Management practices amplify the effects of N deposition on leaf litter decomposition of the Moso bamboo forest

Abstract

Aims The litter decomposition effects of N deposition in combination with management practices are still unclear. The aims of this study were to test the individual and interactive effects of the two factors on Moso bamboo leaf litter decomposition. Methods The experiment was conducted in Moso bamboo forests over a 24-month period and included three N addition treatments (low N, 30 kg N ha −1 yr −1 ;medium N, 60 kg N ha −1 yr −1 ; and high N, 90 kg N ha −1 yr −1 ) and two management practices (conventional management and intensive management). Results The low-N treatment significantly increased the annual decomposition rate, whereas the high-N treatment significantly decreased the annual decomposition rate (P<0.05). Intensive management alone did not significantly influence decomposition, but it amplified both the positive effects of the low-N treatment and the negative effects of the high-N treatment on litter decomposition. Intensive management weakened the positive effects of N addition on N loss but enhanced the positive effects on P loss during the early stage. Conclusions The effects of increasing N deposition in a plantation ecosystem were altered by the management practices, and these changes should be considered when estimating the biological effects of N deposition at regional and global scales.

Effects of Nitrogen Deposition on Soil Dissolved Organic Carbon and Nitrogen in Moso Bamboo Plantations Strongly Depend on Management Practices

“…The soils are named yellow-red soil and classified as Ferrisols derived from granite [19]. IM practices were conducted in half of the CM Moso bamboo forests since 2001.…”

“…IM practices were conducted in half of the CM Moso bamboo forests since 2001. In September of each year, the IM Moso bamboo forests were fertilized and then plowed to a depth of 0.3 m. The application of the nitrate of S-based compound fertilizer (N-P 2 O 5 -K 2 O: 15%-6%-20%, 450 kg ha −1 ) is equivalent to the annual addition of 67.5 kg N, 11.8 kg P, and 74.7 kg K per hectare [19].…”

“…Detailed information on the experimental design can be found in Song et al [19]. The local background atmospheric N deposition rate is 30-37 kg N ha −1 year −1 , with an average NH 4 + :NO 3 − of 1.28 [23].…”

“…Thus, IM can affect soil organic carbon (SOC) [20], soil microbial biomass [21], and enzyme activities [22], which may affect the soil DOM. Moso bamboo plantations are mainly distributed in subtropical China, which is suffering severe N deposition of 30-37 kg N ha −1 year −1 [19]. Our previous study [21] found that IM and N deposition significantly increased soil MBC but decreased bacterial diversity, and the combination of management practices and N deposition had greater effects on soil microbial biomass and diversity than either practice system or N deposition independently, which may impact soil DOC and DON.…”

“…IM includes the removal of understory weeds, application of fertilizers, and soil tilling [18]. Typically, conventional management (CM) requires the regular harvest of bamboo stems and shoots, without any of the IM practices mentioned [19]. Thus, IM can affect soil organic carbon (SOC) [20], soil microbial biomass [21], and enzyme activities [22], which may affect the soil DOM.…”