Populations of desert shrubs Encelia farinosa from 1981 to 2019 was reduced in two regions of the Mojave desert: 17 percent in Othman and 15 percent in Death Valley. Against the background of climate change, which was accompanied by an increase in the concentration of carbon dioxide in the air and a decrease in total annual rainfall, the plants living there have adapted to tougher conditions with more effective absorption of water. The results of a study published in the journal Proceedings of the National Academy of Sciences.
In the context of climatology scientists ‘ attention is traditionally drawn to the forests: they have more biodiversity and productivity have a large impact on the climate and at the same time bear the expense of changing it. At the same time, their areas are rapidly declining on the background of the spread of the deserts biome. Arid deserts occupy about 14 percent of the land surface and their area will increase due to global climate change.
Sustainable land use in deserts and adjacent regions crucial will be the number and biodiversity of specific vegetation and its response to climate change. Currently available studies of the physiological response of vegetation to climate change encompass no more than four growing seasons in a row. The results of these observations are contradictory and often do not signal any pronounced effects.
Scientists led by Avery Driscoll (Driscoll W. Avery) from 1981 to 2019 studied the response of shrubs Encelia farinosagrowing in the Mojave desert on climate change. In 1981, they planted a test plot by selecting the sites in the desert with a large projective cover of Encelia farinosa in Death Valley and in the area of Othman at a distance of more than 200 kilometers from each other. The authors then made up geobotanical maps of the area, inventoried the vegetation and started to carry out annual ecological monitoring in the last two weeks of March (in accordance with the peak growing season).
In the course of monitoring, the scientists recorded data on the condition of the plants, their flowering and the presence of parasites, and was collected 5-10 leaves from some bushes for the analysis of biogenic elements and the isotope ratios of carbon. In 39 years of botany 1863 selected sample of leaves from shrubs of the Valley of Death and 1346 of Othman. Climate variables (precipitation, atmospheric pressure, air temperature, etc.) for the study was taken from the open database PRISM.
The authors adhered to the hypothesis of adaptation of plants to water stress by increasing their coefficient of efficiency of water use (intrinsic water-use efficiency, iWUE). iWUE calculated as the ratio of the speed of photosynthesis with the conductive (relative to CO2) the ability of the stomata of the leaf. This option is the mathematical expression of the changes in the stomata, which occur in response to the change in the concentration of carbon dioxide in the air.