三峡水库峡谷地貌区消落带土壤氮磷钾、有机质含量和pH值的时空动态

基于三峡水库巫山段和秭归段消落带海拔155～172 m区段经历水库水位涨落前(2008年)和经历1次(2009年)、4次(2012年)、7次(2015年)水库水位涨落后土壤化学性质的长期定位监测,研究峡谷地貌区消落带土壤氮(N)、磷(P)、钾(K)、有机质(OM)含量和pH值的时空动态变化规律,并对其养分状态进行评价.结果表明: 随着经历水库水位涨落次数的增多,消落带土壤全氮(TN)、速效氮(AN)、速效钾(AK)和OM含量减少,全磷(TP)、全钾(TK)、速效磷(AP)含量和pH值增加;经历水库水位涨落前和经历1次水库水位涨落后,消落带各土层的TP、TK和AP含量为巫山样地>秭归样地,经历4次和7次水库水位涨落后,变为秭归样地>巫山样地;随着经历水库水位涨落次数的增多,消落带大多数土壤化学指标含量在土层间的差异减小.对照全国第二次土壤普查养分分级标准,经历7次水库水位涨落后,秭归样地土壤TP和AP含量达到极高等级,巫山样地土壤AP含量为高等级,其他指标为中等及以下等级.三峡水库的水文特征、人为活动的干扰,以及不同土壤化学指标性质的差异,是峡谷地貌区消落带土壤N、P、K、OM含量和pH值时空变化的主要驱动因素.

Temporal and spatial dynamics of soil nitrogen,phosphorus, potassium,organic matter and pH in the water level fluctuation zone of canyon landform area of the Three Gorges Reservoir,China.

Based on the long-term monitoring data of soil chemical properties before never experiencing water level fluctuation (2008) and after experiencing 1 time (2009), 4 times (2012), 7 times (2015) of water level fluctuation in the water level fluctuation zone with the altitude of 155-172 m, located at the Wushan and Zigui section of the Three Gorges Reservoir (TGR), the temporal and spatial dynamics of soil nitrogen (N), phosphorus (P), potassium (K), organic matter (OM) and pH value were studied and their nutrient status were evaluated. The contents of soil total nitrogen (TN), available nitrogen (AN), available potassium (AK) and OM gradually decreased with the increasing times of experiencing water level fluctuation, while the contents of total phosphorus (TP), total potassium (TK) and available phosphorus (AP), and pH value exhibited the opposite trend. The contents of TN, TK and AP in different soil layers displayed as Wushan > Zigui before never experiencing water level fluctuation and after experiencing 1 time of water level fluctuation. However, after experiencing 4 times and 7 times of water level fluctuation, they changed as Zigui > Wushan. Differences of soil chemical indicators in different soil layers gradually decreased with the increasing times of experiencing water level fluctuation. Compared with the nutrient classification standard of the national second soil census, the contents of TP and AP were extremely high grade in Zigui plot and the content of AP was high grade in Wushan plot after experiencing 7 times of water level fluctuation, and other soil indicators were in the middle or below grade. The hydrolo-gical regime characteristics of the TGR and the interference of human activities, as well as the diffe-rences of soil chemical indicators in nature were the major driving factors that caused the temporal and spatial dynamics of soil N, P, K, OM and pH in the water level fluctuation zone of canyon landform area of the TGR.