Are differences among forest tree populations in carbon isotope composition an indication of adaptation to drought?

Water plays a significant role in the life cycle of plants. However, insufficient or excess of water can be detrimental and pose a serious threat to plants.

Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.

Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.

Every organism has an optimum temperature range within which healthy growth and physiological functioning can occur. At the ends of this range, there will be a minimum and maximum temperature that interrupt biological processes.

During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of plant leaves is the site of this exchange of gasses. A single opening is called a stoma—derived from the Greek word for “mouth.” Stomata open and close in response to a variety of environmental cues.

Softwoods and hardwoods, derived from different types of trees, are distinguished by their leaf structures and cellular compositions, each serving unique purposes in construction and manufacturing. Softwoods come from cone-bearing trees with needle-like leaves and are predominantly composed of longitudinal cells called tracheids and a smaller proportion of radial cells known as rays. Due to their cellular structure, softwoods are commonly used in construction for structural frames, sheathing,...