Data from: Effects of litter size and quality on processing by decomposers in a savannah aquatic system

Plants can have decreased litter leaf size and quality by fragmentation or when exposed to drought, which can affect ecosystem functioning. We evaluated the organic matter fragment size and quality on feeding preference and case construction by Phylloicus larvae, and leaf processing by microorganisms from savannah headwater streams. Containers (16 cm x 16cm x 12 cm, ~ 3L) with either Phylloicus (cases removed; n = 16) or microorganisms (n = 16) were supplied with litter from the species Inga laurina, Maprounea guianensis and Richeria grandis, cut into discs of 18.7, 13.2 and 8.1 mm size (3 sizes × 3 species = 9 discs per container). Smaller leaf discs of higher litter quality increased leaf mass loss, mainly by higher microbial activity. This likely occurs due to increased surface area to volume ratio in smaller, higher quality litter. Phylloicus exhibited preferences for fragment size only for case building, using mostly larger leaves of M. guianensis and R. grandis, likely due increased robustness for case formation. Microorganisms presented similar potential to Phylloicus for decomposing organic matter. Microbial decomposition resulted in ~20% mass loss compared to 30% in Phylloicus despite the higher invertebrate individual biomass (8% for case-building and 24% for food resource). This suggests that a decrease in leaf size after exposure to drought may lead to increased microbial decomposition. However, our results suggest that although shredders typically have low densities in savannah streams, they nonetheless play key roles in energy flow by leaf litter processing due to higher biomass.

植物的凋落叶经破碎或遭受干旱胁迫后，其尺寸与质量会发生下降，这一变化会对生态系统功能产生影响。本研究探究了有机质碎屑的尺寸与质量对叶石蛾属（Phylloicus）幼虫取食偏好、筑巢行为，以及来自稀树草原源头溪流的微生物介导的凋落叶分解过程的影响。实验容器规格为16 cm × 16 cm × 12 cm（容积约3 L），分为两组：移除筑巢护管的叶石蛾属（Phylloicus）幼虫组（n=16）与微生物组（n=16），供试凋落叶取自Inga laurina、Maprounea guianensis和Richeria grandis三个物种，将其切割为18.7、13.2和8.1 mm直径的圆片（3种尺寸×3个物种，每个容器内放置9片圆片）。凋落叶质量更高的小型叶圆片可提升叶片质量损失率，这一现象主要源于更高的微生物活性，其潜在机制为尺寸更小、质量更高的凋落叶具备更大的表面积体积比。叶石蛾属（Phylloicus）幼虫仅在筑巢过程中表现出对碎屑尺寸的偏好，它们优先选用Maprounea guianensis与Richeria grandis的较大尺寸叶片，这可能是因为较大叶片可提升筑巢结构的坚固性。微生物与叶石蛾属（Phylloicus）幼虫在有机质分解方面具备相近的潜力：尽管无脊椎动物个体生物量更高（筑巢个体占8%，取食个体占24%），但微生物介导的分解仅造成约20%的质量损失，而叶石蛾属（Phylloicus）幼虫介导的分解质量损失可达30%。该结果表明，植物遭受干旱胁迫后叶片尺寸减小，可能会提升微生物介导的分解效率。然而，本研究结果还显示，尽管稀树草原溪流中的碎屑撕食者（shredder）通常密度较低，但由于其生物量较高，它们仍可通过凋落叶分解过程在能量流动中发挥关键作用。