INVESTIGADORES
PARUELO Jose Maria
artículos
Título:
Potential long-term impacts of livestock introduction on carbon and nitrogen cycling in grasslands of Southern South America
Autor/es:
PIÑEIRO, G., J.M. PARUELO Y M. OESTERHELD
Revista:
GLOBAL CHANGE BIOLOGY
Referencias:
Año: 2006 p. 1267 - 1284
ISSN:
1354-1013
Resumen:
Abstract
Empirical evidence based on grazing exclusion at the scale of years to decades shows that
grazing modifies carbon (C) and nitrogen (N) cycling. However, long-term effects at the
scale of centuries are less known, yet highly relevant to understand local and global
impacts of grazing. Additionally, most studies have focused on the isolated response of C
and N, with little understanding of their interactions. Using CENTURY, a process-based
biogeochemical model, we analyzed the impacts of 370 years of livestock grazing (i.e.
long term, from early European colonization to present) in 11 sites across the Rý´o de la
Plata grasslands and compared them with those resulting from two decades of grazing
(i.e. mid-term, typical exclosure experiment). In the long term, livestock grazing primar-ily
altered the N cycle through faster N returns to the soil via urine and dung, which were
offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic
N decreased by 880 kg ha
(i.e. mid-term, typical exclosure experiment). In the long term, livestock grazing primar-ily
altered the N cycle through faster N returns to the soil via urine and dung, which were
offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic
N decreased by 880 kg ha
Plata grasslands and compared them with those resulting from two decades of grazing
(i.e. mid-term, typical exclosure experiment). In the long term, livestock grazing primar-ily
altered the N cycle through faster N returns to the soil via urine and dung, which were
offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic
N decreased by 880 kg ha
(i.e. mid-term, typical exclosure experiment). In the long term, livestock grazing primar-ily
altered the N cycle through faster N returns to the soil via urine and dung, which were
offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic
N decreased by 880 kg ha
Rý´o de la
Plata grasslands and compared them with those resulting from two decades of grazing
(i.e. mid-term, typical exclosure experiment). In the long term, livestock grazing primar-ily
altered the N cycle through faster N returns to the soil via urine and dung, which were
offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic
N decreased by 880 kg ha
(i.e. mid-term, typical exclosure experiment). In the long term, livestock grazing primar-ily
altered the N cycle through faster N returns to the soil via urine and dung, which were
offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic
N decreased by 880 kg ha
grasslands and compared them with those resulting from two decades of grazing
(i.e. mid-term, typical exclosure experiment). In the long term, livestock grazing primar-ily
altered the N cycle through faster N returns to the soil via urine and dung, which were
offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic
N decreased by 880 kg haa
1
or 19%. Higher N outputs (mainly as NH3) opened the N
cycle, potentially decreasing N2O and NOx emissions and increasing N depositions over
the region. These greater outputs of N constrained C accumulation in soils, reducing soil
organic C by 21 200 kg ha
the region. These greater outputs of N constrained C accumulation in soils, reducing soil
organic C by 21 200 kg ha
cycle, potentially decreasing N2O and NOx emissions and increasing N depositions over
the region. These greater outputs of N constrained C accumulation in soils, reducing soil
organic C by 21 200 kg ha
the region. These greater outputs of N constrained C accumulation in soils, reducing soil
organic C by 21 200 kg ha
H3) opened the N
cycle, potentially decreasing N2O and NOx emissions and increasing N depositions over
the region. These greater outputs of N constrained C accumulation in soils, reducing soil
organic C by 21 200 kg ha
the region. These greater outputs of N constrained C accumulation in soils, reducing soil
organic C by 21 200 kg ha
N2O and NOx emissions and increasing N depositions over
the region. These greater outputs of N constrained C accumulation in soils, reducing soil
organic C by 21 200 kg haa
1
( 22%, a reduction of 1.5 Pg of C for the whole region) and
net primary production by 2192 kg haa
1
yrr
1
( 24%). Mid-term simulations showed that
the effects of livestock introduction in a decadal time scale were substantially different
both in magnitude and direction from long-term responses. Long-term results were not
substantially affected when atmospheric CO2 content, species composition and fire
regime were changed within plausible ranges, but highlighted fire-grazing interactions
as a major constraint of long-term C and N dynamics in these grasslands.
regime were changed within plausible ranges, but highlighted fire-grazing interactions
as a major constraint of long-term C and N dynamics in these grasslands.
O2 content, species composition and fire
regime were changed within plausible ranges, but highlighted fire-grazing interactions
as a major constraint of long-term C and N dynamics in these grasslands.
Keywords: ammonium, atmospheric chemistry, fire, grazing, plant production, soil organic matter,
species composition, temporal scales
species composition, temporal scales
ammonium, atmospheric chemistry, fire, grazing, plant production, soil organic matter,
species composition, temporal scales