Data from: Combined effects of seed and soil quality drive seedling performance of a late-successional canopy tree in a tropical forest

Habitat loss and fragmentation affect the structure and functioning of forested ecosystems worldwide, yet we lack an understanding of how species respond to environmental changes. Here we examined reproductive success and seedling performance of Poulsenia armata (Moraceae) in continuous and fragmented forests of Los Tuxtlas, southern Mexico. We further investigated how maternal habitat and soil conditions manifested in the seedling stage. We determined seed quality and seedling performance by combining isotopic analyses in seed quality with field observations of P. armata fruit production and a common garden experiment. Soil conditions in forest fragments negatively impacted P. armata reproductive success. Trees of P. armata in forest fragments were smaller in size, produced fewer fruits and smaller seeds with lower quality compared to trees from the continuous forest. The combined effects of maternal habitat and soil conditions determined seedling survival and growth of this tropical tree. Notably, seedlings had restricted plasticity for biomass allocation to roots, limiting the capacity of fragmented populations to compensate for the initial low N content in seeds. Trees in forest fragments at Los Tuxtlas produced offspring competitively inferior and potentially less resilient than counterparts in continuous forest, jeopardizing future persistence of this late-successional tree species.

生境丧失与片段化会影响全球森林生态系统的结构与功能，但目前我们对物种如何响应环境变化仍缺乏认知。本研究以墨西哥南部洛斯图斯特拉斯（Los Tuxtlas）地区的连续森林与片段化森林为研究对象，探究了桑科（Moraceae）植物Poulsenia armata的繁殖成效与幼苗表现，并进一步探讨了母株生境与土壤条件如何在幼苗阶段体现其影响。本研究通过结合种子质量的同位素分析、P. armata结实量的野外观测以及同质园实验（common garden experiment），对种子质量与幼苗表现进行了测定。森林片段化后的土壤条件对P. armata的繁殖成效产生了负面影响：相较于连续森林中的植株，片段化森林内的P. armata植株体型更小，结实量更少，所结种子体积更小且质量更低。母株生境与土壤条件的共同作用决定了该热带树种的幼苗存活与生长状况。值得注意的是，幼苗的根系生物量分配可塑性受限，限制了片段化种群弥补种子初始氮含量较低的能力。洛斯图斯特拉斯地区片段化森林中的P. armata植株所产生的后代，在竞争力与恢复力上均弱于连续森林中的同类植株，这将危及该晚演替树种的未来存续。