Final answer:
The most likely answer to the changes in air temperature and soil surface temperature in a 20-50 year abandoned forest understory is A) The air temperature increases, while the soil surface temperature decreases, due to the moderating effects of forest growth and leaf litter insulation.
Step-by-step explanation:
The question revolves around the changes in air temperature and soil surface temperature in the understory of a forest ecosystem that has been abandoned for 20 to 50 years. Considering the effects of forest growth on microclimates, trees tend to moderate temperatures—cooling the air during the day and keeping the soil warmer during the night. The accumulation of leaves from deciduous trees also acts as an insulation layer for the soil, thereby usually leading to a decrease in soil surface temperature due to shading and protection against direct sunlight.
In context with climate warming, the increased growth due to higher COâ‚‚ levels could initially enhance growth but may be contradictory if respiration rates rise more rapidly than photosynthesis, especially in conditions like drought or stress. Also, warmer temperatures are attributed to decreasing growing seasons and increasing risks for plants, such as low productivity and damaging infestations. With rising temperatures and increased leaf litter, soil temperature could potentially decrease due to insulation and shading effects while the air temperature may increase.
Therefore, the most likely answer to the question is: A) The air temperature increases, while the soil surface temperature decreases.