生态袋护坡技术在三峡水库消落带植被恢复中应用的可行性研究

通过对三峡水库重庆市巫山县双龙镇和巫峡镇段消落带开展生态袋护坡复绿试验7年后,生态袋上（内）、生态袋堆叠处上方和左侧消落带狗牙根（Cynodon dactylon）的种群密度、表型生长性状、地上和地下生物质量,以及土壤理化性质的测定,探讨以狗牙根为生态袋上的种植植物,将生态袋护坡技术用于三峡水库消落带植被恢复的可行性。结果表明：（1）各试验地生态袋上与其堆叠处上方和左侧消落带的狗牙根种群密度和地上生物质量差异不显著。（2）狗牙根的表型生长性状和根系生物质量因地和在生态袋堆叠处的方位不同而异。在双龙镇试验地,生态袋上比其堆叠处上方消落带上狗牙根的植株长度和节间长度低23.9%和22.6%（P<0.05）,除此之外的各项指标差异均不显著;生态袋内0-5 cm土层的根系生物质量比其堆叠处上方消落带增加了75.7%（P<0.05）,比其堆叠处左侧消落带降低了11.8%,在5-15 cm各土层降低了91.6%-96.9%（P<0.05）,15-20 cm土层的差异不显著。在巫峡镇试验地,生态袋上与其堆叠处上方和左侧消落带的各表型生长性状的差异均不显著;生态袋内各土层的根系生物质量均比其堆叠处上方和左侧消落带增加了20.0%-138.7%。（3）各试验地生态袋内与其堆叠处上方和左侧消落带土壤容重的差异不显著,土壤化学性质因地和在生态袋堆叠处的方位不同而异。在双龙镇试验地,生态袋内的土壤全氮和速效氮含量比其堆叠处上方消落带分别降低了13.6%和40.9%（P<0.05）,比其堆叠处左侧消落带分别降低了11.9%和33.0%（P<0.05）;速效钾含量比其堆叠处上方和左侧消落带分别增加了18.3%和34.1%（P<0.05）;除此之外各指标的差异均不显著。在巫峡镇试验地,生态袋内的土壤pH值和全氮含量比其堆叠处上方消落带分别降低了1.4%和27.9%（P<0.05）,全钾含量增加了6.1%（P<0.05）;土壤全钾和速效钾含量比生态袋堆叠处左侧消落带分别降低了8.1%和24.9%（P<0.05）;除此之外各指标的差异也不显著。（4）狗牙根种群密度、大多数生长指标和生物质量与土壤理化指标相关不紧密。总体上,生态袋上（内）与其堆叠处上方和左侧消落带的大多数表型生长指标,地上和地下生物质量,以及土壤理化指标的差异不显著。狗牙根耐淹、抗旱、耐贫瘠,根系发达,且穿透力强,能够在生态袋上正常生长;生态袋透水不透土,且具有一定的保肥能力。因此,以狗牙根为生态袋上的种植植物,将生态袋护坡技术用于三峡水库消落带植被恢复具有一定的可行性。

Potential of ecological bag slope protection technology in vegetation restoration in the water level fluctuation zone of Three Gorges Reservoir

Vegetation restoration in the water level fluctuation zone (WLFZ) is vital for maintaining the health and stability of the Three Gorges Reservoir. Many technical methods (i.e. planted species and concrete-engineered methods) of vegetation restoration were performed in this zone. However, these methods are not suitable for the WLFZ with repeated collapse and soil erosion. To evaluate the potential of ecological-bag (eco-bag) slope protection technology, an effective method for slope fixation and re-greening in various environments, population characteristics (density, morphological traits and biomass) of Cynodon dactylon, and physicochemical indicators of soil on/in the eco-bag and around the eco-bag stacking (upper and left sides) at two plots (Shuanglong and Wuxia) in Wushan County of Chongqing Municipality were investigated after 7-year of experimental setup. The results showed that population density and aboveground biomass at two plots were no significant differences between on the eco-bag and around the eco-bag stacking. However, morphological traits and root biomass varied with different plots and positions. In Shuanglong plot, length and inter-node length of C. dactylon on the eco-bag decreased by 23.9% and 22.6% than those around the upper side of the eco-bag stacking, respectively (P<0.05). Root biomass of 0-5 cm in the eco-bag was 75.7% more than around the upper side of the eco-bag stacking (P<0.05), while was 11.8% lower than around the left side of the eco-bag stacking. And root biomass of 5-15 cm in the eco-bag were lower than around the eco-bag stacking, with proportion of 91.6%-96.9%. In Wuxia plot, root biomass of 0-20 cm in the eco-bag increased by 20.0%-138.7% than around the eco-bag stacking, while there were no significant differences in morphological traits and aboveground biomass. Additionally, soil chemical indicators also changed with different plots and positions. In Shuanglong plot, soil total nitrogen and available nitrogen in eco-bag was significantly lower than that around the eco-bag stacking, with proportion of 11.9%-40.9%; while soil available potassium increased by 18.3% (upper side) and 34.1% (left side), respectively (P<0.05). In Wuxia plot, soil pH and total nitrogen in the eco-bag decreased by 1.4% and 27.9% than around the upper side of the eco-bag stacking, respectively, but total potassium increased by 6.1% (P<0.05); soil total potassium and available potassium were 8.1% and 24.9% lower than around the left side of the eco-bag stacking, respectively (P<0.05). Further, not all significant relationships were found between population density, morphological traits, above- and underground biomass and soil physicochemical indicators. In total, population characteristics of C. dactylon and physicochemical indicators of soil had no obvious differences between on/in the eco-bag and around the eco-bag stacking. C. dactylon, one of species with resistance to flood, drought and poor fertility, had stronger root and grew well on the eco-bag. On the other hand, eco-bag is permeable to water but no to soil, implying some retention ability for fertility. Thus, eco-bag slope protection technology has huge potential for vegetation restoration in the WLFZ of the Three Gorges Reservoir.