In:
Biogeosciences, Copernicus GmbH, Vol. 15, No. 2 ( 2018-01-22), p. 447-455
Abstract:
Abstract. Forests along the Amazon Basin produce significant quantities of organic
material, a portion of which is deposited in floodplain lakes. Deforestation
in the watershed may then have potentially important effects on the carbon
fluxes. In this study, a sediment core was extracted from an Amazon
floodplain lake to examine the relationship between carbon burial and
changing land cover and land use. Historical records from the 1930s and satellite
data from the 1970s were used to calculate deforestation rates between 1930
to 1970 and 1970 to 2010 in four zones with different distances from the
margins of the lake and its tributaries (100, 500, 1000 and 6000 m
buffers). A sediment accumulation rate of ∼4 mm yr−1 for
the previous ∼120 years was determined from the 240+239Pu
signatures and the excess 210Pb method. The carbon burial rates
ranged between 85 and 298 gCm-2yr-1, with pulses of high
carbon burial in the 1950s, originating from the forest vegetation as
indicated by δ13C and δ15N signatures. Our
results revealed a potentially important spatial dependence of the organic carbon (OC) burial
in Amazon lacustrine sediments in relation to deforestation rates in the
catchment. These deforestation rates were more intense in the riparian
vegetation (100 m buffer) during the period 1930 to 1970 and the
larger open water areas (500, 1000 and 6000 m buffer) during 1970 to
2010. The continued removal of vegetation from the interior of the forest was
not related to the peak of OC burial in the lake, but only the riparian
deforestation which peaked during the 1950s. Therefore, this supports the
conservation priority of riparian forests as an important management practice
for Amazon flooded areas. Our findings suggest the importance of abrupt and
temporary events in which some of the biomass released by deforestation,
especially restricted to areas along open water edges, might reach the
depositional environments in the floodplain of the Amazon Basin.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-15-447-2018
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2158181-2
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