Unexpected reduction of soil mesofauna under canopy N deposition in a subtropical forest

2022 ◽  
Vol 504 ◽  
pp. 119738
Author(s):  
Guoliang Xu ◽  
Hongfang Lu ◽  
Jiaen Zhang ◽  
Leilei Shi ◽  
Shiqin Yu ◽  
...  
Keyword(s):  
N Deposition ◽  
Subtropical Forest ◽  
Soil Mesofauna

scholarly journals Responses of soil respiration to elevated carbon dioxide and nitrogen addition in young subtropical forest ecosystems in China

2010 ◽  
Vol 7 (1) ◽  
pp. 315-328 ◽  
Author(s):  
Q. Deng ◽  
G. Zhou ◽  
J. Liu ◽  
S. Liu ◽  
H. Duan ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Elevated Co2 ◽  
Forest Ecosystems ◽  
N Deposition ◽  
Subtropical Forest ◽  
N Addition ◽  
Above Ground Biomass ◽  
Respiration Rates ◽  
Ambient Co2 ◽  
Ambient N Deposition

Abstract. Global climate change in the real world always exhibits simultaneous changes in multiple factors. Prediction of ecosystem responses to multi-factor global changes in a future world strongly relies on our understanding of their interactions. However, it is still unclear how nitrogen (N) deposition and elevated atmospheric carbon dioxide concentration [CO2] would interactively influence forest floor soil respiration in subtropical China. We assessed the main and interactive effects of elevated [CO2] and N addition on soil respiration by growing tree seedlings in ten large open-top chambers under CO2 (ambient CO2 and 700 μmol mol−1) and nitrogen (ambient and 100 kg N ha−1 yr−1) treatments. Soil respiration, soil temperature and soil moisture were measured for 30 months, as well as above-ground biomass, root biomass and soil organic matter (SOM). Results showed that soil respiration displayed strong seasonal patterns with higher values observed in the wet season (April–September) and lower values in the dry season (October–March) in all treatments. Significant exponential relationships between soil respiration rates and soil temperatures, as well as significant linear relationships between soil respiration rates and soil moistures (below 15%) were found. Both CO2 and N treatments significantly affected soil respiration, and there was significant interaction between elevated [CO2] and N addition (p<0.001, p=0.003, and p=0.006, respectively). We also observed that the stimulatory effect of individual elevated [CO2] (about 29% increased) was maintained throughout the experimental period. The positive effect of N addition was found only in 2006 (8.17% increased), and then had been weakened over time. Their combined effect on soil respiration (about 50% increased) was greater than the impact of either one alone. Mean value of annual soil respiration was 5.32 ± 0.08, 4.54 ± 0.10, 3.56 ± 0.03 and 3.53 ± 0.03 kg CO2 m−2 yr−1 in the chambers exposed to elevated [CO2] and high N deposition (CN), elevated [CO2] and ambient N deposition (CC), ambient [CO2] and high N deposition (NN), and ambient [CO2] and ambient N deposition (CK as a control), respectively. Greater above-ground biomass and root biomass was obtained in the CN, CC and NN treatments, and higher soil organic matter was observed only in the CN treatment. In conclusion, the combined effect of elevated [CO2] and N addition on soil respiration was apparent interaction. They should be evaluated in combination in subtropical forest ecosystems in China where the atmospheric CO2 and N deposition have been increasing simultaneously and remarkably.

scholarly journals Different Molecular Characterization of Soil Particulate Fractions under N Deposition in a Subtropical Forest

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 914
Author(s):  
Jing Geng ◽  
Shulan Cheng ◽  
Huajun Fang ◽  
Jie Pei ◽  
Meng Xu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Structure ◽  
Critical Role ◽  
N Deposition ◽  
Subtropical Forest ◽  
Gas Chromatography Mass Spectrometry ◽  
N Addition ◽  
Pyrolysis Gas ◽  
C Cycle ◽  
N Treatment

