Review of Palaeobotany and Palynology最新文献

Modern pollen distribution and its relationship to environmental variables in tropical to alpine vegetation zones are investigated to provide a reference for palaeoenvironmental reconstructions and to improve the understanding of pollen dispersal patterns in Central Nepal. A total of 100 samples (from soil and moss) were collected from along an elevational gradient ranging from 173 to 4615 m above sea level. Results show that the alpine zone is dominated by arboreal pollen (AP) and the sub-alpine zone also shows good representation of coniferous taxa pollen such as Pinus, Abies, Tsuga, and Picea along with Ericaceae. The temperate zone has a good representation of Quercus (Evergreen) and Pinus pollen, whereas the sub-tropical zone is characterized by Alnus pollen and agricultural taxa such as Cerealia (planted Poaceae) and Brassicaceae. In the tropical zone, non-arboreal pollen (NAP), mainly Cerealia dominate, reflecting intensive agricultural practices. Shorea is completely silent in pollen representation. A redundancy analysis indicates that elevation is the primary factor influencing pollen distribution in this region. Overall, the pollen data reflect the vegetation distribution but Pinus is over-represented and Shorea is unrepresented, which should be taken into consideration when interpreting fossil pollen in Central Nepal.

Palynological studies from Europe and North America have repeatedly considered the Carboniferous miospore genus Vestispora a useful biostratigraphic indicator, resulting in a detailed review and discussion of its variable morphotypes. This was not the case in Gondwana, where Vestispora has rarely been reported. However, a few studies from India and South America used the absence of this taxon as an argument for a Permian age.

The present work introduces a well-preserved and diverse record of five species of Vestispora from the Pennsylvanian (Moscovian-Gzhelian) of the Dhiffah Formation, north Western Desert (NWD), Egypt. Moreover, a detailed review of previous records of Vestispora was introduced in a trial to understand its regional distribution in Gondwana. It turned out that Vestispora is restricted to the Tethyan realm or the vegetation belt stretching North of Gondwana. However, the genus seems to exhibit a wider stratigraphic range in the Tethyan realm of Gondwana than in the Euramerican Province, with the youngest occurrences up to the top of the Carboniferous.

Modern pollen assemblages from moss polsters, topsoils, and lake surface sediments are crucial for interpreting palaeovegetational and palaeoclimatic conditions from fossil pollen records. While a large number of modern pollen assemblages exist from Yunnan Province, SW China, few are derived from lake surface sediments with depositional environments similar to those of fossil pollen records. In this study, we present modern pollen assemblages from lake surface sediments across 36 lakes in Yunnan, spanning spatially from the southeast to the northwest of the region. These lakes encompass a range of vegetation types, varying from alpine meadow grasslands to tropical seasonal and montane rainforests. Our findings demonstrate that modern pollen assemblages from lake surface sediments can effectively identify various vegetation zones. Redundancy analysis (RDA) reveals a strong correlation of pollen assemblages with climate factors (e.g., temperature and precipitation) but a weak correlation with human activities. This study suggests that modern pollen assemblages from lake surface sediments in Yunnan can be used not only to reflect changes in vegetation and climate, but also as reliable indicators for reconstructing the history of human activities to some extent.

This study presents a 40,000-year-old pollen record from Los Tollos Lake in the Baetic-Rifan region of southernmost Spain. The data offer insights into the past ecosystems of a current biodiversity hotspot situated at the ecotone between the Atlantic and the Mediterranean. This new sequence encompasses Mediterranean and Ibero-North African sclerophylls, broad-leaf trees, conifers, and Tertiary relicts. The full-glacial abundance of mesothermophytes, particularly oaks, is among the highest recorded for the European Quaternary. Notably, the presence of ecologically significant pollen taxa, which are poorly dispersed and currently occur outside the study area, suggests that this biodiversity hotspot was more extensive in the Pleistocene. During the period of c. 40.8–36.5 ka, three Artemisia maxima at 40.6, 38.9, and 36.9 ka coincide with decreases in Quercus, indicating the spread of steppes in response to the abrupt coolings of the GS10, GS9 (HS4), and GS8 events. Similarly, increases in Quercus around 41, 40, and 37.2–38.3 ka parallel the GI10, GI9, and GI8 warm events. A forested period from 36.5–32 ka includes oak expansions during the GI7 and GI6 interstadials. From 32 to 19.2 ka, more xerophytic vegetation is observed, including the HS3, GS5-GS3, HS2, and GS2.1b-c cold spells, although the correlation with vegetation changes is not synchronous. As early as approximately 21 ka, Artemisia definitively declines, while the region was reforesting, likely due to the presence of stationary populations of broadleaf trees and conifers in the southern Baetic mountains. From approximately 12 ka onwards, the highest values of angiosperm trees are recorded, with oaks dominating throughout most of the Holocene. The pollen record and the correlation with marine records suggest a more intense hydrological regime during the first half of the Holocene, but there is also archaeobotanical evidence for human activity during the second half, resulting in a more open landscape, making it difficult to discriminate the impact of each factor. Some abrupt aridity events during the Holocene coincide with small variations in tree cover, particularly at 9.2, 8.2, 6.8, 5.5–4.8, 4.2, and 2.8 ka. Since the Neolithic and during the metallurgic stages, forest species, especially broad-leaf trees, experienced range retraction accompanied by population extinctions. The region's plant communities have been subject to fire regimes since the Pleistocene, seemingly dependent on the available tree biomass.