Ironically it can be the very system established to protect biodiversity, such as national parks, that has a negative impact on biodiversity. Here the most detrimental impacts can be from the visiting public to protected areas and other sites rich in biodiversity but fragile environments, in that visitors bring an increased risk of fire (including the removal of branches for firewood) and the introduction of harmful pests and diseases. Many touristic sites include mountainous areas where conifers often prevail.