Volume 184, 1 February 2014, Pages 41–50
Native and non-native herbaceous species dependence on tree cover in grazing systems from northern Chilean Patagonia
Highlights
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- Do lenga trees help conserving native forest herbs within grazing systems?
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- Trees altered the herbaceous communities by changing their species composition.
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- Native and non-native species differed in their response to tree cover.
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- Diversity increased with decreasing tree cover by favoring the non-native species.
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- Native forest herbs were associated to dense forests but not to isolated trees.
Abstract
Grazing
systems that combine grasslands and woodlands represent changes in tree
cover that influences herbaceous vegetation and may threaten the native
forest flora. We studied these influences in Chilean Patagonia where
recent colonization resulted in the fragmentation of the lenga (Nothofagus pumilio)
forests leading to a mosaic-type landscape. The herbaceous vegetation,
transmitted photosynthetically active radiation (PAR) and other forest
structure characteristics were sampled in 15 (20 m × 20 m) plots
differing in tree cover for two years, while considering the relative
position (below or beyond) of tree crowns. Herbaceous species were
classified as forest, non-forest, and forest indifferent species
according to their preference, rejection or indifference to the forest
environment. Species richness decreased with increasing PAR but this was
dependent on the response of non-natives. Species composition varied
gradually from open grasslands to dense forests, according to
transmitted PAR values. Native species were associated to either forests
or open areas, but the number of native species did not vary along the
tree cover gradient (beyond tree crowns) or even decreased (below tree
crowns). Non-native species dominated in the open grasslands and beyond
tree crowns and its richness increased with transmitted PAR. The
occurrence of grasslands and dense forests within this grazing system is
shown to promote higher species richness. Management will consider that
dense forest patches are necessary for maintaining a high diversity of
native species, since isolated trees or low wooded areas do not
guarantee the persistence of all native species associated to the
original forests.
Keywords
- Agroecosystem;
- Grassland;
- Agroforestry landscapes;
- Plant species richness;
- Forest;
- Understory vegetation
- Corresponding author at: Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Bilbao 328, Coyhiaque, Chile. Tel.:
+56 67 2247801.
Copyright © 2013 Elsevier B.V. All rights reserved.
