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Functional Plant Biology Functional Plant Biology Society
Plant function and evolutionary biology
RESEARCH ARTICLE

Evaluating physiological changes of grass and semishrub species with seasonality for understanding the process of shrub encroachment in semiarid grasslands

Liu Yang https://orcid.org/0000-0001-9422-2613 A B , Jihua Zhou A , Liming Lai A , Qinglin Sun A B , Sangui Yi A B , Lianhe Jiang A and Yuanrun Zheng orcid.org/0000-0002-2050-1967 A C
+ Author Affiliations
- Author Affiliations

A Key Laboratory of Resource Plants, West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, China.

B University of Chinese Academy of Sciences, Beijing, China.

C Corresponding author. Email: zhengyr@ibcas.ac.cn

Functional Plant Biology 47(7) 628-638 https://doi.org/10.1071/FP19194
Submitted: 9 July 2019  Accepted: 18 February 2020   Published: 15 May 2020

Abstract

Shrub encroachment occurs worldwide, especially in arid and semiarid grasslands. Changes in soil water in different layers affect the process of shrub encroachment. Understanding the biological and physiological responses of plant species to shrub encroachment is essential for explaining shrub encroachment. The dominant species in six typical plant communities changed from Stipa bungeana Trin. to Artemisia ordosica Krasch., representing different shrub-encroached grasslands. The gravimetric soil water content (SWC) and enzyme and osmotic adjustment compounds of the dominant species across shrub encroachment stages and growing seasons were measured to explain the shrub encroachment. Results showed that SWC decreased and then increased during the growing seasons. With the process of shrub encroachment, SWC first increased, then decreased. With increasing soil depth, SWC increased or decreased. Across seasons with decreasing SWC, enzyme activity decreased and then increased, and malondialdehyde content and osmotic adjustment compounds increased. With the process of shrub encroachment, enzyme activity, malondialdehyde content and osmotic adjustment compounds increased or decreased. The two dominant species (S. bungeana and A. ordosica) enhanced their drought resistance abilities by regulating their antioxidant systems and osmotic adjustment compounds when soil water in a specific layer was not over the threshold. We recommend increasing the clay content to increase the water holding capacity in the surface soil layer to restore the zonal vegetation of S. bungeana.

Additional keywords: antioxidant enzyme activity, osmotic adjustment compounds.


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