Reducing nitrogen inputs mitigate <i>Spartina</i> invasion in the Yangtze estuary

This dataset includes data obtained from landscape-scale surveys and three field experiments. To explore how N reductions contributed to native community recovery in estuarine marshes degraded by plant invasions. Using ongoing, landscape-scale N reductions in the Yangtze River, we conducted landscape-scale surveys to determine the responses of Phragmites australis patches in their density (no. km-2) and size (m2 per patch) in Spartina alterniflora-invaded marshes before and after reducing N inputs in the Yangtze estuary from 2009 to 2020 using satellite images. To uncover the mechanisms driving this temporal response of P. australis patches, we investigated how the growth performances (maximum NDVI) of S. alterniflora and P. australis responded to decreased N inputs at landscape scales. We then validated the growth dynamics (aboveground biomass, g/m2) of both species in the ambient plots of the SINE experiment after reducing N inputs. Furthermore, we determined how the competitive impacts (dominance as represented by aboveground biomass ratio in the mixed stands) of S. alterniflora on P. australis responded to reduced N conditions by transplanting previously N-fertilized and unfertilized S. alterniflora from the SINE experiment into plots with ambient and enriched N conditions and co-planting it with P. australis. Lastly, we used the framework of modern coexistence theory to characterize the changes in competitive outcomes between S. alterniflora and P. australis by evaluating niche and relative fitness differences under ambient and enriched N conditions in existing P. australis patches in the S. alterniflora-invaded marshes.