The Characteristics Of Annual Ring Width Of Tamarix Shrub In Lop Nor Area And Its Response To Environmental Factors

Genetic and ecological factors are the main factors affecting the growth of trees.The influence of external environment on the growth and development of trees can be reflected by the width of tree rings.Lop Nor region is one of the most representative regions of environmental change in arid areas of China and even the world.Due to its special geographical location,harsh environment and exceptionally fragile ecosystem,Lop Nor region is very sensitive to global climate change.Although the harsh climate conditions in Lop Nor area limit the growth and development of trees,Tamarix shrubs and other shrubs are widely distributed in some areas.The study on the width characteristics of Tamarix shrubs in this area and its response to local environmental changes is of great significance for the implementation of ecological protection in Lop Nor area in the future.In this paper,the Tamarix tree ring in Lop Nor area was taken as the research object,and a series of stem sampling methods were adopted to collect the Tamarix wheel,and the timely processing,cross-dating and growth ring width measurement were carried out strictly in accordance with the standard of growth ring experiment.Different habitats in this paper,we study the Lop Nor were systematically stud Ed under Philippine wheel brush tree characteristics and differences,and USES the correlation analysis for the annual ring width of four areas and regional differences in the correlation of temperature,precipitation and its response to the environmental elements relations,Philippine thickets to a deeper understanding of the Lop Nor were systematically stud Ed the changing rule of the ecosystem,to protect its ecological system and used to provide theoretical basis.The main conclusions are as follows:(1)In Lop Nor area,the color of Tamarix shrubs tree rings early wood is lighter and pale yellow,and the color of late wood is darker and dark red,with very clear boundaries.Affected by its own genetic characteristics and extreme habitats,the eccentricity of Tamarix shrubs growth is common.There are single or multiple growth areas in some tree rings,and the morphology of the tree disk is irregular,such as a star or fan.(2)The number of tree rings of sapwood in Tamarix shrubs in Lop Nor area is mainly concentrated between 4-5 rings,accounting for more than 79% of the total sample,of which 4 rings are the most,accounting for 49% of the total sample.There is no obvious relationship between the number of sapwood and tree age.The width of the sapwood band is wider in young tree stems and narrower in old trees.(3)The width of the annual ring of Tamarix shrubs in the study area is relatively small,basically below 1 mm.There are also obvious differences in the annual ring width of Tamarix shrubs in different regions.The average annual ring width of the four sampling points is 0.83-1.21 mm,of which the Hongliugou area is the largest with 1.21mm;the second is Hongliujing and Yingpan regions,with0.91 mm and 0.83 mm respectively;the average annual ring width in Milan is the smallest.It is 0.82 mm.(4)The tree-ring sensitivity of Tamarix shrubs in Lop Nor area is different in region and has a very significant negative correlation with tree age.Generally speaking,the sensitivity of Tamarix shrubs tree-ring is better,and the average sensitivity is above 0.18.The average sensitivity of Hongliugou area is 0.27,the average sensitivity of Hongliujing area is 0.20,the average sensitivity of Yingpan area is 0.20,and the average sensitivity of Milan area is 0.18.(5)The radial growth of Tamarix shrubs in different areas of Lop Nor has great difference in response to climate factors.The radial growth of Tamarix in Hongliugou area is significantly positively correlated with the average maximum temperature in May,the average temperature in winter and the average maximum temperature in winter.The radial growth of Tamarix in Hongliujing area was negatively correlated with the average maximum temperature in June of last year and the average maximum temperature in summer of the same year(mainly in August).There was a significant negative correlation between the growth of Tamarix in Milan and the average maximum temperature in August of last year and the average maximum temperature in January of the current year and the radial growth of Tamarix in Milan,and the effect of the average maximum temperature in August on the growth of Tamarix showed a significant "lag".There was a significant negative correlation between the growth of Tamarix shrubs and the mean temperature and the mean maximum temperature in September.(6)The radial growth of Tamarix is not significantly correlated with precipitation in Lop Nor area.The climate in this area is dry and the precipitation is rare.The Tamarix shrubs are mainly non-zonal hidden vegetation,and their survival does not depend on precipitation.(7)The radial growth of Tamarix shrubs in the Lop Nor area is the result of the comprehensive influence of climate factors,water conditions,soil types,salinity and wind-sand activities.Hongliugou area Hongliugou area is located near the river,with the best water conditions,and it has not developed into Tamarix sandbags.The high temperature in the peak season does not restrict the growth of Tamarix shrubs,and the low temperature in winter restricts the Tamarix shrubs growth more obviously;the Hongliujing area is adjacent The Lop Nor Dry Lake Basin is rich in groundwater,but the soil has a high salt content.The Tamarix shrubs growth is mainly affected by extreme temperatures due to its own salt secretion mechanism,and the average temperature is not significant;the wind-sand activity in Milan is strong and the sand dunes are widely distributed And the cover thickness is large,the growth of Tamarix shrubs is mainly affected by extreme temperature and the "lag effect" is more obvious;Yingpan area is located on the second-level terrace of Kongque River,and the water condition is good.The high temperature in the peak growing season will restrict the growth of Tamarix.