Fig. 2 Redundancy analysis ordination of microclimates used as
simulated natural habitats in glass houses for seed germination
experiments (r2=0.88), ellipses are exposed and shaded
sites (confidence limit= 0.95), green text is explanatory factors
(Comp=compartment, Exp=level of exposure to sun), blue text are
microclimate variables achieved from data loggers at site (s=from data
logger at soil surface, temp=temperature).
Shaded microclimates obviously received less light intensity (731±240
lux shaded, 4491±1621 lux exposed) (Fig. S1) and had a lower maximum
temperature (25.8±1.0°C shaded, 40.7±7.1°C). In the soil, the maximum
temperature, again, was less at shaded sites compared to exposed sites
(19.5±2.2°C shaded, 27.1±4.6°C exposed). The relationship between light
intensity and temperature at the soil surface was asymptotic, above 2000
lux there was very little increase in temperature (Fig. S2).
Effects of microclimate factors on seed germination
In simulated-NHs, no seeds germinated in any shaded microclimates. These
were then excluded from statistical analysis. Compartment and depth
remained in the MAM, species and year were excluded after testing (Fig.
3a). Seeds had significantly higher probability of germinating in the
two compartments that have a higher heating regime (compartments Mabundu
, z=4.531, p<0.001, and Tropical z=6.586, p<0.001).
Across all rooms, shallower buried seeds were more likely to germinate
(z=6.491, p<0.001).
Seedling emergence happened sooner after sowing in the compartments with
warmer heating regimes (Mabundu, t=8.557, p<0.001 and Tropical
6.805, p=<0.001, Fig. 3b). Predictably, shallow buried seeds
at 1 cm emerged quicker than those buried at 7 cm (t=2.657, p=0.010).
There was no effect of species on time to germination (seedling
emergence), so this was excluded from the model, leaving compartment and
burial-depth.
Synchronization was significantly greater in the cooler compartments
(Spring and Leuven) for M. balbisiana (Fig. 3c), particularly in
the pairwise contrast between Leuven and Mabundu (z=3.110, p=0.010).