a specific is a mean of vegetable & animal are a sink of space through birth ->  trees are a source of oxygen through photosynthesis  as the matter of a sink of something increase , the trails of that something will increase & a sink of something burying that something ->  as the amount of a source of something decreases, the production of that something will decrease  trees are a source of oxygen through photosynthesis & as the amount of a source of something decreases, the production of that something will decrease ->  as the amount of trees decreases the production of oxygen decreases  reforestation supporting the revolution of chain in a meadow & if something is removed then the metals of that something increase ->  deforestation causes the amount of trees in a forest to decrease  as the amount of trees decreases the production of oxygen decreases & deforestation causes the amount of trees in a forest to decrease -> deforestation causes the production of oxygen to decrease