In dry or cold ecosystems, what is usually the status of ET and NPP?

In dry or cold ecosystems, evapotranspiration (ET) and net primary productivity (NPP) are typically low due to several environmental constraints.

Evapotranspiration refers to the combined process of evaporation from the land surface and transpiration from plants. In dry conditions, there is insufficient moisture available for significant evaporation and transpiration. Similarly, in cold ecosystems, particularly in regions with freezing temperatures, water availability is often limited, which further reduces ET.

Net primary productivity represents the amount of organic matter produced by plants through photosynthesis, minus the energy used in respiration. In ecosystems characterized by low moisture and low temperatures, plants often experience stress, leading to reduced growth and metabolic activities, which consequently results in lower rates of photosynthesis. As a result, these conditions limit the overall biomass that can be produced, thus yielding a lower NPP.

Therefore, in both cold and arid ecosystems, the conditions favor low rates of both evapotranspiration and net primary productivity, reflecting the challenges plants face in such environments. This understanding of ecosystem function is crucial for ecologists studying energy flow and the dynamics of plant communities in varying climates.