3Wassen M J, Venterink H G M O, De Swart E O A M, et al. Nutrient concentrations in mire vegetation as a measure of nutrient limitation in mire ecosystems[J]. Journal of Vegetation Science, 1995,6(1): 5-16.
4Koerselman W, Meuleman A F M. The vegetation N:P ratio: A new tool to detect the nature of nutrient limitation[J]. Journal of Applied Ecology, 1996, 33(6): 1 441-1 450.