Author(s):
Fabião, António 
; Reino, Luís ; Osborne, Patrick E. ; Beja, Pedro ; Morgado, Rui ; Rotenberry, John T.
Date: 2009
Persistent ID: http://hdl.handle.net/10400.5/1376
Origin: Repositório da UTL
Subject(s): afforestation; edge effects; landscape management; grassland; steppe birds; Mediterranean farmland
Description
Afforestation often causes direct habitat losses for farmland birds of conservation concern,
but it is uncertain whether negative effects also extend significantly into adjacent open
land. Information is thus required on how these species react to wooded edges, and how
their responses are affected by edge and landscape characteristics. These issues were
examined in Mediterranean arable farmland, using bird counts at 0, 100, 200, 300 and
>300 m from oak, pine and eucalyptus edges, embedded in landscapes with variable
amounts and spatial configurations of forest plantations. Bird diversity declined away from
edges, including that of woodland, farmland and ground-nesting birds. Positive edge
responses were also found for overall and woodland bird abundances, and for five of the
nine most widespread and abundant species (Galerida larks, stonechat, linnet, goldfinch
and corn bunting). Strong negative edge effects were only recorded for steppe birds, with
reduced abundances near edges of calandra larks and short-toed larks, but not of little bustards
and tawny pipits. Edge contrast affected the magnitude of edge effects, with a tendency
for stronger responses to old and tall eucalyptus plantations (hard edges) than to
young and short oak plantations (soft edges). There were also species-specific interactions
between edge and fragmentation effects, with positive edge responses tending to be strongest
in less fragmented landscapes, whereas steppe birds tended to increase faster away
from edges and to reach the highest species richness and abundances in large arable
patches. Results suggest that forest plantations may increase overall bird diversity and
abundance in adjacent farmland, at the expenses of steppe birds of conservation concern.
