Optimizing minirhizotron sample frequency for an evergreen and deciduous tree species

Area of Science:

• Ecology
• Plant Biology
• Forest Science

Background:

• Minirhizotrons are essential tools for studying fine root dynamics in natural ecosystems.
• Accurate estimation of fine root production and mortality is critical for understanding ecosystem processes.
• The frequency of sample collection can influence the accuracy of these estimates.

Purpose of the Study:

• To determine how minirhizotron sampling frequency affects estimates of fine root production and mortality in mature trees.
• To quantify the degree of underestimation of fine root dynamics at different sampling intervals.

Main Methods:

• Collected minirhizotron images twice weekly from mature Pseudotsuga menziesii and Tilia cordata trees.
• Analyzed images to estimate fine root production and mortality.
• Created datasets simulating sampling frequencies of 1, 2, 4, and 8 weeks.

Main Results:

• Longer sampling intervals (e.g., 8 weeks) led to significant underestimation of fine root production (24% in P. menziesii, 35% in T. cordata).
• Fine root mortality estimates were similarly sensitive to sampling frequency.
• Experimental results aligned with previous simulation analyses.

Conclusions:

• Sampling frequency is a critical factor affecting the accuracy of minirhizotron-based fine root production and mortality studies.
• A previously published simulation tool can help select optimal sampling frequencies to balance accuracy and effort.
• Careful consideration of sampling frequency is necessary for reliable ecological interpretations.