FSI (Fig. 1). The conception of forest vulnerability as statistically significant
trends in the FSI for eachmonth across years is a potentially important
new way to monitor forest vulnerability. The FVI characterizes
interannual trends in the FSI, highlighting months where forest areas
are experiencing longer-term increasing temperatures and water deficits,
which does not coincide with the month of peak stress annually
in our study region. The highest FSI values were detected during
July (data not shown), but the FVI for July was largely decreasing,
while the peak months for the FVI were in August and September