IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
artículos
Título:
Influence of precipitation pulses on long-term Prosopis ferox dynamics in the Argentinean intermontane subtropics
Autor/es:
MORALES, M.; VILLALBA, R.
Revista:
OECOLOGIA
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2011 vol. 92 p. 3 - 14
ISSN:
0029-8549
Resumen:
Biological processes in arid communities are
associated with episodic precipitation pulses. We postulate
that annual to decadal-scale precipitation pulses modulate
the dynamics of the intermontane Prepuna woodlands. To
study this hypothesis, we have assessed the influence of
precipitation pulses on the rates of growth and survival of
Prosopis ferox in the Prepuna woodlands during the past
century. Tree ages from several P. ferox stands were used
to reconstruct the establishment patterns at each sampling
site. Ring-width chronologies provided the basis to assess
the influence of annual versus multiannual precipitation
pulses on radial growth and establishment over time. Both
the radial growth and the stand dynamics of P. ferox at the
regional scale were found to be largely modulated by climate,
with precipitation the dominant factor influencing
interannual variations in P. ferox ring-widths. Our analysis
of dendrochronological dating data on 885 individuals of
P. ferox revealed a period of abundant establishment from
the mid-1970s to beginning of 1990s, which is coincident
with an interval of remarkable above-average precipitation.
However, tree-growth and establishment patterns at the
local scale in the Prepuna also reflected land-use changes,
particularly long-term variations in livestock intensity. The
P. ferox dynamics documented here substantiates the
hierarchical concept of ??resource-pulse?? in dry ecosystems,
with precipitation pulses of different lengths modulating
distinct dynamic processes in the P. ferox
woodlands. Interannual variations in precipitation influence
year-to-year patterns of P. ferox radial growth, whereas
multiannual oscillations in rainfall influence episodic
events of tree establishment. The long-term interval considered
in this study enabled us to disentangle the roles of
natural versus human controls on P. ferox dynamics in the
region.