Why is deforestation rate higher in developing countries than in developed?

First, that's "severe" problem..

The rest of a partial answer is, (1) rain forest plants are the main contributors to the biOSphere's Oxygen-Carbon Dioxide cleanup / renewal cycle, so deforestation results in a decrease in available oxygen, an increase in carbon dioxide, & a rise in temperature for the biOSphere (global warming). Then (2), forest floors are not particularly high in nutrients because decomposition occurs more slowly there, in the deep shade & with less rain getting there thru the tree tops, so there are far fewer plant roots to hold what is on the forest floor. (3) Deforestation removes foods for birds, animals, & humans, resulting in species reduction & / or extinction. (4) Deforestation removes plant medicines, which affects the health of animals & humans alike. (5) Deforestation results in gross unbalancing of a previously balanced bio-system, with unpredictable additional problems, since humans do not "know everything" in the first place, including what was in the area they deforested.