Which drivers influence plant diversity and composition in forest systems in Biscay (Basque Country) at different landscape scales?

This is the authors' abstract. We don't add key points for this paper.

Globally, the establishment of forest plantations of fast-growing exotic species for the timber industry has increased rapidly, becoming a significant feature of the landscape that can influence biodiversity due to intensive management. In the Basque Country (northern Iberian Peninsula), during the 19th century, deforested land was reforested with pine plantations. In recent decades, however, those plantations have been replaced by eucalypt plantations, mainly in Biscay. This shift may negatively impact biodiversity, for instance due to the shorter rotation cycle of eucalypt plantations compared to pine. The main objective of this study was to identify the factors (including forest type, surrounding landscape, and stand characteristics) that influence vascular plant diversity and composition across the three major forest systems of Biscay (Eucalypt plantations, Native forests, and Pine plantations) at four landscape scales. Bayesian hierarchical models were employed to identify the factors that influenced overall plant diversity and diversity within each life form, and a CCA was used to assess the factors of species composition. Additionally, we compared the three forest systems using the Kruskal-Wallis test and bootstrap methods to determine which landscape or forest management better contributes to conserve biodiversity. Finally, a NMDS analysis was conducted to illustrate the distribution of species and stands. The results indicated that plant diversity was highest in Native forests, followed by Pine plantations. Moreover, the species composition of Native forests was significantly distinct from that of forest plantations. Furthermore, higher percentage of native forests, pine plantations and open habitats in the surrounding landscape were associated with enhanced plant diversity, while the presence of eucalypt plantations and urban areas reduced it. In relation to stand characteristics, higher soil organic matter content, proximity to water, and low tree density were also found to promote plant diversity. In conclusion, maintaining native forests across the landscape is essential for preserving typical forest plant diversity, and eucalypt plantations are not a suitable alternative for replacing pine plantations.