Effects of thinning on nitrogen status of a larch plantation, illustrated by ¹⁵N natural abundance and N resorption

ABSTRACT

Larch (Larix spp.) is widely distributed in the boreal and temperate areas. Nitrogen (N) is considered as the major limiting element for these areas. Thinning is a common forest management practice. Thus, it is imperative to obtain a better understanding on how thinning could affect N status of larch plantations, and thus optimize the thinning intensity for sustainable forest management. In this study, we measured N concentrations and ¹⁵N natural abundance (δ¹⁵N) of needles and surface soil (0–10 cm) in a larch plantation with T0, T25 and T50 treatments (0%, 25% and 50% thinning intensities, respectively) in Northeast China. We found that needle and soil δ¹⁵N in T25 was the lowest, and the highest in T50. No significant differences were observed for needle and soil N concentrations among the thinning intensities. T25 exhibited the highest N resorption efficiency, indicating highest N use efficiency. Overall, N cycling in T25 was more closed than the control, and with lower soil N availability, while N cycling in T50 was more opened. Our study indicates that foliar ¹⁵N natural abundance is sensitive to thinning and can be potentially used to optimize thinning intensity from the perspective of N cycling.

KEYWORDS:

• Larix spp
• thinning
• nitrogen cycling
• ¹⁵N natural abundance
• plant–soil interaction

Acknowledgments

We thank Dr Lining Song, Dr Yirong Sun and Mr Ang Wang for their helpful suggestions on the earlier version of this manuscript. We also thank Ms Brittany DiRienzo and Dr Geoff Wang from Clemson University, USA for their English edition on our manuscirpt.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the National Basic Research Program of China (973 Program) [grant number 2012CB416906] and the National Natural Science Foundation of China [grant number 41371511].