Carbon, nitrogen and phosphorus stoichiometry of five common herbaceous species across islands in the Yellow Sea and the East China Sea

Understanding variation of carbon (C), nitrogen (N) and phosphorus (P) stoichiometry in common plant species across islands along a latitude gradient is insightful to reveal the adaptation strategies of plant species to environmental changes. Five common herbaceous species including Artemisia argyi, Setaira viridis, Humulus japonicus, Ophiopog onjaponicus, and Oxalis corniculata were sampled in 125 plots across nine islands in Eastern China. C, N and P contents in leaves, stems, and roots of five plant species were measured, and their relationships with soil C, N and P contents as well as mean annual air temperature (MAT) and mean annual precipitation (MAP) were investigated. The results showed that the range of C, N and P contents in aboveground parts of five species across nine islands was 352.16-518.16, 10.81-34.43, 0.58-2.38 mg•g^-1, while the range of C:N, N:P and C:P was 11.98-38.99, 4.67-27.47, 133.39-748.54, respectively. In terms of roots, the range of C, N and P contents of five species was 312.28-493.34, 9.26-23.27, 0.40-2.10 mg•g^-1, while the range of C:N, N:P and C:P was 18.18-46.79, 8.53-37.38, 174.45-1120.40, respectively. With the increases of latitude, contents of N and P in aboveground parts increased, but N:P decreased. Relative to N content, P content showed higher variation and was largely dependent on environment. Climate factors explained 60% of the variation of N and P contents and N:P across nine islands. In contrast, N and P contents and N:P of roots were independent of latitude, with climatic factors only explained 6%-10% of their variations. The contribution of climatic factors and soil nutrients contributed to the variations of N and P contents differed between above ground parts and roots of five species. Soil N and P had significant effects on P content in roots. Soil P content was positively correlated to aboveground P content. Soil properties explained 37% of the variation in N and P contents of plant roots. Our results suggested that latitude-associated environment shifts were the main drivers of variation in N and P contents and N:P in aboveground parts, and soil nutrients especially affected variation in P in roots of five common plant species, when the effects of plant phylogeny was controlled.