Grasslands of the World.pdf - Disasters and Conflicts - UNEP

Grasslands of Patagonia 145
2001). Currently, nitrogen dynamics are being studied in relation to: the effect
of litter nitrogen content of different plant life forms on soil N fractions in
the grass-steppe ecosystems (Sain, Bertiller and Carrera, 2001) and the Monte
shrub steppes (Carrera et al., 2001); effects of levels of soil nitrogen fractions
on the segregation of male and female Poa ligularis individuals (Bertiller, Sain
and Carrera, 2001); soil nitrogen mineralization rates in relation to grazing
(Anchorena et al., 2001); decomposition rates of litter with different nitrogen
content (Semmartin et al., 2001); and nitrogen use efficiency (together with
water use efficiency) of 26 species of plants from Patagonian ecosystems
(Golluscio, Oesterheld and Soriano, 2001).
Current studies on the effects of fire on Patagonian ecosystems mostly
include monitoring of vegetation following natural wildfire outbreaks. Such
studies include: descriptions of post-burn secondary succession patterns
(Ghermandi, Guthmann and Bran, 2001; González et al., 2001; Rafaelle and
Veblen, 2001); study of biotic and abiotic (including weather) conditions that
promote wildfire outbreaks (Defossé et al., 2001; De Torres Curth, Ghermandi
and Pfister, 2001); and effects of wildfires on survival of adult tussocks or seeds
in soil seed-banks (Gittins, Bran and Ghermandi, 2001; González, Ghermandi
and Becker, 2001). Almost all fire-related studies have been conducted either in
the shrub-steppe ecosystems or the steppe-forest ecotones .
Current studies on wildlife in Patagonia include: surveys of animal numbers
such as guanaco population numbers in relation to sheep density and forage
availability (Baldi, Albon and Elston, 2001); calculations of Rhea densities
using improved field methods (Funes et al., 2001); census of migratory bird
species in southern Patagonia (Manero et al., 2001); predator -prey relations
studying fox and European hare populations and diets of a number of predators
of the shrub steppe ecosystems (Donadío et al., 2001; Novaro et al., 2001);
habitat use by Rheas (Bellis et al., 2001); and deer reproductive ecology in relation
to droughts (Flueck, 2001).
ANPP of Patagonian ecosystems is currently being studied in relation to
range condition (Bonvissuto, González Carteau and Moraga, 2001), grazing
system (Collantes, Stoffella and Pomar, 2001), competition among plant lifeforms
(Schlichter, Fernández and Gyenge, 2001), or forage production (Bustos
and Marcolín, 2001). Satellite image analysis using NDVI at regional scales
continues to be used as a tool to estimate ANPP (Fabricante et al., 2001).
Decomposition is being studied at regional scales either along rainfall gradients
(Austin and Sala, 2001), or in relation to a species’ successional status within
the plant community and its litter N content (Semmartin et al., 2001). At local
scales, decomposition of forbs is being studied in relation to increased ultraviolet-B
radiation, derived from the thinning in the ozone layer at high latitudes in
the southern hemisphere (Pancotto et al., 2001).
A number of ongoing research projects include the study of aspects of
the biology of a few shrub species, namely: shrub secondary compounds