Figure Legends (also included below figures in this draft form)
Figure 1. Leaf photosynthetic rate
(Amax-leaf ), leaf transpiration rate
(Eleaf) and leaf water potential range
of Acacia drepanolobium trees in Transition sites (that were
invaded by P. megacephala in December 2017 after initial wet and
dry season surveys) and in paired Control sites (that were protected byC. mimosae throughout the study). Effect tests are reported in
each panel, with significant interactions terms indicating an effect of
invasion distinct from interannual change. In wet seasons,
Amax-leaf and
Eleaf in Control trees were
significantly lower and leaf water potential range was higher in 2018
than in 2017, yet these leaf physiological variables for Transition
trees did not differ from 2017 (immediately before invasion) to 2018
(ca . 6 months after invasion) (A ,C ,E ).
In dry seasons, trees in Transition sites had lowerAmax-leaf in 2018 (ca . 9 months
after invasion) than in 2017 and this difference was significantly
larger than the interannual decline for Control trees (B ).
Also, in dry seasons, Eleaf increased
between 2017 and 2018 for Control trees but was consistent for
Transition trees (D ), and leaf water potential range was
consistent for all trees (F ).
Figure 2. Differences in leaf-
(Amax-leaf ; i.e., per-unit-leaf-area)
and canopy-level (Amax-canopy ; i.e.,
canopy photosynthetic capacity) photosynthesis (means ± SEM) ofP. megacephala - vs. C. mimosae- occupied Acacia
drepanolobium adults in wet and dry seasons at long-term Invaded and
Uninvaded sites. (A) Trees occupied by P. megacephala workers
have significantly lower Amax-leaf andAmax-canopy than do uninvaded trees in
wet conditions; (B) invaded trees have higherAmax-leaf during dry conditions, butAmax-canopy did not significantly differ
for invaded and uninvaded trees during the dry season. Results of
pairwise comparisons are indicated as significant (* P < 0.05,
** P < 0.001, *** P < 0.0001) or not significant
(NS).
Figure 3. Differences in photosynthesis (means ± SEM) ofP. megacephala -occupied Acacia drepanolobium adults in a
2x2 full-factorial experiment (presence/absence of ants, large
herbivores) conducted at 3 long-term Invaded sites in wet and dry
seasons. Photosynthetic indices are estimated at the leaf-
(Amax-leaf ) and canopy-level
(Amax-canopy ). Results of effect tests
are reported in panels. In wet seasons, (A ) vertebrate
herbivory causes decline in Amax-leafand (C ) vertebrate herbivory and invasive ant presence both
cause declines in Amax-canopy ; whileAmax-leaf andAmax-canopy are lower during dry
seasons, vertebrate herbivores and invasive ant presence does not affect
either response variable in dry conditions (B and D ).
Figure 4. Differences in canopy transpiration capacity
(Ecanopy ) and leaf water potential range
(means ± SEM) for Acacia drepanolobium adults in a 2x2
full-factorial experiment (presence/absence of ants, large herbivores)
conducted at 3 long-term Invaded sites in wet and dry seasons.
Significant results of effect tests are reported in subfigures (factors
at left, P values at right; refer to main text for full output): in wet
seasons, (A ) vertebrate herbivory and P. megacephalapresence both cause declines in Ecanopyand (C ) invasive ant presence causes a small but significant
reduction in leaf water potential range. In the dry season, (B )
vertebrate herbivory and P. megacephala presence both cause
declines in Ecanopy but do not affect
leaf water potential range (D ). The diurnal change in leaf
water potential (C and D ) is likely driven by a
combination of increased transpirational water loss (A andB ) and hydraulic resistance.