Spatial variation in litter production by the mangrove Avicennia marina var. australasica in Rangaunu Harbour, Northland, New Zealand

Litter fall was measured at two intertidal levels within two stands of the mangrove Avicennia marina (Forsk.) Vierh. var. australasica (Walp.) Moldenk e in Rangaunu Harbour, New Zealand (34 degrees 57'S, 173 degrees 15'E). The seasonal pattern of litter fall was typical of A. marina at high latitudes . Flowering occurred in March-April and fruit fell 9 months later during De cember-January. Leaf fall was highest from November to February and was pos itively correlated with temperature and negatively correlated with sediment water availability (total rainfall minus total evaporation). Total annual litter fall ranged from 1.8 t ha(-1) yr(-1) to 6.2 t ha(-1) yr(-1) and was proportional to mean tree height at each site. Leaves constituted on averag e 73% of the total litter fall and were the only litter component to show s ignificantly lower magnitude at both elevated sites. The largest litter col lections were made during the summer months coincident with peak falls of l eaves and fruit. The possible contribution of mangrove litter to estuarine food chains in northern New Zealand estuaries is discussed.