scholarly journals Input and output of dissolved organic and inorganic nitrogen in subtropical forests of South China under high air pollution

2007 ◽  
Vol 4 (6) ◽  
pp. 4135-4171 ◽  
Author(s):  
Y. T. Fang ◽  
P. Gundersen ◽  
J. M. Mo ◽  
W. X. Zhu
Keyword(s):  
Air Pollution ◽  
South China ◽  
N Deposition ◽  
Organic N ◽  
N Leaching ◽  
Minor Importance ◽  
Old Growth ◽  
Subtropical Forests ◽  
N Retention ◽  
Old Growth Forest

Abstract. The nitrogen (N) emissions to the atmosphere and are thereby N deposition to forest ecosystems increasing rapidly in Southeast Asia, but little is known about the fate and effects elevated N deposition in warm and humid forests. Here we report the concentrations and fluxes of dissolved inorganic (DIN) and organic N (DON) in precipitation, throughfall, surface runoff and soil solution for three subtropical forests in a region of South China under high air pollution, to investigate how deposited N is processed and examined the importance of DON in N budget. The precipitation DIN input was 32–34 kg N ha−1 yr−1. An additional input of 18 kg N ha−1 yr−1 as DON was measured in 2005, which to our knowledge is the highest DON flux ever measured in precipitation. Dry deposition was of minor importance at the site. A canopy uptake of DIN was indicated in two young conifer dominated forests (72–85% of DIN input reached the floor in throughfall), whereas no uptake occurred in an old-growth broadleaf forest. The DON fluxes in throughfall of all forest were similar to that of precipitation. In the young forests DIN was further retained in the soil, but 41–63% of precipitation DIN was still leached. Additionally, about half of the DON input was retained in these forests. The N retention in the two young aggrading forests (21–28 kg N ha−1 yr−1) was in accordance with estimates of N accumulation in biomass and litter accretion. In the old-growth forest, no N retention occurred, but rather a net loss of 8–16 kg N ha−1 yr−1 from the soil was estimated. In total up to 60 kg N ha−1 yr−1 was leached, indicating that this forest was completely N saturated and could not retain additional anthropogenic N inputs. We found that the majority of DIN deposition and DIN leaching simultaneously occurred in the rainy season (March to August) and monthly DIN concentrations and fluxes in leaching were positively related to those in throughfall in all three forests, implying that part of the N leaching was hydrological driven by the abundant precipitation in the monsoon climate at the site. Our results suggest that long-term high N deposition has caused elevated N leaching in all studied forest types although most pronounced in the old-growth forest where wood increment was negligible or even negative. N availability even exceeded the biotic N demand in the young aggrading forests, albeit intensive rain in the growing season is likely to enhance N leaching in these forests.

scholarly journals Input and output of dissolved organic and inorganic nitrogen in subtropical forests of South China under high air pollution

2008 ◽  
Vol 5 (2) ◽  
pp. 339-352 ◽  
Author(s):  
Y. T. Fang ◽  
P. Gundersen ◽  
J. M. Mo ◽  
W. X. Zhu
Keyword(s):  
Air Pollution ◽  
South China ◽  
Forest Ecosystems ◽  
N Deposition ◽  
Organic N ◽  
N Leaching ◽  
Old Growth ◽  
Subtropical Forests ◽  
N Retention ◽  
Old Growth Forest

Abstract. The nitrogen (N) emissions to the atmosphere and N deposition to forest ecosystems are increasing rapidly in Southeast Asia, but little is known about the fates and effects of elevated N deposition in forest ecosystems in this warm and humid region. Here we report the concentrations and fluxes of dissolved inorganic (DIN) and organic N (DON) in precipitation, throughfall, surface runoff and soil solution for three subtropical forests in a region of South China under high air pollution over two years (2004 and 2005), to investigate how deposited N is processed, and to examine the importance of DON in the N budget. The precipitation DIN input was 32–34 kg N ha−1 yr−1. An additional input of 18 kg N ha−1 yr−1 as DON was measured in 2005, which to our knowledge is the highest DON flux ever measured in precipitation. A canopy uptake of DIN was indicated in two young conifer dominated forests (72–85% of DIN input reached the floor in throughfall), whereas no uptake occurred in an old-growth broadleaf forest. The DON fluxes in throughfall were similar to that in precipitation in all forests. In the younger forests, DIN was further retained in the soil, with 41–63% of precipitation DIN leached below the 20-cm soil depth. Additionally, about half of the DON input was retained in these forests. The N retention in two young aggrading forests (21–28 kg N ha−1 yr−1) was in accordance with the estimates of N accumulation in biomass and litter accretion. In the old-growth forest, no N retention occurred, but rather a net loss of 8–16 kg N ha−1 yr−1 from the soil was estimated. In total up to 60 kg N ha−1 yr−1 was leached from the old-growth forest, indicating that this forest was completely N saturated and could not retain additional anthropogenic N inputs. We found that the majority of DIN deposition as well as of DIN leaching occurred in the rainy season (March to August) and that monthly DIN concentrations and fluxes in leaching were positively related to those in throughfall in all three forests, implying that part of the N leaching was hydrologically driven. Our results suggest that long-term high N deposition has caused elevated N leaching in all three forest types although most pronounced in the old-growth forest where wood increment was negligible or even negative. N availability even exceeded the biotic N demand in the young aggrading forests, with intensive rain in the growing season further enhancing N leaching in these forests.

