Limits to Tree Growth and Longevity.

Tree growth and longevity are key features to understand fundamental issues of plant biology, environmental sciences, and current forest management plans. Here I discuss current evidence on the limits of tree growth and longevity and present a new conceptual framework to understand how and why they are closely interconnected. Despite the tremendous plasticity of trees, growth and longevity are limited not only by biotic and abiotic stresses, but also by age-related structural constraints such as height-related hydraulic limitations and vascular discontinuities, which are strongly species specific. Continuous growth and plastic branching may serve as a means to reach extreme longevities in some nonclonal trees, but even in these millennial organisms immortality can be attained only through the germ line.