Replication Data for: Litterfall dynamics along a successional gradient in a Brazilian tropical dry forest

ABSTRACT Background: This study aimed to determine the influence of soil traits, vegetation structure and climate on litterfall dynamics along a successional gradient in a tropical dry forest (TDF) in southeastern Brazil. We used a chronosequence design consisting of three successional stages (early, intermediate, and old-growth) defined based on forest age and vertical and horizontal structures. Methods: Litterfall was recorded monthly for three years in 12 plots of 50 × 20 m (four plots per stage) where vegetation parameters (species richness, basal area, density and height for trees with diameter at breast height ≥ 5 cm) and soil chemical and physical traits were previously obtained. We placed eight 0.5-m2 litter traps in each plot, totalling 96 traps. Samples were sorted into leaves, twigs, reproductive parts, and debris. Results: Litterfall mass was composed mainly of leaves and varied slightly among years (4 to 4.5 Mg∙ha− 1), within the range observed for other TDFs. Annual litterfall mass was higher at the old-growth forest than at the early and intermediate forest stages and this successional pattern was driven by vegetation characteristics (forest structural parameters and plant functional groups) and soil traits related to water-holding capacity. Litter amount in the intermediate stage was lower than expected for its forest structure (and similar to the early stage), possibly because its higher soil clay content increased the water holding capacity and leaf retention during the dry season. Seasonal variations in monthly litterfall were strongly driven by forest deciduousness and affected by climatic factors related to water availability. This pattern was consistent across the successional gradient, although differences for each litterfall component were observed. Conclusions: Our results suggest that litter production in the studied TDF is influenced by multiple factors along succession, such as above-ground biomass and the degree of leaf retention mediated by soil water-holding capacity. Further studies on community phenological patterns can allow a better understanding of successional changes on litterfall and how fast this fundamental function recovers in secondary forests.

摘要 背景：本研究旨在探明巴西东南部热带旱林（tropical dry forest, TDF）沿演替梯度的凋落物动态，及其受土壤性状、植被结构与气候的调控作用。本研究采用年代序列设计，依据林分年龄及垂直、水平结构划分出3个演替阶段：早期、中期与成熟林。方法：本研究在12块50×20 m的样地中开展了为期3年的月度凋落物监测，每个演替阶段设置4块样地。此前已在样地内测定了植被参数——胸径≥5 cm的乔木的物种丰富度、断面积、密度与树高，以及土壤理化性状。每块样地布设8个0.5 m²的凋落物收集器，总计96个收集器。收集的凋落物样品被分为叶片、枝条、繁殖器官与碎屑四类。结果：凋落物生物量以叶片为主，各年度间波动幅度较小（4~4.5 Mg·ha⁻¹），处于其他热带旱林的观测范围内。成熟林的年凋落物量显著高于早期与中期演替林分，该演替格局由植被特征（林分结构参数与植物功能群）及与持水能力相关的土壤性状驱动。中期演替阶段的凋落物量低于其林分结构所预期的水平，与早期林分相近，这可能是因为其较高的土壤黏粒含量提升了土壤持水能力，进而在旱季延长了叶片留存时间。月度凋落物的季节波动主要受森林落叶性调控，并受与水分可利用性相关的气候因子影响。该规律沿演替梯度保持一致，尽管不同凋落物组分间存在差异。结论：本研究结果表明，所研究的热带旱林的凋落物生产受演替过程中多重因素的共同影响，如地上生物量以及由土壤持水能力介导的叶片留存程度。后续针对群落物候模式的研究，可进一步明晰凋落物动态的演替变化，以及次生林这一基础生态系统功能的恢复速率。