Final answer:
Increasing desiccation leads to the drying and dying of leaf tips, which is part of a plant's protective strategy to conserve water and nutrients under drought conditions. Increased humidity reduces evaporation rates and can mitigate desiccation to an extent.
Step-by-step explanation:
With increasing desiccation, leaf tips typically begin to dry out and may turn brown and die. This drying out, or dehydration, happens because the water potential gradient causes water to move from areas of higher water potential (inside the leaf) to areas of lower water potential (the atmosphere). When the humidity increases, it leads to reduced evaporation rates due to a decreased difference in water vapor pressure between the leaf and the atmosphere, which could help in preventing further desiccation of the leaves. However, under severe drought conditions where the soil is very dry, the stomata of the plant may close to conserve water and leaves can be shed, as the plant prioritizes survival over growth. This response to a lack of water, including the shedding of leaves, is a protective strategy for the plant and also relates to nutrient recycling, where the plant reclaims nutrients from the dying leaves.