Final answer:
Plants have a positive impact on sand-dune environments by preventing erosion, providing habitat and shelter, and increasing biodiversity.
Step-by-step explanation:
Plants have several effects on a sand-dune environment. They help stabilize the sand dunes by anchoring the soil with their roots, preventing erosion. Additionally, plants provide shade and shelter for other organisms, creating a habitat for various animals. Lastly, the presence of plants can enhance the diversity of the sand-dune ecosystem by attracting different species of insects, birds, and other wildlife.