Study On The Virescence Technology Of High Crags By Woody Vines In Limestone Mines

Mining in limestone areas usually produces exposed crags,causing environmental damage which shows soil erosion and geological disasters(collapse,landslide and others).In order to choose woody vine species that were suitable for high crags for greening,and to provide planting management techniques in limestone mines,this study was carried out.Three woody vine plants,Parthenocissus tricuspidata,Parthenocissus quinquefolia and Pueraria lobata,were set up to carry out L9(34)orthogonal experiment with three nitrogen fertilizer application rates of 0g/m2,15g/m2 and 30g/m2.Moreover,three planting soil layer thicknesses of 25cm,50cm and 75cm and three watering intervals of 10 days,20 days and 30 days were set up in the experiment.Range and variance analysis of 22 indexes were performed for 3 woody vine plants.These indexes included Coverage height,Duration of defoliation,Branch number,New branch diameter,New branch length,Stem tissue density,Stem dry matter content,Specific stem length,Specific leaf area,Dry matter content of leaves,Relative water content of leaf,Tissue density of leaf,Thickness of leaf,Pn,Gs,Ci,Tr,WUE,chlorophyll a,chlorophyll b,total chlorophyll content,chlorophyll a/b,etc.18 representative test indexes were selected from 22 indexes,To get indicator weight by AHP framework,CRITIC method and expert scoring method were used.The results of the comprehensive analysis are listed as follows.(1)Species significantly effected the indexes that included Coverage height,New branch diameter,Branch number,New branch length,Stem dry matter conten,Specific stem length,Stem tissue density,Specific leaf area,Dry matter content of leaves,Relative water content of leaf,Tissue density of leaf,Thickness of leaf,Pn,Gs,Ci,Tr,WUE,chlorophyll a,chlorophyll b,total chlorophyll content and chlorophyll a/b among 3 woody vines.Besides,Parthenocissus tricuspidata had maximum values of Duration of defoliation,Branch number,Pn,Gs,Ci and WUE;the highest values of Stem dry matter conten,Specific stem length,Stem tissue density,Dry matter content of leaves,Relative water content of leaf,Tissue density of leaf,Thickness of leaf,Tr and chlorophyll a/b appeared on Parthenocissus quinquefolia;and the highest value indexes of Pueraria lobata were Coverage height,New branch length,New branch diameter,Specific leaf area,chlorophyll a,chlorophyll b and total chlorophyll content.(2)The thickness of planting soil layer had extremely significant effects on indexes that were New branch diameter,Branch number,Specific stem length,Relative water content of leaf,Thickness of leaf,Pn,Gs,Tr,chlorophyll a,chlorophyll b,total chlorophyll content and chlorophyll a/b;it had significant effects on New branch length,Stem dry matter content,Stem tissue density and Tissue density of leaf.With the adding of the planting soil layer thickness,the numbers of Leaf phase to life and Duration of defoliation were first decreased and then increased;while the numbers of Branch number and WUE were first increased and then decreased.The deeper soil layer thickness can promote Coverage height,Stem dry matter conten,Specific stem length,Stem tissue density,Relative water content of leaf,Thickness of leaf,chlorophyll a/b,while it restrains Specific leaf area,Tissue density of leaf,chlorophyll a,chlorophyll b and total chlorophyll content.(3)The time interval of watering had extremely significant effects on indexes that were New branch diameter,Stem dry matter content,Stem tissue density,Thickness of leaf,Pn,Tr,WUE,chlorophyll a,chlorophyll b,total chlorophyll contentl and chlorophyll a/b,and it had significant effect on Branch number,New branch length,Specific stem length,Specific leaf area,Dry matter content of leaves,Relative water content of leaf,Tissue density of leaf and Gs.With the increase of water interval time,the numbers of Duration of defoliation,New branch diameter,Specific leaf area,Dry matter content of leaves,Tissue density of leaf,chlorophyll a,chlorophyll b and total chlorophyll content were first decreased and then increased,while the numbers of New branch length,Stem dry matter content,Relative water content of leaf.WUE were first increased and then decreased.(4)The application of nitrogen fertilizer had extremely significant effects on indexes that were Coverage height,New branch diameter,Branch number,New branch length,Relative water content of leaf,Pn,WUE,chlorophyll a,chlorophyll b,total chlorophyll content and chlorophyll a/b;it had singnificant effects on Specific stem length,Stem tissue density,Specific leaf area,Dry matter content of leaves,Tissue density of leaf and Gs.With the increase of nitrogen application,the numbers of Stem dry matter conten and Specific leaf area were first decreased and then increased,while the numbers of chlorophyll a,total chlorophyll content and chlorophyll a/b were first increased and then decreased.The increase of nitrogen application can promote Coverage height,Duration of defoliation,New branch length,Branch number,Dry matter content of leaves,Thickness of leaf,WUE and chlorophyll b,but it also can restrain New branch diameter,Specific stem length,Stem tissue density and Tissue density of leaf.(5)It is concluded that the best woody vine on high crags for greening is Parthenocissus quinquefolia and followed by Pueraria lobata by AHP method.The best technical conditions are soil thickness of 75cm,watering intervals of 10 days and nitrogen fertilizer application rate of 15g/m2 respectively.The research results can provide a technical method for the virescence of woody vines on high crags in limestone mines in Hebei province.Moreover,it can provide a theoretical basis for the greening of rocky steep slopes in construction of highways or railways and vertical greening of cities by woody vines.