Data from: Leaf litter nutrient uptake in an intermittent blackwater river: influence of tree species and associated biotic and abiotic drivers

1. Organic matter may sequester nutrients as it decomposes, increasing in total N and P mass via multiple uptake pathways. During leaf litter decomposition, microbial biomass and accumulated inorganic materials immobilize and retain nutrients, and therefore, both biotic and abiotic drivers may influence detrital nutrient content. We examined the relative importance of these types of nutrient immobilization and compared patterns of nutrient retention in recalcitrant and labile leaf litter. 2. Leaf packs of water oak (Quercus nigra), red maple (Acer rubrum) and Ogeechee tupelo (Nyssa ogeche) were incubated for 431 days in an intermittent blackwater stream and periodically analysed for mass loss, nutrient and metal content, and microbial biomass. These data informed regression models explaining temporal changes in detrital nutrient content. Informal exploratory models compared estimated biologically associated nutrient stocks (fungal, bacterial, leaf tissue) to observed total detrital nutrient stocks. We predicted that (i) labile and recalcitrant leaf litter would act as sinks at different points in the breakdown process, (ii) plant and microbial biomass would not account for the entire mass of retained nutrients, and (iii) total N content would be more closely approximated than total P content solely from nutrients stored in leaf tissue and microbial biomass, due to stronger binding of P to inorganic matter. 3. Labile litter had higher nutrient concentrations throughout the study. However, lower mass loss of recalcitrant litter facilitated greater nutrient retention over longer incubations, suggesting that it may be an important long-term sink. N and P content were significantly related to both microbial biomass and metal content, with slightly stronger correlation with metal content over longer incubations. 4. Exploratory models demonstrated that a substantial portion of detrital nutrients was not accounted for by living or dead plant and microbial biomass, especially in the case of N. This suggests increased importance of both N and P sorption to inorganic matter over time, with possible additional storage of N complexed with lignin. A better understanding of the influence of these mechanisms may improve our understanding of detrital nutrient uptake, basal resource quality and retention and transport of nutrients in aquatic ecosystems.

1. 有机质在分解过程中可固持养分，通过多种吸收途径提升自身总氮（N）与总磷（P）的质量。凋落叶分解阶段，微生物生物量与累积的无机物质会固持并留存养分，因此生物与非生物驱动因子均可影响碎屑养分含量。本研究针对这类养分固持过程的相对重要性展开探究，并对比了难降解与易降解凋落叶的养分留存模式。
2. 将水栎（Quercus nigra）、红枫（Acer rubrum）与奥奇李榄（Nyssa ogeche）的叶袋置于间歇性黑水溪流中培养431天，定期测定其质量损失、养分与金属含量以及微生物生物量。基于这些数据构建回归模型，以阐释碎屑养分含量的时间动态变化。通过非正式探索性模型，对比了估计得到的生物相关养分库（真菌、细菌与叶片组织）与观测到的碎屑总养分库。本研究提出三项预测：其一，易降解与难降解凋落叶将在分解过程的不同阶段发挥养分汇的作用；其二，植物与微生物生物量无法涵盖全部留存养分的总量；其三，相较于总磷，仅基于叶片组织与微生物生物量储存的养分可更精准地估算总氮含量，这是由于磷与无机物质的结合作用更强。
3. 整个实验周期内，易降解凋落叶的养分浓度始终更高。但难降解凋落叶的质量损失率更低，使其在更长培养周期中实现了更高的养分留存，表明其可能是重要的长期养分汇。总氮与总磷含量均与微生物生物量及金属含量显著相关，且在培养周期延长时，与金属含量的相关性略有增强。
4. 探索性模型结果显示，相当一部分碎屑养分无法通过活体或死亡的植物与微生物生物量来解释，这一情况在总氮中尤为明显。这表明随着时间推移，养分吸附至无机物质的过程愈发重要，同时可能存在氮与木质素结合形成的额外储存形式。深入理解这些机制的影响，将有助于我们更好地认识碎屑养分吸收、基础资源质量，以及水生生态系统中的养分留存与运移过程。