Wood anatomy and hydraulic architecture of stems and twigs of some Mediterranean trees and shrubs along a mesic-xeric gradient

Abstract

Woody species populating the major Mediterranean ecosystems in the world are characterized by different levels of adaptation to the seasonal Mediterranean climate conditions. Many species of these ecosystems show wood features that allow high efficiency of transport when water is available, while maintaining hydraulic safety during drought periods. This study focuses on the anatomy of juvenile and mature wood of some species representative of continuous sequences of Mediterranean vegetation formations according to gradients of water availability, from xeric to relatively mesic: Cistus monspeliensis L., Rhamnus alaternus L., Myrtus communis L., Pistacia lentiscus L., Olea europaea L., Quercus ilex L., Fraxinus ornus L. and Ostrya carpinifolia L. Twigwood collected in Southern Italy was anatomically compared with the stemwood of the same species represented in the reference slide collection of the National Herbarium of the Netherlands (Lw). The ''hydraulic distance'' between the wood of main stems and twigs was estimated on the basis of suites of anatomical features related to water efficiency/safety. Although some attributes (i.e. porosity and type of imperforate tracheary elements) were similar in young twigs and older rings, other traits (i.e. vessel frequency and size) evidenced the different hydraulic properties of twig and stemwood. The difference between juvenile and mature structures was large in the species of the mesic end of the gradient while it was relatively small in those more xeric. This tendency is in agreement with the habit gradient from medium-sized trees to small evergreen/drought deciduous shrubs according to decreasing water availability in Mediterranean vegetation types.

Morphological Characteristics and Water-Use Efficiency of Siberian Elm Trees (Ulmus pumila L.) within Arid Regions of Northeast Asia

“…Such adjustments in hydraulics enabled trees in arid areas to have a higher sap flux density and stomatal conductance than the same species in mesic areas, particularly when the vapor pressure deficit was low [27,65]. Thus, trees in arid areas would be able to sequester substantial amounts of carbon while environmental conditions were favorable, such as during the morning hours prior to stomatal closure [12,13,[68][69][70][71][72]. Shorter tree height during water shortages ( Figure 3A,C) would be beneficial for the survival of Siberian elm under dry conditions, not only by decreasing the risk of wind fall, especially in the high windy areas of the Mongolian desert, but also by changing the hydraulic characteristics of trees.…”

Differences in functional and xylem anatomical features allow Cistus species to co-occur and cope differently with drought in the Mediterranean region

“…Further related to drought resistance, De Micco et al (2008) reported a gradual adaptation in different Mediterranean trees and shrubs species to severe drought periods after evaluating their wood anatomical traits along a mesic-xeric gradient. However, how these strategies and xylem features, including resistance to embolism, vary between co-existing Mediterranean species but within a single genus has been poorly evaluated.…”

Research Advances on Leaf and Wood Anatomy of Woody Species of a Tamaulipan Thorn Scrub Forest and its Significance in Taxonomy and Drought Resistance

“…Similarly Ref. [69] conducted a study focussing on the anatomy of juvenile and mature wood of some species representative of continuous sequences of Mediterranean vegetation formations according to gradients of water availability, from xeric to relatively mesic. The difference between juvenile and mature structures was large in the species of the mesic end of the gradient while it was relatively small in those more xeric, vessels were narrow resistant to cavitation during drought and freezing conditions.…”

“…The difference between juvenile and mature structures was large in the species of the mesic end of the gradient while it was relatively small in those more xeric, vessels were narrow resistant to cavitation during drought and freezing conditions. A study was undertaken on the seasonal dimorphism in wood anatomy [69] in Mediterranean sub sp. Cistus incanus revealed that brachyblast wood was safer than dolichoblast and has narrower and more frequent vessels.…”

“…Vessel grouping is a widespread phenomenon in most woody species, especially those from the arid desert flora and Mediterranean species [68]. The wood anatomy and hydraulic architecture of stems and twigs of some Mediterranean trees and shrubs along a mesic-xeric gradient [69]. Similarly Ref.…”