Impact of pine invasion on the taxonomic and phylogenetic diversity of a relict Mediterranean forest ecosystem

Abstract

a b s t r a c tInvasion by non-native tree species is a major driver of reduction and fragmentation of forest ecosystems, also altering biodiversity components. However, the effects of this process on the phylogenetic structure and diversity of Mediterranean woodlands are still unknown. Accordingly, we used cork oak (Quercus suber) stands invaded by self-sowing populations of maritime pine locally introduced ca. 70 years ago as a model system to assess the impact on the taxonomic and phylogenetic diversity of the native seed plant community. We performed vegetation sampling of the two forest types in sites of central Italy with similar conditions. Taxonomic diversity was negatively affected by the pine at three levels (gamma, alpha, beta). Indicator species were significantly less numerous than in cork oak stands, and did not include two growth-forms such as herbs and vines. Phylogenetic diversity metrics were inferred from an evolutionary tree of seed plants based on a ITS-5.8S nuclear DNA dataset including original sequences from local plant material. Phylogenetic diversity (PD) was positively related to species and genus richness, showing a marked decrease in the pine stands. Seven major clades (orders) of angiosperm dicots were only represented in the cork oak community. Both the NRI and NTI indices showed a significant reduction of phylogenetic evenness in the pine forest. Here, the proportional increase of related taxa with acid-tolerance specialization suggests that soil acidification is a major driver for a ''habitat filtering" effect causing the exclusion of several understorey species and genera of cork oak forests. Progressive thinning of the pine stands is advocated to avoid further acidification and promote the re-conversion to oak woodlands by natural regeneration. This will ultimately favor the recovery of the associated plant diversity and the restoration of a vanishing forest ecosystem of the ancient Mediterranean landscape.

Range shifting species reduce phylogenetic diversity in high latitude communities via competition

“…Recent work also suggests that colonization by range‐shifting species or invaders often reduces phylogenetic diversity of impacted communities (Lessard et al . ; Selvi, Carrari & Coppi ), but it is unknown whether or how this process results from patterns of competition between colonizing and native species. Understanding of these underlying mechanisms is critical in order to mitigate loss of phylogenetic diversity at high latitudes.…”

“…However, other analyses suggest that colonizing species may typically outcompete and replace native species at high latitudes (Alexander, Diez & Levine 2015), resulting in irreversible species loss and biotic homogenization along latitudinal gradients (Dornelas et al 2014). Recent work also suggests that colonization by range-shifting species or invaders often reduces phylogenetic diversity of impacted communities (Lessard et al 2009;Selvi, Carrari & Coppi 2016), but it is unknown whether or how this process results from patterns of competition between colonizing and native species. Understanding of these underlying mechanisms is critical in order to mitigate loss of phylogenetic diversity at high latitudes.…”

Dynamique de Colonisation des Zones Rudérales d’un Massif Forestier Urbain par les Espèces Végétales Exotiques Envahissantes : Cas du Parc National du Banco (Côte d’Ivoire)

“…Les plantes invasives constituent la deuxième cause directe de perte de la biodiversité dans le monde (Vitousek et al, 1996 ;UICN, 2000 ;MEDD, 2004 ;MEA, 2005). Elles engendrent de nombreux impacts négatifs sur le plan écologique, environnemental, social et économique (Pimentel et al, 2000 ;Marck et al, 2000 ;McNeely et al, 2001 ;Selvi et al, 2016). Sur le plan économique, le coût des espèces invasives est estimé à 150 milliards d'euros par an aux Etats-Unis.…”

Patterns of change in α and β taxonomic and phylogenetic diversity in the secondary succession of semi-natural grasslands in the Northern Apennines

“…Indeed, according to Chase & Myers (2011), β-diversity can provide considerable insights into the importance of deterministic and stochastic processes in generating community structure along spatial and ecological gradients. In addition, the use of molecular phylogenies may be helpful in analyzing the forces that influence patterns of biodiversity and biogeography and in depicting the interactions among co-occurring species (Selvi, Carrari & Coppi, 2016). Indeed, in the last decades, the use of molecular phylogeny has increased widely for ecological purposes, contributing also to the emerging area of community phylogenetics (Webb et al, 2002).…”