Grasses are some of the most drought-resistant plants in the world. Their ability to survive arid conditions can play a vital role in grassland ecosystems, especially with the added toll of climate change. A Kansas State University-led study documented just how tolerant grasses can be and explained their function in the environment.
The Role of Grasses
Grasses survive because of their adaptations and ability to store carbon dioxide. This means that they can form a reliable food source for grazers. In addition, they can also help cool the surrounding environment, another means to prevent excess water loss.
The researchers gauged the ability of 500 plant species from around the world to survive drought conditions. While all plants had some breaking point, the varied pattern of tolerance suggests that the best ecological advantage for grasses comes from diverse environments. When stressed, grasses are better suited to arid conditions than forbs.
The team developed a drought index to measure this ability and give ecologists a useful tool for gauging the tolerance of grassland ecosystems. This can provide important information for managing these habitats.
Adapted for Stress
Grasslands typically occur in environments which receive between 25 and 75 cm of annual precipitation. Because of the variability of water availability, they have evolved ways to maximize water efficiency, giving them an ecological edge over trees and non-native plants during droughts. The Kansas State University study confirms these observations.
A key part of their ecological edge comes from the modified process of photosynthesis that these plants use. They can produce food faster and more efficiently in high temperatures, while reducing unnecessary water loss. This adaptation helps lessen the stress that these plants may experience during drought-like conditions. They can still produce seed and continue the life cycle of grasses.
Climate Change and Grasses
These findings show that some plants have a competitive edge against climate change. The biomass of prairie grasses, such as big bluestem, is composed of 50 percent or more in roots. Even if precipitation is low, their expansive root systems can allow them to tap into water sources far below the surface.
As the researchers concluded, biodiversity is key to the continued existence of grassland ecosystems in the face of climate change. The ability to survive stressful conditions will ensure the health of these habitats.