Tropical rain forest cover has reduced from ________ to ________...

According to the NCERT Biology textbook, habitat loss and fragmentation is the most important cause driving animals and plants to extinction, which is a major component of the 'evil quartet'.

The most dramatic examples of habitat loss come from tropical rain forests. Once covering more than $14\%$ of the earth's land surface, these rain forests now cover no more than $6\%$.

Therefore, the tropical rain forest cover has reduced from $14\%$ to $6\%$.

Answer: $14\%$, $6\%$