Key Findings: Combining physical fractionation and pyrolysis–gas chromatography/mass spectrometry (py-GC/MS) technique can help better understand the dynamics of soil organic matter (SOM). Background and Objectives: SOM plays a critical role in the global carbon (C) cycle. However, its complexity remains a challenge in characterizing chemical molecular composition within SOM and under nitrogen (N) deposition. Materials and Methods: Three particulate organic matter (POM) fractions within SOM and under N treatments were studied from perspectives of distributions, C contents and chemical signatures in a subtropical forest. N addition experiment was conducted with two inorganic N forms (NH4Cl and NaNO3) applied at three rates of 0, 40, 120 kg N ha−1 yr−1. Three particle-size fractions (>250 μm, 53–250 μm and <53 μm) were separated by a wet-sieving method. Py-GC/MS technique was used to differentiate between chemical composition. Results: A progressive proportion transfer of mineral-associated organic matter (MAOM) to fine POM under N treatment was found. Only C content in fine POM was sensitive to N addition. Principal component analyses (PCA) showed that the coarse POM had the largest plant-derived markers (lignins, phenols, long-chain n-alkanes, and n-alkenes). Short-chain n-alkanes and n-alkenes, benzofurans, aromatics and polycyclic aromatic hydrocarbons mainly from black carbon prevailed in the fine POM. N compounds and polysaccharides from microbial products dominated in the MAOM. Factor analysis revealed that the degradation extent of three fractions was largely distinct. The difference in chemical structure among three particulate fractions within SOM was larger than treatments between control and N addition. In terms of N treatment impact, the MAOM fraction had fewer benzofurans compounds and was enriched in polysaccharides, indicating comparatively weaker mineralization and stronger stabilization of these substances. Conclusions: Our findings highlight the importance of chemical structure in SOM pools and help to understand the influence of N deposition on SOM transformation.

scholarly journals Contrasting growth responses among plant growth forms to nitrogen fertilization in a subtropical forest in China

2016 ◽  
Author(s):  
Di Tian ◽  
Peng Li ◽  
Wenjing Fang ◽  
Jun Xu ◽  
Yongkai Luo ◽  
...  
Keyword(s):  
Plant Growth ◽  
Tree Growth ◽  
Ground Cover ◽  
N Fertilization ◽  
N Deposition ◽  
Subtropical Forest ◽  
Forest Community ◽  
Growth Forms ◽  
Growth Responses ◽  
Understory Shrubs

Abstract. Atmospheric nitrogen (N) deposition has been a noteworthy aspect of global change. Previous observational studies in temperate and tropical forests have focused on the effects of N deposition on tree growth. Here we asked how trees and other plant growth forms respond to experimental N deposition in a subtropical forest in China. We conducted a four-year N fertilization experiment in a subtropical evergreen forest in southeastern China with three treatment levels applied to 9 20 × 20 m plots and replicated in three blocks. We classified the plants to trees, saplings, shrubs(including tree seedlings) and ground-cover plants (ferns) according to the growth forms, then we measured the absolute and relative basal area increments of trees and saplings, and the aboveground biomass of understory shrubs and ferns. In addition, we grouped individuals of the dominant tree species Castanopsis eyrei into three size classes and analyzed their growth responses to N fertilization separately. Although the total tree growth on plot level did not show a significant response to the N fertilization, the small trees with DBH (diameter at breast height) values of 5–10 cm were hindered by N fertilization, while the growth of large trees with DBH > 10 cm showed neutral or weakly positive responses to N fertilization. Small trees, saplings and particularly understory shrubs and ground-cover ferns suppressed seriously by increasing N fertilization. The proportions of plant mortality in N-fertilized plots were higher than in unfertilized plots and most of the dead individuals were small trees, saplings, shrubs and ferns. N deposition potentially leads to increased growth of larger plant individuals at tree layer in the forest community and suppresses the growth and survival of other individuals at understory and ground-cover layers. Therefore, differences in the growth responses of different plant growth forms and individual sizes should be taken into account when evaluating the effects of N deposition on the functioning of these forest ecosystems, including their potential for carbon storage.

