Yes, all lacertids should have some substrate in their enclosures since they have psychological need to dig and burrow, and keeping them on artifitial substrates such as newspaper or "astroturf" is cruel. Washed children playground sand, or a mixture of sand and potting soil or small-graded gravel are good options (personaly, I use sand with good results). Substrat should have depth of 2-5 inches.