Nutrient Elements in Leaves of Rare and Endangered Species in Wuhan Botanical Garden,China

Characteristics of mineral elements in plants are often strongly influenced by species' abundance and heterogeneous habitats. Therefore, nutrient analysis, after excluding interference of habitat heterogeneity, would directly reflect genetic traits of species in the community. From another aspect, knowledge of responses of species to environmental variation would be helpful in the management of natural and man-made ecosystems, especially those containing rare and endangered plants conserved in gardens. We studied the characteristics of twelve nutrient elements in 90 species in Wuhan Botanical Garden (WBG) and provided explanations of their survival status.

Concentrations of the 12 nutrients in the artificial garden were consistent with those in other natural communities in the subtropical zone of China. Features of nutrient-limited at the community level were also consistent with the regional characteristics (N:P ratio being 9.79 ± 3.22, as exhibiting N-limited). The Ca + Mg concentrations differed between evergreen and deciduous species. The 90 species were clustered into various functional nutrition groups.

The artificial community of the garden was a “sick” one relative to natural ones with wholesome ecological functions. The proportion of element-pairs with significant correlations (P < 0.01 or P < 0.05) to total element-pairs was only 24.2%, being lower than that of species in the natural community, This suggests that the harmonious relationship among nutrient elements in these species was yet to be achieved. Correlation analysis between survival status of the 90 species and their foliar nutrient ratios were positive for nitrogen (N), phosphorus (P), potassium (K), iron (Fe), zinc (Zn), copper (Cu), and sodium (Na), but negative for calcium (Ca), magnesium (Mg), manganese (Mn), and aluminum (Al). Cluster analysis suggested that, among 23 species with the poorest survival status, 21 species had higher Ca and Mg, but lower N and P concentrations.