Landscapes Forest and Global Change - ESA - Escola Superior ...

A.L. Teixido et al. 2010. Impacts of changes in land use and fragmentation patterns on Atlantic coastal forests
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The forest loss was associated with eucalypt plantations and, in lesser degree, with the building
of a water reservoir. This contrasts with the high forest losses reported over the last decades,
which were mostly due to logging and agriculture, particularly for tropical areas (e.g. Gaveau et
al. 2007). Those factors were also important for European forests, but in historical times prior to
the period of our study (Santos et al. 2002). Forest cover was similar to those for other
fragmented temperate forests (Fuller 2001; García et al. 2005; but see Santos et al. 2002). Our
results also showed changes in forest spatial patterns, thus suggesting an increase in the degree
of forest fragmentation over time and they were qualitatively similar to those reported for other
forest studies (Fuller 2001; Echeverria et al. 2006). At this point is worth noting the importance
of the fine resolution (0.01 ha) used to map patches in this study More than 20% of patches
were smaller than 0.1 ha and more than 60% smaller than 1 ha in any of the study years.
Temporal changes in forest patterns also implied changes in the nature of the adjacent land
cover classes. The more relevant changes were the increase in adjacency with eucalypts and the
water reservoir. It is known that exotic eucalypts easily spread around and into native forest
patches due to their high growth rate and ability to alter forest floor quality (Fabião et al. 2002).
Changes in forest patterns over time and increase in forest edge length adjacent to eucalypt
plantations may have negative ecological implications on forest specialists. Eucalypt plantations
generate ecological disturbances, such as increases in soil dryness and erosion, which may result
in declines in plant species diversity (Fabião et al. 2002) and density of some animals as the
northern-Iberian endemic amphibian C. lusitanica (Vences 1993). However, a recent genetic
study in the area showed low among-population genetic variation for the protected and forest
specialist ferns Culcita macrocarpa and Woodwardia radicans (Quintanilla et al. 2007).
Riparian forests appeared to be relatively well-conserved, because 76% of total river course
length was still covered by riparian forest in 2003. However, it was one of the land cover classes
that suffered a larger decline over the study period (34%). Thus, evaluation of conservation
status for habitats based only on a snapshot of the landscape could lead to equivocal conclusions.
Riparian forests have a range of ecological properties which makes them particularly important
components of landscapes. Firstly, riparian forests have been acknowledged as dispersal
corridors, hence facilitating individual exchange between natural habitat patches (Naiman et al.
1993). Secondly, riparian forests may act as buffers for some forest specialists in fragmented
landscapes, as for instance mitigating the impacts derived from forest harvesting and exotic
plantations (Homyack and Haas 2009).
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