Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (6): 641-649.DOI: 10.17521/cjpe.2021.0020

• Research Articles • Previous Articles     Next Articles

Growth responses of Tamarix austromongolica to extreme drought and flood in the upper Yellow River basin

FANG Ou-Ya1,*(), ZHANG Yong2, ZHANG Qi1,3, JIA Heng-Feng1,3   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    3University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2021-01-14 Accepted:2021-04-26 Online:2021-06-20 Published:2021-09-09
  • Contact: FANG Ou-Ya
  • Supported by:
    National Natural Science Foundation of China(31700412);Second Tibetan Plateau Scientific Expedition and Research (STEP) Program, China(2019QZKK0301)

Abstract:

Aims The riparian forests in the upper reaches of the Yellow River are typically fragile ecologically. However, the frequent extreme hydrological events induced by climate warming may pose increasing threats to ecological stability and security of this fragile ecosystem type. The ecological resilience and adaptation of riparian forests to extreme hydrological events are of key considerations in eco-environmental management of river basins. This paper aims to determine how Tamarix austromongolica, a major tree species in riparian forests of the upper Yellow River basin, responds to extreme drought and flood and explain the resistance and morphology of these riparian plants against environmental stresses.

Methods We selected 47 Tamarix austromongolica trees from three sampling sites along the upper reaches of the Yellow River. Two mutually perpendicular cores were taken from the trunk of the each sampling tree for estimation of the past annual growth, one from the direction facing the slope and the other along the contour of the nearby mountain. We compared the tree-ring growth between cores from the two sides and grouped them according to whether the growth was strongly affected by geohazards. We analyzed the resistance of the two groups to extreme hydrological events during the past 63 years. The statistical growth difference between two sampling directions from each group was performed by using paired test.

Important findings Tamarix austromongolica trees were found to be very resistant to extreme drought events. The diverse sources of water in riparian zones attributed to their stable growth, which helps enhance their tolerance to hydrological drought events. But the trees injured by geohazards appeared to be more severely affected by droughts. The legacy effect in trauma-associated recovery might initiate high sensitivity to interferences. Moreover, T. austromongolica trees are adapted to a wide range of water conditions and their growth did not appear to be substantially affected by flooding. Well-watered condition along with fully hydrated shoots could promote the growth and counteract the potentially negative effects of submergence in T. austromongolica. However, flood induced geohazards, such as mudslides, could have significantly different impacts on growth in different directions, such that the side facing the nearby mountain slope suffered more growth suppression. These processes could lead to modification of morphology. Studying the growth response of T. austromongolica to extreme drought and flood on the upper reaches of the Yellow River will help assess the ecological resilience of ecologically fragile areas and provide a scientific basis for ecological construction and restoration in riparian zones on the Qingzang Plateau.

Key words: ecological resilience, resistance, ecological fragile region, drought, flood, climate change, Tamarix austromongolica