Responses of woody and grassland ecosystems to increased carbon dioxide as water supply varies

This publication contains data used to explore how woody and grassland ecosystems respond to interactions of elevated carbon dioxide concentration (eCO₂) manipulated by experiments and water supply. This study included data, collected between 1989 and 2016, from 14 long-term ecosystem-scale CO₂ experiments in the United States, Switzerland, and Australia. Data include annual measurements of aboveground net primary productivity (ANPP) under ambient CO2 concentration (ANPPa) and under higher CO2 treatments (ANPPe), enhancement ratio (EAPP = ANPPe/ANPPa), annual precipitation, growing season precipitation, mean annual temperatures, leaf area indices, enhancement ratios of LAI (ELAI), mean precipitation of the site (MAP), mean enhancement ratio of the site (EANPPAV), enhancement ratios (EAPP) of C3 and C4 plants, enhancement ratios after adjusting experimental CO2 levels to 550 ppm, and modeling results of the Farquhar model. Some of above data are directly accessible from the journal website, others are archived in this package.
Free-air CO₂ enrichment (FACE) experiments and open-top chamber (OTC) systems have been used for many years to investigate in situ responses of intact plant communities to eCO₂ at ecosystem scales. Published results indicate that, for a ~50% increase in CO₂ concentration to ~560 ppm, aboveground net primary productivity (ANPP) and total net primary productivity `(NPP) in forests increase on average by ~25%. In contrast, results from grassland experiments show that growth responses to eCO₂ (~650 ppm) are somewhat less than in forests, with increases in ANPP ranging from 11% to 17%. Across all forest and grassland experiments, stomatal conductance consistently decreased and instantaneous water-use efficiency (WUE) increased by 4% to 44%. However, leaf-level changes did not always lead to ecosystem-scale reductions in total water use or increases in soil moisture because of additional transpiration from increased leaf areas. Although CO₂ fertilization might be expected to have a greater effect in xeric ecosystems and in drier conditions where and when the benefits of increased WUE are potentially stronger, evidence from enrichment studies is conflicting. Inconsistencies in eCO₂ responses of plants to water availability may reflect variation in other factors, such as soil nutrient availability, light limitation, or indirect effects of eCO₂ on leaf area index(LAI) via changes of carbon allocation and soil water. Leaf and root structures and mechanisms for acquiring CO₂, water, light, and nutrients vary for different plant life-forms, which may also contribute to differences in eCO₂ responses to water availability. The purpose of this study was to investigate mechanisms underpinning such inconsistencies.
For more information about this study and these data see Pan et al. (2022), which also includes a full description of the original data Supplementary Tables 1-4. Data published on 01/13/2022. Minor metadata updates made on 05/07/2024, which included updating all references from "Center Plains Experimental Range" to the correct name "Central Plains Experimental Range".