The World Wildlife Foundation recently reports that the number of monarch butterflies overwintering in Mexico has declined drastically. When monarch butterflies arrive in Mexico from Canada and the United States, they converge on oyamel fir trees. The trees provide shelter to monarch butterflies they are also essential to the communities that surround the forests. In the past, residents used the wood for cooking and heating, but recently, they have began to sell it in order to support their livelihoods. Te destruction of their overwintering grounds also poses a considerate threat.
Why have the ovamel fir tree forests decreased in recent years?