Vegetos

Abstract

Nutrient depletion is one of the main limiting factors for plant growth and distribution in coastal sand dunes in southeast of China. In order to evaluate the adaptability of different tree species to the infertile environment of coastal sand dunes, we investigated the seasonal dynamics of leaf and litter stoichiometry for five tree species (including Casuarina equisetifolia, Acacia crassicarpa, Pinus elliottii, Eucalyptus grandis × E. urophylla, and Litsea glutinosa) on the coastal sand dunes in southern subtropical China. Results show that the leaf and litter carbon (C), nitrogen (N) and phosphorus (P) contents and C: N, C: P, N: P ratios of different tree species exhibited large variations. The mean leaf C, N and P content of different tree species were 465–508, 13.1–42.3 and 0.6–3.1 g kg⁻¹, respectively. The mean litter C, N and P content were 424–520, 7.7–21.8 and 0.1–1.2 g kg-1, respectively. The mean leaf C: N, C: P and N: P ratios were 11.4–37.5, 255–887 and 18.9–38.4, respectively. The mean litter C: N, C: P and N: P ratios were 19.6–68, 471–4779 and 24.0–117.2, respectively. The mean N and P resorption rates of the five tree species ranged from 25–54.4% and 52–78.1%, respectively, the mean N resorption rate of nitrogen fixation trees was lower than that of non-nitrogen fixation trees, while its P resorption rate was higher. The nutrient limitation of five tree species varied in different seasons, briefly, the Eucalyptus grandis × Eucalyptus urophylla was under nitrogen limitation in spring and phosphorus limitation in autumn, while A cacia crassicarpa and Casuarina equisetifolia were under phosphorus limitation across all seasons. Pinus elliottii was under nitrogen and phosphorus colimitation in spring, nitrogen limitation in summer, and phosphorus limitation in autumn and winter. Litsea glutinosa was under nitrogen limitation in spring, nitrogen and phosphorus limitation in summer, and phosphorus limitation in autumn and winter. The leaf C: N and C: P ratios of different tree species were mainly affected by N and P contents, and the dynamic changes in N: P ratio was mainly affected by P content. The results indicate that different tree species grown on coastal sand dunes can take different nutrition utilization strategies during the growth process to adapt to the infertile environment of coastal sand dunes.