An Assessment of the Effectiveness of Mangrove Restoration Projects Along the Kenyan Coast

Abstract

Kenya has made several initiatives to support restoration of lost and degraded mangrove forest areas along the coast. The initiatives have involved both mangrove reforestation and natural regeneration. This study investigated the effectiveness and the outcome of mangrove restoration programs along the Kenyan coast. It mapped the location of the project sites, areal extent, and evaluated success indicators, underlying challenges, and community perception towards mangrove restoration. The study adopted vegetation and social survey methods. Square plots of 10 x 10m were randomly established on reforested areas in order to assess the growth performance of replanted mangroves. Purposive sampling was used in questionnaire administration for social surveys. Arc GIS software was used to develop a geolocation map; whilst MINITAB software and Shannon Wiener diversity index (H) formula were used for statistical and diversity analysis, respectively. Statistical Package for Social Sciences (SPSS) software was employed for analysis of social survey data through descriptive statistics. A total of 107 respondents including 7 key informants were interviewed. A total of 19 project areas with a total of 53 replanted sites were surveyed; translating to an estimated area of 93.5 ha of replanted mangroves. Rhizophora mucronata and Ceriops tagal were the most preferred mangrove species reforestation. The survival rate of surveyed plantations ranged from 0 – 97.8% (mean 55.4±31.2%). Sites with high survival rates (>80%) included Mikindani, Jomvu Kuu, and Pate, while some sites in Mwache, Kiwegu, Jimbo recorded more than 90% mortality. Failure of restoration success was attributed to species mismatch, change in site conditions as well as biophysical disturbances while successes saw the application of best practices and good governance. Stocking rates of 5 – 24-year-old mangrove plantations ranged from 3575 – 7825 stems/ha; with Mean Annual Increment (MAI) of height, diameter and biomass estimated of

0.34m/yr (range: 0.11 – 0.57m/yr), 0.35cm/yr (range: 0.12 – 0.52cm/yr) and 5.96t/ha/yr (range: 2.02 – 15.67t/ha/yr) respectively. Natural recruitment in reforested areas ranged from 175 – 7150 saplings/ha (mean: 2081 saplings/ha) while the biodiversity index (H) of macrofauna (crabs and mollusks) was between 1.60 – 1.87. Ecological and economic benefits were the main factors that motivated local communities to participate in restoration activities. To ensure future restoration success, this study emphasizes the need to apply principles of ecological mangrove restoration, strengthen stakeholders’ participation, incentivize restoration activities as well as promote long-term monitoring of replanted mangrove sites. This will accelerate the achievement of the local and national priorities of the United Nations Decade (2021-2030) on Ecosystem Restoration.