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| Titel |
Carbon stocks in a miombo woodland landscape: spatial distribution and controls |
| VerfasserIn |
Emily Woollen, Mathew Williams, Casey Ryan, John Grace |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045980
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| Zusammenfassung |
| Carbon accounting in terrestrial ecosystems has received increased attention in light
of recent global climate change and the consequent development of international
treaties and emissions trading schemes. Despite being the second largest continent on
earth, knowledge on Africa’s carbon stocks is limited. The most common savanna
type in sub-Saharan Africa is miombo woodland, which covers 2.7 million km2 of
southern, central and eastern Africa, and is relatively understudied compared to other
biomes. To increase our understanding of the distributions of vegetation and soil C
stocks in miombo woodlands we conducted a field study in a miombo woodland
landscape in central Mozambique. Our objective was to determine how vegetation
and soil carbon stocks are distributed in a miombo woodland landscape, and to
asses what controls the vegetation and soil C stock distributions. To address the
lack of landscape scale studies on spatial variability of carbon stocks in miombo
woodland we sampled along a 5km transect, using a cyclic sampling scheme to
allow geostatistical analyses of the data. We sampled multiple variables such as soil
C stocks at two depths (0.05 and 0.30 m), soil texture, above-ground biomass C
stocks, litter and altitude simultaneously along the transect. Soil C stocks (9-22
Mg C ha-1 and 29-79 Mg C ha-1 in the top 0.05 m and 0.3 m respectively) and
above-ground biomass C stocks (8-42 Mg C ha-1) varied significantly at short
distance intervals, reflecting the inherent high heterogeneity of the miombo woodland
landscapes. 70% of above-ground biomass C stocks were found in large trees (diameter at
breast height > 30 cm). Geostatistical analyses revealed spatial autocorrelations at
short distances for soil C stocks (< 15 m and < 31 m in the top 0.05 m and 0.3 m
respectively), and at larger distances for above ground biomass C stocks. Soil C
stocks in the top 0.05 m were significantly correlated to altitude (r2=0.33), as was
large-tree above-ground biomass C stocks (r2=0.70). Deeper soil C stocks at 0.3 m were
significantly correlated to soil clay content (r2=0.38), and soil clay content was negatively
correlated to altitude (r2=-0.54). High values of large-tree above-ground biomass and
surface-soil C stocks are found on ridges and at higher altitudes, where soils are better
drained. Opposite to this, deeper-soil C stocks are larger in areas with higher soil
clay content, such as in seasonally water logged soils (dambos) found in low lying
areas. The distribution of soil and vegetation carbon stocks in miombo woodland is
controlled by micro relief and resultant distributions of soil textural properties and
vegetation. The strong correlation found between micro-relief and above-ground biomass
could be used in remote sensing studies to estimate biomass C stocks on regional
scales in miombo woodlands, although an altitudinal resolution of less than 10
m would be necessary. Management of C stocks in miombo woodlands should
consider conserving areas with large trees on ridge tops and low lying dambos. |
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