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 increas...

植物可因凋落叶破碎化或遭受干旱胁迫，导致其凋落叶尺寸减小、质量下降，进而影响生态系统功能。本研究以稀树草原源头溪流中的Phylloicus属幼虫为研究对象，探究了有机凋落片段的尺寸与质量对其取食偏好、虫巢构建的影响，以及微生物对叶片的分解过程。实验采用容积约3升的培养容器（尺寸为16 cm ×16 cm ×12 cm），每组设置16个重复：一组放置去除虫巢的Phylloicus幼虫，另一组仅接种微生物群落；向每个容器中添加取自Inga laurina、Maprounea guianensis与Richeria grandis三个物种的凋落叶，将其切割为18.7、13.2及8.1 mm三种直径的圆片（3种尺寸×3个物种=每容器9片圆片）。结果显示，凋落叶圆片尺寸越小、凋落物质量越高，其叶片质量损失率越高，该现象主要由更高的微生物活性介导；究其原因，或在于尺寸更小、质量更高的凋落物具有更大的表面积体积比。Phylloicus幼虫仅在构建虫巢时表现出对凋落片段尺寸的偏好，优先选用Maprounea guianensis与Richeria grandis的较大叶片，这可能是由于