The tundra ecosystem of alaska is known as a “cold desert.” it receives very little precipitation, about four inches annually. however, it is rich in wetlands due to permafrost, which traps moisture close to the surface. the temperatures vary widely, also producing persistent winds. although treeless, the arctic tundra is an abundant ecosystem. many organisms find their niche here including many migratory bird species and mammals such as caribou, foxes, bears, and small rodents. which element of the tundra ecosystem is biotic?
a. wind
b. dead bird
c. carbon dioxide
d. temperature

its B. dead bird

since biotic is something that is alive or has once been and abiotic is something that has never been alive

The correct answer is option B. dead bird

In an ecosystem two types of components exist which are known known as biotic and abiotic.

A biotic component is the one which has life or had life at some point of time. A dead bird is therefore considered as biotic component because even though at present it doesn't have life yet earlier it had life. Abiotic components are those components which neither have life at present nor they had in past. Wind, carbon dioxide and temperature are therefore considered as abiotic components of tundra ecosystem.

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.    

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.