Effects of long-term nitrogen addition on fine root dynamics in a temperate natural secondary forest

ABSTRACT

In order to study the response of fine root production (FRP), mortality (FRM) and turnover (FRT) to nitrogen (N) addition, we have conducted 12 years of continuous N addition experiments in the natural secondary forest in Northeast China. According to the local N deposition, three N treatments were set up. The response of FRP, FRM and FRT to N addition during the growing season was studied. The results showed that N addition would lead to phosphorus (P) limitation, and fine roots could increase the absorption of N and P by increasing their diameter. The increase in the diameter of fine roots led to a decrease in the FRT, and the soil layer also affected the FRT. Nitrogen addition increased the FRP and FRM in all soil layers. Nitrogen addition did not change the seasonal variation of FRP and FRM. The highest value of FRP occurred in May, and the lowest value of FRM occurred in August. Nitrogen addition increased the total number (TNLR) and surface area (TSALR) of live fine root in all soil layers. The TNLR and TSALR decreased with the deepening of soil layer. Collectively, fine roots may respond to environmental stress through self-regulation and changing growth strategies.

KEYWORDS:

• Fine root
• fine root dynamics
• nitrogen deposition
• temperate natural secondary forest

Acknowledgements

We gratefully acknowledge Professor Yuanxing Wang from Lushuihe Forestry Bureau, Jilin Province, China, for his advice about field experiment design and suggestions on an earlier draft of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

QW designed the study, got grants from the foundation, supervised data collection and edited the manuscript. YX and GL contributed equally to this work. QW, YX, GL, LL, GY and BH contributed to the whole manuscript preparation and designed and wrote the main manuscript text. QW, YX, GL, LL, GY and BH prepared all Figures, GL, YX, GY, BH, LL and QW prepared field experiments, prepared tables and collected literatures. All authors reviewed the manuscript.

Data availability statement

Data are available from the corresponding author on reasonable request.

Additional information

Funding

This research was supported by grants from the National Natural Science Foundation of China [42230703, 41575137, 41773075].