scholarly journals Effects of nitrogen and phosphorus additions on nitrous oxide emission in a nitrogen-rich and two nitrogen-limited tropical forests

2016 ◽  
Vol 13 (11) ◽  
pp. 3503-3517 ◽  
Author(s):  
Mianhai Zheng ◽  
Tao Zhang ◽  
Lei Liu ◽  
Weixing Zhu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Tropical Forests ◽  
N2o Emission ◽  
N Deposition ◽  
Soil N ◽  
N Addition ◽  
Old Growth ◽  
Old Growth Forest ◽  
P Addition ◽  
Stimulation Of

Abstract. Nitrogen (N) deposition is generally considered to increase soil nitrous oxide (N2O) emission in N-rich forests. In many tropical forests, however, elevated N deposition has caused soil N enrichment and further phosphorus (P) deficiency, and the interaction of N and P to control soil N2O emission remains poorly understood, particularly in forests with different soil N status. In this study, we examined the effects of N and P additions on soil N2O emission in an N-rich old-growth forest and two N-limited younger forests (a mixed and a pine forest) in southern China to test the following hypotheses: (1) soil N2O emission is the highest in old-growth forest due to the N-rich soil; (2) N addition increases N2O emission more in the old-growth forest than in the two younger forests; (3) P addition decreases N2O emission more in the old-growth forest than in the two younger forests; and (4) P addition alleviates the stimulation of N2O emission by N addition. The following four treatments were established in each forest: Control, N addition (150 kg N ha−1 yr−1), P addition (150 kg P ha−1 yr−1), and NP addition (150 kg N ha−1 yr−1 plus 150 kg P ha−1 yr−1). From February 2007 to October 2009, monthly quantification of soil N2O emission was performed using static chamber and gas chromatography techniques. Mean N2O emission was shown to be significantly higher in the old-growth forest (13.9 ± 0.7 µg N2O-N m−2 h−1) than in the mixed (9.9 ± 0.4 µg N2O-N m−2 h−1) or pine (10.8 ± 0.5 µg N2O-N m−2 h−1) forests, with no significant difference between the latter two. N addition significantly increased N2O emission in the old-growth forest but not in the two younger forests. However, both P and NP addition had no significant effect on N2O emission in all three forests, suggesting that P addition alleviated the stimulation of N2O emission by N addition in the old-growth forest. Although P fertilization may alleviate the stimulated effects of atmospheric N deposition on N2O emission in N-rich forests, this effect may only occur under high N deposition and/or long-term P addition, and we suggest future investigations to definitively assess this management strategy and the importance of P in regulating N cycles from regional to global scales.

scholarly journals Nitrogen input <sup>15</sup>N-signatures are reflected in plant <sup>15</sup>N natural abundances of sub-tropical forests in China

2016 ◽  
Author(s):  
Geshere Abdisa Gurmesa ◽  
Xiankai Lu ◽  
Per Gundersen ◽  
Yunting Fang ◽  
Qinggong Mao ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Southern China ◽  
Nitrogen Addition ◽  
N Deposition ◽  
Pine Forest ◽  
N Cycling ◽  
N Addition ◽  
Higher Plant ◽  
Old Growth ◽  
Old Growth Forest

