- Implications of mangrove dynamics for private land use in Bragança - 97 Journal of Coastal Conservation 8: 97-102, 2002 © EUCC; Opulus Press Uppsala. Introduction Mangroves, as other coastal wetlands, are consid- ered highly susceptible to sea-level rise (Gornitz 1991; Boorman 1999). Their extent is governed by tidal expo- sure and depends on the balance between sea level and sediment accumulation (Chapman 1960). Thus, a rela- tive sea-level rise can result in both a mangrove retreat near the shoreline and a landward migration as a result of the increase in inundation frequency (Hanson & Maul 1989). Similarly, inland vegetation on elevated mud flats undergoes adjustment in its boundaries, since man- groves migrate to higher locations and invade these areas (Cohen unpubl.). The Brazilian coast possesses the world’s second largest mangrove region, estimated to cover a total area of 1.38 million ha along a coastline of approximately 6800 km (Kjerve & Lacerda 1993). The most exuberant mangrove habitats are found in North Brazil, where similar geomorphological features caused the develop- ment of analogous biological units with a common fauna and flora and similar patterns of resource exploi- tation (Szlafsztein et al. 2000). Tide records obtained over the last 50 yr show a general rise in relative sea level along the Brazilian coast; Pirazolli (1986) reported a rising trend at four locations for the period 1950-1970. Studies in the South- east region also indicate a rise since 1960 (Mesquita & Harari 1983; Mesquita & Leite 1985; Silva & Neves 1991; Silva 1992). Based on a time span of ca. 20 yr ending in 1968, Aubrey et al. (1988) reported rates of relative sea-level rise along the Brazilian coast from 0.3 to 3.6 mm/yr. Muehe & Neves (1995) indicated that the high tidal amplitude and the low gradient of the rivers in North Brazil makes them particularly sensitive to sea-level rise. This would significantly increase the tidal propaga- tion into rivers, probably influencing their sediment budget and salt content. Large-scale destruction of man- groves at the oceanic front in North Brazil and French Abstract. This work analyses effects of recent variations in the tidal inundation frequency in a mangrove ecosystem in the Bragança peninsula, North Brazil, and its implications for land occupation and use. Field data, time series of remote sensing images and local legislation were analysed focusing on the potential socio-economic impact of a changing environmental setting due to a rise in relative sea level. In the investigated period (1972-1997), vegetation changes along the coastline indicate net losses of mangrove coverage. In the central part of the peninsula, a topographically higher herbaceous plain con- stituting part of a farm presents an active progression of mangrove forest into an area previously dominated by grasses and herbs. This area measured 8.8 km 2 in 1972 but was gradually reduced to 5.6 km 2 in 1997, while progressively replaced by a monospecific stand of the black mangrove, Avicennia germinans. A linear extrapolation indicates that the elevated plain may be completely covered by mangrove by 2035. Current Brazilian legislation prohibits the extraction of mangrove trees without an officially approved management plan. Thus, the usable area of the farm has suffered a reduction by ca. 36% over 25 yr and we predict that it could be entirely replaced by mangroves in the next 35 yr. In this case study, legislation and ecosystem characteristics are analysed and a management plan discussed which could represent income alternatives for affected resource users at the local and re- gional level. Keywords: Avicennia germinans; Legislation; Sea-level rise; Wetland. Abbreviation: GPS = Global Positioning System. Implications of mangrove dynamics for private land use in Bragança, North Brazil: a case study Lara, Rubén 1* ; Szlafsztein, Claudio 2 ; Cohen, Marcelo 2 ; Berger, Uta 1 & Glaser, Marion 1 1 Zentrum für Marine Tropenökologie, Fahrenheitstr. 6, 28359 Bremen, Germany; 2 Laboratorio de Dinámica Costeira, Universidade Federal do Pará, Avda. Perimetral 2651, 66077-530 Belém, Pará, Brazil; * Corresponding author: E-mail belmadam@supridad.com.br