Research being developed in Dpto. Ecología Universidad Complutense de Madrid (laurasj@bio.ucm.es) - Reprint of the poster contribution to las 22th General Meeting of the European Grassland Federation (EGF) 'Biodiversity and animal feed - future challenges for grassland production' held in Uppsala, Sweden, 8-12 Jun 2008

1. Laura Sánchez-Jardón
22nd General Meeting of the European Grassland Federation –
Biodiversity and Animal Feed – Uppsala, Sweden 9 -12 June 2008
Grassland productivity and consumption under
different tree cover in the Aysén region
Patagonia, Chile
Sánchez-Jardón L.1, Casado M.A.1, Del Pozo A.2, Ovalle C.3, Acosta B.1, De Miguel J.M.1
1Universidad Complutense de Madrid, Fac. Biología, Departamento de Ecología E-28040
Madrid, Spain. 2Universidad de Talca, Facultad de Ciencias Agrarias, Casilla 747, Talca,
Chile. 3INIA, CRI, Chillan, Chile
Introduction In Aysén, in the last century, massive human-set
fires transformed over five million ha from forest to
grasslands. Today, soil erosion and forest loss
count as a major problems. There is a need for
scientific research to test the feasibility of
agroforestry in this region, to allow pasture and
animal production without compromising forest
preservation. Presence of disperse tree should
have an influence on grassland productivity and Simpson valley (Coyhaique county, XI Chilean region):
one of the first colonized areas. Lenga forests persist
consumption by cattle. Above-ground herbaceous
commonly in elevated locations whereas it has been
biomass production of grasslands was analysed
cleared for pastures in lower areas during the 1930-40s
along a gradient of forest fragmentation. massive human-set fires.
Methods Results
Where – in a moderately altered Lenga 100 100
A.
NPP (g m month )
B.
NPP (g m month )
-1
(Nothofagus pumilio [Poepp. et Endl.]
-1
80 80
Krasser) forest. 60 60
-2
-2
40 40
How – in plots (20x20 m) in five classes of 20 20
tree cover from open grassland to dense
0 0
forest: 0%, 1 to 25%, 25 to 50%, -25 0 25 50 75 100 125 -25 0 25 50 75 100 125
1-25
0 25-50 50-75 >75 0 1-25 25-50 50-75 >75
50 to 75%, and over 75%. 200 200
C. D.
• Two patches were considered in each 150 150
(g m month )
(g m month )
Consumption
-1
Consumption
-1
plot: under and between tree crowns. 100 100
• Exclusion cages were used to
-2
-2
50 50
determine net primary production (NPP) 0 0
and consumption. -25 0 25 50 75 100 125
0 25-50 50-75 >75
1-25 0 1-25 25-50 50-75 >75
-25 0 25 50 75 100 125
Tree cover (%) Tree cover (%)
Effects of tree cover on mean values of NPP (A), and consumption by cattle (C). In (B) and
(D), values under trees (continuous line) and in gaps (dashed line) are shown separately.
• Only the plots representing dense forest (over 75%) tended to have a NPP
slightly lower than that of the other cover classes (Fig. A).
• The tree crown had an effect on NPP which was evident with tree cover
higher than 25% (Fig. B). Above this value NPP diverged, increasing between
tree crowns and decreasing under the trees.
• Consumption values decreased as tree cover increased (Fig. C). This was
Herbaceous vegetation under canopy in a
representative Lenga forest of the Aysén region. associated with differential consumption under trees and in gaps (Fig. D)
Conclusion
Grassland productivity and consumption show no significant differences in different scenarios of forest fragmentation below values
of tree cover of 50%: the loss of these parameters under the trees is compensated by higher values in gaps between trees.
Therefore it is possible to maintain high herbaceous production along with naturalistic values associated to native trees,
which are currently under study as well. Thus, results to date support the implementation of a silvopastoral management
system as an alternative to the dominant open-pasture model in Aysén.