Diurnal and seasonal variation in tree stem circumference using automated self-reporting dendrometer bands (TreeHuggers)

Background/Question/Methods

The Reynolds Creek Critical Zone Observatory (RC CZO) is a new CZO in southwestern Idaho whose research objectives are to quantify soil carbon storage and flux, and the factors governing these from pedon to landscape level. Aboveground carbon pools and fluxes are an important contributor to soil carbon, and quantifying variation in these is important for understanding critical-zone carbon processes. To estimate changes in aboveground carbon pools, we deployed automated, self-reporting dendrometer bands (TreeHuggers©) on three tree species (Juniperus occidentalis, Populus tremuloides, Psuedotsuga menziesii). These species represent the dominant tree species in Reynolds Creek watershed, and occupy sites of varying aspect and microclimates. We installed TreeHuggers onto at least 6 trees per species, and tree-circumference-data (accurate to within 2 µm) were recorded at 15-20 minute intervals. 

Results/Conclusions

Data suggest that the mean changes in tree circumference were 0.282±0.056 cm, 0.603±0.126 cm, and 1.126±0.628 cm for J. occidentalis, P. menziesii, and P. tremuloides, respectively, during growing season. Tree circumference-growth began on 160, 162, and 158 DOY respectively, based on dendrometer traces. Diurnal variation in tree circumference averaged about 0.017±0.006 cm, 0.067±0.051 cm, and 0.261±0.170 cm for J. occidentalis, P. menziesii, and P. tremuloides, respectively. Future research includes deploying litterfall traps to measure the aboveground carbon inputs to soil and installing sap flux sensors to measure the whole tree transpiration in all three species to examine the plant physiological compared to critical zone controls on aboveground productivity and inputs.