东北两种桦木导管和纤维细胞特征及其与气候关系

[Objective]To clarify the response and adaptation strategies of trunk conduits and wood fibre cells of Betula spp.to climate under the influence of climate,so as to better understand the macroscopic growth-climate relationship,and to provide theoretical basis and scientific evidence for the prediction of the productivity of temperate forests and vegetation productivity in Northeast China.[Method]In this study,we measured and compared the annual ring width(RW),vessel number(VN),mean vessel area(MVA),total vessel area(TVA),vessel density(VD),specific theoretical hydraulic conductivity(Ks),theoretical hydraulic conductivity(Kh),mean percentage of vessel area within xylem(RVTA),fiber cell number(FN),total fiber cell area(TFA),mean fiber cell area(MFA),fibre cell density(FD),overall mean thickness of all fiber cell walls(CWTall)and mean percentage of fiber cell area within xylem(RFTA),etc.,and analysed the relationship of the characteristics of the two species with seasonal and wood fibre cell characteristics.We analysed the relationship between conduit and wood fibre cell characteristics and seasonal climatic factors,temporal stability,and growth resistance and resilience to climatic extremes in both species.[Result]B.platyphylla and B.costata belong to the same genus of bulkhead timber,with wide distribution range,strong adaptive ability,and similar xylem anatomical structure,but there are still significant differences.There was a significant positive correlation between the width of annual rings and the number of conduits between B.platyphylla and B.costata(p<0.05).B.costata had large and few conduits,small wood fibre cells and thicker wood fibre cell walls;B.platyphylla had small but numerous conduits and larger and more wood fibre cells.Radial growth of B.platyphylla and B.costata was mainly limited by temperature and moisture factors,and the effect of climatic factors on the characteristics of wood fibre cells was weak relative to the anatomical characteristics of the ducts.As the climate warmed,B.platyphylla,due to the influence of precipitation,had a greater number of conduits,but smaller conduits.B.costata,on the other hand,adapted to the environment by decreasing the number of ducts and increasing their size;the number of B.platyphylla wood fibre cells tended to increase,but the opposite was true for B.costata wood fibre cells.B.platyphylla and B.costata radial growth resistance and resilience to growing season drought and non-growing season high temperature trends were basically the same,no significant difference,and both of them had lower resistance and resilience to non-growing season high temperature.[Conclusion]In this study,we found that different birch xylem conduits and wood fibre cells had different strategies to cope with climate warming,and we could not explore the growth mechanism and adaptation strategy of the tree species as a whole by using the family alone.Birch mainly produces more and smaller conduits to maintain hydraulic safety and more wood fibre cells to ensure normal radial growth.B.costata,on the other hand,adopts large conduits to increase the efficiency of water transport,but at the same time,B.costata has a greater probability of embolism,which may result in B.costata being the first to die.