Vertical patterns and controls of soil nutrients in alpine grassland: Implications for nutrient uptake

Liming Tian; Lin Zhao; Xiaodong Wu; Hongbing Fang; Yonghua Zhao; Guangyang Yue; Guimin Liu; Hao Chen

doi:10.1016/j.scitotenv.2017.07.080

Vertical patterns and controls of soil nutrients in alpine grassland: Implications for nutrient uptake

Sci Total Environ. 2017 Dec 31:607-608:855-864. doi: 10.1016/j.scitotenv.2017.07.080. Epub 2017 Jul 27.

Authors

Liming Tian¹, Lin Zhao², Xiaodong Wu³, Hongbing Fang³, Yonghua Zhao³, Guangyang Yue³, Guimin Liu⁴, Hao Chen⁵

Affiliations

¹ Cryosphere Research Station on the Qinghai-Tibetan Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; College of Earth Environmental Sciences, Lanzhou University, Lanzhou 730000, China.
² Cryosphere Research Station on the Qinghai-Tibetan Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: linzhao@lzb.ac.cn.
³ Cryosphere Research Station on the Qinghai-Tibetan Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
⁴ School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China.
⁵ School of Geography and Environment, Baoji University of Science and Art, Baoji 721013, China.

PMID: 28711847
DOI: 10.1016/j.scitotenv.2017.07.080

Abstract

Vertical patterns and determinants of soil nutrients are critical to understand nutrient cycling in high-altitude ecosystems; however, they remain poorly understood in the alpine grassland due to lack of systematic field observations. In this study, we examined vertical distributions of soil nutrients and their influencing factors within the upper 1m of soil, using data of 68 soil profiles surveyed in the alpine grassland of the eastern Qinghai-Tibet Plateau. Soil organic carbon (SOC) and total nitrogen (TN) stocks decreased with depth in both alpine meadow (AM) and alpine steppe (AS), but remain constant along the soil profile in alpine swamp meadow (ASM). Total phosphorus, Ca²⁺, and Mg²⁺ stocks slightly increased with depth in ASM. K⁺ stock decreased with depth, while Na⁺ stock increased slightly with depth among different vegetation types; however, SO₄^2- and Cl^- stocks remained relatively uniform throughout different depth intervals in the alpine grassland. Except for SOC and TN, soil nutrient stocks in the top 20cm soils were significantly lower in ASM compared to those in AM and AS. Correlation analyses showed that SOC and TN stocks in the alpine grassland positively correlated with vegetation coverage, soil moisture, clay content, and silt content, while they negatively related to sand content and soil pH. However, base cation stocks revealed contrary relationships with those environmental variables compared to SOC and TN stocks. These correlations varied between vegetation types. In addition, no significant relationship was detected between topographic factors and soil nutrients. Our findings suggest that plant cycling and soil moisture primarily control vertical distributions of soil nutrients (e.g. K) in the alpine grassland and highlight that vegetation types in high-altitude permafrost regions significantly affect soil nutrients.

Keywords: Alpine grassland; Nutrient cycling; Permafrost; Qinghai-Tibet plateau; Soil nutrient.