What is a heat tree and how to interpret it?

Heat Tree is a powerful method which allows users to visually compare abundance between two groups at different taxonomic levels. It uses hierarchical structure of taxonomic classifications to quantitatively (based on median abundance) and statistically (based on Wilcoxon Rank Sum test ) depict taxon differences among communities.

The Fig. below shows a differential heat tree between two groups (CD vs Control). You can clearly see which taxa are more/less abundance in each group. For more details, please refer Zachary S. L. Foster, et al..