In the heatmap clustering results, the color represents the abundance of species. The vertical clustering indicates the similarity of the abundance between different species. The shorter the distance between the two species, the shorter the branch length of the two species, indicating that the two species have more similar abundance between the samples. The horizon clustering indicates the similarity of the abundance of different species between samples, as the vertical clustering, the closer and shorter of the branch length between the samples, indicating the more similarity of the abundance.