Physiological factors contribute to increased competitiveness of grass relative to sedge, forb and legume species under different N application levels

Hao Shen; Shikui Dong; Antonio DiTommaso; Anna S Westbrook; Shuai Li; Hanzhong Zheng; Yangliu Zhi; Hui Zuo; Qiyun Wang; Junxiang Liu

doi:10.1016/j.scitotenv.2023.167466

Physiological factors contribute to increased competitiveness of grass relative to sedge, forb and legume species under different N application levels

Sci Total Environ. 2024 Jan 1:906:167466. doi: 10.1016/j.scitotenv.2023.167466. Epub 2023 Oct 1.

Authors

Hao Shen¹, Shikui Dong², Antonio DiTommaso³, Anna S Westbrook³, Shuai Li⁴, Hanzhong Zheng⁵, Yangliu Zhi⁶, Hui Zuo¹, Qiyun Wang⁷, Junxiang Liu⁸

Affiliations

¹ School of Grassland Science, Beijing Forestry University, Beijing, 100083, China.
² School of Grassland Science, Beijing Forestry University, Beijing, 100083, China; School of Environment, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Beijing Normal University, Beijing, 100875, China; Department of Natural Resources, Cornell University, Ithaca, NY 14853, United States. Electronic address: dongshikui@bjfu.edu.cn.
³ Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, United States.
⁴ College of Resource and Environment, Shanxi Agricultural University, Taigu 030801, China.
⁵ Department of Environmental Science, Radboud University, 6526 AJ Nijmegen, The Netherlands.
⁶ School of Environment, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Beijing Normal University, Beijing, 100875, China.
⁷ State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China.
⁸ State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.

PMID: 37788779
DOI: 10.1016/j.scitotenv.2023.167466

Abstract

In alpine grasslands, increased N deposition is increasing the dominance of grasses relative to other functional types according to our previous study Shen et al. (2022). However, the mechanisms that drive this compositional change are not fully understood. We measured the effects of 4-6 years' N addition to simulate N deposition at rates of 0 (CK), 8 (N1), 24 (N2), 40 (N3), 56 (N4), and 72 (N5) kg N ha^-1 year^-1 on dominant representatives of four functional types, Leymus secalinus (grass), Carex capillifolia (sedge), Potentilla multifidi (non-leguminous forb), and Medicago ruthenica (legume), in the alpine grassland on the Qinghai-Tibetan Plateau (QTP). In-situ experiment showed that N addition increased aboveground biomass in L. secalinus but had negative or neutral effects on aboveground biomass in the other species. Consistent with this finding, N addition increased net photosynthesis, chlorophyll content, and rubisco activity in L. secalinus with less positive effects on the other species. Nitrogen addition increased leaf N content in L. secalinus and C. capillifolia and reduced leaf non-structural carbohydrate content in all four species. In L. secalinus, the highest N addition rate (N5) reduced MDA content, a marker of oxidative stress, by enhancing antioxidant enzyme activity. Overall, our findings suggested that physiological factors can contribute to increased competitiveness of grass relative to sedge, forb and legume species under high N application levels. The rapid growth of this grass species reduces resource availability to non-grass species, increasing its dominance in the alpine meadow.

Keywords: Alpine meadow; Functional groups; Nitrogen deposition; Non-structural carbohydrates; Photosynthesis.

MeSH terms

Biomass
Grassland*
Medicago
Poaceae* / physiology
Soil / chemistry
Vegetables

Substances

Soil