Between Land and Sea: Livelihoods and Environmental Changes in Mangrove Ecosystems of Senegal

Abstract

Unlike the global trend, the area of mangrove forest increased in the estuaries of Low Casamance and Sine-Saloum, Senegal, between 1986 and 2006. We collected multisource data (social and spatial) and applied a mix of qualitative and quantitative analytical methods to investigate the human–mangrove interactions during this period and to understand the causes of the observed increase. Our research demonstrates that, after several decades of drought, the wetter conditions of recent years were the main determinant for the increase in mangrove area. Results, however, suggest that the increase in mangrove forest is not per se an indicator of sustainability and that the increase likely masked a decline in the capacity of these mangrove forests to provide key ecosystem goods and services. The surveyed communities clearly perceived a diverging trend between the increase in area and the decline in the productivity of mangrove forests. The increasing and unregulated pressure on mangrove-based fisheries and unsustainable practices such as the extensive use of mangrove wood for fish smoking heavily contributed to the perception of the qualitative degradation in these mangroves. As local livelihoods are intimately linked to the productivity of these mangrove ecosystems, policy interventions should integrate the social and environmental components of mangroves to ensure the sustainability of these human–mangrove coupled systems.

A diferencia de lo que muestra la tendencia global, el área de manglares de los estuarios del Bajo Casamance y Sine-Saloum, Senegal, se amplió entre 1986 y 2006. Recogimos datos de múltiples fuentes (sociales y espaciales) y aplicamos una mezcla de métodos analíticos cualitativos y cuantitativos para investigar las interacciones sociedad humana–manglar durante este período con el propósito de comprender las causas del incremento observado. Nuestra investigación demuestra que, después de décadas de sequía, las condiciones más húmedas de años recientes fueron el principal determinante del aumento del área de manglares. Los resultados, sin embargo, sugieren que el incremento de los bosques de mangle no es por sí mismo un indicador de sustentabilidad y que el incremento disfrazó muy bien una reducción en la capacidad de aquellos bosques para producir bienes y servicios ecosistémicos claves. Las comunidades estudiadas claramente percibieron una tendencia divergente entre el incremento en área y la declinación de productividad en estos bosques. La presión creciente y no regulada sobre las áreas pesqueras asociadas con el manglar y las prácticas insostenibles, tales como el uso extensivo de la madera de mangle para ahumar pescado, contribuyeron fuertemente a la percepción del deterioro cualitativa de estos manglares. En la medida en que los medios de vida locales están ligados a la productividad de los ecosistemas de manglar, la intervención política debería buscar la integración de los componentes sociales y ambientales de los manglares para asegurar la sustentabilidad de estos sistemas humano-manglar acoplados.

Key Words:

• human–environment interactions
• integrated analysis
• qualitative degradation
• spatial increase

关键词:

• 人与环境的相互作用
• 综合分析
• 质量上的退化
• #x7A7A;间增加

Palabras clave:

• interacción humano–ambiental
• análisis integrado
• degradación cualitativa
• incremento espacial

Acknowledgments

The research supporting this study was made possible with the financial support of the Joint Research Centre of the European Commission. The authors would like to thank Tidiane Sane and Ngor Ndour for their invaluable support during field work. We are especially grateful to the four anonymous reviewers for thoughtful comments and to the editor Karl Zimmerer for suggestions and guidance.

Notes

1. In Sine-Saloum, an ancient Serere saying states, “No household can have a decent life without having a migrated member” (Fall 1991, 147).

2. Mangrove-swamp rice is one of the five types of rice ecologies defined by the West African Development Association.

3. On average, fifteen persons belonging to all professional categories associated with the uses of mangrove resources attended the interviews. Sex and age composition was well balanced in the groups, although women were less represented in the interviews toward the end of field work because they were harvesting rice fields. The survey lasted approximately two months (November and December 2006). The local staff of the International Union for the Conservation of Nature (branch of Sokone) in Sine-Saloum and a local association of enumerators and sociologists in Low Casamance helped with pretesting the questionnaire, translating it into the local languages, and facilitating the interviews. A geographer and socioeconomist from the CSE of Dakar also accompanied us during the entire survey.

4. We used the ArcGIS software for spatial analyses.

5. We analyzed livelihood as a multifaceted concept that represents more than just income as it encompasses the social institutions, the gender relations, as well as the access to, and the benefits derived from, social and public services (Ellis 1998, 2000).

6. To construct this index we divided the years of existence (as reported in the interviews) of the main primary school by a coefficient ranging from 1 to 1.8 with an interval of 0.2 points according to the distance between the school and the village center. For instance, the index of accessibility for a school located 2 kilometers from the village center and existing for the last thirty years is 30 divided by 1.2, thus 25. Larger values indicate better access to primary schools.

7. We tested the independence of irrelevant alternative (So and Kuhfeld 2005) through the likelihood ratio (LR) test. This compares the log likelihood from the reduced model with the full model that takes into account the interactions across the independent variables. The difference between the model without cross-interactions and the full model is not statistically significant (p> 0.05). Hence, the cross-interactions between the independent variables do not influence the predictive capacity of the reduced model.

8. We gathered anecdotal evidence of this destructive practice. While navigating for our interviews in the wide Saloum River, we crossed a large pirogue of local fishermen using this net and they all jumped into the water and hid behind the pirogue for fear of being recognized.

9. National law 98–32 of 14 April 1998—Code on Maritime Fisheries.

10. In this respect, the diversity of local institutions and committees that developed in Sine-Saloum to control access to fishery resources (e.g., the comites de vigilance and comites de plage, literally vigilance and beach committees) is likely better equipped to ensure a sustainable use of resources (Curran and Agardy 2002; Janssen et al. 2006) compared to Low Casamance, where these forms of organization were lacking. Interesting indications in the development of local organizational forms within the artisanal fisheries can be found on the Development Gateway Web site of Senegal (in French), in the section “Maritime Economy” (http://www.senegaldeveloppement.org, last accessed 2 November 2010).