Nitrogen loading increases the ozone sensitivity of larch seedlings with higher sensitivity to nitrogen loading

Sci Total Environ. 2019 May 1:663:587-595. doi: 10.1016/j.scitotenv.2019.01.292. Epub 2019 Jan 24.

Abstract

Larch (Larix sp.) tree is a critical species for the future afforestation in Northeast Asia. The impacts of elevated concentrations of ground-level ozone (O3) and nitrogen (N) deposition are raising concerns. However, knowledge of the combined effects of elevated O3 and N loading are still limited. We investigated whether nitrogen loading mitigates the negative impacts of ozone on two larch species: the Japanese larch (L. kaempferi) and its hybrid larch F1 (L. gmelinii var. japonica × L. kaempferi) or not. We used open-top cambers and compared responses of the larch seedlings. Results showed the N loading mitigated the negative effects of O3 on Japanese larch. However, in hybrid larch F1, N loading did not mitigate O3-induced inhibition of growth and photosynthetic capacity. Mitigation effect of N loading on negative O3 impacts may vary between the two Larix spp., Hybrid larch F1 could be more affected by the combined effects of O3 and N loading due to its higher growth response to N loading. Elevated O3 also reduced leaf nitrogen/phosphorus (N/P) ratio by elevated O3, with significant effects in hybrid larch F1, particularly under N loading. In the present study, leaf N/P ratio was utilized to validate the hypothesis that a positive effect of N loading may be observed if O3 does not induce P limitation in Larix spp. We demonstrated a potential leaf N/P ratio function, which could reflect responses to O3 and N loading in hybrid larch F1.

Keywords: Hybrid larch F(1); Interspecific difference; Larix kaempferi; Nitrogen loading; Nitrogen phosphorus ratio; Ozone sensitivity.

MeSH terms

  • Air Pollutants / adverse effects*
  • Larix / drug effects*
  • Larix / growth & development
  • Nitrogen / adverse effects*
  • Ozone / adverse effects*
  • Seedlings / drug effects
  • Seedlings / growth & development

Substances

  • Air Pollutants
  • Ozone
  • Nitrogen