AP BIOLOGY

Detailed explanation-1: -Because of these low temperatures and short growing seasons, net primary productivity is very low in the tundra, between 100–200 g m-2 yr-1.

Detailed explanation-2: -The highest net primary productivity in terrestrial environments occurs in swamps and marshes and tropical rainforests; the lowest occurs in deserts.

Detailed explanation-3: -Desert ecosystems cover a substantial portion of the Earth terrestrial surface1 and are characterized by very low productivity which is limited by water and nitrogen (N) availability2, 3, 4.

Detailed explanation-4: -Deserts are areas of low available water. In extreme desert, be it hot or cold, the absence of water will prevent most plants surviving and, hence, productivity is negligible. Plants may show similar adaptations to conserve water in both environments (xerophytism).