Jianhua Zhang1, He Li2, Hufang Zhang1, Hong Zhang3, Zhiyao Tang4. 1. Department of Biology, Xinzhou Teachers University, Xinzhou, China. 2. Department of Geographical Sciences, School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou, China. 3. College of Environment and Resource, Shanxi University, Taiyuan, China. 4. Department of Ecology, College of Urban and Environmental Sciences, and Key Lab for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China.
Abstract
Plant litter decomposition is a crucial ecosystem process that regulates nutrient cycling, soil fertility, and plant productivity and is strongly influenced by increased nitrogen (N) deposition. However, the effects of exogenous N input on litter decomposition are still poorly understood, especially in temperate shrublands, which hinders predictions of soil C and nutrient dynamics under the context of global change. Temperate shrub ecosystems are usually N-limited and particularly sensitive to changes in exogenous N input. To investigate the responses of Vitex negundo and Spiraea trilobata litter decomposition to N addition, we conducted a field experiment in Vitex- and Spiraea-dominated shrublands located on Mt. Dongling in Beijing, North China. Four N treatment levels were applied: control (N0; no N addition), low N (N1; 20 kg⋅N⋅ha-1⋅year-1), moderate N (N2; 50 kg⋅N⋅ha-1⋅year-1), and high N (N3; 100 kg⋅N⋅ha-1⋅year-1). The litter decomposition in V. negundo was faster than that in S. trilobata, which may be due to the differences in their nutrient content and C/N ratio. N addition increased the amount of remaining N in the two litter types but had no effect on the remaining mass, C, or P. Nitrogen treatment did not affect the litter decomposition rates (k) of either litter type; i.e., N addition had no effect on litter decomposition in temperate shrublands. The neutral effect of N addition on litter decomposition may be primarily explained by the low temperatures and P limitation at the site as well as the opposing effects of the exogenous inorganic N, whereby exogenous N inhibits lignin degradation but promotes the decomposition of readily decomposed litter components. These results suggest that short-term N deposition may have a significant impact on N cycling but not C or P cycling in such shrub ecosystems.
class="Chemical">Plant litter decomclass="Chemical">position is a crucial ecosystem class="Chemical">process that regulates nutrient cycling, soil fertility, and class="Chemical">plant class="Chemical">productivity and is strongly influenced by increased class="Chemical">pan class="Chemical">nitrogen (N) deposition. However, the effects of exogenous N input on litter decomposition are still poorly understood, especially in temperate shrublands, which hinders predictions of soil C and nutrient dynamics under the context of global change. Temperate shrub ecosystems are usually N-limited and particularly sensitive to changes in exogenous N input. To investigate the responses of Vitex negundo and Spiraea trilobata litter decomposition to N addition, we conducted a field experiment in Vitex- and Spiraea-dominated shrublands located on Mt. Dongling in Beijing, North China. Four N treatment levels were applied: control (N0; no N addition), low N (N1; 20 kg⋅N⋅ha-1⋅year-1), moderate N (N2; 50 kg⋅N⋅ha-1⋅year-1), and high N (N3; 100 kg⋅N⋅ha-1⋅year-1). The litter decomposition in V. negundo was faster than that in S. trilobata, which may be due to the differences in their nutrient content and C/N ratio. N addition increased the amount of remaining N in the two litter types but had no effect on the remaining mass, C, or P. Nitrogen treatment did not affect the litter decomposition rates (k) of either litter type; i.e., N addition had no effect on litter decomposition in temperate shrublands. The neutral effect of N addition on litter decomposition may be primarily explained by the low temperatures and P limitation at the site as well as the opposing effects of the exogenous inorganic N, whereby exogenous N inhibits lignin degradation but promotes the decomposition of readily decomposed litter components. These results suggest that short-term N deposition may have a significant impact on N cycling but not C or P cycling in such shrub ecosystems.
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