Why should we only breathe through nose

Because while breathing through our nose, thanks to the hair we have around our nostrill walls, air is purified which maintains our lungs cleaner and healthier. When we breathe through our mouth, air is not purified so dust goes in which can cause damage to our throat and lungs.

Hope it helped,

BioTeacher101

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.