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Sci Total Environ. 2018 Jun 1;625:440-448. doi: 10.1016/j.scitotenv.2017.12.292. Epub 2017 Dec 29.

Long-term N and P additions alter the scaling of plant nitrogen to phosphorus in a Tibetan alpine meadow.

Author information

1
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
2
State Key Laboratory of Grassland and Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, China.
3
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China. Electronic address: hui.guo@njau.edu.cn.
4
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China; Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695, United States. Electronic address: shuijin_hu@ncsu.edu.

Abstract

Nitrogen and phosphorus are two important nutrient elements for plants. The current paradigm suggests that the scaling of plant tissue N to P is conserved across environments and plant taxa because these two elements are coupled and coordinately change with each other following a constant allometric trajectory. However, this assumption has not been vigorously examined, particularly in changing N and P environments. We propose that changes in relative availability of N and P in soil alter the N to P relationship in plants. Taking advantage of a 4-yr N and P addition experiment in a Tibetan alpine meadow, we examined changes in plant N and P concentrations of 14 common species. Our results showed that while the scaling of N to P under N additions was similar to the previously reported pattern with a uniform 2/3 slope of the regression between log N and log P, it was significantly different under P additions with a smaller slope. Also, graminoids had different responses from forbs. These results indicate that the relative availability of soil N and P is an important determinant regulating the N and P concentrations in plants. These findings suggest that alterations in the N to P relationships may not only alter plant photosynthate allocation to vegetative or reproductive organs, but also regulate the metabolic and growth rate of plant and promote shifts in plant community composition in a changing nutrient loading environment.

KEYWORDS:

Allometry; Alpine meadow; Ecological stoichiometry; N and P addition; Plant functional group; Tibetan plateau

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