紫色土区坡耕地植物篱模式综合生态效益评价

科学评价植物篱模式提高坡耕地生态效益是进一步评价其生态经济社会综合效益的基础,可促进优化植物篱模式在山丘区的推广与应用。针对已有文献对植物篱模式生态效益评价存在评价指标片面等问题,选择植物篱模式下水土与农业面源污染物流失、土壤抗侵蚀力与土地生产力4方面指标,应用层次分析法与熵权法相结合计算评价指标权重,多因素综合评价法对西南紫色土区坡耕地紫穗槐、香根草、紫花苜蓿与蓑草4种植物篱模式进行综合生态效益评价。结果表明,植物篱模式的综合生态效益和不同类型生态效益较常规横坡农作模式明显提高,其中综合生态效益指数(A)、保持水土效益指数(B1)、控制农业面源污染效益指数(B2)、土壤抗侵蚀力效益指数(B3)、土地生产力效益指数(B4)分别增加206.4%~301.9%、228.6%~278.4%、212.6%~346.6%、93.7%~126.0%、23.6%~35.8%。植物篱模式不同类型生态效益指数大小顺序为B2(1.165)B1(0.962)B4(0.495)B3(0.332)。不同植物篱模式提高坡耕地综合生态效益的效应表现为20坡地紫穗槐模式香根草,13坡地紫花苜蓿蓑草。20坡耕地植物篱模式综合生态效益指数平均增加幅度(295.0%)大于13坡地植物篱模式(211.0%)。说明在西南紫色丘陵区的坡耕地,尤其是20以上坡耕地推广与实施灌木类植物篱可大幅提高其综合生态效益。

Evaluation on comprehensive ecological benefits of different hedgerow patterns on slope-farmland in purple soil area

Hedgerow patterns have been used to control soil and water loss, agricultural non-point source pollution (especially nitrogen and phosphorus from slope-farmlands) in hilly areas. A comprehensive and rational evaluation of the ecological benefits of hedgerow patterns in slope-farmlands was critical for further evaluating eco-economic and social benefits of hedgerows. This has been deemed necessary for promoting and popularizing the application of optimized hedgerow patterns in hilly areas. However, critical questions (e.g., the use of unilateral evaluation indexes) have persisted relative studies on evaluation of the ecological benefits of hedgerow. These indexes have generally not accounted for controlling agricultural non-point source pollutants. Hence this paper established an evaluation index system including indexes for soil and water loss, agricultural non-point pollutants, anti-erosion forces and land productivity. It also evaluated the comprehensive ecological benefits of Amorpha fruticosa, Vetiveria zizaniodes, Medicago sativa and Eulaliopsis binata hedgerow patterns on slope-farmlands of the southwestern purple soil zone. The weights of the evaluation indexes were integrated in analytical hierarchy process and entropy weight decision-making calculations. The results showed a significant increase in comprehensive ecological benefits. The indexes for comprehensive ecological benefit (A), soil and water conservation one (B₁), agricultural non-point source pollutant control (B₂), soil anti-erosion force (B₃) and land productivity (B₄) of hedgerow patterns increased by 206.4% 301.9%, 228.6% 278.4%, 212.6% 346.6%, 93.7% 126.0% and 23.6% 35.8%, respectively, compared with the conventional cross-slope farming pattern. The order of different type ecological benefits for hedgerow patterns was B₂ (1.165) > B₁ (0.962) > B₄ (0.495) > B₃ (0.332). The order of improvement of comprehensive ecological benefits for different hedgerow patterns was A. fruticosa > V. zizaniodes Vetiver on 20° slope-farmland, M. sativa > E. binata in 13° slope-farmland. The mean increase in comprehensive ecological benefit of hedgerow patterns on 20° slope-farmland was 295.0%, which was higher than that of 13° slope-farmland by 211.0% over the conventional cross-slope farming pattern. Therefore maintaining shrub hedgerow patterns on slope-farmlands of southwest purple hilly region (especially on lager than 20° slope- farmlands) greatly increased the comprehensive ecological benefits.