Unveiling the adaptation strategies of woody plants in remnant forest patches to spatiotemporal urban expansion through leaf trait networks

Background:With the expansion of urban areas,the remnants of forested areas play a crucial role in preserving biodiversity in urban environments.This study aimed to explore the impact of spatiotemporal urban expansion on the networks of leaf traits in woody plants within remnant forest patches,thereby enhancing our understanding of plant adaptive strategies and contributing to the conservation of urban biodiversity.Methods:Our study examined woody plants within 120 sample plots across 15 remnant forest patches in Guiyang,China.We constructed leaf trait networks (LTNs) based on 26 anatomical,structural,and compositional leaf traits and assessed the effects of the spatiotemporal dynamics of urban expansion on these LTNs.Results and conclusions:Our results indicate that shrubs within these patches have greater average path lengths and diameters than trees.With increasing urban expansion intensity,we observed a rise in the edge density of the LTN-shrubs.Additionally,modularity within the networks of shrubs decreased as road density and urban expansion intensity increased,and increases in the average path length and average clustering coefficient for shrubs were observed with a rise in the composite terrain complexity index.Notably,patches subjected to‘leapfrog’expansion exhibited greater average patch length and diameter than those experiencing edge growth.Stomatal traits were found to have high degree centrality within these networks,signifying their substantial contribution to multiple functions.In urban remnant forests,shrubs bolster their resilience to variable environmental pressures by augmenting the complexity of their leaf trait networks.

Assessing 40 years of spatial dynamics and patterns in megacities along the Belt and Road region using satellite imagery

The Belt and Road(B&R)region,a vital area with historical,economic,cultural and political significance,has undergone rapid urbanization in the past several decades,especially in the form of urban expansion.In this study,20 megacities in the B&R region were selected to explore different spatiotemporal patterns of urban expansion.Object-oriented support vector machines(SVM),annual growth rate(AGR)models,and landscape metrics were employed to delineate the urban areas and characterize spatiotemporal characteristics and landscape patterns of these megacities during 1975–2015.All urban maps presented high overall accuracies(80.70%–95.90%)and overall Kappa coefficients(0.76–0.95).The study revealed that megacities in the B&R region have undergone different types of urban sprawl,mainly adopting a‘concentric circle’pattern in inland areas and a‘sector’pattern in coastal areas.Besides,six expansion modes were summarized according to the AGRs of individual megacities.Differences existed in megacities of the developing and developed countries and among five sub-regions.Moreover,‘dispersion,gathering,and re-dispersion’and‘coalescence’were two major landscape patterns of megacities in developing and developed countries.Results of this study can provide a scientific reference for urban planning and aid in sustainable development of local areas.