Bands were installed at approximately breast height (1.35 m) in May
2014, prior to the establishment of the throughfall exclusion
treatment. All trees greater than 10 cm DBH within each 15 x 15 m
throughfall exclusion plot were fitted with bands at this time. Bands
were measured using digital calipers approximately monthly during the
growing season. Measurements were taken on the same dates for the
CCASE and DrougtNet bands from 2016-2021, though sometimes
measurements were taken on different dates in 2014-15.
Throughfall exclusion of approximately 50% was initiated in each of
these two 15 x 15m plots in May 2015. The throughfall exclusion was
increased to 95% in May 2019, and the structures were removed in March
2020. The band measurements therefore include pre-treatment,
treatment, and post-treatment conditions, though data from 2014 may
reflect some degree of “settling” of these bands, as is common in the
first few months following installation.
A large number of bands were damaged during the winter of 2020 and
were not replaced due to the long time necessary for bands to settle
and begin recording good data.
Data recorded on field datasheets were quality controlled after data
entry. Impossible or large outlier values were flagged and removed.
Small decreases in measurements likely reflect the imprecision of
caliper measurements as well as real shrink-swell of the trees with
variation in moisture conditions. There was little or no evidence of
band slippage at any time during the study.
Procedures for converting band measurements to diameter growth are
described here:
http://richardcondit.org/data/dendrometer/calculation/Dendrometer.php
