| Dry-hot valley area is one of the worst environments in the world.Vegetation degradation,poor soil,serious soil erosion,and extremely fragile ecological environment in this area.The dry-hot valley in Western Panzhihua City has typical characteristics of dry-hot valley.Drought and high temperature often occur in the same season.The unstable nature of the soil,and the desertification of the land are prominent.The harsh ecological environment has led to the increasingly serious problem of ecological management in the dry-hot valley of Western Panzhihua,which has restricted the development of local social and economic.Puelia sinese is widely used for vegetation restoration in areas with poor ecological environment because of its strong stress resistance,low planting cost,easy survival and high comprehensive benefits.Therefore,this article focuses on the subject of the P.sinese,through the introduction experiments of different slope positions in the dry-hot valley of Western Panzhihua,the effects of different slope positions,root orders,dry and wet seasons on root growth characteristics,distribution characteristics,C,N,P contents and stoichiometric characteristics of P.sinese were studied,the interannual dynamics of C,N,P contents and stoichiometric characteristics of root system were tracked and studied,analyses the ecological adaptability,introduction feasibility and ecological recovery potential of P.sinese in the dry-hot valleys,to provides a theoretical basis for the promotion and application of P.sinese in dry and hot river valley,thesis the main research results are as follows:(1)It is been introduced since 2013,P.sinese can survive and grow normally in the upper,middle and lower slope,and the middle slope has the best growth.(2)From the slope position,the biomass,diameter,root length density(RLD),root volume density(RVD)and root surface area density(RSAD)of the root system of P.sinese showed middle slope > lower slope > upper slope,specific root length(SRL)showed upper slope > lower slope > Middle slope;content of C and C/P showed lower slope >upper slope > middle slope,N,P content and N/P showed lower slope > middle slope >upper slope,C/N,C/N/P showed upper slope > middle slope > lower slope.(3)From the root order,the biomass,diameter,C content,C/N,C/P and C/N/P of the root system of P.sinese increased with the increase of root order grade,and root biomass at1-order root accounted for 5%-10% of total root biomass;SRL,RLD,RVD,RSAD,content of N,P and N/P decreased with the increase of root order grade,and RLD,RVD and RSAD of 1-order root and 2-order root accounted for 91% to 98% of the total root RLD,RVD and RSAD.(4)From the seasonal and year point of view,the biomass,diameter,SRL,RLD,RVD,RSAD,N,P,N/P of the root system of P.sinese were higher in rainy season than in dry season,while C,C/N,C/P were higher in dry season than in rainy season;C,N,P,C/N/P of the root system of P.sinese had no significant changes in the same season.According to the difference of biomass,diameter,RLD,RVD and RSAD of the root system of P.sinese at different slope positions,the growth of Puelia sinese was the best on the middle slope,the contact area between root system and soil was larger,and the effect of soil and water conservation was the best.On relatively barren and arid slopes,P.sinese can adapt to the environment by regulating root morphology and improving nutrient use efficiency;The biomass of 1-order root has smaller biomass,but it is most widely distributed in the soil and has the largest contact area with the soil,which plays a major role in soil consolidation and protection.In the rainy season,the contents of C,N and P and the characteristics of stoichiometric of the root system of P.sinese had little difference between years,which was mainly affected by the dry and wet seasons.In the rainy season,despite the common limitation from N and P,the root system of P.sinese absorbed a large amount of N and P at the cost of consuming a large amount of C.It can be seen that in the environment of the dry and hot valley,the nutrient absorption and return of the root system of P.sinese have reached a general balance.In summary,P.sinese shows good ecological adaptability in dry-hot valley area,and has a certain capacity of soil and water conservation and ecological improvement effect.It has a good potential of vegetation restoration,we can expand the scope of introduction and establish a larger demonstration area of introduction... |
