The end-Cretaceous event was catastrophic for terrestrial communities worldwide, yet its long-lasting effect on tropical forests remains largely unknown. We quantified plant extinction and ecological change in tropical forests resulting from the end-Cretaceous event using fossil pollen (>50,000 occurrences) and leaves (>6000 specimens) from localities in Colombia. Late Cretaceous (Maastrichtian) rainforests were characterized by an open canopy and diverse plant–insect interactions. Plant diversity declined by 45% at the Cretaceous–Paleogene boundary and did not recover for ~6 million years. Paleocene forests resembled modern Neotropical rainforests, with a closed canopy and multistratal structure dominated by angiosperms. The end-Cretaceous event triggered a long interval of low plant diversity in the Neotropics and the evolutionary assembly of today’s most diverse terrestrial ecosystem.

Societal Impact Statement Urban forests are recognized for the multiple benefits they provide to city‐dwellers. However, climate change will affect tree species survival and persistence in urban ecosystems. Tree failures will cause economic losses and jeopardize the delivery of societal benefits. The impacts of climate change will depend on the species’ resilience and adaptive capacity, as well as management actions which may ameliorate some of the negative impacts. Here, we assessed the potential vulnerability of Australia's urban forests to climate extremes. Our results can be used for future urban planning aiming to incorporate species that are well‐adapted to the hotter, drier climates expected with climate change. Summary Urban forests (UFs) are recognized for the multiple benefits they provide to city‐dwellers. However, global climate change—particularly predicted increases in the frequency and intensity of heatwaves and drought—will affect tree species’ performance and survival in urban ecosystems. Here, we assessed species composition and potential vulnerability of UFs in 22 Australian significant urban areas (SUAs) to heat and/or moisture stress. We quantified species’ realized climatic niches across their known distribution, and assessed the extent to which baseline climate in the SUAs where a particular species is planted fell within its niche. We used three environmental variables to group species based on their potential climate vulnerability. UFs varied in species composition and climate vulnerability across the continent. In general, neither climate similarity nor geographical proximity were good predictors of species composition among UFs. Of 1,342 tree species assessed (68.4% natives), 53% were considered potentially vulnerable to heat and/or moisture stress in at least one city where they are currently planted. Our results highlight the climate vulnerability of current plantings across Australian SUAs and can be used to direct future species selection that considers the species’ climate of origin and climatic niche. UF planning can incorporate species from SUAs with similar climates and with low vulnerability to contemporary, as well as future climate conditions. Species with high climate vulnerability, in contrast, may require more intensive management to avoid failure under future hotter, drier climate conditions.

Question When did vegetation assemblages that occupy modern central Mexico appear within the context of the late Quaternary? Location Central Mexico. Methods We used modern and fossil pollen data sets from central Mexico to explore the evolution of regional vegetation through the late Quaternary. A total of 1397 samples (1357 fossil samples distributed in 17 records and 40 modern samples) were analysed through detrended correspondence analysis to evaluate the degree of analogy between modern and past vegetation assemblages, and regional vegetation compositional turnover through time. Results There was a high degree of analogy between modern and glacial vegetation, whereas the early and mid‐Holocene were characterized by a high frequency of no‐modern‐analogue pollen assemblages. Vegetation turnover during the glacial time was characterized by both pulses of abrupt change and episodes of stability. In contrast, vegetation turnover was high through most of the Holocene. Both vegetation turnover and past vegetation analogy to modern were not synchronous in altitudinal zones, except for the past 2000 yrs, when pollen assemblages suggest a high vegetation analogy to modern‐day throughout the region. Conclusions Human impacts on central Mexico regional vegetation were consistently evident during the last 2000 yrs, suggesting that biodiversity expressed in the modern vegetation assemblages incorporates a high anthropogenic imprint. High resemblance of glacial and modern landscapes suggests that the effect of human occupation on the landscape is similar to that exerted by glacial time environmental stress. However, loss of ecosystem connectivity under the modern pattern of landscape homogenization represents an unprecedented threat for regional biodiversity.

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The human impact imprint on modern pollen spectra of the Maya lands The human impact imprint on modern pollen spectra of the Maya lands