Spatiotemporal Distribution Characteristics Of Non-structural Carbohydrates In Main Woody Plants In Sygera Mountain

In this study,12 species of woody plants with representative,typical characteristics and different site conditions in Sejila Mountain:Pinus armandii,Spruce in Nyingchi,Betula vulgaris,Quercus sibiricum,Rhododendron in snowy mountains,Rhododendron in snow,Rhododendron in Nyingchi,The research objects are the sharp-pointed long-bud fir firs,square cypresses,sage cedar,alpine pine,and giant cypresses at different altitudes.Multi-factor analysis of variance and least significant difference(LSD)multiple comparison analysis methods are used to analyze 12 different life-type plants,The changes of non-structural carbohydrates(NSC)in different altitudes and different vegetative organs of Fir Fir and different vegetative organs were compared and analyzed,aiming to explore the temporal and spatial distribution characteristics of NSC of main woody plants in Sejila Mountain,and clarify the adaptation of plants to high mountains.The physiological and ecological mechanism of the alpine environment and the formation mechanism and influencing factors of the alpine forest line are explored,in order to better understand the adaptability and response of plants to the adverse environment from the perspective of plant physiology and ecology.The main findings are as follows:(1)Tree species,tissues and their interactions significantly affect the NSC content,soluble sugar and starch content and their ratios of plants in different growing seasons(P<0.05).There is a significant linear relationship between the soluble sugar and starch content of plants in the growing season.The linear relationship of plants in the non-growing season cannot explain the correlation between soluble sugar and starch.Due to seasonal growth,the main woody plants in Sejila Mountain in the non-growing season have reduced low-temperature respiration consumption and weakened photosynthesis(deciduous plants have no photosynthesis),resulting in an increase in NSC content.The main woody plants of Sejila Mountain in the non-growing season have high levels of soluble sugar content and starch reserves,which ensures that the plants can withstand the cold in the cold winter.(2)Life forms,tissues and their interactions significantly affect the content of plant NSC and starch in different growing seasons.The ratios of soluble sugar and starch of different life-type plants are not significantly different in different growing seasons.Plants with different leaf phenology have different utilization and storage of NSC in different growing seasons.In order to have a higher level of NSC content after deciduous plants,deciduous plants will store more plants during the growing season to survive the cold winter and grow the next year.Plant growth at the beginning of the season;evergreen plants have photosynthetic products in different growing seasons and also store carbohydrates during the growing season.The difference in leaf traits will cause differences in the photosynthesis intensity of plants,leading to differences in NSC between coniferous and broad-leaved species.Plant tissues have different functional traits in different growing seasons.The branches and stems of plants transport more carbohydrates than reserves during the growing season,while the branches and stems of evergreen plants store more carbohydrates than transport during the non-growing season.,On the one hand,because of the storage of plants in the middle and late growing seasons,on the other hand,the photosynthesis of evergreen plants is still going on.The contents of NSC and its components in different life-type plants are also different in different tissues.The NSC and soluble sugar content of each tissue of evergreen broad-leaved trees in the growing season and the starch content of five life-type plants are shown as follows:root>leaf>branch>stem,while the NSC and soluble sugar content of each tissue of the other four life-type plants are all The performance is:leaf>root>branch>stem(except evergreen shrubs);the performance characteristics of different life-type plants in non-growing seasons are different.This also indicates to a certain extent that different plants have their own unique adaptive strategies and self-protection measures to severe environmental changes.(3)Trees in the transition zone of the forest line(fir and cypress)did not show "carbon balance imbalance" in the growing and non-growing seasons.The two major factors that limit the upper limit of the distribution of trees in the alpine forest line are caused by low temperature."Growth inhibition" and shrubs are "carbon limited" and formed a "grain" that hinders the settlement and upward migration of tree seedlings.The slope aspect caused the difference of plant NSC content and its components in the forest line transition zone,but the results of this study were too many uncontrollable factors to indicate whether the slope aspect had an impact on the formation and height of the forest line.The NSC content of plant tissues is affected by "rhizosphere low temperature",and it remains at a high level even in the non-growing season.The high level of soluble sugar content and the continuous dynamic conversion process between soluble sugar and starch are both self-protection strategies for plants in the cold mountain environment,and are the guarantee for the plants to survive the winter smoothly.(4)In the different growing seasons of Sejila Mountain,the sharp-pointed long-bud fir firs did not have insufficient carbon supply,and the NSC source-sink content remained in a stable equilibrium state.The upper limit of the distribution of trees in the alpine forest line is more limited."Growth restriction" caused by environmental stresses such as low temperature,rather than "carbon balance imbalance",of course,may also be subject to "regeneration and reproduction obstacles."In different growing seasons,plant tissues will show different functional traits in response to changes in the external environment.The high-altitude,sharp-pointed long-bud fir branches in the growing season have more carbohydrate transport functions than storage functions,and dry growth is better than carbohydrate reserves;High-altitude branches and stems in the non-growing season store a large amount of non-structural carbohydrates to ensure sustainable survival.The strategy for plants to spend the long and cold winter is mostly to maintain a high level of soluble sugar,the conversion between starch and soluble sugar,and so on.With the increase of altitude,the ratio of soluble sugar to starch in the leaves of Fir leaves in the growing season and non-growing season gradually increases.Plants have a positive response to changes in the environment.The self-protection strategies of plant tissues are in The more severe the environment,the more obvious.