What is diffusion? Include in your explanation “area of high concentration” and “area of low concentration”.
Does diffusion occur across a membrane, without a membrane, or can diffusion occur in both situations?

Diffusion is the net movement of anything (for example, atoms, ions, molecules) from a region of higher concentration to a region of lower concentration. Diffusion can occur in any mixture, including one that includes a semipermeable membrane, while osmosis always occurs across a semipermeable membrane.

Explanation:

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.