Contrasting xylem vessel constraints on hydraulic conductivity between native and non-native woody understory species

Abstract

We examined the hydraulic properties of 82 native and non-native woody species common to forests of Eastern North America, including several congeneric groups, representing a range of anatomical wood types. We observed smaller conduit diameters with greater frequency in non-native species, corresponding to lower calculated potential vulnerability to cavitation index. Non-native species exhibited higher vessel-grouping in metaxylem compared with native species, however, solitary vessels were more prevalent in secondary xylem. Higher frequency of solitary vessels in secondary xylem was related to a lower potential vulnerability index. We found no relationship between anatomical characteristics of xylem, origin of species and hydraulic conductivity, indicating that non-native species did not exhibit advantageous hydraulic efficiency over native species. Our results confer anatomical advantages for non-native species under the potential for cavitation due to freezing, perhaps permitting extended growing seasons.

Nutrient-Induced Modifications of Wood Anatomical Traits of Alchornea lojaensis (Euphorbiaceae)

“…Confirming that hypothesis, we determined a decrease in V S and an increase in V G and V M after addition of N and N+P in A. lojaensis. Hence, other vessel anatomical traits like, e.g., intervessel pit membrane structure or perforation pits are possibly responsible to provide more safety in the hydraulic system of angiosperms and also conifers (Tyree and Zimmermann, 2002;Cochard et al, 2009;Smith et al, 2013). Overall, despite the high vulnerability values, the risk of hydraulic failure for A. lojaensis at our study site can be deemed as rather small, because the per-humid conditions considerably minimize water stress, and risks of freezing or excessive heating are not given.…”

“…Changes in vessel diameter size generally provide inferences about the potential radial growth rates of trees, since larger vessels have a higher k theo s and consequently ensure increased water supply to support enhanced transpiration and photosynthetic rates (e.g., Meinzer et al, 2008Meinzer et al, , 2010Smith et al, 2013;Hoeber et al, 2014;Oladi et al, 2014). The relation between higher growth capacity and vessel size becomes understandable, considering that the theo.…”

Xylem vessel traits predict the leaf phenology of native and non‐native understorey species of temperate deciduous forests

“…As reported in Smith et al . (), non‐native species had a higher proportion of solitary vessels in secondary xylem compared to natives. More solitary vessels (or less vessel groupings) in non‐native species can decrease their vulnerability to cavitation by decreasing the probability of cavitation spread to adjacent vessels (Loepfe et al .…”

“…Metaxylem vessels tended to be grouped together, especially in non‐native species: they had a higher number of ≥5‐vessel grouping compared to native species, as reported by Smith et al . (). Higher vessel grouping, usually with higher vessel density, can potentially result in a hydraulically functional advantage under stressed environments because it allows water to bypass cavitated vessels via alternative pathways created by intervessel pits connectivity within a vessel group (Loepfe et al .…”

“…However, Smith et al . () observed smaller average VD in non‐native understorey woody species than their native counterparts, even though spring bud and leaf emergence was similar between natives and non‐natives (Fridley ).…”