Answer: the crowds of people that are attracted can disrupt the ecosystem.
National parks can be a double-edged sword because the people that come visit them can often disrupt the ecosystem. This defeats the original purpose, as national parks are established in order to protect the ecosystem from the damage of humans. However, some measures can be taken in order to reduce the damage. For example, crowds can be reduced by introducing daily limits, or increasing the price of tickets. Security can be increased in order to monitor the crowds. Finally, reminding the crowds of the fragility of the parks can sometimes improve the people's behaviour.