Abstract. Natural abundance of 15N (δ15N) in plants and soils can provide integrated information on ecosystem nitrogen (N) cycling, but it has not been well tested in warm and humid sub-tropical forests. In this study, we examined the measurement of δ15N for its ability to assess changes in N cycling due to increased N deposition in an old-growth broadleaved forest and a secondary pine forest in a high N deposition area in southern China. We measured δ15N of inorganic N in input and output fluxes under ambient N deposition, and N concentration (N %) and δ15N of major ecosystem compartments under ambient and after decadal N addition at 50 kg N ha−1 yr−1. Our results showed that the N deposition was δ15N-depleted (−12 ‰) mainly due to high input of depleted NH4&amp;plus;-N. Plant leafs in both forest were also δ15N-depleted (−4 to −6 ‰). The old-growth forest had higher plant and soil N %, and was more 15N-enriched in most ecosystem compartments relative to the pine forest. Nitrogen addition did not significantly affect N % in both forests, indicating that the ecosystem pools are already N-rich. Soil δ15N was not changed significantly by the N addition in both forests. However, the N addition significantly increased the δ15N of plants toward the 15N signature of the added N (~ 0 ‰), indicating incorporation of added N into plants. Thus, plant δ15N was sensitive to ecosystem N input manipulation although N % was unchanged in these N-rich sub-tropical forests. We interpret the depleted δ15N values of plants as an imprint from the high and δ15N-depleted N deposition. The signal from the input (deposition or N addition) may override the enrichment effects of fractionation during the steps of N cycling that are observed in most warm and humid forests. Thus, interpretation of ecosystem δ15N values from high N deposition regions need to include data on the deposition δ15N signal.

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.

The effects of different human disturbance regimes on root fungal diversity ofRhododendron ovatumin subtropical forests of China

2017 ◽  
Vol 47 (5) ◽  
pp. 659-666 ◽  
Author(s):  
Yanhua Zhang ◽  
Jian Ni ◽  
Fangping Tang ◽  
Lifen Jiang ◽  
Tianrong Guo ◽  
...  
Keyword(s):  
Human Disturbance ◽  
Mycorrhizal Fungi ◽  
Fungal Diversity ◽  
High Throughput Sequencing ◽  
Fungal Communities ◽  
Soil Parameters ◽  
Old Growth ◽  
Subtropical Forests ◽  
Old Growth Forest ◽  
Hair Roots

Ericoid mycorrhizal associations are a symbiotic relationship between soil fungi and ericaceous plants. Diversity of fungi associated with hair roots of ericaceous plants may vary as a result of frequent disturbances by human activities. The fungal diversity and communities associated with hair roots of Rhododendron ovatum were investigated along a human disturbance gradient in subtropical forests of China. Nine hundred fungal operational taxonomic units were determined by high-throughput sequencing, including different phyla such as Ascomycota, Basidiomycota, Zygomycota, Chytridiomycota, and Glomeromycota. The dominant phylum in Cunninghamia lanceolata plantations and old-growth forest was Ascomycota, while Basidiomycota was the dominant phylum in secondary forests. The indicator species analyses showed that more pathogenic indicator fungi appeared in the disturbed forests, whereas more putative ericoid mycorrhizal fungi existed in the old-growth forests. Principal component analysis also showed that the fungal communities in the hair roots of R. ovatum were distinct between natural forests and plantations, suggesting that the fungal communities associated with hair roots of R. ovatum after logging were resilient and could recover to predisturbance status. The results of envfit analysis showed that performance of host plants rather than accompanying plant community and soil parameters of plots was the key determinant of the root-associated fungal community of R. ovatum.

scholarly journals Effects of nitrogen and phosphorus additions on nitrous oxide emission in a nitrogen-rich and two nitrogen-limited tropical forests

2016 ◽  
Author(s):  
M. H. Zheng ◽  
T. Zhang ◽  
L. Liu ◽  
W. X. Zhu ◽  
W. Zhang ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Tropical Forests ◽  
N2o Emission ◽  
N Deposition ◽  
Soil N ◽  
N Addition ◽  
Old Growth ◽  
Old Growth Forest ◽  
P Addition ◽  
Stimulation Of

Abstract. Nitrogen (N) deposition is generally considered to increase soil nitrous oxide (N2O) emission in N-rich forests. In many tropical forests, however, elevated N deposition has caused soil N enrichment and further phosphorus (P) deficiency, and the interaction of N and P to control soil N2O emission remains poorly understood, particularly in forests with different soil N status. In this study, we examined the effects of N and P additions on soil N2O emission in an N-rich old-growth forest and two N-limited younger forests (a mixed and a pine forest) in southern China, to test the following hypotheses: (1) soil N2O emission is the highest in old-growth forest due to the N-rich soil; (2) N addition increases N2O emission more in the old-growth forest than in the two younger forests; (3) P addition decreases N O emission more in the old-growth forest than in the two younger forests; and (4) P addition alleviates the stimulation of N2O emission by N addition. The following four treatments were established in each forest: Control, N addition (150 kg N ha–1 yr–1), P addition (150 kg P ha–1 yr–1), and NP addition (150 kg N ha–1 yr–1 plus 150 kg P ha–1 yr–1). From February 2007 to October 2009, monthly quantification of soil N2O emission was performed using static chamber and gas chromatography techniques. Mean N2O emission was shown to be significantly higher in the old-growth forest (13.86 ± 0.71 μg N2O-N m–2 h–1) than in the mixed (9.86 ± 0.38 μg N2O-N m–2 h–1) or pine (10.83 ± 0.52 μg N) forests, with no significant difference between the latter two. N addition significantly increased N2O emission in the old-growth forest but not in the two younger forests. However, both P- and NP-addition had no significant effect on N2O emission in all three forests, suggesting that P addition alleviated the stimulation of N2O emission by N addition in the old-growth forest. Although P fertilization may alleviate the stimulated effects of atmospheric N deposition on N O emission in N-rich forests, we suggest future investigations to definitively assess this management strategy and the importance of P in regulating N cycles from regional to global scales.

