IADIZA   20886
INSTITUTO ARGENTINO DE INVESTIGACIONES DE LAS ZONAS ARIDAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Dry matter production of plant communities and goat selection during dry season in rangelands of the northeastern Mendoza, Argentina
Autor/es:
FUCILI MERCEDES; PAEZ SEBASTIAN; EGEA VANINA; SALVA JUAN; GUEVARA JUAN CARLOS; ALLEGRETTI LILIANA
Lugar:
Islas Canarias
Reunión:
Conferencia; XI International Conference on Goats; 2012
Institución organizadora:
INTERNATIONAL GOAT ASSOCIATION
Resumen:
To
evaluate the relationships between productivity of plant communities and goat
selection during the dry season (winter), seven females of a free-ranging
Creole goats herd (n=150) were fitted with GPS collars to record the grazing
itineraries. Plant communities were determined by an unsupervised
classification of a Landsat-5 satellite image and subsequent field
corroboration. The positions corresponding to grazing were overlaid on the
classified image to calculate the selection index (SI): ratio between the
proportion of grazing positions within a plant community and the proportional
area of that plan community. In 13 sites, the available dry matter production
(DM) of the main forage species was estimated by the closest individual method.
The record of height, average diameter and distance of the nearest individual
along linear transects, allowed to determinate plant density of woody species
and estimated the forage phytovolume by referring each plant to the ideal
volume of a cylinder. Available production was harvested from 10 plants per
species to determinate the relationship between phytovolume and DM production
by linear regression. An ANOVA procedure was used to analyze differences in the
DM production and in the SI. The relationship between DM production and SI was
determined by linear regression. We identified 4 different plant communities:
semi-closed woodlands of Prosopis flexuosa (Algarrobal), open woodlands of
Prosopis flexuosa with Tricomaria usillo and Atriplex lampa (Algarrobal
abierto), open woodlands of Tricomaria usillo (Usillar) and shrublands of
Larrea divaricata (Jarillal). The DM production (kg ha-1) of Algarrobal abierto
(363.25) was higher (p<0.05) than that of Algarrobal (175.29), Usillar
(172.50), and Jarillal (130.49). The SI of Jarillal (0.56) and Algarrobal
(0.68) were lower (p<0.005) than those of Algarrobal abierto (1.33) and
Usillar (1.33). There was a positive relationship (r=56 p<0.0001) between
the SI and DM production. The DM production of the most selected communities
had a great contribution of species that had been determined as preferred by
goats in previous studies: 22% P. flexuosa, 22% A. lampa and 18% T. usillo in
Algarrobal abierto and 50% T. usillo in Usillar. Concluding, during the dry
season, the DM production could be considered one of the factors influencing
the grazing behavior of goats that selected mainly the plant communities that
offer greater amount of available forage, specially of preferred species.