scholarly journals Soil Nitrogen and Sulfur Leaching in a Subtropical Forest at a Transition State under Decreasing Atmospheric Deposition

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1798
Author(s):  
Piaopiao Ke ◽  
Gaoyue Si ◽  
Yao Luo ◽  
Zhenglin Cheng ◽  
Qian Yu ◽  
...  
Keyword(s):  
Transition State ◽  
Soil Layer ◽  
N Deposition ◽  
Subtropical Forest ◽  
N Leaching ◽  
N Saturation ◽  
Subtropical Forests ◽  
Net Flux ◽  
Throughfall Deposition

Anthropogenic emissions of nitrogen- (N) and sulfur (S)-containing pollutants have declined across China in recent years. However, the responses of N and S depositions and dynamics in soil remain unclear in subtropical forests. In this study, the wet and throughfall depositions of dissolved inorganic N (DIN) and SO42− were continuously monitored in a mildly polluted subtropical forest in Southeast China in 2017 and 2018. Moreover, these solutes in soil water along the soil profile were monitored in 2018. Throughfall deposition of DIN and S decreased by 59% and 53% in recent 3 years, respectively, which can be majorly attributed to the decreases in wet depositions of NO3− and SO42−. Meanwhile, NH4+ deposition remained relatively stable at this site. Even though N deposition in 2018 was below the N saturation threshold for subtropical forests, significant N leaching still occurred. Excess export of N occurred in the upper soil layer (0–15 cm), reaching 6.86 ± 1.54 kg N/ha/yr, while the deeper soil (15–30 cm) was net sink of N as 8.29 ± 1.71 kg N/ha/yr. Similarly, S was excessively exported from the upper soil with net flux of 14.7 ± 3.15 kg S/ha/yr, while up to 6.37 ± 3.18 kg S/ha/yr of S was retained in the deeper soil. The significant N and S leaching under declined depositions suggested that this site possibly underwent a transition state, recovering from historically high acid deposition. Furthermore, the rainfall intensity remarkably regulated leaching and retention of SO42− and DIN at this site. The impacts of climate changes on N and S dynamics require further long-term monitoring in subtropical forests.

scholarly journals Species Differences in Nitrogen Acquisition in Humid Subtropical Forest Inferred From 15N Natural Abundance and Its Response to Tracer Addition

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 991 ◽  
Author(s):  
Geshere Abdisa Gurmesa ◽  
Xiankai Lu ◽  
Per Gundersen ◽  
Qinggong Mao ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Plant Species ◽  
N Uptake ◽  
N Deposition ◽  
Subtropical Forest ◽  
Species Variation ◽  
N Addition ◽  
Subtropical Forests ◽  
The Impact ◽  
N Acquisition ◽  
Leaf N

Differences in nitrogen (N) acquisition patterns between plant species are often reflected in the natural 15N isotope ratios (δ15N) of the plant tissues, however, such differences are poorly understood for co-occurring plants in tropical and subtropical forests. To evaluate species variation in N acquisition traits, we measured leaf N concentration (%N) and δ15N in tree and understory plant species under ambient N deposition (control) and after a decade of N addition at 50 kg N ha−1 yr−1 (N-plots) in an old-growth subtropical forest in southern China. We also measured changes in leaf δ15N after one-year of 15N addition in both the control and N-plots. The results show consistent significant species variation in leaf %N in both control and N-plots, but decadal N addition did not significantly affect leaf %N. Leaf δ15N values were also significantly different among the plant species both in tree and understory layers, and both in control and N-plots, suggesting differences in N acquisition strategies such as variation in N sources and dominant forms of N uptake and dependence on mycorrhizal associations among the co-occurring plant species. Significant differences between the plant species (in both control and N-plots) in changes in leaf δ15N after 15N addition were observed only in the understory plants, indicating difference in access (or use) of deposited N among the plants. Decadal N addition had species-dependent effects on leaf δ15N, suggesting the N acquisition patterns of these plant species are differently affected by N deposition. These results suggest that co-occurring plants in N-rich and subtropical forests vary in their N acquisition traits; these differences need to be accounted for when evaluating the impact of N deposition on N cycling in these ecosystems.

