怀来盆地弃耕地自然恢复过程中土壤养分动态

研究了怀来盆地丘陵区弃耕地自然恢复过程中土壤养分的变化规律。采取空间代替时间的方法,确定了代表弃耕地初期阶段、草地阶段和灌丛地阶段的3种样地,通过分层取样测定了土壤有机质、全量养分和速效养分含量。结果表明,全量养分对生态系统恢复的响应与其相应的速效养分明显不同。随着弃耕地的恢复,土壤有机质有明显增加的趋势,P循环和K循环由物质控制向生物控制转换,但速效P在恢复初期增加缓慢。速效N由于耕种期施肥的影响表现出先降低而后增加的特点。全量养分中,只有全N在弃耕地自然恢复中有增加的趋势。灌丛可以在更深的层次上影响土壤养分。植被的恢复与土壤肥力的提高密切相关,这种作用随着植被的恢复而不断增强。

Dynamics of Soil Nutrients during Natural Recovery Process of Abandoned Farmland in Huailai Basin, Hebei Province

Dynamics of soil nutrients during the natural restoration process of farmland were studied with the method of substituting time with space.Three tracts of sample fields were selected to represent three different phases of the restoration process,initial period of deserted farmland,grassland,and shrub land.Soil samples from different profile depths were collected and analyzed for soil organic matter,total nutrients and readily available nutrients.Results showed that responses to the recovery process were obviously different between the total nutrient and its corresponding available one.Soil organic matter increased with the process of the restoration.The P and K circulation shifted from under physical control to under biological control step by step,but available P increased slowly in the early stage.Available N increased after an initial decrease at the beginning.As for total nutrients,only total N showed an increasing trend with the restoration process.The deeper rooting of shrubs affected soil organic matter and available nutrients obviously in the deep soil layers.Restoration of vegetation is closely related to increase in soil fertility and this relationship is strengthened with the restoration process.