Plants in the dry steppes and deserts of Xinjiang do not adapt to drought according to a single template. Instead of completely restructuring their entire organism, they change individual "parts" of their body—above-ground and below-ground—independently of one another.
Scientists from the Chinese Academy of Sciences studied hundreds of grasses at different altitudes and in different climates. It turned out that grasses use a flexible modular strategy. In the driest places, leaves become thicker to retain water inside and prevent drying out in the sun. In arid soil, roots become thinner and longer per unit of their mass. This allows them to spend a minimum of resources on growth while covering the maximum area to collect moisture. Where there is slightly more water, plants do not lengthen their roots, but make them more branched, extracting the maximum from the available soil.
Previously, it was believed that plants change as a whole—if the top dries out, the entire root system changes synchronously. But the study showed: shoots and roots work as independent modules. Leaf size is linked to the strength and thickness of the main roots, while the ability to quickly absorb water depends on thin lateral roots.
These processes are influenced not only by heat and the lack of rain, but also by local "mediators": the amount of organic matter and nitrogen in the soil, as well as the activity of soil microbes.
Understanding that grasses adapt in a targeted manner will help to more accurately predict how the ecosystems of arid regions will survive global warming and the expansion of deserts.
