Browsing by Author "Gao, Dexin"

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    Enhanced coupling of light use efficiency and water use efficiency in arid and semi-arid environments
    (Wiley, 2021) Gao, Dexin; Wang, Shuai; Wang, Lixin; Li, Zidong; Pan, Ning; Liu, Yanxu; Fu, Bojie; Earth Sciences, School of Science
    Both light use efficiency (LUE) and water use efficiency (WUE) play essential roles in ecosystem production. The extent to which ecosystem production is affected by the coupling between LUE and WUE remains unclear. In this study, we used data from flux measurements and weather stations in the Heihe River Basin, China, along a strong climatic gradient to quantify the relationship between LUE and WUE. Variations of LUE explained up to 85% of the variations of WUE. The contribution of LUE to WUE increased with increasing water stress. Pearson’s correlation coefficient between LUE and WUE increased from −0.12 to +0.63 with decreasing LUE. The coordination between LUE and WUE was essential to explaining the insensitive of WUE and GPP with increasing water stress. These results suggest that ecosystems enhance the coordination between light and water use when water stress is high. They enhance our understanding of the drought resilience of ecosystems and reduce uncertainties associated with the carbon cycle in drylands.
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    The vulnerability of ecosystem structure in the semi-arid area revealed by the functional trait networks
    (Elsevier, 2022-06) Gao, Dexin; Wang, Shuai; Wei, Fangli; Wu, Xutong; Zhou, Sha; Wang, Lixin; Li, Zidong; Chen, Peng; Fu, Bojie; Earth and Environmental Sciences, School of Science
    The ecosystems were characterized by complex, nonlinear interactions determined by different plant functional traits. The characteristics of the multiple relationships between ecosystem functional traits affected the vulnerability to drought. A three-level network analysis on instead of the network metrics, relationships among inter-components, and essential traits was conducted in dryland ecosystems of China. The new network of functional traits included leaf, root, and biomass components was constructed to simulate different aridity conditions. Results show that the multiple relationships of functional traits that co-regulated ecosystem biomass differ along an aridity gradient. The highest network modularity and degree centrality were observed in the semi-arid ecosystems indicating low integration and high sensitivity of semi-arid ecosystems (269% and 23.7% higher than in dry sub-humid site, and 142% and 51.1% higher than arid sites). The leaf quantity strongly affected the connection between functional traits at the semi-arid zone. The semi-arid areawas found to have relatively low resistance to environmental change because of low integration and high sensitivity of the ecosystem structure at that site. An increase of degree centrality of the root traits and trade-off relationships between roots and leaves indicated greater allocation of resources by vecgetation to underground components by the arid ecosystems to increase water absorption. The study reveals the complex relationships between leaf, root, and biomass components, and the essential traits of the ecosystem. It enhanced understanding of the vulnerability of semi-arid ecosystems to environmental change.
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    Threshold of vapour–pressure deficit constraint on light use efficiency varied with soil water content
    (Wiley, 2022-07) Gao, Dexin; Wang, Shuai; Li, Zidong; Wei, Fangli; Chen, Peng; Song, Shuang; Wang, Yaping; Wang, Lixin; Fu, Bojie; Earth Sciences, School of Science
    Understanding the constraints on light-use efficiency (LUE) induced by high evaporative water demand (vapour–pressure deficit; VPD) and soil water stress (soil moisture content; SMC) is crucial for understanding and simulating vegetation productivity, particularly in the arid and semi-arid regions. However, the relative impacts of VPD and SMC on LUE are unclear, as we lack a mechanistic understanding of impacts and their interactions. In this study, we quantified the relative roles of VPD and SMC in limiting LUE and analysed the interactions among VPD, SMC and LUE using data from CO2 and water flux stations and weather stations along a climatic gradient in the Heihe River Basin, China. We found a threshold of VPD constraint on LUE; above the threshold, LUE decreased at only 3.6% to 23.1% of the rate below the threshold. As SMC decreased, however, the VPD threshold increased, and the reduction of LUE caused by VPD decreased significantly, which is more than half of that in moister regions. Therefore, both VPD and SMC played essential roles in LUE limitation caused by water stress. A threshold also existed for heat flux and the correlation between SMC and LUE; the strength of the correlation first decreased and then increased with increasing VPD. Our results clarified the relative impacts of VPD and SMC on LUE, and can improve simulation and prediction of plant productivity.