Leaf nitrogen and phosphorus are more coupled in legumes than in non-legumes, globally

Despite nitrogen (N) and phosphorus (P) being biologically coupled and controlling many biochemical reactions, few studies have examined the N: P patterns and controls of legumes and non-legumes at a global scale. Herein, we explored how the ratio of N and P in legumes and non-legumes responds to environmental factors, globally. Our results indicated that legumes exhibit stronger N-P coupling (R² = 0.39, P < 0.0001) in warm-humid environments (mean precipitation: 988.94 mm, temperature: 12.63 °C), and the N:P is negatively affected by the soil total P (scored at = –0.25). In contrast, non-legumes are more flexible in N and P (R2 = 0.23, P < 0.0001) in semihumid regions (precipitation = 785.01 mm, temperature = 8.85 ℃), where soil total N (scored at = –0.22) and biodiversity (scored at = 0.16) emerge as dominant drivers for the N:P. Although legumes are expected to be more soil P-limited, our findings reveal that the leaf N and P are more coupled in legumes than in non-legumes, which offers a unique perspective on resource utilization and survival strategies in different plant functions.