What is often preceded by a crash since the growing population eventually is too large for the available resources

If a population eventually is too large for the available resources, the first thing that would happen is competition resources between individuals in a given population. The most fit will be the ones who will survive. The predator of the new dominating population also increases and the cycle continues — but eventually the population balances itself naturally (if not intervened by humans).

Apparently the fungus is called a club

Cis your correct answer