Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Correlation between Radial Growth and NDVI of Typical Desert Plants Haloxylon Ammodendron and Tamarix Ramosissima

Auteur : 孙甜甜

Grade : Master 2022

Université : Shihezi University

Résumé partiel
Due to its wide spatial distribution and high resolution,tree-ring data can accurately record the change process of natural environment and be used to reconstruct historical climate changes.It plays an important role in the interdisciplinary research of climatology,forestry,ecology and other disciplines.In recent years,with the vigorous development of dendrochronology,shrubs have received increasing attention as new tree-ring research objects.The woody plants are mostly shrubs and semi-shrubs in arid and semi-arid desert regions or high-altitude and high-latitude mountainous areas in China.The distribution characteristics of shrubs and high sensitivity to climate change determine the irreplaceable role in revealing regional climate change,environmental protection and ecological restoration.However,due to the special shape of shrub tree-ring,radial allometric growth and high measurement difficulty,there are few reports on the radial growth of shrub tree-ring and its correlation with environmental factors.Therefore,it is of great significance to explore the measurement methods and measurement index suitable for shrub rings in cold and arid areas,and analyze the correlation between shrub tree-ring and environmental factors,which is of great significance for studying regional climate and environmental changes and reconstructing historical NDVI sequence.In this study,Haloxylon ammodendron and Tamarix ramosissima,which are typical desert plants in cold and arid regions,were selected as the research objects.Firstly,the tree-ring parameters of Haloxylon ammodendron were extracted and measured based on ENVI and GIS software,and the accuracy was verified by Win DENDRO professional tree-ring analysis software,aiming to propose a measurement method suitable for shrub dendrochronology.Secondly,the tree-ring characteristics of Tamarix ramosissima were extracted through U-Net image semantic segmentation and GIS measurement,and the tree-ring growth rate index（TRGR）was proposed,which was compared with tree-ring width（TRW）and basal area increment（BAI）,in order to provide a new substitute index for the study of shrub dendrochronology.In addition,the seasonal curve parameters of NDVI are reconstructed by using TIMESAT time series analysis software,and the interannual variation trends of NDVI under different scales were analyzed.Finally,the early-wood radial growth of Haloxylon ammodendron and the TRGR of Tamarix ramosissima were correlated with the key parameters of NDVI seasonal curve,respectively,to explore the response of their radial growth to environmental changes.The main findings of the study are as follows :（1）The study combined with ENVI image classification and GIS measurement and analysis,a method was proposed for measuring the tree-ring parameters of Haloxylon ammodendron,which can automatically extract the tree-ring boundary line,effectively improve the measurement efficiency and reduce human interference.This method lays a foundation for the automatic measurement of tree-ring parameters such as perimeter and area.Professional ring analysis system Win DENDRO was used to test the measurement results.The results were proved that the accuracy of the method meets the measurement requirements.In addition,the method constructed in this study is universal and suitable for any tree ring analysis

Mots clés : Haloxylon ammodendron ;Tamarix ramosissima ;Tree-ring measurement ;Radial growth ;NDVI;

Présentation (CNKI)