title: Fragmentation patterns of evergreen oak woodlands in Southwestern Iberia: identifying key spatial indicators.
abstract: Mediterranean evergreen oak woodlands (composed of Quercus suber L. and Quercus rotundifolia Lam.) are becoming increasingly fragmented in the human-modified landscapes of Southwestern Portugal and Spain. Previous studies have largely neglected to assess the spatial changes of oak woodlands in relation to their surrounding landscape matrix, and to characterize and quantify woodland boundaries and edges. The present study aims to fill this gap by analyzing fragmentation patterns of oak woodlands over a 50-year period (1958-2007) in three landscapes. Using archived aerial imagery from 1958, 1995 and 2007, for two consecutive periods (1958-1995 and 1995-2007), we calculated a set of landscape metrics to compare woodland fragmentation over time. Our results indicated a continuous woodland fragmentation characterized by their edge dynamics. From 1958 to 2007, the replacement of open farmland by shrubland and by new afforestation areas in the oak woodland landscape surrounding matrix, led to the highest values for edge contrast length trends of 5.0 and 12.3, respectively. Linear discriminant analysis was performed to delineate fragmented woodland structures and identify metric variables that characterize woodland spatial configuration. The edge contrast length with open farmland showed a strong correlation with F1 (correlations ranging between 0.55 and 0.98) and may be used as a proxy for oak woodland mixedness in landscape matrix. The edge dynamics of oak woodlands may result in different patterns of oak recruitment and therefore, its study may be helpful in highlighting future baselines for the sustainable management of oak woodlands.
authors.affiliation: Center for Environmental and Sustainability Research (CENSE), Faculdade de Ciências e Tecnologia (DCEA), Universidade Nova de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal; Instituto Nacional de Investigação Agrária e Veterinária, I.P., Quinta do Marquês, Av. da República, 2780-159 Oeiras, Portugal. Electronic address: augusta.costa.sousa@gmail.com.
authors.forename: Augusta
authors.initials: A
authors.lastname: Costa
authors.affiliation: Centro de Estudos Florestais, Universidade de Lisboa, Instituto Superior de Agronomia, Tapada da Ajuda, 1349-017 Lisbon, Portugal. Electronic address: mavmadeira@isa.ulisboa.pt.
authors.forename: Manuel
authors.initials: M
authors.lastname: Madeira
authors.affiliation: Centro de Estudos Florestais, Universidade de Lisboa, Instituto Superior de Agronomia, Tapada da Ajuda, 1349-017 Lisbon, Portugal. Electronic address: jlsantos@isa.ulisboa.pt.
authors.forename: José
authors.initials: J
authors.lastname: Lima Santos
authors.affiliation: Department of Geosciences and Natural Resource Management, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark. Electronic address: tobias.plieninger@ign.ku.dk.
authors.forename: Tobias
authors.initials: T
authors.lastname: Plieninger
authors.affiliation: Center for Environmental and Sustainability Research (CENSE), Faculdade de Ciências e Tecnologia (DCEA), Universidade Nova de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal. Electronic address: mjs@fct.unl.pt.
authors.forename: Júlia
authors.initials: J
authors.lastname: Seixas
mesh_terms: D017753:Ecosystem; D011174:Portugal; D029963:Quercus; D014197:Trees
keywords: Forest change; Forest spatial pattern; Mediterranean forest; Oak woodlands; Quercus rotundifolia; Quercus suber