Differential sectoriality in long-distance transport in temperate tree species: evidence from dye flow, 15N transport, and vessel element pitting

Abstract

The capture of patchily distributed nutrients by tree roots has received extensive research, but the fate of those nutrients has not. We performed experiments to determine if nutrient transport within tree species is preferentially transported from specific roots to specific branches. Saplings of five species with contrasting growth requirements were examined: two Betula species (B. papyrifera and B. lenta), Populus tremuloides, and two Acer species (A. saccharum and A. rubrum). To quantify patterns of long-distance transport, we examined the accumulation of safranin-O dye and 15 N in branches when these tracers were applied to isolated lateral roots (dye and 15 N) and to the main root system ( 15 N). Because transport of nutrients between sectors requires flow through intervessel pit pairs of adjacent xylem vessel elements, we quantified the area of intervessel pits, the number of pits per unit vessel wall area, and the % vessel wall area as pits in Acer and Betula. We found that the two Betula species were integrated (tracers applied to isolated roots were likely to accumulate in all branches), while P. tremuloides and the two Acer species were sectorial (tracer accumulation was more concentrated in particular branches). Betula had the largest number of intervessel pits per unit vessel wall area and the largest percentage of vessel wall area as pits. The high density of bordered pits may explain the ease of tracer movement throughout the two Betula species. Greater integration may allow certain trees (e.g., Betula) to exploit nutritionally patchy environments such as rocky soils, and may alter plant-herbivore interactions.

Infestation and Hydraulic Consequences of Induced Carbon Starvation

“…Branch die-back tended to occur abruptly across a whole branch. Aspen has highly "sectored" xylem, and SAD crown dieback patterns align with expected patterns of hydraulic failure from aspen xylem structure (Orians et al, 2004).…”

Hydraulic integration and shrub growth form linked across continental aridity gradients

“…Water-filled libriform fibers and fiber tracheids can conduct water (26), but their conductivity is likely to be extremely low and is likely to be zero if they are filled with gas, as has been shown to occur in several tree species (27)(28)(29). Anatomical traits that reduce lateral water flow among neighboring vessels or groups of vessels reduce the ratio of tangential and/or radial to axial water flow (11,24,30) and result in sectorial patterns of water ascent (31).…”

How are leaves plumbed inside a branch? Differences in leaf-to-leaf hydraulic sectoriality among six temperate tree species

“…An extremely sectored plant would behave as if constructed of autonomous subunits while an integrated plant would behave as if it were a single unit. In sectored plants, restricted transport of resources within these subunits can lead to differential rates of water and nutrient supplies between parts, such as between specific roots and leaves or branches, and between leaves on a branch (Rinne and Langston, 1960;Stryker et al, 1974;Horwath et al, 1992;Larson et al, 1994;Hay and Sackville Hamilton, 1996;Fort et al, 1998;Orians et al, 2000Orians et al, , 2002Orians et al, , 2004. Restricted transport of sugars, nutrients, and signal molecules can lead to within-plant variation in tissue development, chemistry, and systemic induction (Watson and Casper, 1984;Orians et al, 2000Orians et al, , 2002Schittko and Baldwin, 2003).…”