Disturbances During Minirhizotron Installation Can Affect Root Observation Data

Abstract

Use of minirhizotrons in forested ecosystems has produced considerable information on production, mortality, distribution, and the phenology of root growth. But installation of minirhizotrons severs roots and disturbs soil, which can cause root proliferation in perennial plants. We compared the magnitude and vertical distribution of root growth observations in a mature hardwood forest during the growing season immediately after minirhizotron installation with observations more than two years later. We also compared the vertical root growth distribution during these two different years with the preinstallation distribution of fine root biomass. Before minirhizotron installation and again two years later, about 74% of fine root biomass was in the upper 30 cm of soil, but immediately after installation, 98% of the root elongation was in the upper 30 cm. Large differences in the quantity of root elongation were observed across different slope positions in the minirhizotron data from the first growing season (approximately four times greater on the upper slope as the lower slope). Such differences with slope position were not seen in the later minirhizotron data, nor in the preinstallation fine root biomass data. The evidence suggests that the minirhizotron data collected immediately after installation can be biased by disturbance of roots and soil during installation, which result in excessive root proliferation, particularly near the soil surface. Root proliferation appears to be the result of a response to both root pruning and to nutrient release in microsites near the newly installed minirhizotron.

Estimating fine root longevity in a temperate Norway spruce forest using three independent methods

“…The aboveground parts of the minirhizotron tubes were laminated with tape to avoid the penetration of sunlight to the soil. After the installation of the minirhizotrons, the first image collection was delayed by 6 months in order to allow for a steady-state of fine root density in proximity to the tubes (Joslin and Wolfe 1999). Between December 2005 and December 2006, coloured images with a resolution of 200 dpi were taken every~4 weeks using a scanner system (CI-600 Root Growth Monitoring System, CID, Camas, WA, USA).…”

“…One limitation of this method is the difficulty of distinguishing between live and dead roots on minirhizotron images (Comas et al 2005;Withington et al 2006). In addition, soil disturbance after tube installation and the tubes themselves can influence fine root longevity (Joslin and Wolfe 1999;Withington et al 2006).…”

Fine root dynamics along a 2,000-m elevation transect in South Ecuadorian mountain rainforests

“…Five months after installation of the tubes we recognized a steady-state of visible root length in most of the tubes in all stands except for the uppermost stand. Hence, only data from November 2005 onwards were considered for analysis to avoid artifacts due to disturbance during tube installation (Hendrick and Pregitzer 1996;Majdi 1996;Joslin and Wolfe 1999). In each scanning procedure, we recorded a 345°sector of a soil compartment of 20 cm length at the tube's inner surface (i.e.…”

Dynamics of root systems in native grasslands: effects of elevated atmospheric CO2

“…The end result of these shifts might be a movement of C and nutrient cycling, and possibly C sequestration, to shallower soil layers. Effects of disturbance resulting from installation of minirhizotron tubes (Hendrick & Pregitzer, 1996 ;Majdi, 1996 ;Joslin & Wolfe, 1999) might have contributed to the continual increase in RLD in both ambient and elevated CO # treatments into the winter of the first year (Fig. 4) followed by a drop in RLDs in the second year, but these potential effects do not preclude reliable and robust treatment comparisons.…”