Determination of soil-related factors controlling initial mangrove (Rhizophora apiculata BL.) growth in an abandoned shrimp pond

Abstract

To elucidate factors contributing to plant growth in a mangrove plantation, the height of mangrove trees (Rhizophora apiculata BL.) was measured in addition to relative ground level and soil properties in an abandoned shrimp pond in Thailand. Tree height was measured at 1,853 points in the 25 ha experimental site. Soil was sampled from 74 points and physical (hardness, water content) and chemical (e.g. total C and N) properties were determined. The mean tree height of 58.3 cm was relatively small for 2-year-old trees, and varied considerably with a coefficient of variation of 32.4%. The relatively low total C content of the soil, 0.68 × 10−2 kg kg−1, indicated a decline in organic matter content during the conversion from mangrove into shrimp pond. The negative correlation of tree height with relative ground level (P < 0.01) suggested that better growth was observed at a lower area. The important role of soil properties in determining tree height was demonstrated. By combining geostatistics with multivariate analysis, as much as 90% of the spatially structured or non-random variation of tree height was explained by taking into account soil properties in addition to topography. Together, the results suggest that site-specific management, such as site-specific organic matter application, is a feasible and effective option for mangrove rehabilitation.