Final answer:
Studies indicate that higher atmospheric CO₂ levels lead to increased stomatal density in plants, which may be a negative feedback mechanism to optimize photosynthesis and minimize water loss. However, under drought conditions, this trait could lead to a positive feedback effect, exacerbating water stress in plants with high stomatal density.
Step-by-step explanation:
The topic revolves around how stomatal density in plants varies with changes in atmospheric CO₂. Research, including the studies by Engineer and colleagues (2014) and Teng and co-workers (2009), indicates that in Arabidopsis, a higher stomatal density is observed with elevated CO₂ levels. Woodward's study (1987) also supports this by showing an increase in stomatal index with a rise in atmospheric CO₂ concentration over time. These adaptations in stomatal density may be part of a negative feedback mechanism, where plants adjust their stomata to optimize CO₂ uptake for photosynthesis and minimize water loss under changing environmental conditions.
However, elevated CO₂ has also led to changes in climate patterns, including alterations in precipitation. Under drought conditions, plants with a high stomatal density but limited water availability may encounter stress, leading to reduced survival rates, as suggested by Manea and Leishman's studies (2011, 2014). This situation might trigger a positive feedback effect, where the presence of more stomata leads to more water loss, aggravating the impacts of drought on forest ecosystems.