Aim: Plant trait databases often contain traits that are correlated, but for whom direct (undirected statistical dependency) and indirect (mediated by other traits) connections may be confounded. The confounding of correlation and connection hinders our understanding of plant strategies, and how these vary among growth forms and climate zones. We identified the direct and indirect connections across plant traits relevant to competition, resource acquisition and reproductive strategies using a global database and explored whether connections within and between traits from different tissue types vary across climates and growth forms. Location: Global. Major taxa studied: Plants. Time period: Present. Methods: We used probabilistic graphical models and a database of 10 plant traits (leaf area, specific leaf area, mass- and area-based leaf nitrogen and phosphorous content, leaf life span, plant height, stem specific density and seed mass) with 16,281 records to describe direct and indirect connections across woody and non-woody plants across tropical, temperate, arid, cold and polar regions. Results: Trait networks based on direct connections are sparser than those based on correlations. Land plants had high connectivity across traits within and between tissue types; leaf life span and stem specific density shared direct connections with all other traits. For both growth forms, two groups of traits form modules of more highly connected traits; one related to resource acquisition, the other to plant architecture and reproduction. Woody species had higher trait network modularity in polar compared to temperate and tropical climates, while non-woody species did not show significant differences in modularity across climate regions. Main conclusions: Plant traits are highly connected both within and across tissue types, yet traits segregate into persistent modules of traits. Variation in the modularity of trait networks suggests that trait connectivity is shaped by prevailing environmental conditions and demonstrates that plants of different growth forms use alternative strategies to cope with local conditions.

中文翻译：

---

跨环境梯度和生长形式的性状连接的稳健性

目的：植物性状数据库通常包含相关性状，但直接（无向统计依赖性）和间接（由其他性状介导）的联系可能会混淆。相关性和联系的混淆阻碍了我们对植物策略的理解，以及这些策略如何在生长形式和气候带之间变化。我们使用全球数据库确定了与竞争、资源获取和繁殖策略相关的植物性状之间的直接和间接联系，并探讨了来自不同组织类型的性状内部和之间的联系是否因气候和生长形式而异。地点：全球。研究的主要分类群：植物。时间段：现在。方法：我们使用概率图形模型和 10 个植物性状（叶面积、特定叶面积、基于质量和面积的叶氮和磷含量、叶寿命、植物高度、茎比密度和种子质量），有 16,281 条记录，用于描述热带、温带、干旱、寒冷地区的木本植物和非木本植物之间的直接和间接联系和极地地区。结果：基于直接连接的特征网络比基于相关的特征网络更稀疏。陆地植物在组织类型内和组织类型之间的性状之间具有高度连通性；叶寿命和茎比密度与所有其他性状有直接联系。对于这两种成长形式，两组特质构成了更高度联系的特质模块；一个与资源获取有关，另一个与植物结构和繁殖有关。与温带和热带气候相比，木本物种在极地具有更高的性状网络模块性，而非木本物种在不同气候区域的模块化方面没有表现出显着差异。主要结论：植物性状在组织类型内部和组织类型之间高度相关，但性状分离成持久的性状模块。性状网络模块性的变化表明性状连通性受主要环境条件的影响，并表明不同生长形式的植物使用替代策略来应对当地条件。