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

Area of Science:

• Forest ecology
• Environmental science
• Plant physiology

Background:

• Larch species are vital for Northeast Asian afforestation.
• Rising ground-level ozone (O3) and nitrogen (N) deposition pose threats.
• Combined effects of O3 and N on larch are not well understood.

Purpose of the Study:

• To investigate if nitrogen loading mitigates ozone's negative impacts on Japanese larch and hybrid larch F1.
• To compare the responses of two larch species to combined O3 and N loading.
• To analyze the role of leaf nitrogen/phosphorus (N/P) ratio in mediating these effects.

Main Methods:

• Utilized open-top chambers to simulate environmental conditions.
• Compared the growth and photosynthetic capacity of larch seedlings under different treatments.
• Measured leaf N/P ratios to assess nutrient limitations.

Main Results:

• Nitrogen loading mitigated ozone's negative effects on Japanese larch.
• Hybrid larch F1 showed no mitigation; ozone inhibited growth and photosynthesis, exacerbated by N loading.
• Elevated ozone reduced leaf N/P ratios, especially in hybrid larch F1 under N loading.

Conclusions:

• Nitrogen's mitigation effect on ozone damage varies between larch species.
• Hybrid larch F1 may be more vulnerable to combined O3 and N loading.
• Leaf N/P ratio can indicate nutrient limitations and responses to O3 and N loading in larch.