黄河三角洲滨海滩涂不同微地形改造的盐地碱蓬恢复效应评价

为提高植被覆盖率,探索适宜的植被恢复模式,以光滩裸地为对照,在黄河三角洲滨海滩涂地势平坦地段设置S形、条带形、品字形和月牙形4种微地形改造模式,测定分析其工程量、地表粗糙度、植被生长及改良土壤效应指标,并采用主成分及模糊数学隶属函数法分析评价其植被恢复效应。结果表明:微地形显著影响土壤理化性质与植被生长状况(P0.05),与裸地相比显著降低了土壤容重、含盐量、pH值等,增加了土壤养分,孔隙度,持水量等。4种微地形改造模式中月牙形模式与光滩裸地相比显著降低了44.19%的土壤盐分,并且月牙形改造模式最利于促进植被恢复效果;条带形模式可显著增加土壤养分,其坑底土壤有机质含量为裸地的2.87倍;品字形模式可显著提高土壤孔隙度,显著降低了15.24%的土壤容重;S形模式在植被恢复及土壤改良效应上表现较差。不同微地形改造模式对植物生长和改良土壤效应综合评价结果从大到小依次为:月牙形、条带形、品字形、S形、裸地,建议在黄河三角洲滨海滩涂进行微地形改造时,首先考虑月牙形,其次是条带性、品字形,S形可不采用。研究结果可为黄河三角洲滨海滩涂植被恢复与生态修复提供理论依据与技术支持。

Evaluating Suaeda salsa restoration after micro-topography reconstruction in the coastal beach of the Yellow River Delta, China

Abstract: Coastal beaches are mostly distributed in the silt-type muddy coastal zone, particularly in the Yellow River Delta of China. The typical ecologically fragile areas have suffered from severe soil degradation, where the ground vegetation is scarce. Furthermore, the tides and evaporation have also posed great damage to forming bare beaches with dry surface and flat terrain. In this study, four types of micro-topography transformation models were established in the flat terrain of the Yellow River Delta beach, in order to explore suitable vegetation restoration. Specifically, S-, strip-, pin-, and crescent-shaped topographies were selected in the bare land of the light beach. The specific parameters were then measured to analyze the engineering quantity in the four micro-terrain reconstructions, including the surface roughness, vegetation growth, and soil improvement. A principal component and fuzzy mathematics membership functions were used to comprehensively evaluate the vegetation restoration and soil improvement in the four micro-terrain reconstructions. The results showed that the surface roughness increased, but the wind speed reduced under the various micro-topography of bare land in the light beach. The probability of seed retention increased in this case, where a warm zone formed at the bottom of the pit, thereby to promoting seed germination and growth. It was found that the micro-topography significantly enhanced the physical and chemical properties of soil for the growth of vegetation (P<0.05). Meanwhile, the micro-topography significantly reduced the soil bulk density, salinity, and pH value, whereas, it increased soil nutrients, porosity, and water-holding capacity, compared with the bare land of the light beach. The indicators were systematically evaluated in the four micro-terrain reconstructions. The Crescent-shaped model significantly reduced the soil salinity by 44.19% (P<0.05), indicating a much more excellent performance to promote the vegetation restoration, compared with the bare land in the four micro-terrain reconstructions. The content of soil organic matter in the striped transformation model significantly increased by 65.11% (P<0.05), indicating a significant effect on the soil improvement, compared with the bare land of the bare beach. The pattern of the pin-shaped model greatly increased the soil porosity, while reduced the soil bulk density by 15.24% (P<0.05), indicating a better improvement in the physical properties of soil. Nevertheless, the S-shaped pattern performed a relatively weak correlation on vegetation restoration and soil improvement. Therefore, four micro-topography modification modes were ranked in a descending order: crescent-shaped, strip-shaped, pin-shaped, S-shaped, and bare land, after the comprehensive evaluation on the plant growth and soil improvement. A strong recommendation was that the crescent-shaped should be considered firstly, when carrying out the micro-topography transformation on the beaches of the Yellow River Delta, followed by the stripe-shaped and pin-shaped ones, where the S-shaped one cannot be adopted. There were still some limitations here, where the moist area at the bottom of the pit was first used to promote the growth of Suaeda salsa. It is also expected to measure the environmental changes at the bottom of pits in a long term, due mainly to the short testing period here. The finding can provide insightful technical support to the vegetation restoration for the coastal beaches of the Yellow River Delta in China.