Results
Soil Moisture and
Temperature
Gravimetric soil moisture was positively correlated with moss depth
during the summer (r =0.35) and negatively correlated during the
winter months (r =-0.39, Fig. 1). Moisture was highest under
thicker moss (F 5,79=3.60,p <0.01) in winter and vice versa in summer
(F 5,107=3.91; p <0.005). There
was marginally less fluctuation of soil temperature when the surface was
covered by moss (Fig. 1). In winter, temperatures were lower under moss
cover in the daytime and higher during the night
(F 1,908=21.93; p <0.001); mean
diurnal fluctuation of bare soil was 1.3oC compared to
0.4oC under a thin layer of moss. During the summer,
there was a diurnal fluctuation of 1.39oC for bare
soil and 0.68oC for the thin moss cover
(F 2,4554=22.55; p <0.001). In
summer, no differences in daytime soil temperature could be attributed
to the moss layers.
Soil Nitrogen
Soil ammonium and nitrate concentrations in bare soil were within the
range expected for typical soils (2-30 mg L-1 and 1-20
mg L-1 respectively (Allen et al. 1989)) although
nitrate levels were low and below 1.0 mg L-1 in winter
(Fig. 2). Both nitrate and ammonium were higher in bare soil than under
a moss covering (p <0.05).
Glasshouse Study
By the end of the experimental period, germination rates were highest in
bare soil for C. australis (H(4)=13.06, p =0.011) as were
establishment rates for C. australis (H(4)=15.54, p =0.004)
and K. serotina (H(4)=10.75, p =0.029) (Fig. 3).Kunzea serotina biomass was highest in bare soil (H(4)=36.09,p <0.001), whilst moss cover increased biomass forP. amoena ; particularly robust plants were observed beneath the
deeper moss layers (H(4)=19.89, p =0.001). All seeds in the moss
treatments germinated without contact with the soil and observation of
rooting revealed that all plants were rooting into the dead moss layer
beneath the live moss, as well as in the soil. Soil moisture and nitrate
concentrations were not significantly different between the treatments
but there was less nitrate under deeper moss (Table 1). C.
australis produced root nodules (for nitrogen fixation) in the moss
treatments but not in bare soil.
Field Study
Clear patterns of plant cover were observed in relation to distance into
both remnants, away from the fenceline and adjacent pasture (Fig. 4).
Moss cover increased with increasing distance from the pasture
(F(8,99)=10.83, p <0.001) whilst the
canopy cover was lowest at the fenceline (F(8,99)=3.40,p =0.002). There was a negative correlation between exotic grass
cover and associated litter and distance into the centre of the
remnants, this was significant for ESR (H(8)=18.65,p =0.017). Olsen P concentrations were highest at 0 and 10 m from
the fenceline with a maximum mean of 7.9 µg g-1, and
lowest near the middle of the remnants (F(8,96)=3.05,p =0.004). Nitrate concentrations were highest closer to the
fenceline and also lowest in the middle of the remnants
(F(8,82)=2.16, p =0.039). The soil pH and ammonium
concentrations did not differ significantly throughout the remnants.