关键词: 滨水植被缓冲带, 截留率, 水质净化, 丹江口库区

Abstract:

Objective: To explore the effects of interception of runoff pollutants N and P by the buffer zone of the waterfront vegetation of different vegetation types in Danjiangkou Reservoir area, with a view to providing a scientific basis for vegetation buffer construction and water purification Method: Five types of vegetation buffer of Pinus massoniana pure forest, Quercus variabilis pure forest, mixture of P. massoniana and Q. sinensis, Phyllostachys viridis forest and barren land were studied. Three 20 m×20 m plots were set for each vegetation type, and a simple runoff field of 2 m×20 m was set in each plot. Soil permeability was determined by double-ring infiltration test; soil density and maximum moisture capacity were measured by ring cutter method; surface runoff simulation experiment was conducted to study the interception effects of the five types of vegetation buffers on runoff pollutants of total nitrogen (TN), total phosphorus (TP), ammonium nitrogen, and nitrate nitrogen. Result: The double-ring infiltration test showed that the mixture of P. massoniana and Q. sinensis displayed the highest initial infiltration rate and steady infiltration rate, and the lowest ones in the Q. sinensis forest. The ring-knife test showed that the soil density of the mixture of P. massoniana and Q. sinensis was the smallest, and the maximum moisture capacity was the largest. Q. sinensis forest had the largest soil density and the smallest maximum moisture capacity. The interception rate of each type of waterfront vegetation increased with the increase of buffer zone width. The TN interception rate (up to 71.8%) of the mixture of P. massoniana and Q. sinensis was the best when the waterfront vegetation buffer zone was 20 m in width. The interception rate (only 36.1%) of Q. sinensis was the lowest. The interception rate of ammonium nitrogen was not significantly different among P. massoniana, the mixture of P. massoniana and Q. sinensis, Phyllostachys viridis and wild grasses (P>0.05). The interception range was 48.97%-55.11% when the buffer zone was 20 m in width. However, the interception rate of the Q. sinensis (only 29.78%) was significantly lower than those of the other four forest stands (P < 0.05). The mixture of P. massoniana and Q. sinensis had the best interception rate of nitrate nitrogen, and the Q. sinensis had the worst, 58.17% and 34.00% respectively. The interception rate of TP by the mixture of P. massoniana and Q. sinensis and the pure forest of Phyllostachys viridis was 79.77% and 74.21% respectively with a buffer zone of 20 m in width, and the interception rate of Q. sinensis was 60.83%. Regression and Sperson correlation, showed that the interception rate of different vegetation types was mainly affected by physical properties of the soil. Conclusion: If the geographical conditions permit, the width of waterfront vegetation buffer zone should be increased as much as possible to improve its interception and decontamination ability. P. massoniana and Q. sinensis are the main tree species in the reservoir area. When constructing the waterfront vegetation buffer zone, the proportion of the mixture of P. massoniana and Q. sinensis should be increased as much as possible.

Key words: waterfront vegetation buffer zone, interception rate, water purification, Danjiangkou reservoir area