| Under the Populus euphratica forest in the saline-alkali land of the arid area,the use of the neighboring desalination effect of the positive interaction between plant species to solve the problem of vegetation restoration in the saline-alkali environment is conducive to promoting the utilization and improvement of the resources of salinealkali land and the regeneration and regeneration of Populus euphratica seedlings.The formation and evolution of Populus euphratica are closely related to soil properties.Due to the poor adaptability of Populus euphratica to the saline-alkaline environment at the seedling stage,plus the drought and semi-arid Xinjiang Tarim River Basin due to artificial long-term improper use and warm drying The impact of chemical on the area is strong,and the soil salinization is intensifying,which seriously inhibits the regeneration and regeneration of Populus euphratica.In order to select the associated halophytes suitable for the best desalination of Populus euphratica seedlings and the greatest positive effect on the seedlings of Populus euphratica seedlings,the one-year-old Populus euphratica seedlings were used as experimental materials,using potted salt stress control and field saline-alkali field test verification methods,The common halophytes Suaeda glauca(Bunge)Bunge,Salicoria europaea and Halocnermum str were selected as their associated plants for the desalination test to determine the soil electrical conductivity,photosynthetic index and growth Indicators and make a comprehensive evaluation.Under the gradient of soil salt stress,the theory of using positive interactions between plant species to restore degraded soil and rebuild vegetation is proposed,which provides a basic theoretical basis for the practice of vegetation restoration under the constraints of environmental resources.Research indicates:(1)Associated halophytes have obvious desalination effect on soil.In the controlled pot experiment,Suaeda glauca(Bunge)Bunge treatment had the best effect on desalination of soil(13.1%)under the condition of 5 g/L NaCl concentration.The treatment of Salicornia europaea in the concentration of 11 g/L NaCl and 15 g/L NaCl Soil has the best desalination effect(12.1%,4.0%).In the field saline-alkali environment,the soil electrical conductivity at different depths of 0 cm(soil surface),20 cm,40 cm,and 60 cm changes as follows: Salicornia europaea>Halocnermum str>Suaeda glauca(Bunge)Bunge;in general,the electrical conductivity is The soil below 40 cm is not obvious,the soil volumetric water content only changes significantly at depths of 20 cm and 40 cm,and the soil temperature decreases only at 0 cm(soil surface layer).(2)The effect of neighbor desalination on the photosynthetic physiological characteristics of Populus euphratica seedlings is significant.In the controlled pot experiment,the effects of the desalination effect of the neighbors on the gas exchange parameter values of the leaves of Populus euphratica seedlings showed significant differences.Under the condition of 5 g/L NaCl concentration,the seedlings of Populus euphratica seedlings with Suaeda glauca(Bunge)Bunge Strong,the ability to adapt to low light is stronger,followed by Salicornia europaea,followed by the seedlings of Populus euphratica with 11 g/L NaCl and 15 g/L NaCl as the neighbors,which has stronger light and ability and light inhibition,Followed by Halocnermum str;the effect of different treatments on various gas exchange parameter values under different salt stresses is: 11 g/L NaCl>15g /L NaCl>5 g/L NaCl.In the saline-alkali environment in the wild,the seedlings of Populus euphratica with Salicornia europaea as neighbors have strong light and ability,high photosynthetic potential,followed by Halocnermum str,and Suaeda glauca(Bunge)Bunge is the worst.(3)The neighbor desalination effect has a significant effect on the ecological characteristics of Populus euphratica seedlings.Under the two test conditions,the plant height,ground diameter and biomass increased under different treatments;under three different concentrations of salt level stress,the relative treatments of Suaeda glauca(Bunge)Bunge,Salicornia europaea and Halocnermum str are the neighbors.The relative interaction index is 11 g/L NaCl(0.12)>15 g/L NaCl(0.09)=5 g/L NaCl(0.09);11 g/L NaCl(0.19)>15 g/L NaCl(0.17)>5 g/L NaCl(0.06);11 g/L NaCl(0.19)>(0.15)>15 g/L NaCl(0.14)>5 g/L NaCl(0.03),that is,as the salt content increases,the Populus euphratica seedlings the net effect of plants and plants has changed from neutral to reciprocity and has become a weakening trend.In the salinealkali environment in the wild,the Populus euphratica seedlings with Suaeda glauca(Bunge)Bunge as the relative interaction index(0.09),and the Populus euphratica seedlings with Salicornia europaea and Halocnermum str(0.21,0.15).(4)Use the membership function method to comprehensively evaluate the optimal desalination effect of associated halophytes on the soil under Populus euphratica seedlings and the maximum positive effect of the neighbor effect between plants.Under the controlled conditions of potted plants,the treatment effect with Salicornia europaea as neighbors under salt stress of 11 g/L NaCl and 15 g/L NaCl was significantly better than other treatments,and the average membership function values were 0.92 and 0.87 respectively,Salicornia europaea had the highest comprehensive score(0.84)under the conditions of saline-alkali environment in the wild.In summary,through pot control to simulate the salinity gradient in desert habitats and further verification under the saline-alkaline environment in the wild,Salicornia europaea as a companion to the neighboring plants as Populus euphratica seedlings showed a reciprocal effect and had the largest positive effect on Populus euphratica seedlings.It has a certain buffering effect on the saline-alkali environment,which is conducive to increasing the probability of successful reconstruction of Populus euphratica seedlings,and is suitable for popularization. |
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