Naturalizations have led to homogenization of the Malesian flora in the Anthropocene

Aim: Worldwide, floras are becoming homogenized at global scales, but regional patterns vary. Here, we present the first assessment for the Malesian phytogeographical region in terms of the timing of introductions, direction, magnitude and drivers of floristic change due to alien plant naturalizations.Location: Malesian phytogeographic region, including Southeast Asia and the Pacific.Taxon: Tracheophyta (vascular plants).Methods: We compiled data on first records of naturalized plants in Malesia to investigate temporal trends in the rate and origin of introductions. We then calculated β‐diversity (including turnover and nestedness) for the native, naturalized and Anthropocene (native + naturalized) floras for each pair of island groups (36 pairs), and a homogenization index for the native and Anthropocene floras, using presence/absence data for 31,580 plant species. Mantel tests were used to investigate the geographic, climatic and anthropogenic correlates of dissimilarity and homogenization.Results: Around 75% of all naturalized species documented to date were already reported for the first time within Malesia prior to 1950. This has led to homogenization between the historic (native) and contemporary (Anthropocene) floras for all island group pairs. Turnover was the most important process for driving compositional dissimilarity between island groups in Malesia in the native and Anthropocene floras, but homogenization resulted from decreases in nestedness and turnover. Differences in average taxonomic homogenization for island groups were associated with differences in their level of anthropogenic modification.Main Conclusions: This study improves current understanding of the direction and drivers of floristic homogenization in one of the world's most diverse tropical regions. Alien plant introductions carry a long historical legacy in Malesia, and naturalizations of these plants have led to overall taxonomic homogenization of the region's flora. Expected increases in the magnitude of human modification, without appropriate policy, will likely lead to further reductions in the floristic uniqueness of island groups.</p

The naturalized vascular flora of Malesia

Major regional gaps exist in the reporting and accessibility of naturalized plant species distribution data, especially within Southeast Asia. Here, we present the Malesian Naturalized Alien Flora database (MalNAF), the first standardized island-group level checklist of naturalized vascular plant species for the Malesian phytogeographical region. We used MalNAF to investigate the composition, origins, and habitat preferences of the naturalized flora. The naturalized vascular flora of Malesia consists of at least 1177 species. Richness is highest in the Philippines (539 spp.) and lowest in the Maluku Islands (87 spp.). But, the Lesser Sunda Islands had the highest naturalized species richness relative to native richness and Singapore has a higher naturalized plant species richness than would be expected given its size. When comparing the data for Malesia with a global dataset, we found that naturalized richness increased with area for islands but not for continental regions. Across the archipelago, 31 species are widespread, occurring in every island group, but the majority have a limited distribution of 2.4 ± 2.3 (mean ± SD) island groups per naturalized species. The naturalized plant species are representatives of 150 families, twenty of which are newly introduced to the region. Families richest in naturalized plant species in Malesia were Fabaceae (= Leguminosae) (160 spp.), Poaceae (= Gramineae) (138 spp.), and Asteraceae (= Compositae) (96 spp.). Most of these have a native range that includes tropical Asia, closely followed by those from Southern America (inclusive of the Caribbean, Central and South America), although at the island-group level, most have a higher proportion with a Southern American native range. Most naturalized species occur in anthropogenic habitats, but many are present in “natural” habitats with fewer species, such as Leucaena leucocephala, reported from specialized habitats like drylands. MalNAF provides a baseline for future studies of naturalized plant species distributions in the region.</p

sj-docx-2-anr-10.1177_20530196221147607 – Supplemental material for The San Francisco Estuary, USA as a reference section for an Anthropocene series

Supplemental material, sj-docx-2-anr-10.1177_20530196221147607 for The San Francisco Estuary, USA as a reference section for an Anthropocene series by Stephen Himson, Mark Williams, Jan Zalasiewicz, Colin Waters, Mary McGann, Richard England, Bruce E Jaffe, Arnoud Boom, Rachael Holmes, Sue Sampson, Cerin Pye, Juan Carlos Berrio, Genevieve Tyrrell, Ian P Wilkinson, Neil Rose, Pawel Gaca and Andrew Cundy in The Anthropocene Review</p

sj-docx-3-anr-10.1177_20530196221147607 – Supplemental material for The San Francisco Estuary, USA as a reference section for an Anthropocene series

Supplemental material, sj-docx-3-anr-10.1177_20530196221147607 for The San Francisco Estuary, USA as a reference section for an Anthropocene series by Stephen Himson, Mark Williams, Jan Zalasiewicz, Colin Waters, Mary McGann, Richard England, Bruce E Jaffe, Arnoud Boom, Rachael Holmes, Sue Sampson, Cerin Pye, Juan Carlos Berrio, Genevieve Tyrrell, Ian P Wilkinson, Neil Rose, Pawel Gaca and Andrew Cundy in The Anthropocene Review</p

Palaeontological signatures of the Anthropocene are distinct from those of previous epochs

 The “Great Acceleration” of the mid-20th century provides the causal mechanism of the Anthropocene, which has been proposed as a new epoch of geological time beginning in 1952 CE. Here we identify key parameters and their diagnostic palaeontological signals of the Anthropocene, including the rapid breakdown of discrete biogeographical ranges for marine and terrestrial species, rapid changes to ecologies resulting from climate change and ecological degradation, the spread of exotic foodstuffs beyond their ecological range, and the accumulation of reconfigured forest materials such as medium density fibreboard (MDF) all being symptoms of the Great Acceleration. We show: 1) how Anthropocene successions in North America, South America, Africa, Oceania, Europe, and Asia can be correlated using palaeontological signatures of highly invasive species and changes to ecologies that demonstrate the growing interconnectivity of human systems; 2) how the unique depositional settings of landfills may concentrate the remains of organisms far beyond their geographical range of environmental tolerance; and 3) how a range of settings may preserve a long-lived, unique palaeontological record within post-mid-20th century deposits. Collectively these changes provide a global palaeontological signature that is distinct from all past records of deep-time biotic change, including those of the Holocene. </p