Responses of Tree Growth and Intrinsic Water Use Efficiency to Environmental Factors in Central and Northern China in the Context of Global Warming

The Loess Plateau is a fragile ecological zone that sensitive to climate change. response, adaptation, and feedback of tree growth in forest ecosystems global warming CO2 enrichment are urgent scientific issues. Intrinsic water use efficiency (iWUE) an important indicator for understanding ecosystem adaptability change enrichment. In this study, tree-ring width, stable carbon isotope ratio (?13C), iWUE P. tabulaeformis Carr. were established. Climate response analysis showed temperature was the main limiting factor affecting radial relative humidity significantly affected fractionation rings. During 1645–2011, increased by 27.1%. responses factors atmospheric concentrations (Ca) long-term variation Ca, which could explain 69% variation, causing interannual variation. positive rising as its sequestration capacity increased. enrichment, Ca promoted increases but ultimately failed offset negative impact on study area.