A Global Meta-analysis Reveals that Nitrogen Addition Alters Plant Nutrient Concentration and Resorption in Grassland Ecosystems

• Published in: Journal of soil science and plant nutrition 2022-12, Vol.22 (4), p.4960-4971
• Main Authors: Hu, Wanjia, Yuan, Zhiyou, Shi, Xinrong, Lock, Thomas Ryan, Kallenbach, Robert L.
• Format: Article
• Language: English
• Subjects: Agriculture; Biomedical and Life Sciences; Climate change; Ecology; Ecosystems; Efficiency; Environment; Experiments; Functional groups; Grasslands; Humidity; Leaves; Life Sciences; Meta-analysis; Nitrogen; Nitrogen enrichment; Nutrient concentrations; Nutrient cycles; Nutrient resorption; Nutrients; Original Paper; Plant growth; Plant Sciences; Soil Science & Conservation; Terrestrial ecosystems
• ISSN: 0718-9508; 0718-9516
• DOI: 10.1007/s42729-022-00973-y

Knowledge of plant nutrient strategies is crucial for defining and predicting the patterns and mechanisms resulting from nitrogen (N) deposition. However, the impacts of N enrichment on plant nutrient strategies are unclear in global grasslands. We conducted a meta-analysis of 127 publications to synthesize the pathways underlying the responses of plant nutrient concentration and resorption to N addition across global grassland ecosystems. Our analysis indicated that N addition increased the N concentration in green and senesced leaves, the phosphorus (P) concentration in senesced leaves, and aboveground and belowground biomass by about 32%, 50%, 7%, 74%, and 19%, respectively. Meanwhile, it reduced N resorption efficiency (NRE) and P resorption efficiency (PRE) by about 9% and 6%, respectively. Nitrogen addition did not significantly affect green leaf P concentration. These responses were modulated by N application rates and humidity, and they differed among grassland types, plant groups, fertilizer types, and experimental durations. Nitrogen addition changed the relationship between N and P in green leaves and between NRE and PRE, but it did not alter the N:P ratio in senesced leaves. Our results suggest that N addition affects leaf nutrient concentrations and resorption in global grassland ecosystems, although such effects vary among grassland types and among plant functional groups. Nutrient resorption may be a critical pathway that mediates plant regulation of the coupled N:P balance. Changes in humidity due to climate change also mediate the response of plant nutrients to N addition and thereby affect the soil–plant nutrient cycles of grassland ecosystems under future N enrichment.