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| Titel |
The high hydraulic conductivity of three wooded tropical peat swamps in northeast Peru: measurements and implications for hydrological function. |
| VerfasserIn |
Thomas J. Kelly, Andy J. Baird, Ian T. Lawson, Katherine H. Roucoux, Timothy R. Baker, Eurídice Honorio Coronado, Marcos Ríos |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250073475
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| Zusammenfassung |
| Lowland tropical peatlands are a significant component of the global carbon cycle, and are
estimated to store c. 88.6 Pg C (Page et al., 2011). The form and functioning of peatlands
depend strongly on their hydrology, but there are few data available on the hydraulic
properties of tropical peatlands. In particular, the saturated hydraulic conductivity (K) has
not previously been measured in Neotropical peatlands.
This study used piezometer slug tests to measure K at two depths (50 and 90 cm) in three
contrasting forested peatlands in the Peruvian Amazon: Quistococha, San Jorge, and Buena
Vista. These sites broadly represent the range of sites that have been described
from western Amazonia (Lähteenoja et al., 2009a,b, 2011), but the full variety of
Amazonian peatlands remains to be explored. Measured K at 50 cm depth varies between
0.00032 and 0.11cm s-1, and at 90 cm it varies between 0.00027 and 0.057 cm s-1.
Median K values are higher than comparable data from many temperate peatlands,
although they are similar to those obtained in a Norfolk sedge fen (cf. Baird et
al., 2004). They are at least an order of magnitude lower than published K values
from Southeast Asian peatlands, but this may be due to differences in measurement
method.
Linear mixed effect models show that small scale heterogeneity across a few
metres does not make a significant contribution to variance in K(p > 0.05), but
that spatial heterogeneity in K values from areas > 200 m apart accounts for c.
20 % of the within-site variance. K values differ significantly between the sites,
and between-site differences account for c. 18 % of the variance in the dataset.
The relationship between depth and K is less straightforward: whilst depth is a
significant determinant of K at Quistococha, at San Jorge and Buena Vista this is not the
case.
Simulations using a simple hydrological model suggest the relatively high K values could
lead to lowering of the water table by more than 10 cm within 25 m of the peatland edge for
domed peatlands, if subjected to a drought lasting 30 days. For a drought lasting
90 days and with a peatland model that incorporates a lower drainable porosity,
this zone could extend for up to 72.5 m into the peatland. However, under current
climatic conditions, even with high K, peatlands would be unable to shed the large
amount of water entering the system via rainfall through subsurface flow alone. We
conclude that most of the water leaves these peatlands via overland flow and/or
evapotranspiration.
References: Baird et al. (2004) Hydrological Processes 18, 275–291; Lähteenoja et al.
(2009a) Global Change Biology 15, 2311–2320; Lähteenoja et al. (2009b) Catena 79,
140–145; Lähteenoja et al. (2011) Journal of Geophysical Research 116, G02025; Page et al.
(2011) Global Change Biology 17, 798–818. |
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