Considerations in the study of tree fine-root turnover with minirhizotrons

Abstract

Fine-root turnover is an important component of forest carbon dynamics. We detail the characteristics of the minirhizotron method of measuring fine-root turnover and discuss its methodological implications. Minirhizotron data are relative values proportional to the data taken from the bulk, in situ soil, since they are taken at the soil-tube interface, so we propose several ways to validate minirhizotron data. Most short-term studies show fine-root production to be higher than fine-root mortality, suggesting that disturbance resulting from minirhizotron installation continues for several years. Initial-years results tend to lead to overestimates of fine-root dynamics, although these results define the maximal limits of fine-root production and mortality. We compare the definitions of fine-root turnover and methods of calculation used in different studies. We find that values of fine-root turnover depend on the definition of fine roots, methods of measurement, definition of turnover, and methods of calculation, so these factors must be taken into account when turnover values are discussed. In addition, soil depth is a key factor in the study of fine-root turnover, as is variation in the physical qualities, form and function, of the fine roots. Further long-term research into these key factors in relation to biotic and abiotic parameters will improve our knowledge of forest carbon dynamics.

Fine root production and turnover in forest ecosystems in relation to stand and environmental characteristics

“…This suggests that the present results are underestimates of the true FRP and probably more so for temperate and tropical forests than for boreal forests. They may overestimate the FRT rate of fine roots, however, since there are observations that the FRT rate decreases at shallower soil depths (Joslin et al, 2006;Satomura et al, 2007).…”

Roles of dominant understory Sasa bamboo in carbon and nitrogen dynamics following canopy tree removal in a cool‐temperate forest in northern Japan

“…This semi non-destructive method allows individual roots to be 175 followed from birth to death (e.g. Satomura et al 2007 We used the MSU ROOTs Tracer image analysis software (Michigan State University, 184…”

“…This seminondestructive method allows individual roots to be followed from birth to death (e.g. Satomura et al 2007). In June 2001, we installed transparent acrylic tubes (2 m long, 5.08 cm i.d.)…”

Using minirhizotrons to estimate fine root turnover rate as a forest ecosystem health indicator in Moso bamboo forests in Dagang mountain

“…The minirhizotron method is a nondestructive technique for in situ observation of fine root dynamics (Tierney & Fahey 2001), which can be used to quantify rates of root production and mortality (turnover) independently and with more accuracy than soil core methods. Many methods have been developed for the assessment of fine root production and mortality, with three of the most commonly used methods being sequential soil cores, in-growth cores, and minirhizotrons (Gill & Jackson 2000;Satomura et al 2007). The former two traditional biomass-based technologies provide reasonable estimates of standing crop but are less successful at simultaneously monitoring fine root production and death.…”