Patterns of plant carbon, nitrogen, and phosphorus concentration in relation to productivity in China's terrestrial ecosystems
Significance Estimates of nutrient allocation in different plant tissues and the relationships between the nutrient contents and photosynthetic capacity are critical to predicting ecosystem carbon sequestration under global change. Here, we provide an assessment of large scale patterns of community level nitrogen and phosphorus concentrations in different plant tissues and then examine how nutrient allocations are coupled with plant productivity. The results show that nutrient concentrations in leaves are less responsive to abiotic environments than those in woody stems and roots (stable leaf nutrient concentration hypothesis) the relationships between vegetation primary productivity and leaf nutrient contents are stronger when less nutrients are allocated to the woody tissues (productivity nutrient allocation hypothesis) and are stronger in deciduous than in evergreen vegetation (productivity leaf lifespan hypothesis) Plant nitrogen (N) and phosphorus (P) content regulate productivity and carbon (C) sequestration in terrestrial ecosystems. Estimates of the allocation of N and P content in plant tissues and the relationship between nutrient content and photosynthetic capacity are critical to predicting future ecosystem C sequestration under global change. In this study, by investigating the nutrient concentrations of plant leaves, stems, and roots across China's terrestrial biomes, we document large scale patterns of community level concentrations of C, N, and P. We also examine the possible correlation between nutrient content and plant production as indicated by vegetation gross primary productivity (GPP) The nationally averaged community concentrations of C, N, and P were 436.8, 14.14, and 1.11 mg*g 1 for leaves; 448.3, 3.04 and 0.31 mg*g 1 for stems; and 418.2, 4.85, and 0.47 mg*g 1 for roots, respectively. The nationally averaged leaf N and P productivity was 249.5 g C GPP*g 1 N*y 1 and 3,157.9 g C GPP*g 1 P*y 1, respectively. The N and P concentrations in stems and roots were generally more sensitive to the abiotic environment than those in leaves. There were strong power law relationships between N (or P) content in different tissues for all biomes, which were closely coupled with vegetation GPP. These findings not only provide key parameters to develop empirical models to scale the responses of plants to global change from a single tissue to the whole community but also offer large scale evidence of biome dependent regulation of C sequestration by nutrients.
Proceedings of the National Academy of Sciences