THE EFFECTS OF STORMS AND SEA-LEVEL RISE ON A COASTAL FOREST MARGIN IN NEW-BRUNSWICK, EASTERN CANADA

Sea-level rise and storms cause a progressive landward shoreline displ acement along the coast of the Gulf of St. Lawrence in eastern Canada. Forest edges exposed to the sea tend to decline rapidly. The progress ion of an erosion scarp into a forest margin caused severe disturbance s that were dated by dendrochronology. The dates of formation of react ion wood, narrow ring sequences and tree mortality indicated major dis turbances in 1923, 1930, 1938, 1940, 1951, 1959, 1962, 1963, 1971, 197 4, 1976, 1977, 1986, 1987, 1988 and 1989, that are related to storms. Sea-level rise leads to the landward displacement of the disturbance z one, causing the forest edge to regress. It is suggested that the fore st decline in sites lying close to sea level, but protected by sand ba rriers, is due to increasing soil water table associated with sea-leve l rise. According to site microtopography, the stress zone progressed landward into the forest. By crossdating ring-width series from dead t rees with those of adjacent living trees, the progressive landward dis placement of mortality is estimated to a rate of 3 m/yr horizontally ( vertical average: 1.24 cm/yr with a slope <5%) during the 1985-1991 in terval (I tree/160 m(2)/yr). Results highlight the indirect effect of sea-level rise on a tree margin distance of 450 m from water edge.