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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. [ABSTRACT FROM AUTHOR]

How past environments and communities responded to episodes of coastal inundation can inform preparations for future resilience to predicted rises in sea level. Southeast Asia's extensive coastlines and expanding coastal populations mean vast natural and human capital is at risk from future sea level rise. Regional mangroves provide many ecosystem services that can help mitigate such risks, but deforestation has left them threatened and compromised. The present study examines the Holocene development and human use of mangrove forest in northern Vietnam, where existing palaeo-records derive from sedimentary archives in tidal flat, estuarine and deltaic settings. Here, we expand that coverage by describing conditions at an enclosed doline within the Tràng An limestone karst in Ninh Binh province that would have been sheltered from deltaic and marine processes. We present a multi-proxy assessment incorporating pollen analysis of the 8125-year-old discontinuous sediment core obtained from the doline floor, combined with inferences from erosional tidal notches in the enclosing limestone, and analyses of phytolith, vertebrate and mollusc assemblages from an adjacent archaeological cave site with deposits of comparable age. The results provide a detailed example of how enclosed coastal environments and communities responded to Middle Holocene marine inundation. High percentages of pollen from mangroves (17–57%) suggest their colonisation of the doline from ∼8100 cal. BP and persistence until ∼250 cal. BP, well after the intertidal zone regressed seaward beyond the massif. Archaeological assemblages dating to ∼5500 cal. BP and containing palm and woody eudicot phytoliths and sponge spicules, neurocrania of the fish genus Pomadasys ('grunts', 'grunters' or 'javelins') and brackish-water molluscs Sermyla riqueti and Neripteron violaceum support the persistence of mangrove environments through the Middle Holocene high-stand, a period of hiatus within the core, and indicate human foraging and fishing activities took place in mangrove and lagoonal habitats alongside hunting in the surrounding limestone forest. Subsequent structural opening of this latter forest formation from ∼1075 cal. BP (875 CE), evident in the pollen record, coincides with the Medieval Climate Anomaly and with the adjacent development of the ancient capital at Hoa Lu. We propose that given the long-term persistence of mangrove habitats and associated resources documented in this study, regional initiatives aimed at rehabilitating mangroves (with the positive consequences that this holds for biodiversity and socio-economic conditions) may wish to consider selective restorative measures within Tràng An and similar sheltered sub-coastal karst settings. • Mangroves persisted in interior of karst well after sea receded in Late Holocene. • Limestone forest opened after 1075 cal BP, coeval with MCA and build-up of Hoa Lu. • Humans used local mangrove and limestone forest during Middle Holocene high-stand. • Site has potential for future mangrove restoration and resilience to sea level rise. [ABSTRACT FROM AUTHOR]