关键词: 湖南省, 水稻土, 土壤固定态铵, 影响因素

Abstract: Forest litter has considerable eco-hydrological effects in retarding surface runoff, trapping sediment, and equilibrating soil water and heat status. In this paper, a micro-plot field experiment was conducted in a 20-year-old mountainous rubber plantation in Xishuangbanna to study the litter’s eco-hydrological effects in retarding surface runoff and reducing soil loss. In the plots with litter removal, the slope surface runoff in the period of October 2009-September 2010 was 625.7±18.5 mm, being significantly larger than that (185.1±72.7 mm) in the plots with litter remained. Under the treatment of litter removal, the sediment concentration of runoff was significantly positively correlated with the maximum intensity of an episode rainfall (within 1 h) during a day, and the gravimetric water content in surface soil (0-10 cm) at slope stands (except June and July) and terrace stands (except August) decreased significantly. Litter removal made the mean temperature at soil surface and at 10 cm soil depth increased by 0.4 ℃ and 0.3 ℃ in cool-foggy season (from November to next February) and decreased by 0.7 ℃ and 0.4  ℃ in hot-dry season (March and April), respectively. Moreover, the diurnal temperature fluctuation in the surface soil without litter covering was more drastic throughout the year. These results suggested the litter layer in mountainous rubber plantation had great effects in buffering overland flow, trapping sediment, and moderating extreme surface soil water and heat status. However, under the impacts of frequent rubber latex collection, the litter decomposition in the rubber stands at terrace was accelerated in middle and late rainy season, which was obviously not beneficial to the bringing into play of the litter’s eco-hydrological effects. Therefore, in the management and ecological restoration of mountainous rubber plantation ecosystems, it would be necessary to conserve the litter layer with reasonable manners.

Key words: Hunan province, Paddy soil, Fixed ammonium in soil, Influencing factor