3.6 Watershed-level transpiration
Growing season weighted watershed-level transpiration
(Tw ) was similar in 2015 (i.e., 284 mm) and 2016
(i.e., 285 mm, Table 4). In contrast, the growing season watershed-level
transpiration (by zone, T z) in the riparian
buffer ranged from 334 to 363 mm while growing seasonT z in the mid-hillslope ranged from 306 to 313
mm. The growing season T z on the upland-hillslope
produced the lowest transpiration, 245 mm in 2015, and 246 mm in 2016.
The daily growing season T z in 2015 and 2016,
respectively, averaged 1.7 (0.06) mm day-1 and 1.4
(0.06) mm day-1, and reached a maximum of 2.6 mm
day-1 and 2.7 mm day-1 in the
riparian buffer, 1.2 (0.05) mm day-1 and 1.0 (0.05) mm
day-1, and a maximum of 2.4 mm day-1and 2.5 mm day-1 on the mid-hillslope, and 1.0 (0.03)
mm day-1 and 0.9 (0.03) mm day-1,
and a maximum of 2.0 mm day-1 on the upland-hillslope.
There was also a strong seasonal component to T win 2015 and 2016, where 80% (i.e., 284 mm) and 79% (i.e., 285 mm) of
the stand transpiration occurred in the growing season. Regardless of
which zone was used to derive T w, the
non-growing season T w was always statistically
lower than the growing season T w (Table 4).
The annual T w was 361 mm in 2015, and 370 mm in
2016. In 2015 and 2016, loblolly pine accounted for 40-50%, white oak
13-14%, tulip poplar 11-14%, sweetgum 6-7%, Virginia pine 4-8%, and
red maple 4% of growing season T w and
Tz.