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Reichgelt, T., A. Baumgartner, R. Feng, and D. A. Willard. 2023. Poleward amplification, seasonal rainfall and forest heterogeneity in the Miocene of the eastern USA. Global and Planetary Change 222: 104073.

Paleoclimate reconstructions can provide a window into the environmental conditions in Earth history when atmospheric carbon dioxide concentrations were higher than today. In the eastern USA, paleoclimate reconstructions are sparse, because terrestrial sedimentary deposits are rare. Despite this, the eastern USA has the largest population and population density in North America, and understanding the effects of current and future climate change is of vital importance. Here, we provide terrestrial paleoclimate reconstructions of the eastern USA from Miocene fossil floras. Additionally, we compare proxy paleoclimate reconstructions from the warmest period in the Miocene, the Miocene Climatic Optimum (MCO), to those of an MCO Earth System Model. Reconstructed Miocene temperatures and precipitation north of 35°N are higher than modern. In contrast, south of 35°N, temperatures and precipitation are similar to today, suggesting a poleward amplification effect in eastern North America. Reconstructed Miocene rainfall seasonality was predominantly higher than modern, regardless of latitude, indicating greater variability in intra-annual moisture transport. Reconstructed climates are almost uniformly in the temperate seasonal forest biome, but heterogeneity of specific forest types is evident. Reconstructed Miocene terrestrial temperatures from the eastern USA are lower than modeled temperatures and coeval Atlantic sea surface temperatures. However, reconstructed rainfall is consistent with modeled rainfall. Our results show that during the Miocene, climate was most different from modern in the northeastern states, and may suggest a drastic reduction in the meridional temperature gradient along the North American east coast compared to today.

Couvreur, T. L. P., X. Cornejo, J. N. Zapata, and A. Loor. 2022. Two new magnoliid (Annonaceae, Lauraceae) tree species from Manabí, western Ecuador. Blumea - Biodiversity, Evolution and Biogeography of Plants.

Western Ecuador harbours high plant diversity and endemism. The region of Manabí has known intense deforestation over the last decades, but lowland rain forests persist in a network of small forest fragment patches. Here, we describe two new magnoliid tree species from a small privately owned forest fragment known as La Esperanza reserve, in the El Carmen canton (Manabí): Aniba ecuadorica (Lauraceae) and Guatteria esperanzae (Annonaceae). For both species a detailed morphological description, a preliminary conservation status following IUCN criteria, distribution maps and high quality photographs are provided. This represents the second species of Aniba known to occur in western Ecuador, while there are 14 species of Guatteria documented for Ecuador west of the Andes. Aniba ecuadorica is only known from two localities and has a preliminary IUCN conservation status of Critically Endangered, while Guatteria esperanzae is known from six localities and is suggested to be Endangered. Finally, we provide a quick overview of Guatteria species in western Ecuador with a key to the species in the region. The description of these two new tree species underlines the important need of prospection and conservation of the remnant forests in the Manabí region of western Ecuador. We also stress the importance of privately owned forest fragments for biodiversity conservation.

Baumbach, L., D. L. Warren, R. Yousefpour, and M. Hanewinkel. 2021. Climate change may induce connectivity loss and mountaintop extinction in Central American forests. Communications Biology 4.

The tropical forests of Central America serve a pivotal role as biodiversity hotspots and provide ecosystem services securing human livelihood. However, climate change is expected to affect the species composition of forest ecosystems, lead to forest type transitions and trigger irrecoverable losses…

Karger, D. N., M. Kessler, O. Conrad, P. Weigelt, H. Kreft, C. König, and N. E. Zimmermann. 2019. Why tree lines are lower on islands—Climatic and biogeographic effects hold the answer J. Grytnes [ed.],. Global Ecology and Biogeography 28: 839–850.

Aim: To determine the global position of tree line isotherms, compare it with observed local tree limits on islands and mainlands, and disentangle the potential drivers of a difference between tree line and local tree limit. Location: Global. Time period: 1979–2013. Major taxa studied: Trees. Method…