The decomposition of leaf litter is a key ecological process in stream ecosystems. Leaf traits, variable across species and within species, constitute a prime driver of this process. Vitis vinifera, the most valuable horticultural crop in the world, represent a priviledged opportunity to assess the importance of intra-specific leaf variability on litter decomposition due to its high phenotypical diversity across cultivars. This study aims to assess the importance of leaf trait differences of four Vitis vinifera cultivars (Aragonez, Baga, Bical and Fernão Pires) on mass loss and microbial and detritivore descriptors, in a low order stream. Results indicate that leaf trait variability among cultivars is a main driver of leaf mass loss and microbial decomposers activity. Fungal sporulation rates were reduced in leaves from cultivars more defended by structural defenses—thoughness, higher leaf mass per area and trichomes density. Invertebrates’ structure and density of shredders responded to leaf N concentrations more than leaf structural descriptors. Macroinvertebrates seem to play a crucial role as decomposition facilitators, by accelerating fungal colonization and conidial release, particularly in cultivars endowed with a dense indumentum. Our results indicate that V. vinifera leaf litter is a high-quality substratum that may present narrow intra-specific leaf traits variability, determined by distinct cultivar genetics, which are able to modulate the litter decomposition process in streams. We suggest that further research assessing the effects of vegetation alterations on stream ecosystem functioning should include leaf litter intra-specific dissimilarities that, even when subtle, may propagate from terrestrial to aquatic systems with cascading impacts across the stream food chains.

落叶分解是河流生态系统中一个关键的生态过程。不同物种和物种内可变的叶性状构成了这一过程的主要驱动力。Vitis vinifera是世界上最有价值的园艺作物，由于其跨品种的高度表型多样性，代表了评估种内叶片变异性对凋落物分解的重要性的难得机会。本研究旨在评估四种葡萄叶片性状差异的重要性。栽培品种（Aragonez、Baga、Bical 和 Fernão Pires）的质量损失以及微生物和碎屑动物描述符，在低阶流中。结果表明，品种间的叶片性状变异是叶片质量损失和微生物分解活动的主要驱动因素。来自更受结构防御保护的品种的叶子中的真菌孢子形成率降低 - 坚固，单位面积叶质量和毛状体密度更高。无脊椎动物的结构和粉碎机密度对叶 N 浓度的响应大于叶结构描述符。通过加速真菌定植和分生孢子释放，大型无脊椎动物似乎作为分解促进剂发挥着至关重要的作用，特别是在具有致密毛被的品种​​中。我们的结果表明，V. vinifera落叶是一种高质量的基质，可能呈现狭窄的种内叶片性状变异，由不同的栽培品种遗传决定，能够调节溪流中的凋落物分解过程。我们建议评估植被改变对河流生态系统功能影响的进一步研究应包括落叶种内的差异，即使是细微的，也可能从陆地系统传播到水生系统，并在整个河流食物链中产生级联影响。