| Aegiceras corniculatum(Myrsinaceae)which is a true mangrove species and Clerodendrum inerme(Verbenaceae)which is a semi-mangrove species were selected as materials in this experiment.the morphological anatomical characteristics of secondary xylem of study species at different time spans within one year were observed under light microscope(LM)and scanning electron microscope(SEM),and the quantitative anatomical characteristics of secondary xylem were measured using the related measurement software and images taken under LM and SEM while the corresponding soil physicochemical factors were determined and meteorologic data were collected as well.On the basis of those data sets,the relationship between monthly variation of soil physicochemical factors and meteorologic factors and the relationship between the time-series variations of the wood anatomical characteristics and the corresponding soil physicochemical factors were analyzed by means of statistical analysis methods.We draw some conclusions as follows:1.The monthly mean values of soil physicochemical factors in two branch sampling spots were determined and the meteorological data for the monthly mean values were collected to explore the effect of meteorologic factors on the monthly variation of soil physicochemical factors within a year.The results showed that:The total soil salt content and Cl-content in the soil in the A.corniculatum sampling plot showed an increasing trend with the increase of average monthly maximum temperature,while the pH values and K+ content in the soil showed a decreased trend with the increase of monthly average rainfall by stepwise regression analysis between soil physicochemical indexes and meteorologic indexes.The soil total nitrogen content,pH value in the soil,Cl-and Na+ content in the soil in the C inerme sampling plot showed an increasing trend with the increase of average monthly maximum temperature,while the Ca2+ content in the soil showed a increasing trend and Fe3+ content in the soil showed a decreased trend with the increase of monthly average rainfall,while the soil total phosphorus content in the soil showed a decreased trend and Mn2+ in the soil showed a increasing trend with the increase of average monthly lowest temperature by stepwise regression analysis between soil physicochemical indexes and meteorologic indexes.The above results showed that the monthly variations of soil physicochemical properties in two sampling plots were affected by meteorologic factors.2.The morphological structure of secondary xylem of two mangrove plants was observed by LM and SEM.The results showed that the morphological structure of two mangrove plants has ecological adaptation significance.According to the results of structural-functional anatomy,both species of mangrove plants have the phenomenon of coexistence of broad and narrow vessel,special structures on vessel walls(grooves structures in inner pit apertures of pits,uneven thickening in the inner wall of vessel),the starch grain in ray cell,bordered pit and other special structures,7.,habitat selection pressure promotes the morphological structure of mangrove plants to develop in favor of water transport safety and effectiveness.Habitat selection pressure promotes the morphological+ structure of mangrove plants to develop in favor of water transport safety and effectiveness.3.In order to reveal the adaptation significance of the quantitative anatomical characteristics of the secondary xylem of two mangrove plants with the dynamic changes of soil physicochemical factors within one year,the new growth layers were demarcated from two mangrove plants branches collected in 11 different continuous time spans within one year since two mangrove plants was characterized by growth ring in the secondary xylem,the 22 quantitative anatomical features of the new growth layer in 11 different continuous time spans within one year were observed,and variations in soil physicochemical factors in 11 different continuous time spans within one year were determined as well,and apply the canonical correlation analysis to explore the comprehensive internal relationship between them.The results showed that:(1)The canonical correlation analysis between the quantitative anatomical characteristics of the secondary xylem of A corniculatum and the corresponding soil physicochemical factors in 11 different continuous time spans within one year showed that:with the increase of Zn2+ and Mn2+ content,the vessel element showed a decreased trend,it is beneficial to ensure the safety of water transport;With the increase of Na+and Ca2+ content,the vessel cluster size,ray area and ray frequency showed an increasing trend,the plants with high vessel cluster size have multiple pore and pore cluster,which can help reduce and prevent the occurrence of vessel embolism,the hydrolysate of starch in ray cells is helpful for repair of vessel embolism;With the increase of Soil total phosphorus content,the radial pore diameter and pore area showed an increasing trend,under the condition of superior habitat,the "large scale"vessel can improve the efficiency of water transportation.With the increase of total soil salt content and Na+ content,the solitary pore ratio and pore area showed a decreased trend,the decrease of solitary pore ratio is beneficial to improve the safety of water transport,the increase of pore area makes the vessel tend to be miniaturized,which is helpful to prevent the occurrence of vessel embolism;With the increase of total soil salt content and pH,the ray width and ray height showed an increasing trend,it will weaken the mechanical organization ability and the transport organization ability of A comiculatum.The above studies show that the quantitative anatomical characteristics of secondary xylem develop in the direction of adaptation to heterogeneous habitats with the change of soil physicochemical factors.(2)The canonical correlation analysis between the quantitative anatomical characteristics of the secondary xylem of C inerme and the corresponding soil physicochemical factors in 11 different continuous time spans within one year showed that:with the increase of total soil salt conten and Na+ content,the vessel cluster size showed an increasing trend,the pore area and solitary pore ratio showed a decreased trend,it is beneficial to reduce and prevent the occurrence of vessel embolism;With the increase of soil Ca2+ and Mn2+content,the tangential pore diameter and pore area showed a decreased trend,little pore density showed an increasing trend,promoting the miniaturization of the vessel element,it isbeneficial to improve and ensure the safety of water transport.The abovestudies show that the quantitative anatomical characteristics of secondary xylem develop in the direction of adaptation to heterogeneous habitats with the change of soil physicochemical factors.4.In order to reveal the correlation between the monthly variation within one year of the quantitative anatomic characteristics of vestured pit of the secondary xylem and the soil physicochemical factors,the 14 quantitative anatomical characteristics of secondary xylem of vestured pit were observed in different months within one year,and 13 indexed of soil physicochemical factors were determined in different months within one year as well,and apply the stepwise regression analysis was used to explore the relationship between them.(1)The stepwise regression analysis of the monthly variation within one year of the quantitative anatomic characteristics of vestured pit of the secondary xylem and the soil physicochemical factors in different months of A corniculatum showed that:with the increase of total soil salt content,soil total nitrogen content and soil pH,the inner and outer aperture showed an:increasing trend;With the increase of soil Mn2+ and Fe3+content,the inner and outer aperture showed a decreased trend;With the increase of total soil salt content,the frequency of vestured vessel outer aperature showed a decreased trend.Based on the flunction of the vestured pit,the increase of the inner and outer aperture is beneficial to the transverse transport of water,the decrease of the frequency of vestured is not conducive to the safety of water transport.Due to the limitations of the experiment,the complete mechanism and ecological adaptation mechanism need further study.(2)The stepwise regression analysis of the monthly variation within one year of the quantitative anatomic characteristics of vestured pit of the secondary xylem and the soil physicochemical factors in different months of C inerme showed that:with the increase of soil Ca2+ and Zn2+ content,the frequency of vestured vessel inner aperature and the frequency of vestured vessel pit chamber showed a decreased trend;With the increase of soil Mg2+ content,the frequency of vestured vessel outer aperature and the frequency of vestured vessel pit chamber showed an increasing trend;With the increase of soil Mn2+,Ca2+ and Zn2+ content,the inner and out aperture showed a decreased trend;With the increase of soil total phosphorus content and Cl-content,the inner aperture showed an increasing trend.Based on the function of the vestured pit,the increase of the inner and outer aperture is beneficial to the transverse transport of water,the decrease of the frequency of vestured is not conducive to the safety of water transport.Due to the limitations of the experiment,the complete mechanism and ecological adaptation mechanism need further study. |
