Trade is vital to the survival of forests. Information, water, and various magical energies are not evenly spread. Fey creatures help shift resources, but not only are they are massively outnumbered by the sheer number of trees, they have their own lives to go about. Enter: fungus.
Fungal networks, often the size of entire realms, handily prevent backups and energy deserts. Filaments link each tree to its neighbors and to larger pockets, with different types of magical fungi bridging trees for specific purposes. Some network layers transmit water via the astral plane while others balance the flows of energy. Areas being flooded with sunshine trade excess light energy for gloom zest, allowing them to strengthen poisonous barks and sharpen thorns.
Dryads and sprites help maintain the balance, but for the most part, the system is self-maintaining.