Vertical stratification drives divergent spatial trade-offs among xylem cell types in angiosperm trees of a mountain forest in eastern China

Trade-offs among vessels, fibers, and parenchyma fractions shift with different forest vertical strata, driven by changes in the relative demands and limitations associated with light availability, water transport, and mechanical support. Specifically, we predicted that in the canopy stratum, where high demands exist for efficient hydraulic conductance and robust mechanical support, the primary trade-off involves balancing investment between vessels and fibers. Conversely, we expected that in the subcanopy and understory strata, characterized by greater resource limitation (particularly light), and heightened vulnerability to physical disturbances, pest, and pathogen attacks, the dominant trade-off occurs between fibers and parenchyma. This dataset contains fractions of three different cell types (vessels, fibers, ray parenchyma) in the xylem for 119 individuals across 39 species from the mountainous areas of eastern China. The variable level represents the vertical strata classification, VF denotes vessel fraction, FF denotes fiber fraction, and RAPF denotes ray parenchyma fraction. The code analyzes the trade-offs between vessel and fiber fractions, as well as between parenchyma and fiber fractions, and examines the differences in these trade-offs between different vertical strata.导管（vessels）、纤维（fibers）与薄壁组织（parenchyma）占比之间的权衡关系会随森林垂直分层发生变化，其驱动因素为光照可获得性、水分运输及机械支撑相关的相对需求与限制条件的改变。具体而言，我们预测：在冠层（canopy stratum）中，由于高效水力导度与稳固机械支撑的需求较高，核心权衡关系为导管与纤维间的投入平衡；反之，在亚冠层与林下层中，这类生境以更强的资源限制（尤以光照为甚）、更高的物理干扰及病虫害侵袭风险为特征，主导权衡关系则发生于纤维与薄壁组织之间。 本数据集包含采自中国东部山区39个物种的119个个体的木质部（xylem）中三种细胞类型——导管、纤维与射线薄壁组织（ray parenchyma）——的占比数据。其中，变量水平代表垂直分层分类，VF为导管占比（vessel fraction），FF为纤维占比（fiber fraction），RAPF为射线薄壁组织占比（ray parenchyma fraction）。 本代码用于分析导管与纤维占比、薄壁组织与纤维占比之间的权衡关系，并探究不同森林垂直分层间此类权衡关系的差异。