scholarly journals Aboveground forest biomass varies across continents, ecological zones and successional stages: refined IPCC default values for tropical and subtropical forests

2021 ◽  
Author(s):  
Danaë M. A. Rozendaal ◽  
Daniela Requena Suarez ◽  
Veronique De Sy ◽  
Valerio Avitabile ◽  
Sarah Carter ◽  
...  
Keyword(s):  
Secondary Forests ◽  
Ecological Zone ◽  
Old Growth ◽  
Successional Stage ◽  
Subtropical Forests ◽  
Ecological Zones ◽  
Old Growth Forest ◽  
Ipcc Guidelines ◽  
Successional Stages ◽  
The Tropics

Abstract For monitoring and reporting forest carbon stocks and fluxes, many countries in the tropics and subtropics rely on default values of forest aboveground biomass (AGB) from the Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas (GHG) Inventories. Default IPCC forest AGB values originated from 2006, and are relatively crude estimates of average values per continent and ecological zone. The 2006 default values were based on limited plot data available at the time, methods for their derivation were not fully clear, and no distinction between successional stages was made. As part of the 2019 Refinement to the 2006 IPCC Guidelines for GHG Inventories, we updated the default AGB values for tropical and subtropical forests based on AGB data from >25,000 plots in natural forests and a global AGB map where no plot data were available. We calculated refined AGB default values per continent, ecological zone, and successional stage, and provided a measure of uncertainty. AGB in tropical and subtropical forests varies by an order of magnitude across continents, ecological zones, and successional stage. Our refined default values generally reflect the climatic gradients in the tropics, with more AGB in wetter areas. AGB is generally higher in old-growth than in secondary forests, and higher in older secondary (regrowth >20 years old and degraded/logged forests) than in young secondary forests (≤20 years old). While refined default values for tropical old-growth forest are largely similar to the previous 2006 default values, the new default values are 4.0 to 7.7-fold lower for young secondary forests. Thus, the refined values will strongly alter estimated carbon stocks and fluxes, and emphasize the critical importance of old-growth forest conservation. We provide a reproducible approach to facilitate future refinements and encourage targeted efforts to establish permanent plots in areas with data gaps.

Tradable Disturbance Permits for Old-growth Forest Conservation: Experimental Evaluation of Implementation Options

2017 ◽  
Vol 7 (1-2) ◽  
pp. 73-107
Author(s):  
Orsolya Perger ◽  
Curtis Rollins ◽  
Marian Weber ◽  
Wiktor Adamowicz ◽  
Peter Boxall
Keyword(s):  
Experimental Evaluation ◽  
Forest Conservation ◽  
Old Growth ◽  
Old Growth Forest

Old-growth forest reserves in Slovenia: the past, present, and future

2012 ◽  
Vol 163 (6) ◽  
pp. 240-246 ◽  
Author(s):  
Thomas A. Nagel ◽  
Jurij Diaci ◽  
Dusan Rozenbergar ◽  
Tihomir Rugani ◽  
Dejan Firm
Keyword(s):  
Stand Structure ◽  
Growth Conditions ◽  
Ecosystem Functions ◽  
Future Research ◽  
Old Growth ◽  
Forest Reserves ◽  
The Past ◽  
Old Growth Forest ◽  
Forest Remnants ◽  
Basic Characteristics

Old-growth forest reserves in Slovenia: the past, present, and future Slovenia has a small number of old-growth forest remnants, as well as many forest reserves approaching old-growth conditions. In this paper, we describe some of the basic characteristics of these old-growth remnants and the history of their protection in Slovenia. We then trace the long-term development of research in these old-growth remnants, with a focus on methodological changes. We also review some of the recent findings from old-growth research in Slovenia and discuss future research needs. The conceptual understanding of how these forests work has slowly evolved, from thinking of them in terms of stable systems to more dynamic and unpredictable ones due to the influence of natural disturbances and indirect human influences. In accordance with this thinking, the methods used to study old-growth forests have changed from descriptions of stand structure to studies that address natural processes and ecosystem functions.

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