trees

Roots can help to hydrate landscapes and decrease wildfire risk: “In the semi-arid climate of the Great Basin in Utah, sagebrush grows in loam-skeleton soil, soil that sits on beds of alluvial gravel. Two ecologists, Richards and Caldwell set out to measure experimentally the hydraulic lift hypothesis – that is the assumption, that the roots of the trees bring up groundwater and spread it forth into the upper soil layer.  They found that the sagebrush’s roots were indeed bringing up groundwater and spreading it around to the surrounding soil. And not only that, when they put a special isotope of water around the sagebrushes roots, they found that that isotope then spread to neighboring plants. It was curious tree behavior because one might think a tree would keep all its water to itself, and not pass any into the surrounding soil, or to other trees. Rather the ecosystem seemed to be in a state of cooperation, passing the water around to keep all species hydrated. If the whole ecosystem survives better then individual species do too. Its the concept of group selection. […] Her team calculated that a quarter of trees and shrubs in the US regularly tap into the bedrock layer for water, and in California and Texas over 50% of the groundwater used by trees comes from the bedrock layer.”