Conservation of soils in culturally protected woodlands in rural Hong Kong

Abstract

This study evaluates the soils in culturally protected woodlands which are remnant wooded pockets in the rural hinterland of Hong Kong, aiming at gauging their conservation status under the woodland aegis and human imprints. Nine villages with fengshui (traditional geomancy belief) woodlands were chosen for differences in topography and parent materials, and at each site two soil pits, respectively, at a high and mid-slope positions were excavated. Besides evaluating profile morphology, 13 physical and 15 chemical properties were selected for laboratory analysis. Most soils are well developed with the full complement of horizons echoing humid subtropical pedogenesis. Organic matter, and the associated nitrogen and phosphorus, are lower than the norms for comparable soils of undisturbed forests. Aggregate stability results indicate weak macro-scale ped strength, but micro-aggregation is strong and significantly correlated with free Fe and Al, and to a lesser extent to carbon. Bulk density is correlated positively with sand and negatively with both silt and clay; it is lower in the topsoil due to structural organization by physicochemical and biotic processes. CEC and base saturation are low, reflecting the meager organic matter and clay of kaolinitic type. Free Fe and Al and total Ti are relatively high, indicating humid tropical pedogenetic processes of relative accumulation resulting from advanced mineral breakdown and loss of weatherable and mobile constituents. The management implications in the context of woodland conservation and fostering of woodland succession are explored. © 2002 Elsevier Science B.V. All rights reserved.