Data from: Precipitation and nitrogen enrichment impact carbon exchange and stability: From antagonism to synergy with increasing shrub encroachment

Shrub encroachment in arid and semi‐arid grasslands is increasing due to
global environmental changes, leading to greater vegetation and soil
heterogeneity that threatens carbon sequestration. Alterations in global
precipitation patterns and nitrogen (N) deposition impact water and
nutrient availability, affecting carbon dynamics in these ecosystems.
Despite this, existing research mainly focuses on traditional steppe
ecosystems, with limited understanding of variations across different
stages of shrub encroachment and within heterogeneous patches.This study
utilized a 4‐year (2020–2023) experimental approach in Inner
Mongolia's shrub‐encroached grasslands, involving water and nitrogen
(N) additions, to investigate carbon exchange parameters (NEE, GEP and ER)
within both shrub and herbaceous patches. It assessed the effects of
increased precipitation and N enrichment on carbon exchange and stability
(resistance, resilience and temporal stability) across different stages of
encroachment (non‐encroached, light, moderate and severe).Water addition
significantly enhanced net ecosystem carbon exchange (NEE) in
shrub‐encroached grasslands, particularly during dry years (2020 and
2022). Although N addition had a minor impact on NEE, its effect varied
with the extent of shrub encroachment. Herbaceous patches were more
responsive to water addition, while shrub patches showed stronger
responses to N addition.The interaction between water and N was modulated
by interannual precipitation variability and the level of shrub
encroachment. Co‐additions of water and N promoted carbon sequestration
during dry years with synergistic effects but exhibited antagonistic
effects during wet and normal years. As shrub encroachment
increased  the impact of water–N interaction on NEE transitioned
from antagonistic to synergistic or additive. Notably, water addition
enhanced drought resistance in shrub patches. Despite greater stability in
shrub patches compared to herbaceous patches, the post-drought resilience
of ecosystem decreased with increasing encroachment intensity. These
findings provide insights into the long‐term impacts of shrub encroachment
on ecosystem stability. Future assessments should consider differential
responses across encroachment stages and heterogeneous patches to better
understand how changes in precipitation and N deposition affect the
structure, function and stability of shrub‐encroached grasslands. This
study offers a novel perspective on the carbon cycling mechanisms in these
ecosystems, informing evaluations of their carbon sequestration potential.