Complex sentence: Tropical forests around Panama are vital for the functioning of the Panama Canal, providing it with the water required for its operation (a rare example of a vast engineering project in the middle of the forest, which actually helped to preserve that forest).
Split into simpler sentences: Tropical forests around Panama are vital for the functioning of the Panama Canal. These forests provide the canal with the water required for its operation (a rare example of a vast engineering project in the middle of the forest which actually helped preserve that forest).