ABSTRACT
Understanding how plants survive drought and cold is increasingly important as plants worldwide experience dieback with drought in moist places and grow taller with warming in cold ones. Crucial in plant climate adaptation are the diameters of water-transporting conduits. Sampling 537 species across climate zones dominated by angiosperms, we find that plant size is unambiguously the main driver of conduit diameter variation. And because taller plants have wider conduits, and wider conduits within species are more vulnerable to conduction-blocking embolisms, taller conspecifics should be more vulnerable than shorter ones, a prediction we confirm with a plantation experiment. As a result, maximum plant size should be short under drought and cold, which cause embolism, or increase if these pressures relax. That conduit diameter and embolism vulnerability are inseparably related to plant size helps explain why factors that interact with conduit diameter, such as drought or warming, are altering plant heights worldwide.
Subject(s)
Acclimatization , Cold Temperature , Magnoliopsida/growth & development , Tundra , DehydrationABSTRACT
Angiosperm hydraulic performance is crucially affected by the diameters of vessels, the water conducting conduits in the wood. Hydraulic optimality models suggest that vessels should widen predictably from stem tip to base, buffering hydrodynamic resistance accruing as stems, and therefore conductive path, increase in length. Data from 257 species (609 samples) show that vessels widen as predicted with distance from the stem apex across angiosperm orders, habits and habitats. Standardising for stem length, vessels are only slightly wider in warm/moist climates and in lianas, showing that, rather than climate or habit, plant size is by far the main driver of global variation in mean vessel diameter. Terminal twig vessels become wider as plant height increases, while vessel density decreases slightly less than expected tip to base. These patterns lead to testable predictions regarding evolutionary strategies allowing plants to minimise carbon costs per unit leaf area even as height increases.
Subject(s)
Climate , Magnoliopsida/anatomy & histology , Magnoliopsida/physiology , Biological Evolution , Ecosystem , Linear Models , Magnoliopsida/classification , Plant Stems/anatomy & histology , Plant Stems/physiologyABSTRACT
Se describen veintecuatro especies de Nidulariales para México; una corresponde al género Crucibulum y veintetrés a Cyathus. De este último, ocho especies se citan por primera vez en la micobiota mexicana: C. cheluensis Tai et Hung, C. gayanus Tul., C. helenae Brodie, C. julietae Brodie, C. novae-zeelandiae Tul., C. olivaceo-brunneus Tai et Hung, C. pullus Tai et Hung y C. triplex Lloyd. Para cada una de las especies se indican datos ecológicos y de distribución en el país
