The interaction model of lake ice, GPP and environmental factors on the QTP. (a) represents for spearman correlation analysis of lake ice, GPP, meteorological factors, and physical and chemical factors; (b)–(d) represent lake GPP and CO₂ exchange patterns on the QTP under different lake ice cover statuses ((b) where lakes are completely covered by ice; (c) where lake ice calving appears prior to melting; (d) where lake ice has completely melted; red arrows represent gas emissions; black arrows represent gas consumption).