I had the experience of advising in a similar condition. It was pure sand 10 inches down at least. The owner did not want to remove 3-4 inches of sand to make way for organic matter & free soil. Her plants languished & eventually died.

Check how deep the sand is. Maybe there's soil down a bit. How deep is the top layer and what does it seem to be? Mulch? Is this a raised planter bed? Or is it flower beds. Just curious.

It is a flower bed. The sand is about 2 inches and there are mulches above the soil. I will replace the mulch with the pine straw. I just want to know why the planting bed needs sand. Can you explain it or the send is totally unnecessary? If the sand is bad thing for planting, I will remove them and put top soil in the flower bed.

Only 2 inches. Perfect. Dig the mulch (I asssume it is orangic - not rocks) and the 2 inches of sand in with a shovel so it is distributed into the top 8-10 inches. You will learn a lot about your soil in the process. Your plants will be happier. Do you know what soil type you have? Does it drain well? Or does it stay wet and gummy for several days after a rain?

Maybe the sand was spread on top to prevent weeds? Most people dig in sand to loosen up the soil and to improve drainage. The exception is with clay soils. In clay, or adobe, soils sand is a no-no. Organic (like manure) is excellent for all soil types and needs replenishing every year for optimum results.