As a result of the heterogeneous spatial distribution of microorganisms and substrates in soil and their restricted accessibility, biodegradation occurs mainly in hotspots, such as in the detritusphere, induced by decomposing plant residues. Knowing the characteristics of the volume of soil involved in biodegradation of a given organic substrate will facilitate the understanding and prediction of biodegradation.Our objectives were (i) to identify the volume of soil involved in the biodegradation of plant residues and (ii) to determine to what extent this volume is affected by soil moisture under diffusive conditions by monitoring the mineralization and spatio-temporal evolution of residue C and microorganisms in soil at the microbial habitat scale.We incubated repacked soil cores with a central layer of ¹³C-labelled maize residues at three different matric potentials (−0.0031, −0.031 and −0.31 MPa). We monitored ¹³C and total C mineralization, and at different dates over 45 days of incubation, we separated soil slices with increasing distances from the residues and analysed ¹³C from the residues and the microbial community structure and its activity by PLFA and ¹³C-PLFA processing.Residue mineralization increased with increasing soil moisture. A detritusphere a few mm thick was rapidly established, with a decreasing gradient of ¹³C and total PLFAs and ¹³C-PLFAs away from the residue layer. Most ¹³C from the residues was located in the first 2 mm of the detritusphere and was not dependent on the matric potential. Residue mineralization seemed to take place mainly on the residues themselves, but increasing residue C was transferred to the surrounding soil with increasing soil moisture. Dry conditions slowed residue C transfer and favoured fungi, but residue mineralization was carried out by both bacteria and fungi.

由于微生物和底物在土壤中的空间分布不均，并且它们的可及性受到限制，生物降解主要发生在分解植物残渣引起的热点（如碎屑层）中。了解给定有机底物的生物降解涉及的土壤量的特征将有助于对生物降解的理解和预测。我们的目标是（i）识别参与植物残留物生物降解的土壤量和（ii）确定通过监测微生物生境规模中土壤中残留C和微生物的矿化作用和时空演变，研究了扩散条件下土壤水分在多大程度上对土壤水分的影响。我们在重新包装的土壤核心中培养了¹³个中心层C标记的玉米残基处于三种不同的基质势（-0.0031，-0.031和-0.31 MPa）。我们监测的¹³碳和碳的矿化，并且超过潜伏期45天的日期不同，我们分开的土壤片从残留距离增加，并分析¹³从残渣和微生物群落结构和磷脂脂肪酸，其活性Ç ¹³ C- PLFA加工。残留矿化度随土壤湿度的增加而增加。迅速建立了一个几毫米厚的碎屑层，梯度逐渐降低了¹³ C，总PLFA和¹³ C-PLFA远离残留层。最多¹³残留物中的C位于碎屑层的前2 mm，与基质势无关。残留矿化作用似乎主要发生在残留物本身上，但是随着土壤水分的增加，残留物C的增加逐渐转移到周围的土壤中。干燥条件减慢了残留物C的转移并有利于真菌，但是残留物的矿化是由细菌和真菌共同进行的。