High-precision U-Pb age constraints on the Permian floral turnovers, paleoclimate change, and tectonics of the North China block

The Permian marine-terrestrial system of the North China block provides an exceptional window into the evolution of northern temperate ecosystems during the critical transition from icehouse to greenhouse following the late Paleozoic ice age (LPIA). Despite many studies on its rich hydrocarbon reserves and climate-sensitive fossil flora, uncertain temporal constraints and correlations have hampered a thorough understanding of the records of geologic, biologic, and climatic change from the North China block. We present a new chronostratigraphy based on high-precision U-Pb chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) geochronology of tuffs from a near-complete latest Carboniferous–Permian succession in North China. The results indicate that the predominance of continental red beds, climate aridification, and the disappearance of coals and characteristic tropical flora were well under way during the Cisuralian (Early Permian) in the North China block, significantly earlier than previously thought. A nearly 20 m.y. hiatus spanning the early Kungurian to the mid-Guadalupian (or later) is revealed in the northern North China block to have close temporal and spatial associations with the closure and/or subduction of the Paleo-Asian Ocean and its related tectonic convergence. This long hiatus was concomitant with the prominent loss of the highly diverse and abundant Cathaysian floras and the widespread invasion of the monotonous Angaran floras under arid climate conditions in the North China block. Similarities in the floral and climate shift histories between Euramerica and North China suggest that aside from the regional tectonic controls and continental movement, extensive volcanism during the Cisuralian may have played a major role in the global warming and aridification in the aftermath of the LPIA.

The triad of knowledge: Systematic, diversity and conservation status of the Mexican species of Tabernaemontana (Apocynaceae; Rauvolfioideae: tribe Tabernaemontaneae)

In this study, we update the systematics of the Tabernaemontana and describe the general patterns of species diversity and conservation status in Mexico. A total of 18 species were registered, including one cultivated species, two new species described here (T. chamelensis L.O. Alvarado & Lozada-Pérez and T. ochoterenae L.O. Alvarado & S. Islas), and eight species endemic to Mexico, which in total represents 47% of the diversity of the genus in the country. The states of Chiapas, Oaxaca, and Veracruz had the highest species diversity in native and endemic species. A map based on the kriging approach and the sums of species distribution models corroborate the sites of high diversity. A comparison among American countries showed that Central American countries share more specific similarity than South American ones. A risk evaluation showed that six species are under threat, mainly the endemic species. This exercise demonstrated that this genus is an interesting model to understand the biogeography, evolution, and affinities of the tropical flora of the Americas. Our work provides a basis for a deeper study of the biogeography and biology of the members of genus Tabernaemontana.

Pollen and Foraminifera Approaches to Identify Sediment Sources In The River Mouth Mahakam East Kalimantan

The central role of Mahakam River in the construction of Mahakam Delta is to supply sediment from terrestrial to the river mouth. The river upstream comes from Mount Camaru and the downstream part terminate at Makasar Strait. The surrounding area of the river is overgrown by wet tropical flora that produces pollen. The existence pollen in river sediments as an indicator that sediment came from terrestrial, and foraminifera as an indicator that sediment came from marine. The ratio changes of pollen to foraminifera show that there were differences of sediment source supply. The study was conducted at the river mouth. A shallow core, 200 cm depth, composed of sand and mud and sandy mud, from it taken vertically 11 samples to be analyzed pollen and foraminifera. Sample preparation was using standard methods acetolysis. Meanwhile, sample preparation of foraminifera using Hydrogen Peroxide method. Pollen found at all samples, but foraminifera only found in 8 samples. The data indicating that sedimentation process in the mouth of a river not only gets sediment supplies from terrestrial but also from marine. The quantity of pollen and foraminifera varies vertically. The frequency of pollen much higher than foraminifera that indicates of source sediments dominance came from terrestrial which carried by Mahakam river current. Sonneratia caseolaris pollen continuously found in all samples. Stictogongylus vandiemensis is species foraminifera the most common that followed by Ramulina confossa, both of them come from the sea particularly from the shallow sea.

Leaf extracts of Casearia sylvestris and Casearia decandra affect growth and production of ligninolytic enzymes in wood decay basidiomycetes

ABSTRACT White-rot basidiomycetes are able to deteriorate wood products and be pathogenic to living trees, requiring, thus requiring control. The tropical flora is an important source of eco-friendly antifungal compounds; however, the knowledge on how leaf extracts affect the fungal physiology is limited. Therefore, in the present work we investigated the influence of ethanolic leaf extracts of Casearia sylvestris and C. decandra at 0.1 mg mL-1 on the production of ligninolytic enzymes by Trametes villosa, Ganoderma australe and Pycnoporus sanguineus. Overall, the extracts inhibited the mycelial growth and the production of biomass. Additionally, C. sylvestris extract reduced the production of manganese peroxidase and laccase; however, the exposure to C. decandra extract resulted in variable responses. Therefore, enzymes related to lignin degradation are potential targets to control wood decay fungi by plant bioactive compounds, as their ability to colonize the substrate may be impaired.