Early colonizing fungal communities in beech branches exhibit a distinct spatial organization. Decay often begins in distal regions with stain-associated fungi, which derive from latent propagules in the wood and bark, effecting the first stages of colonization. This characteristic assemblage is followed by a more combative group of wood-rotting fungi, particularly Basidiomycotina. The resource at the front of colonization is partitioned between individuals of different species intermixed without clear delimitation. By contrast, the more combative Basidiomycotina which arrive later and displace the fungi in the colonization front usually occupy much larger spatial domains clearly delimited by interaction zone-lines.