Variation in functional traits, growth relationships, and resource allocation among annual twig of dove tree along with latitudes

Dove tree (Davidia involucrata Baill.), a monotypic rare species in China and a famous ornamental plant in the world, was employed as a model species in our study. The  morphological and biomass traits  of annul D. involucrata twigs were investigated in three latitude regions (32°19′ N, 30°08′ and 27°55′) in the Sichuan, Southwest China. , In the flowering stage of D. involucrata populations from mid-April to early May, 6 ‒ 8 healthy plants with similar DBH (diameter at breast height) and no insect pests were randomly selected from the three natural populations in PW, TQ and GX. Selected trees were (a) healthy with similar habitats (soil type, slope and aspect); (b) full grown with similar canopy size; (c) not to be located near the edge of the forest, or next to previously sampled trees. Then, to avoid growth differences derived from light intensity, 3 ‒ 5 annual twigs (including stem and all leaves and flowers above the stem) were randomly collected from the sunny side of the lower crown of each plant. 
The morphological and biomass traits of leaf, stem and flower from each twig were measured. Lamina, petiole, bract and flower stalk were scanned using CanoScan LiDE210, and then the length, width and area of lamina and bract, as well as the petiole length and flower stalk length were measured by the software Image J vers...,

珙桐（Davidia involucrata Baill.）是中国特有的单型珍稀物种，同时也是全球知名的观赏植物，本研究以其作为模式物种。本研究在中国西南四川的三个纬度区域（北纬32°19′、30°08′和27°55′）调查了珙桐一年生枝条的形态与生物量性状。在珙桐种群的花期（4月中旬至5月初），研究人员从PW、TQ、GX三个天然种群中，随机选取6至8株胸径（DBH, diameter at breast height）相近且无虫害的健康植株。所选植株需满足以下标准：(a) 生长健康且生境相似（土壤类型、坡度与坡向一致）；(b) 植株成熟且冠幅相近；(c) 未位于林缘或邻近已采样植株。为避免光照强度差异造成的生长影响，从每株植株冠层下部的向阳面随机采集3至5根一年生枝条（包含茎干以及茎干以上的全部叶片与花器官）。随后对每根枝条的叶片、茎干及花器官的形态与生物量性状进行测定：使用CanoScan LiDE210扫描仪对叶片、叶柄、苞片与花柄进行扫描，再通过Image J软件测量叶片与苞片的长度、宽度及面积，同时测定叶柄长度与花柄长度，相关参数由Image J vers……完成。