Enhanced precipitation has driven the evolution of subtropical evergreen broad‐leaved forests in eastern China since the early Miocene: Evidence from ring‐cupped oaks

Abstract

Subtropical evergreen broad‐leaved forest (EBLF) is the predominant vegetation type in eastern China. However, the majority of the region it covers in eastern China was an arid area during the Paleogene. The temporal history and essential factors involved in the evolution of subtropical EBLFs in eastern China remain enigmatic. Here we report on the niche evolution of Quercus section Cyclobalanopsis, which appeared in south China and Japan during the Eocene and became a dominant component of subtropical EBLFs since the Miocene in eastern Asia, using integrative analysis of occurrences, climate data and a dated phylogeny of 35 species in Cyclobalanopsis. Species within clades Cyclobalanoides, Lamellosa, and Helferiana mainly exist in the Himalaya–Hengduan region, adapting to a plateau climate, while species within the other clades mainly live in eastern China under the control of the East Asian monsoon. Reconstructed history showed that significant divergence of climatic tolerance in Cyclobalanopsis began around 19 million years ago (Ma) in the early Miocene. Simultaneously, disparities in precipitation of wettest/warmest quarter and annual precipitation were markedly enhanced in Cyclobalanopsis, especially in the recent eastern clades. During the Miocene, the marked radiation of Cyclobalanopsis and many other dominant taxa of subtropical EBLFs strongly suggest the rapid formation and expansion of subtropical EBLFs in eastern China. Our research highlights that the intensification of the East Asian monsoon and subsequent occupation of new niches by the ancient clades already present in the south may have jointly promoted the formation of subtropical EBLFs in eastern China since the early Miocene.

Multi‐ecosystem services differently affected by over‐canopy and understory nitrogen additions in a typical subtropical forest

“…The study was performed in a typical subtropical evergreen broadleaved forest ecosystem, which was located at Shimentai National Reserve (113°05′-113°31′ E, 24°22′-24°31′ N), Guangdong province, China. Subtropical evergreen broadleaved forest is the predominant forest type in the monsoon climate of eastern Asia (Jin et al, 2023;Song, 2013). The forest age is about 50 years old, and the mean canopy closure was 92% (Liu et al, 2023).…”

Structural conservation and functional genetic adaptive evolution of chloroplast genomes in Cycle-cup Oaks

“…Adaptive evolution of chloroplast genomes of Quercus section Cyclobalanopsis Species of Quercus section Cyclobalanopsis are widely distributed in the tropical and subtropical regions of East Asia [3]. Over a long evolutionary period, they have adapted to diverse ecological environments and occupy different ecological niches [104]. At the chloroplast genome level, we identi ed nine PCGs subjected to positive selection that underwent ecological adaptation evolution in Quercus section Cyclobalanopsis (Table 4).…”

Complete Chloroplast Genomes of Four Oaks from the Section Cyclobalanopsis Improve the Phylogenetic Analysis and Understanding of Evolutionary Processes in the Genus Quercus

“…Quercus (oaks) section Cyclobalanopsis (cycle-cup oaks) are exclusively found in East and Southeast Asia and are the dominant trees in tropical and subtropical areas with warm and humid climates [13,14]. Cyclobalanopsis is one of the largest sections in Quercus, with approximately 110 species, and has the highest proportion of threatened oaks [15].…”

“…In this context, we collected four cycle-cup oak species (Q. poilanei, Q. helferiana, Q. camusiae, and Q. semiserrata) that are mainly distributed in Southeast Asia. Quercus poilanei, Q. helferiana, and Q. semiserrata are widely distributed in Southwest China, Thailand, Laos, Vietnam, Malaysia, and Myanmar, whereas Q. camusiae is a critically endangered species distributed only in the boundary area between China and Vietnam [14]. Using nextgeneration sequencing data, the chloroplast (cp) genomes of four cycle-cup oak species were assembled and annotated.…”