Example of ecosystem engineering by the earthworm (Nightcrawler)Lumbricus terrestris.
These worms are leaving small stacks of soil, faeces and plant debris, called middens, at the burrow entrance. They also pull surface leaf litter into their burrows in lower soil layers. Middens
promote decomposition of leaf litter and formation of nutrient-rich patches
which facilitate of establishment seedlings with higher nutrient requirements.
This behaviour will increase the diversity of plant communities.

Kuopio, Finland.