New joint research from the University of Wisconsin-Madison and the Australian National University, looks at what factors affect maximum tree height and how their relative importance varies in different parts of the world.
Southern Victoria, Tasmania and northern California all share high rainfall, high humidity and low evaporation rates, underlining the importance of moisture supply to ultra-tall trees. But the study shows that rainfall alone cannot explain maximum tree height.
Warm, dry and sunny conditions cause faster evaporation from leaves, and researchers found a tight relationship between maximum tree height in old stands in Australia and the ratio of annual rainfall to evaporation. As that ratio increased, so did maximum tree height. Researchers also found that hydraulic limitation more strongly constrains maximum tree height under drier conditions, while resource allocation more strongly constrains height under moist conditions.
Newsletter Image credit: Thomas Givnish
