| In the Karst area,the nature of the carbonate rock caused the poor soil environment,low soil forming rate,and difficult vegetation growth.Under the influence of irrational human factors,vegetation destruction,soil erosion,exacerbated the development of rocky desertification in the region.The study found that sloping land reclamation and traditional farming had loosened the soil in the karst area,decreased the vegetation cover area,increased the soil,water and nutrient loss,deepened the degree of rocky desertification.And the process of rocky desertification caused a series of ecological protection and economic development problems such as the weakening of water storage and water retention capacity,the decrease of land productivity,the decrease of agricultural output and the decrease of farmers' income.Soil and water conservation eco-economic plants were a kind of restorative model.Because of their ability to control soil erosion and improve the ecological environment,and generate economic benefits to the maximum extent,and combined economically beneficial with ecological management measures.And thus it had been widely used in the process of the mountain ecological restoration.The Huajiang gorge in Anshun city of Guizhou province was the typical karst plateau mountain area.The long-term cultivation of crops on the sloping land in the area had caused the problems of surface crushing,loose soil,soil erosion and land productivity decline.The rocky desertification was extremely serious,so most of the cultivated land is degraded into waste grassland.In recent years,with Zanthoxylum bungeanum,Hylocereus undulatus,etc as the representative of the economic plants in the area of degrading waste grassland to extend cultivation,and promoted the local farmers to increase income and enhance the regional economic benefits.However,the ecological benefits of economic plants in the region were less studied.In this study,we combined the method of field investigation and indoor experiment to study the sustainability of the economic plants that planting and management in Huajiang gorge in the process of rocky desertification control,from the perspective of the soil ecological function of economic plants.Hoping that from the comparative analysis of economic plants and waste grassland to study planting and management the six types of economic forests of pure forest of Zanthoxylum bungeanum,pure forest of Lonicera japonica,pure forest of Broussonetia kaempferi,pure forest of Hylocereus undulatus,pure forest of Amomum villosum and mixed forest of Lonicera japonica and Zanthoxylum bungeanum whether they had the soil ecological function to improve the soil hydrological and physical properties,soil nutrient characteristics and soil anti-erosion ability,and provided the theoretical basis for exploring how the economic plants could exert the soil ecological utility.The main conclusions were as follows:(1)Compared with the waste grassland,the economic plants which were planted and managed in the rocky desertification area of Huajiang gorge had significant improvement on the soil hydrological and physical properties.The mean value soil total porosity of the 6 types of economic plants in the 0 ~ 30 cm layer increased by 1.77%,the non-capillary porosity increased by 19.57%,the density decreased by 2.52%,the soil moisture content increased by 18.17%,the maximum water holding capacity increased by 14.90%,the capillary water holding capacity increased by 14.65%,the field water content increased by 4.93%,the total water storage capacity increased by 1.65%,the initial infiltration rate was 1.6 times,the stable permeation rate was 1.04 times,the mean permeability rate was 1.25 times and the total penetration was 1.28 times.The variance analysis showed that the physical structure index,water storage performance index and permeability index of economic plants were significantly higher than those of waste grassland(p<0.05).The study also found that soil physical and chemical properties of soil not only differ in plant type,but also in the vertical spatial distribution,and the improvement of surface soil was generally better than the lower layer.(2)Compared with the waste grassland,the economic plants planted in the rocky desertification control area of Huajiang gorge had significant soil nutrient improvement.The mean value of soil organic carbon,total nitrogen,total phosphorus,total potassium,available nitrogen,available phosphorus and available potassium of the six kinds of economic plants were increased by 72%,37%,60%,72%,61%,7.24% and 106%,respectively.The variance analysis showed that the soil nutrient content and soil total organic carbon content of the six kinds of economic plants were significantly higher than that of the waste grassland(p<0.05),and showed a good soil nutrient and carbon sink effect.The vertical direction data of soil layer showed that the improvement of soil nutrient was mainly in the surface soil.we also found that soil N:P was generally less than 14 and C:N is generally greater than 15 in the soil stoichiometric study,indicating that there were different levels of nitrogen and phosphorus nutrient limitation and slow nutrient release in the soil.(3)Compared with the waste grassland,the economic plants planted in the rocky desertification control area of Huajiang gorge had a significant effect on improving soil anti-erosion ability.In the process of water immersion test,the total amount of the soil particles disintegration of the waste grassland was 16.95% higher than that of the economic plants,and the silt content of runoff was about 1.21 times of the average of the 6 kinds of economic plants.The stability anti-erodibility index of 6 kinds of economic plants was 27.53% higher than that of the waste grassland,and the anti-scouribility coefficient was about 1.79 times that of the waste grassland.The results of variance analysis showed that the soil of the economic plants had high soil anti-erosion ability,which could effectively reduce the soil loss caused by the decomposition of soil particles at a certain runoff level,so as to achieve the goal of soil fixation.(4)The correlation analysis showed that there was a significant negative correlation between organic matter,available nutrient indexes and soil bulk density,respectively,and part of them were significant positive correlation with capillary porosity and non-capillary porosity,respectively.The smaller the soil bulk density,the larger the porosity,the more loose the soil,the improved ventilation and water permeability,the increase of soil water storage capacity and the improvement of adjusting the ability of water movement had a significant influence on the soil nutrient.On the other hand,the soil anti-scouribility coefficient and anti-erodibility index were highly significant positive correlation with soil organic matter,available nitrogen,available phosphorus and available potassium,respectively.The improvement of soil anti-erosion ability also had important influence on soil nutrient.(5)Based on the above research results,this study suggest that planted the economic plants could increase the surface litter to improve the soil hydrological and physical properties,the soil anti-scourability,the soil anti-erodibility and permeability,and increase the nutrient return,which had an important impact on soil nutrient.Compared with the waste grassland,the soil of economic plants had good permeability,which could promote the rapid infiltration of rainwater into the soil,and to the benefit of reducing the formation of surface runoff.The water holding capacity and water storage capacity of the soil improved.It is also beneficial to retain more water infiltrated into the soil,and weaken surface runoff formation,and reduced the loss of nutrient.At the same time,the improvement of the anti-erosion ability of economic plants woodland reduced the loss of surface soil,and the loss of the available nutrient which adsorbed in the surface soil was effectively controlled,and the productivity of land was slowly restored. |
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