水盐梯度对闽江河口湿地土壤水稳性团聚体分布及稳定性的影响

为了揭示水盐梯度对河口湿地土壤水稳性团聚体分布及稳定性的影响,对闽江河口不同淹水环境和盐度下短叶茳芏(Cyperus malaccensis)湿地土壤水稳性团聚体进行了测定与分析.结果表明:①闽江河口半咸水湿地和淡水湿地0～30 cm土壤粉+黏团聚体、微团聚体和大团聚体的含量分别为63.12%～77.49%、6.82%～31.64%、4.38%～22.63%.除20～30 cm土层外,高潮滩0～20 cm土壤粉+黏团聚体和大团聚体含量均随盐度的增加而增加,增幅分别为8.74%～9.85%和105.54%～144.40%;0～20 cm土壤微团聚体含量均随盐度的增加而降低,高潮滩降幅为59.56%～65.20%,低潮滩降幅为55.65%～60.92%.②高潮滩土壤团聚体稳定性随盐度的增加而增加,盐度对微团聚体、大团聚体含量(DR_(0.25))和平均重量直径(MWD)的作用力在不同土层均影响显著,盐度和淹水的交互作用对各级土壤水稳性团聚体分布及稳定性的影响均不显著.③土壤团聚体稳定性与土壤TC含量呈倒"U"型关系.综上,淹水环境变化对土壤水稳性团聚体分布及稳定性的影响较小,盐度和有机碳含量是影响闽江河口湿地土壤水稳性团聚体分布及稳定性的重要限制性参数.

Effects of hydrologic and salinity gradients on the distribution and stability of wetland soil water-stable aggregates in the Min River estuary

In order to reveal the effects of hydrologic and salinity gradients on the distribution and stability of wetlands soil water-stable aggregates in estuarine area, the contents of soil water-stable aggregate-size fractions were determined along a hydrologic gradient within a freshwater Cyperus malaccensis marsh and a brackish C. malaccensis marsh in the Min River estuary. The contents of soil silt and clay aggregates, microaggregates and macroaggregates at a soil depth of 0~30 cm in the brackish and freshwater marsh were 63.12%~77.49%, 6.82%~31.64%, and 4.38%~22.63%, respectively. Except that at 20~30 cm depth, the contents of silt+clay aggregates and macroaggregates at 0~20 cm depth in high tidal flat raised with increasing salinity, and increasing ranges were 8.74%~9.85% and 105.54%~144.40%, respectively. While for both high tidal flat and low tidal flat, the contents of microaggregates at 0~20 cm depth decreased by 59.56%~65.20% and 55.65%~60.92% with increasing salinity in high and low tidal flat, respectively. The stability of soil aggregates in high tidal flat raised with increasing salinity. The effects of salinity on the contents (DR_0.25) and mean weight diameter(MWD) of macroaggregates are significant. however, effects of the interaction of salinity and flooding environment on the distribution and stability of soil water-stable aggregate-size fractions among soil layers are insignificant. The relationship between the stability of soil aggregates and soil total carbon contents shows as an inverted "U" shape. In summary, compared with the varied flooding environment, soil salinity and organic carbon content are the important restrictive parameters, demonstrating an obvious effect on controlling the distribution and stability of soil water-stable aggregates in the tidal marsh of the Min River estuary.