Understanding the modern relationships between pollen and vegetation, climate, and human land-use completely, is essential for quantitative reconstructions of past vegetation, climate and human impacts. supported by the Second Tibetan Plateau Scientific Expedition Program, we have collected more than 700 surface-soil samples together with detail vegetation survey. Hitherto, pollen analysis of 318 samples have been completed, and the submitted modern pollen dataset includes the pollen percentages of 24 common taxa, the sampling sites of the dataset cover the all vegetation types on the east and central Tibetan Plateau. The dataset can be utilized in establishment for pollen-climate, pollen-vegetation calibration-sets.
This dataset is the biome change data of the Tibetan Plateau since the last glacial maximum which was reconstructed by using a new method. Firstly, a random forest algorithm was applied to establish a pollen-biome classification model for reconstructing past vegetation changes of the Tibetan Plateau, and 1802 modern pollen assemblages from 17 vegetation zones in and around the Tibetan Plateau were used as the training set for the model development. The random forest model showed a reliable performance (accuracy > 76%) in predicting modern biomes from modern pollen assemblages based on a comparison with the observed biomes. Moreover, the random forest model had a significantly higher accuracy than the traditional biomization method. Then, the newly established random forest model is applied to the paleovegetation reconstruction of 51 fossil pollen sequences of the Tibetan Plateau. New age-depth models were developed for these fossil pollen records using the Bayesian method, and all fossil pollen records were linearly interpolated to 500-year time slices. Finally, the spatiotemporal changes of biomes on the Tibetan plateau over the past 22,000 years at an interval of 500 years were reconstructed by using the random forest model. This dataset can provide evidence for understanding the past variation of alpine vegetation and its mechanism; provide the basis for studying the impact of past climate change on vegetation on the Tibetan Plateau; and provide boundary conditions for climate simulation.
The present data are chronological and palynological data from the Luanhaizi Lake core in the Menyuan Basin, northeastern Tibetan Plateau. We used the AMS14C method to test nine dated samples from the LHZ18 core. Bulk samples were collected from plant remains and organic-rich horizons from the core LHZ18 for accelerator mass spectrometry (AMS)14C dating. Samples were measured at Beta Labs in the USA and Lanzhou University.Pollen analysis was completed at the Key Laboratory of Western China’s Environment Systems,Ministry of Education, Lanzhou University, with 140 stratigraphic pollen samples and 10 topsoil pollen samples. Spore pollen identification statistics were carried out under a light microscope.The pollen results mainly include the number of grains of trees, shrubs, herbs and aquatic plants.