Canopy nitrogen addition enhance the photosynthetic rate of canopy species by improving leaf hydraulic conductivity in a subtropical forest

Wu, Guilin; Chen, Dexiang; Zhou, Zhang; Ye, Qing; Wu, Jianhui

doi:10.3389/fpls.2022.942851

Cited by 4 publications

(4 citation statements)

References 41 publications

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“…Thus, it was understandable that the services of plant C sequestration in our study showed synergetic increases with the significant increase of plant N retention under the over-canopy N additions (Figures 2 and 6). Consistent with our result, another study at our study site found that over-canopy N additions significantly improve the photosynthetic rates of two dominant tree species, while understory N additions show no significant impacts (Wu et al, 2022).…”

Section: Synergetic Response Of Plant C N and P Retention To N Additionsupporting

confidence: 92%

Multi‐ecosystem services differently affected by over‐canopy and understory nitrogen additions in a typical subtropical forest

Tian,

Zhou,

Zhou

et al. 2024

Global Change Biology

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Obtaining a holistic understanding of the impacts of atmospheric nitrogen deposition on multiple ecosystem services of forest is essential for developing comprehensive and sustainable strategies, particularly in heavy N deposition regions such as subtropical China. However, such impacts remain incompletely understood, with most previous studies focus on individual ecosystem function or service via understory N addition experiments. To address this knowledge gap, we quantified the effects of over‐canopy and understory N additions on multiple ecosystem services based on a 7‐year large‐scale field experiment in a typical subtropical forest. Our results showed continued over‐canopy N addition with 50 kg ha−1 year−1 over a period of 4–7 years significantly increased plant nutrient retention, but did not affect the services of soil nutrient accumulation, water yield, C sequestration (in plants and soil), or oxygen release. There were trade‐offs between the soil and plant on providing the services of nutrient accumulation/retention and C sequestration under over‐canopy N addition. However, without uptake and retention of tree canopy, the trade‐off between soil and plant were more weaken under the understory N addition with 50 kg ha−1 year−1, and their relationships were even synergetic under the understory N addition with 25 kg ha−1 year−1. The results suggest that understory N addition cannot accurately simulate the effects of atmospheric N deposition on multiple services, along with mutual relationships. Interestingly, the services of plant N, P retention, and C sequestration exhibited a synergetic increase under the over‐canopy N addition but a decrease under the understory N addition. Our results also found tree layer plays a primary role in providing plant nutrient retention service and is sensitive to atmospheric N deposition. Further studies are needed to investigate the generalized effects of forest canopy processes on alleviating the threaten of global change factors in different forest ecosystems.

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Section: Synergetic Response Of Plant C N and P Retention To N Additionsupporting

confidence: 92%

Multi‐ecosystem services differently affected by over‐canopy and understory nitrogen additions in a typical subtropical forest

Tian,

Zhou,

Zhou

et al. 2024

Global Change Biology

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“…These deposited gaseous and dissolved Nr are mainly intercepted by the canopy leaves and absorbed by ion exchange in the cuticle and/or simple diffusion in the stomata and enter the apoplast ( Rennenberg and Gessler, 1999 ; Sparks, 2009 ), which are then transported to the cells and assimilated and utilized by various enzyme systems such as nitrate reductase (NR), glutamine synthetase/glutamate synthase (GS/GOGAT) cycle in chloroplasts or plastids ( Krupa, 2003 ; Sparks, 2009 ). This process eventually leads to an increase in leaf N content and N metabolites, which in turn induces physiological responses and affects photosynthetic carbon assimilation capacity ( Castro et al., 2008 ; Mao et al., 2018 ; Hu et al., 2019 ; Wu et al., 2022 ), and also causes changes in leaf morphological and anatomical traits ( Zhu et al., 2020 ; Khan et al., 2020 ). Therefore, canopy leaves are also the first vegetative organ of plants to respond to dry and wet N deposition.…”

Section: Introductionmentioning

confidence: 99%

Alternating processes of dry and wet nitrogen deposition have different effects on the function of canopy leaves: Implications for leaf photosynthesis

Zhou²,

Cheng³

et al. 2023

Front. Plant Sci.

