Seasonal Dynamics of the Phenology of Native Species from the Seasonally Dry Tropical Forest

Abstract Phenological processes are strongly affected by environmental conditions. In this study we investigate the phenological patterns of six tree/shrub species in three Caatinga fragments and analyze the influence of rainfall and air temperature on these processes. Circular statistics was used to analyze the vegetative and reproductive phenophases over 12 months (dry and rainy seasons) in the years 2016 to 2017 and 2018 to 2019. Spearman’s linear correlation test (r) was applied to verify the influence of meteorological variables of the two years of study on the phenological stages for each species. All species showed a seasonal pattern for vegetative phenophases. Reproductive phenophases were recorded in the two study periods only for one species. There was correlation of the phenophases only with rainfall, but not for all species. The amount of rainfall below the historical average indicates that precipitation is the most limiting factor for flowering in the evaluated species.摘要 物候过程（phenological processes）受环境条件的强烈调控。本研究针对3处卡廷加植被片段（Caatinga fragments）内的6种乔木/灌木物种的物候模式展开调查，并分析降雨量与气温对这些物候过程的影响。研究采用圆形统计方法（circular statistics），对2016至2017年、2018至2019年两个年度内为期12个月（包含旱季与雨季）的营养物候期与生殖物候期进行分析；同时采用斯皮尔曼线性相关检验（Spearman’s linear correlation test，相关系数r），验证两个研究年度的气象变量对各物候阶段的影响。结果显示，所有物种的营养物候期均呈现季节性模式；仅在1个物种的两个研究时段中观测到生殖物候期。物候期仅与降雨量存在相关性，但并非所有物种均符合该规律。降雨量低于历史均值的观测结果表明，降水是本研究所评估物种开花过程的最关键限制因子。