Changes in carbon isotope ratios of soil organic matter following conversion of tropical deciduous forest to pasture
- Centro de Ecologia, Mexico D.F. (Mexico)
- Instituto de Fisica, Mexico D.F. (Mexico)
Near the Chamela Biological Station in Jalisco Mexico, tropical deciduous forest was cut, burned and planted with C, grasses for conversion to cattle pastures by local farmers. We estimated soil organic matter (SOM) turnover under intact forest and in a pasture chronosequence (1, 3, 7, and 11 years old). Total SOM in the surface soil under intact forest was 30,098 kg ha[sup [minus]1] (0-12 cm depth) with more than 50% in the uppermost 4 cm. Total SOM increased by 18% following cutting and burning, but exhibited a net decrease of 19% in the 11 year old pasture. Carbon ratios were determined by mass spectrometry; the dominant forest trees are C[sub 3], and the [delta][sup 13]C of forest huer was [minus]27.4, while the [delta][sup 13]C of pasture litter was [minus]15.9. The [delta][sup 13]C signatures of the 7 and 11 year old pastures were significantly different than the forest (p < 0.0001, R[sup 2]=0.77) and in the 11 year old pasture, only 54% of the original forest SOM remained. The estimated turnover rate for forest SOM following clearing was 1.024 kg ha[sup [minus]1] yr[sup [minus]1] and interestingly, the SOM associated with the sand fraction displays a turnover rate considerably higher than that associated with the silt or clay fractions.
- OSTI ID:
- 6142772
- Report Number(s):
- CONF-930798--
- Journal Information:
- Bulletin of the Ecological Society of America; (United States), Journal Name: Bulletin of the Ecological Society of America; (United States) Vol. 74:2; ISSN BECLAG; ISSN 0012-9623
- Country of Publication:
- United States
- Language:
- English
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095000 -- Biomass Fuels-- Environmental Aspects-- (1990-)
54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
CARBON
CARBON SOURCES
DEFORESTATION
ELEMENTS
FORESTS
MATTER
NONMETALS
ORGANIC MATTER
PASTURES
PLANTS
SOILS
TREES
TROPICAL REGIONS