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Canopy leaves are sinks of dry and wet nitrogen (N) deposition, most studies have not considered the response of canopy leaves to the alternating processes of dry and wet N deposition. We manipulated a close top chamber experiment to observe the effects of simulated N deposition with the same total deposition flux but different dry to wet ratios on leaf structure and physiology by spraying NH4Cl solution or supplying gaseous NH3 over the canopy of seedlings of three species (Betula platyphylla, Fraxinus mandshurica, Pinus koraiensis) placed in the chamber. After 32 days of N deposition and relative to the control, the leaf morphology and mesophyll tissue structure of the three species had no significant changes under all N deposition treatments. With the increase in the ratio of dry to wet N deposition, the N concentration, N metabolizing enzyme activity and soluble protein concentration in leaves of all three species increased continuously, but for the leaf light-saturated net photosynthesis rate, B. platyphylla showed a continuous increase, F. mandshurica showed a continuous decrease, and P. koraiensis showed no significant change. We found that F. mandshurica was the only species whose foliar chlorophyll and potassium concentration decreased with the increase in the ratio of dry to wet N deposition and its leaf light-saturated net photosynthesis rate was positively correlated with foliar chlorophyll and potassium concentration, respectively. Our results indicate that dry deposition is relatively more important on leaf physiological functions in alternating deposition. B. platyphylla and P. koraiensis may better acclimate to canopy NH3/NH4+ deposition than F. mandshurica. Most importantly, the results indicate that a single simulated dry and wet deposition would overestimate and underestimate the response of leaf function to atmospheric N deposition, respectively. Alternating processes of dry and wet deposition should be considered for more realistic assessments of the effects of atmospheric N deposition in forests.

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“…It is important to note that CN played a dual role in our study by reducing N leaching while increasing the annual mineralization rates in the spring, winter, and autumn, a finding that differs from the results of previous studies (Figure 3d,e). Previous research has linked CN with N leaching due to the N concentrations in tree organs, reflecting increased photosynthetic rates in forests [44,45].…”

Section: Seasonal Dynamics and The Impact Of Cn On N Processesmentioning

confidence: 99%

Effects of Canopy Nitrogen Addition and Understory Vegetation Removal on Nitrogen Transformations in a Subtropical Forest

Ullah,

Liu,

Shah

et al. 2024

Forests

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The management of understory vegetation and anthropogenic nitrogen (N) deposition has significantly resulted in a nutrient imbalance in forest ecosystems. However, the effects of canopy nitrogen addition and understory vegetation removal on N transformation processes (mineralization, nitrification, ammonification, and leaching) along with seasonal variations (spring, summer, autumn, and winter) remain unclear in subtropical forests. To fill this research gap, a field manipulation experiment was conducted with four treatments, including: (i) CK, control; (ii) CN, canopy nitrogen addition (25 kg N ha−1 year−1); (iii) UR, understory vegetation removal; and (iv) CN+UR, canopy nitrogen addition plus understory vegetation removal. The results revealed that CN increased net mineralization and nitrification by 294 mg N m−2 month−1 in the spring and 126 mg N m−2 month−1 in the winter, respectively. UR increased N mineralization and nitrification rates by 618 mg N m−2 month−1 in the summer. In addition, CN effectively reduced N leaching in the spring, winter, and autumn, while UR increased it in the spring and winter. UR increased annual nitrification rates by 93.4%, 90.3%, and 38.9% in the winter, spring, and summer, respectively. Additionally, both net N ammonification and annual nitrification rates responded positively to phosphorus availability during the autumn. Overall, UR potentially boosted nitrification rates in the summer and ammonification in the spring and winter, while CN reduced N leaching in the spring, winter, and autumn. Future research should integrate canopy nitrogen addition, understory vegetation removal, and phosphorus availability to address the global N deposition challenges in forest ecosystems.

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Canopy nitrogen addition enhance the photosynthetic rate of canopy species by improving leaf hydraulic conductivity in a subtropical forest

Cited by 4 publications

References 41 publications

Multi‐ecosystem services differently affected by over‐canopy and understory nitrogen additions in a typical subtropical forest

Multi‐ecosystem services differently affected by over‐canopy and understory nitrogen additions in a typical subtropical forest

Alternating processes of dry and wet nitrogen deposition have different effects on the function of canopy leaves: Implications for leaf photosynthesis

Effects of Canopy Nitrogen Addition and Understory Vegetation Removal on Nitrogen Transformations in a Subtropical Forest

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