Distribution of white spruce lateral fine roots as affected by the presence of trembling aspen: root mapping using simple sequence repeat DNA profiling

Abstract

Mixedwood forests of white spruce ( Picea glauca (Moench) Voss) and trembling aspen ( Populus tremuloides Michx.) may possess ecological advantages over monospecific white spruce stands. Belowground competition may be reduced through vertically stratified roots; facilitation of growth may occur in upper soil layers through nutrient-rich trembling aspen litterfall. These effects may incentivize white spruce to preferentially exploit upper soil layers in mixedwood stands, resulting in wider root systems. This research contrasted white spruce fine root (diameter <2 mm) distributions in organic layers of white spruce and mixedwood stands. Research occurred at the Fallingsnow Ecosystem Project site in northwestern Ontario. Eighteen plots represented mixedwood and pure white spruce stands. Trees were mapped; foliage and root samples were collected. Roots were separated by species and scanned to determine length. Simple sequence repeat DNA profiles were determined for all white spruce trees and for 45 white spruce root fragments per plot. Root and tree DNA profiles were matched; corresponding distances were calculated. Most (80%) root fragments were within 3.2 m of tree stems. Root prevalence decreased rapidly with distance. Organic layer pH was significantly less acidic in mixedwood plots, but only in one block. A subtle significant trend towards wider root distributions occurred in mixedwood stands.

The influence of competition and species mixture on plantation-grown white spruce: Growth and foliar nutrient response after 20 years

“…This increase in soil nutrient levels has, in turn, resulted in higher nutritional levels in spruce foliage (Ballard and Carter 1986, Wang and Klinka 1997, McAlister and Timmer 1998, Boivin et al 2004). In addition, if vertical and horizontal root stratification occurs when spruce and aspen are grown in mixtures (Lawrence et al 2012), both species may access more space for root growth, thus improving their ability to capture soil resources (Man and Lieffers 1999) and/or leading to enhanced nutrient uptake during the growing season. Through the mechanisms of facilitation (e.g., higher quality foliar litter) and/or complementarity (e.g., foliar and rooting stratification), the presence of aspen may affect the amount and availability of soil nutrients, thus benefiting white spruce.…”

Spatial Distribution of Organic Matter and Nitrogen in the Entic Podzols of the Prioksko-Terrasnyi Reserve and Its Relationship with the Structure of Forest Phytocenoses

“…An increased nitrogen content and the high rate of turnover of the mass of thin roots are combined with their definite localization in space with a minimum near the tree base and a maximum (both in the number and Table 3. The C org and N tot contents in forest litter (O) and gray-humus (AY) horizons under different tree species in dependence on the position of sampling points (the arithmetic mean is above the line, and minimum and maximum are given in parentheses; SB-near the tree stem, UC-under the crown; and n-sampling size for the corresponding soil horizon) total mass) along the periphery of the crown [27,46,51,58]. Root competition between neighboring plants is an additional factor affecting the spatial distribution of roots in soil horizons [43,57].…”