Correlation Between Anatomical Characteristics Of Roots And Leaves And Soil Physical And Chemical Properties Of Major Afforestation Tree Species In Coastal Saline-alkali Land In Shandong Province

Vegetation restoration and community construction in saline-alkali land is a systematic forestry ecological project.In the traditional saline-alkali vegetation restoration,the relationship between “species-environment” is established by screening salt-tolerant tree species.However,there are many kinds of tree species,and the screening indicators are complicated,so it is difficult to form a unified standard.In contrast with species,Plant functional traits are stable and conservative,and can better reflect their adaptation to environmental changes.In the process of vegetation restoration,according to plant functional traits,it is possible to break through the tree species level and establish a stable relationship between “traits-environment”,which is of great significance for changing the traditional vegetation restoration and community construction theory.As an important link with the above-ground and underground environments,the search for plant traits with strong response to stress in root-leaf organs is a key issue in vegetation restoration.Based on this,In this study,11 tree species in different forests of coastal saline-alkali land(Gleditsia sinensis ?Ailanthus altissima?Fraxinus chinensis?Sophora japonica?Populus×euramericana ‘I-107'?Salix matsudana?Platanus orientalis?Ulmus pumila?Ziziphus jujuba?Amygdalus persica?Pyrus bretschneideri)were studied.By observing and measuring the leaf organs and fine root anatomical structures of tree species under different saline environments,the adaptability of leaf anatomical structure and fine root anatomical structure to coastal saline-alkali soil environment was studied.and this study screens some root anatomical traits of tree species that play important roles in salt stress.At last,the relationship between leaf-root anatomical structure and salt stress was established.The study found that:(1)By comparing the anatomical characteristics of leaf organs of different tree species,it was found that there were significant differences among the anatomical characteristics of leaf organs of different tree species(P < 0.05).In coastal salt stress,the leaf thickness of tree species increased,stomatal holes in the upper epidermis were depressing,and stomatal holeswere formed.At the same time,mesophyll palisade tissue was developed,and arranged on the paraxial surface of mesophyll closely with 3-5 layers.In the anatomical structure of leaf veins,the diameter of main vascular column was developed,and the proportion of xylem increased,which plays an active role in regulating water transport.There are synergistic changes between the diameter of main vein and xylem thickness,phloem thickness,leaf thickness and palisade tissue thickness.In coastal saline-alkali soil,the thickness ratio of palisade tissue to sponge tissue of different tree species was generally higher,ranging from0.85 to 1.42.(2)By comparing the anatomical characteristics of fine roots of different tree species,it was found that there were significant differences in the anatomical structure of fine roots of the same order among different tree species(P < 0.05).It was found that the lower roots of tree species play an absorptive role,while the higher roots play a structural transport role.In coastal saline-alkali environment,the cortex thickness of 1-2 order roots of tree species increased,and the surface of 1-2 order roots appeared uneven folds to prevent salt ions from entering into fine roots in large quantities.The Kelvin zone was found in the endodermis,which has the function of barrier sodium ions into plants and water regulation.With the increase of root order,cortex tends to decrease and eventually disappear.The diameter of high-grade root vascular column was larger than that of fine root section.In coastal saline-alkali environment,tree species can improve transportation efficiency and safety by increasing vessel density and vessel thickness.Fine root diameter of different tree species was positively correlated with vascular column diameter(P < 0.05).(3)The soil physical and chemical properties of stands around different tree species were significantly different from each other(P < 0.05).In coastal saline environment,soil pH was negatively correlated with soil available nutrient content,which was negatively correlated with soil nitrate nitrogen content(r=-0.823,P < 0.01).There was also a significant positive correlation between soil pH and soil conductivity.However,the correlation between soil available nutrients in stands was not significant.(4)Combining the physical and chemical properties of Forest Land soil,leaf anatomical structure and fine root anatomical structure of different tree species,it was found that in coastal saline environment,the thickness of palisade tissue,the ratio of palisade tissue thickness to sponge thickness and the anatomical structure of 1-2 order fine roots were most closely related to soil environment,which could explain the different characteristics of many tree species.The variation process played a dominant role and showed strong response to saline environment.These dominant anatomical traits can be used to detect the adaptability ofdifferent tree species to the environment in the actual saline-alkali land greening.It has important reference value for vegetation restoration and community construction in saline-alkali land.