Soil fauna as drivers of the architecture of forest floors

土壤动物是森林地表结构和动态的主要驱动因素。我们使用最先进的方法来调查哪些土壤腐生物类群对森林凋落物的处理有贡献。分析稳定同位素比率的自然变化，结合标签方法和实验操作，对食腐物消费者的化合物特定脂质和氨基酸进行分析，将使人们能够以前所未有的细节了解它们在森林地面形成和动态中的作用。我们将重点讨论三个中目动物（弹虫科、甲虫科、叶虫科）和大型动物（蚓目、双足目、等足目）的营养分类。根据研究单元的总体设计，将对12个以山毛榉为主但点缀着枫木和云杉的地点进行调查。该项目包括三个工作包：在工作包1中，我们将研究温度和林分营养状况对主要腐殖生物类群能量通道的影响。作为食物网微生物群落的基础，将利用磷脂脂肪酸标记进行研究。通过稳定同位素的自然变化以及化合物特异性氨基酸分析，研究了营养动物的营养生态位。结合体型测量，将评估受温度和林分营养状况影响的基础资源（凋落物、细菌、真菌）进入腐食分类群的渠道。在工作包2中，将使用能够操纵中小型和大型动物进入的中生态系统来评估这些食腐动物行会对森林地面形成和动态的长期影响。使用13C和15N标记的凋落物将允许跟踪凋落物材料的加工并纳入腐殖生物分类群。复合特定脂质分析将深入了解凋落物被纳入腐食物消费者的途径，以及主要土壤腐食物类群对森林地表动态的长期影响，这些影响受森林林分温度和营养状况的影响。在工作包3中，我们将研究腐食性土壤动物对凋落物空间扩散的作用。利用15N标记凋落物并测量其与腐殖生物分类群的结合，将有助于了解凋落物的水平和垂直分布及其时间动态。总的来说，拟议的项目将使人们对土壤腐生物群落的功能及其在森林地面形成和动态中的作用，以及它们随温度和林分营养状况的变化有新的认识。

Soil animals are major driving factors of the structure and dynamics of forest floors. We use state-of-the-art methodologies to investigate which soil detritivore taxa contribute to the processing of forest litter material. Analysing natural variations in stable isotope ratios, compound specific lipid and amino acid analyses in detritivore consumers combined with labelling approaches and experimental manipulations will allow understanding their role in the formation and dynamics of forest floors in unprecedented detail. We will focus on three meso- (Collembola, Oribatida, Enchytraeidae) and macrofauna detritivore taxa (Lumbricidae, Diplopoda, Isopoda). Following the overall design of the Research Unit 12 sites dominated by beech but interspersed with maple and spruce will be investigated. The project comprises three work packages: In work package 1, we will study the energy channelling through major detritivore taxa as affected by temperature and nutrient status of forest stands. As basis of the food web microbial communities will be studied using phospholipid fatty acid markers. Trophic niches of detritivores will be investigated by natural variations in stable isotopes as well as compound specific amino acid analysis. Combined with measurements of body size the channelling of basal resources (litter, bacteria, fungi) into detritivore taxa as affected by temperature and nutrient status of forest stands will be evaluated.In work package 2, mesocosms allowing to manipulate access by meso- and macrofauna will be used to evaluate the long-term effects of these detritivore guilds for the formation and dynamics of forest floors. The use of 13C and 15N labelled litter will allow to follow the processing of litter material by and incorporation into detritivore taxa. Compound specific lipid analyses will provide insight into the pathways litter materials are incorporated into detritivore consumers and into long-term effects of major soil detritivore taxa for the dynamics of forest floors as affected by temperature and nutrient status of the forest stands. In work packages 3, we will investigate the role of detritivore soil animals for the spatial spread litter materials. Using 15N labelled litter and measuring its incorporation into detritivore taxa will provide insight into the horizontal and vertical spread of litter materials and its temporal dynamics. Overall, the proposed project will allow novel insights into the functioning of soil detritivore communities and their role in the formation and dynamics of forest floors, and their variation with temperature and nutrient status of forest stands.