures showed that the organic matter is likely a mix of mangrove and marine sources, with mangrove-derived sources contributing 42–58 %.
KeywordsBlue carbon Forested wetland Organic matter Soil carbon Soil nitrogen Zambezi River Delta
Denise Nicolau, Itelvino Cunat, and Rito Mabunda provided invaluable logistical support during the planning and implementation of field missions. Célia Macamo and Salamão Bandeira assisted prior to, and during field work, with identification of mangrove and other plant species. The staff of the Soils Lab at Universidade de Eduardo Mondlane processed the soil samples. Julie Arnold and Artheera Bayles at the USFS Center for Forested Wetlands Research assisted with soil carbon analyses. The success of this project would not have been possible without the hard work and dedication of the 2012 and 2013 mission field crews. This work was made possible by US AID support to the USFS under the US AID Mozambique Global Climate Change Sustainable Landscape Program, in collaboration with the Natural Resource Assessment Department of the Government of Mozambique. Three anonymous reviewers also provided thorough reviews and thoughtful suggestions that greatly improved the manuscript.
USDA Forest Service, USAID.
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