scholarly journals Physical protection by soil aggregates stabilizes soil organic carbon under simulated N deposition in a subtropical forest of China

Geoderma ◽  
2017 ◽  
Vol 285 ◽  
pp. 323-332 ◽  
Author(s):  
Xiao-lan Zhong ◽  
Jiang-tao Li ◽  
Xiao-jia Li ◽  
Yong-chang Ye ◽  
Song-song Liu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Aggregates ◽  
N Deposition ◽  
Subtropical Forest ◽  
Physical Protection

Evaluating P availability influenced by warming and N deposition in a subtropical forest soil: a bioassay mesocosm experiment

2019 ◽  
Vol 444 (1-2) ◽  
pp. 87-99
Author(s):  
Liuming Yang ◽  
Zhijie Yang ◽  
Yuanzhen Peng ◽  
Yanyu Lin ◽  
Decheng Xiong ◽  
...  
Keyword(s):  
Forest Soil ◽  
N Deposition ◽  
Subtropical Forest ◽  
Mesocosm Experiment ◽  
P Availability

scholarly journals High abundance of ammonia-oxidizing archaea in acidified subtropical forest soils in southern China after long-term N deposition

2012 ◽  
Vol 80 (1) ◽  
pp. 193-203 ◽  
Author(s):  
Kazuo Isobe ◽  
Keisuke Koba ◽  
Yuichi Suwa ◽  
Junko Ikutani ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Forest Soils ◽  
Southern China ◽  
N Deposition ◽  
Subtropical Forest ◽  
High Abundance ◽  
Ammonia Oxidizing Archaea

scholarly journals Topography modulates effects of nitrogen deposition on microbial resource limitation in a nitrogen-saturated subtropical forest

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hao Chen ◽  
Junjie Tang ◽  
Xibin Sun ◽  
Kayan Ma ◽  
Huaihai Chen ◽  
...  
Keyword(s):  
Resource Limitation ◽  
N Deposition ◽  
Subtropical Forest ◽  
N Saturation ◽  
N Addition ◽  
Microbial Decomposition ◽  
Organic C ◽  
Soil Microbial ◽  
N Limitation ◽  
P Limitation

Abstract Background Nitrogen (N) saturation theory proposes that an ecosystem might switch from N limitation to carbon (C), phosphorus (P), or other nutrient limitations if it receives continuous N input. Yet, after N limitation is removed, which nutrient is the most limited and whether topography modulates such change is rarely tested at a microbial level. Here, we conducted a two-year N addition experiment under two different topography positions (i.e. a slope and a valley) in a N-saturated subtropical forest. Soil enzyme activity was measured, and ecoenzymatic stoichiometry indexes were calculated as indicators of microbial resource limitation. Results In the valley, two-year N addition changed the activity of all studied enzymes to various degrees. As a result, microbial C limitation was aggravated in the valley, and consequently microbial decomposition of soil labile organic C increased, but microbial P limitation was alleviated due to the stoichiometry balance. On the slope, however, N addition did not significantly change the activity of the studied enzymes, and did not alter the status of microbial resource limitation. Conclusions These results indicate that C is a more limited element for microbial growth than P after removing N limitation, but we also highlight that topography can regulate the effect of N deposition on soil microbial resource limitation in subtropical forests. These findings provide useful supplements to the N saturation theory.

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