The existing mycelia mat isn’t going to be huge, it might only be under one tree, the surrounding habitat is likely suitable for new mycelia growth. The existing mycelia can continue producing morels every year but it will only produce a large number if the habitat becomes unsuitable or the host tree is dying and the fungus is trying to relocate to more suitable habitat. The population in the area will drop drastically if over harvested every year due to a lack of spores. Returning the spores to the area they were harvested will allow for possible propagation and since the area is suitable habitat propagation is likely. Returning the spores could produce new mycelia possibly helping to maintain or increasing the population size, more morels in the area.