The Relative Influence of Environmental and Human Factors on Seed Plant Richness at the Province Scale in China

Seed plant diversity is under threat due to human over-exploitation and changes in land use. There is a need to identify regions where seed plant diversity is most at risk and establish nature reserves to protect the most important species. This study collected province scale seed plant richness data and corresponding environmental, social and, economic data in China in order to assess the impact of environmental and socio-economic factors on seed plant diversity and to quantify the relative importance of climate, human disturbance, and habitat heterogeneity on the distribution of seed plant diversity. A downscaling model was established to map the spatial distribution of seed plant diversity at a 1-km resolution. The results showed that temperature and precipitation seasonality, potential evapotranspiration, humidity index, altitude range, and gross domestic product were important determinants of seed plant diversity. The relative contribution of temperature seasonality was the most important factor (explaining 29.9-36.2% of the variation). Climate, human disturbance, and habitat heterogeneity explained much of the seed plant richness and density variation (about 69.4-71.9%). A scale-down model explained 72% of seed plant richness variation and showed that the center of seed plant species diversity was mainly located in the southeast area of China in the Qing-Tibet Plateau, Yun-Gui Plateau, Hengduan Mountain region, middle of the Sichuan Basins, Taiwan island, and Hainan island. This study improves our understanding of biodiversity hotspot regions and is a useful tool for biodiversity conservation policy and nature reserve management in China

Al/Fe Mineral Controls on Soil Organic Carbon Stock Across Tibetan Alpine Grasslands

Adequate understanding of the controlling factors of soil carbon (C) stock is crucial for improving the predictability of Earth System Models in exploring terrestrial C-climate feedback. Current studies, however, mainly focus on climatic and edaphic variables and rarely explore the effects of mineral protection in regulating soil organic carbon (SOC) stock over broad geographic scale. Particularly, the relative importance of mineral protection compared with other factors is unclear. Based on large-scale soil inventory, here we filled this knowledge gap by exploring the effects of Al/Fe-(hydr) oxides on SOC and three C fractions across Tibetan alpine grasslands via linear regression, partial correlation, and variance partitioning analyses, and also by comparing the degree of mineral protection in alpine grasslands with other ecosystems. Our results showed that SOC and C fractions across Tibetan alpine grasslands were regulated by Al/Fe-(hydr) oxides, with the incorporation of mineral variables increasing the explained variations by 10.1% for SOC content, 13.4% for coarse particulate organic matter, 12.6% for microaggregate associated C, and 21.9% for silt and clay associated C. Moreover, the contribution of mineral effects exceeded that of climatic and edaphic factors, particularly in the silt and clay associated C fraction. In addition, about 15.812.0% of SOC pools were associated with Fe, which was equal to or higher than those in temperate and tropical-subtropical ecosystems. Taken together, these results demonstrate the significant role of Al/Fe minerals in the stabilization of SOC across Tibetan alpine grasslands, highlighting the importance of incorporating C-mineral interactions into ESMs for better understanding the terrestrial C-climate feedback

Palaeovegetation in China during the late Quaternary: Biome reconstructions based on a global scheme of plant functional types

Two previous reconstructions of palaeovegetation across the whole of China were performed using a simple classification of plant functional types (PFTs). Now a more explicit, global PFT classification scheme has been developed, and a substantial number of additional pollen records have become available. Here we apply the global scheme of PFTs to a comprehensive set of pollen records available from China to test the applicability of the global scheme of PFTs in China, and to obtain a well-founded reconstruction of changing palaeovegetation patterns. A total of 806 pollen surface samples, 188 mid-Holocene (MH, 6000 14C yr BP) and 50 last glacial maximum (LGM, 18,000 14C yr BP) pollen records were used to reconstruct vegetation patterns in China, based on a new global classification system of PFTs and a standard numerical technique for biome assignment (biomization). The biome reconstruction based on pollen surface samples showed convincing agreement with present potential natural vegetation. Coherent patterns of change in biome distribution between MH, LGM and present are observed. In the MH, cold and cool-temperate evergreen needleleaf forests and mixed forests, temperate deciduous broadleaf forest, and warm-temperate evergreen broadleaf and mixed forest in eastern China were shifted northward by 200–500 km. Cold-deciduous forest in northeastern China was replaced by cold evergreen needleleaf forest while in central northern China, cold-deciduous forest was present at some sites now occupied by temperate grassland and desert. The forest–grassland boundary was 200–300 km west of its present position. Temperate xerophytic shrubland, temperate grassland and desert covered a large area on the Tibetan Plateau, but the area of tundra was reduced. Treeline was 300–500 m higher than present in Tibet. These changes imply generally warmer winters, longer growing seasons and more precipitation during the MH. Westward shifts of the forest–shrubland–grassland and grassland–desert boundaries imply greater moisture availability in the MH, consistent with a stronger summer monsoon. During the LGM, in contrast, cold-deciduous forest, cool-temperate evergreen needleleaf forest, cool mixed forests, warm-temperate evergreen broadleaf and mixed forest in eastern China were displaced to the south by 300–1000 km, while temperate deciduous broadleaf forest, pure warm-temperate evergreen forest, tropical semi-evergreen and evergreen broadleaf forests were restricted or absent from the mainland of southern China, implying colder winters than present. Strong shifts of temperate xerophytic shrubland, temperate grassland and desert to the south and east in northern and western China and on the Tibetan Plateau imply drier conditions than present