Design and analysis of laboratory experiments on aquatic plant litter decomposition

Microcosm studies are a useful tool when it comes to studying leaf litter decomposition but designing and analysing them can be a tricky path with many pitfalls. Because there is a plethora of drivers of leaf decomposition, it is important to be precise about the scientific questions that can be addressed with microcosm set-ups, and to use experimental designs that have minimal logistic implications but, at the same time, high statistical power. In this chapter, we first set the scene by introducing a hypothetical study that has the aim to estimate how leaf decomposition is driven by different decomposers and abiotic conditions. Following on from this scenario, we give an overview of the main biotic and abiotic drivers of leaf decomposition that will play a role in laboratory settings (with special attention to consumer species identity, species richness, body size and metabolic capacity, and also temperature, time scales and stressors). We then explain how to design and analyse laboratory experiments on aquatic leaf litter decomposition including the mathematics for calculating the metabolic power of leaf decomposers and some statistical models. Further three case studies are given—highly controlled experiments that can be analysed by analysis of variance.