Ellison & Simmonds: Inland mangroves at Lake MacLeod 
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w 
o 
3 
T3 
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8/98-12/98 12/98-3/99 3/99-6/99 6/99-9/99 
Date 
Figure 5. Mangrove litter production, Lake MacLeod site 1. 
4- 
3 
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CJ 
3 
33 
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8/98-12/98 12/98-3/99 3/99-6/99 6/99-9/99 
Date 
Figure 6. Mangrove litter production, Lake MacLeod site 2. 
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□ Flowers 
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8/98-12/98 12/98-3/99 3/99-6/99 6/99-9/99 
Date 
Figure 7. Mangrove litter production, Lake MacLeod site 3. 
between sites. Sites 1 and 3 closely correspond, while site 
2 differs only in showing slightly later commencement of 
fruiting. Site 1 showed the highest fruit productivity, 
which occurred over a longer period, resulting in the 
highest annual production of sites (Table 1). This may 
reflect more equable conditions at site 1, being the closest 
of all sites to the vents, also demonstrated by the taller 
mean tree heights (Table 1). 
Litter productivity over the year is also similar 
between sites. All sites recorded a maximum leaf 
production of around 3-4 g m' 2 d' 1 in the spring/summer 
period August to December. The average annual 
production for MacLeod mangroves of 855 g dry wt m' 2 
is surprisingly high, given the stunted stature of the trees 
and environmental stresses at the site. However, the 
mangrove margin is narrow and dense, so this 
production rate is over a very limited area compared 
with coastal mangroves. While there are few studies of 
Avicennia productivity in Australia (Saenger & Snedaker, 
1993), a similar result was found for a 4 m stand in 
Queensland by Duke et al. (1981). Mackey & Smail (1995) 
found annual litter fall of subtropical Avicennia marina in 
the Brisbane River, southern Queensland, to be 831-922 g 
dry wt m' 2 over two years of measurement. Of this, leaf 
fall accounted for 47% of the total litter fall, reproductive 
litter 30%, and woody litter 23%. By comparison, during 
measurement of the Lake MacLeod mangrove production 
in the September 1998 to September 1999 period, leaf fall 
accounted for 68% of the total litter fall, reproductive 
litter 20%, and woody litter 12%. 
This above-ground mangrove biomass from Lake 
MacLeod Avicennia marina (Table 2) is equivalent to 121.3 
t ha 1 . This result is compared with published above¬ 
ground biomass results for Avicennia marina of similar 
height ranges in Australian temperate latitudes (Saenger 
& Snedaker 1993) in Fig 8. While results are similar, 
Avicennia trees stunted by aridity as opposed to 
temperature are of heavier biomass, which is to be 
expected given the butt and multi-branched architecture 
of these trees (Clough et al. 1997). 
200 
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a 
£ 
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5 
n Biomass (t ha' 1 ) 
a Lake MacLeod 
A 
□ 
□ 
o 
□ 
a 
m 
a 
a 
10 
12 
Height (m) 
Figure 8. Biomass of Avicennia marina at Lake MacLeod 
compared with Avicennia biomass/height records from 
temperate Australia (data from Saenger & Snedaker, 1993) 
29 
