What is ecosystem ?

An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life.

So, the hot desert ecosystem is the planet's driest ecosystem, and thus, it has less diversity of life and little vegetation. Being a part of the terrestrial ecosystem, it houses animals and plants that can live in harsh weather conditions. 

Cold deserts are found typically in temperate regions at high elevations, on plateaus, or in mountainous areas; however, they also occur in polar regions. Shrubs and grasses are the main types of vegetation, and most plants and other organisms have adaptations that enable them to survive the dry, frigid conditions.

Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy, and rainfall is scant. Tundra lands are covered with snow for much of the year, but summer brings bursts of wildflowers.

The tropical rainforest is a hot, moist biome where it rains all year long. It is known for its dense canopies of vegetation that form three different layers. The top layer or canopy contains giant trees that grow to heights of 75 m (about 250 ft) or more.

Grassland Ecosystem is an area where the vegetation is dominated by grasses and other herbaceous (non-woody) plants. It is also called transitional landscape because grassland ecosystems are dominated by the grass with few or no trees in the area where there is not enough for a forest and too much of a forest.