Dwarfing and the underlying morphological changes of Poa alpigena plants in response to overgrazing conditions
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Abstract
Poa alpigena as the research object on alpine meadow in this paper,analyzed the change characteristics of the stem and leaf anatomical structures of Poa alpigena plants under the overgrazing and enclosed conditions aims to revealed the dwarfing of morphological mechanism in overgrazing.the results show that that leaf thickness, leaf epidermal thickness, epidermal cell area, and phloem thickness increased with increasing grazing intensity (p < 0.05). In contrast, xylem thickness, mesophyll cell area, and guide wall thickness decreased with increasing grazing intensity (p < 0.05). Mesophyll cell density was relatively unaffected by grazing intensity. Additionally, the plasticity indices were high (i.e., greater than 0.5) for leaf area, upper epidermal cutin layer thickness, and leaf xylem thickness. The plasticity indices were greater than 0.4 for stem tube diameter, epidermal cell size, and epidermal cuticle thickness. These results reflected the Poa alpigena stem and leaf structural changes induced by the water and mechanical stresses caused by grazing livestock. Thus, plateau plants adapt to grazing stress by increasing the thickness of their leaves, cuticles, and phloem. The Poa alpigena mesophyll cell area as well as the stem epidermal cell area and density decrease in response to minor changes in grazing intensity, which ultimately result in the shortened leaves and stems of dwarf plants.
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2018. Dwarfing and the underlying morphological changes of Poa alpigena plants in response to overgrazing conditions. PeerJ Preprints 6:e27322v1 https://doi.org/10.7287/peerj.preprints.27322v1Author comment
This is a preprint submission to PeerJ Preprints.
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Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Shi hongxiao conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Hou xiangyang conceived and designed the experiments.
Wu xinghong conceived and designed the experiments, authored or reviewed drafts of the paper.
Song haiqun performed the experiments, contributed reagents/materials/analysis tools.
Yang tingting performed the experiments.
Data Deposition
The following information was supplied regarding data availability:
Data are not provided with this preprint.
Funding
This work was supported by the National Basic Research Program(grant number 2014CB138802) in China, the Project of Qinghai Science & Technology Department (2016-ZJ-Y01), the Open Project of State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University (2016KF-06), Central Non-profit Research Institutes Fundamental Research Funds of China (1610332016003), Key Laboratory of Superior Forage Germplasm in the Qinghai-Tibetan Plateau (2017-ZJ-Y12). and the International Science and Technology Project of China (31560668). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
