The influence of seed predation and site factors on the establishment of Xylocarpus granatum, a high-value mangrove species in Micronesia.
KRAUSS, K.W.*, J.A.ALLEN and R.G.HAUFF
USDA Forest Service, Honolulu HI 96813 USA 1
Micronesians are noted for their abilities to produce high-quality wood carvings. The most preferred wood for this economically important industry is produced by the mangrove species, Xylocarpus granatum. X. granatum is distributed throughout the Old World tropics, yet little is known about factors influencing its regeneration and early establishment. Here, we report on a study installed on Kosrae, Federated States of Micronesia, to quantify seed predation by crabs, and survival and growth of seedlings in relation to intertidal location and light level. These are believed to be among the most important factors influencing mangrove species distribution. Cumulative seed predation by crabs among all locations after 34 days was 22% but was not significantly different among intertidal locations. Likewise, predation within a particular intertidal location did not differ significantly under the canopy or in the gap. Yet, establishment of seedlings at both 73 days and 161 days averaged 40% in the upper intertidal locations, which is where most Xylocarpus are found, and only 2.3% in middle and lower intertidal locations. This study suggests that crabs are not the major factor affecting seedling establishment among contrasting intertidal locations. However, along with data from two complementary studies, this investigation indicates that seedling establishment and early growth are influenced more by physiochemical conditions, including salinity and light, and possibly by dispersal characteristics of the seed and/or leaf herbivory on established seedlings.
Keywords: wetlands, estuary, mangroves, regeneration, forest ecology, Pacific islands, Kosrae, Federated States of Micronesia
This abstract is being presented at: 1:45 PM in session:
Oral Session #18: Mangrove Ecology.