Response of carbon and nitrogen release to simulated nitrogen deposition in

natural evergreen broad-leaved forests in a rainy area in Western China

Shixing Zhou, Congde Huang ⁎, Yuanbin Xiang, Yongxiang Xiao, Jiandong Tang, Bohan Han, Chao Luo

College of Forestry, Sichuan Agricultural University, Chengdu 611130, China

Abstract Over the last several decades, human activities have increased the nitrogen input in terrestrial ecosystem, and the alteration of the N cycle has profoundly affected the cycles of many other elements, especially carbon (C). Litter decomposition is an important ecosystemprocess that plays a key role in the balance of global carbon and nitrogen cycles. To investigate the effects of simulated nitrogen (N) deposition on litter decomposition, a one-year field experiment on litter decomposition following N addition treatments was conducted in a natural evergreen broad-leaved forest in a rainy area of Western China. Beginning November 2013, we conducted a field experiment using the litterbagmethod that included four treatments: 0, 50, 150, and 300 kg N hm−2 a−1 as the control (CK), low(L), medium(M), and high (H) nitrogen deposition, respectively. Every 15 days, NH4NO3 was added to the N-treated plots. The results indicated that after one year of decomposition, the remaining rate in each treatment was between 54.71% and 63.52%, L, M, and H rates were 4.18%, 6.53%, and 8.81% higher, respectively than the CK. N deposition significantly increased the remaining rate and inhibited the decomposition of leaf litter in this ecosystembecause of the addition of N. Greater increases in N strengthened the inhibition effect. N addition significantly increased the concentration of carbon and nitrogen in leaf litter. The decomposition coefficient of C and Nwere in the order k(CK) N k(L) N k(M) N k(H), although Nwas released faster. The time for 95% C decomposition of foliar litter increased by 0.92–2.20 a from4.09 a (T95% of CK) because of N addition, and that for N decomposition increased by 0.64–1.22 a from3.73 a. After decomposing for 1 a, the C remaining rates for L, M, and H were 6.00%, 9.89%, and 14.11%, respectively, higher than CK, whereas the N remaining rate was 4.13%, 6.75% and 10.08%, respectively. Thus, nitrogen addition significantly increased the C and N remaining rates and significantly inhibited the release of carbon and nitrogen. The L, M, andHtreatments increased the C/Nratio of the leaf litter by 3.33%, 5.40% and 6.38%, respectively, suggesting that theMandH treatments significantly increased the C/N ratio. Nitrogen treatments weakened the correlation between the mass remaining and C and N remaining, but strengthened the correlation between mass remaining and the C/N ratio. The correlation coefficient of mass remaining and C and N remaining was reduced by N deposition, whereas the C/N ratio was increased. Under simulated N deposition, C remaining was still a good indicator of litter decomposition relative to theN remaining and C/N ratio.

Keywords Litter decomposition; N deposition; C release; N release; Rainy area of Western China; Natural evergreen broad-leaved forest

http://dx.doi.org/10.1016/j.chnaes.2017.02.013

https://www.researchgate.net/publication/318348376_Response_of_carbon_and_nitrogen_release_to_simulated_nitrogen_deposition_in_natural_evergreen_broad-leaved_forests_in_a_rainy_area_in_Western_China