Attacks, not much can attack Treeclan but here is what can and what will happen when they are not defeated.

Squirrels, large groups of squirrels can attack the clan and is a big threat they tend to steal herbs and sticks.

Rouges, some rouges that know how to balance and climb trees can attack they will take herbs, prey, sticks, and possibly cats. They also might get she-cats that they take pregnant.

Birds, they can take small cats, prey, herbs and sticks.

Natural disasters, not all affect the clan but some do like forest fires.

Saplings challenge, happens when the Tree dies and the Saplings have to try to become the next trees.

Sleepless night, happens every 10 moons Treeclan tries to get there ancestors back. The next moon all cats will be a bit tired.

That's all for now suggest any more you feel I should add if there are any.