scholarly journals Nitrogen and phosphorus addition differentially enhance seed production of dominant species in a temperate steppe

2021 ◽  
Author(s):  
Lei Su ◽  
Mengzhou Liu ◽  
Chengming You ◽  
Qun Guo ◽  
Zhongmin Hu ◽  
...  
Keyword(s):  
Seed Production ◽  
Nutrient Enrichment ◽  
Plant Density ◽  
N Availability ◽  
P Availability ◽  
N Addition ◽  
Temperate Steppe ◽  
Nitrogen And Phosphorus ◽  
Phosphorus Addition ◽  
P Addition

Previous studies have demonstrated changes in plant growth and reproduction in response to nutrient availability, but how investigations of such responses to multiple levels of nutrient enrichment remains unclear. In this study, we manipulated nitrogen (N) and phosphorus (P) availability to examine seed production responses to three levels each of N and P addition in a factorial experiment: no N addition (0 g N m-2 yr-1), low N addition (10 g N m-2 yr-1), high N addition (40 g N m-2 yr-1), and no P addition (0 g P m-2 yr-1), low P addition (5 g P m-2 yr-1), high P addition (10 g P m-2 yr-1). Low N addition enhanced seed production by 814%, 1371%, and 1321% under ambient, low, and high P addition levels, respectively. High N addition increased seed production by 2136%, 3560%, and 3550% under ambient, low, and high P addition levels, respectively. However, P addition did not affect seed production in the absence of N addition, but it did enhance it under N addition. Furthermore, N addition enhanced seed production mainly by increasing the tiller number and inflorescence abundance per plant, whereas P addition stimulated it by decreasing the plant density yet stimulating height of plants and their seed number per inflorescence. Our results indicate seed production is limited not by P but rather by N in the temperate steppe, whereas seed production will be increased by P addition when N availability is improved. These findings enable a better understanding of plant reproduction dynamics of steppe ecosystems under intensified nutrient enrichment and can inform their improved management in the future.

scholarly journals Nitrogen and phosphorus addition differentially affect plant ecological stoichiometry in desert grassland

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lei Li ◽  
Bo Liu ◽  
Xiaopeng Gao ◽  
Xiangyi Li ◽  
Chengdao Li
Keyword(s):  
Field Experiments ◽  
Grass Species ◽  
N Availability ◽  
P Availability ◽  
N Addition ◽  
Desert Grassland ◽  
Nitrogen And Phosphorus ◽  
Desert Ecosystems ◽  
Phosphorus Addition ◽  
N:P Ratios

AbstractPlant C:N:P stoichiometric relations drive powerful constraints on ecological interactions and processes. However, information about plant stoichiometric responses to N and P availability in desert grassland is limited. We conducted two field experiments with 7 levels of N (from 0.5 g to 24 g N ∙ m−2 yr−1) and P (from 0.05 g to 3.2 g P ∙ m−2 yr−1) additions in a desert grassland of Kunlun Mountain in the northwest of China to investigate the effects of these addition rates on the N and P stoichiometry of the dominant grass species Seriphidium korovinii. Nitrogen and P additions both affected plant stoichiometry. N addition suppressed P concentrations, whereas P addition had no effect on plant N concentrations. The N:P ratios of green aboveground biomass (AGB) were positively correlated with N addition ranging from 14.73 to 29.08, whereas those for P additions decreased ranging from 14.73 to 8.29. N concentrations were positively correlated with soil available N:P ratios, whereas, P concentrations were negatively correlated with soil availably N:P. Our results suggest that chemistry and stoichiometry of S. korovinii was directly affected by soil nutrient availability. Soil N availability affects S. korovinii stoichiometry to a greater extent that does soil P availability in this ecosystem. These findings suggest that N-deposition could affect the stoichiometry of this desert grassland ecosystem, and thereby potentially alter litter decomposition, plant community composition, nutrient cycling, and food-web dynamics of these desert ecosystems.

scholarly journals Impact of nitrogen and phosphorus addition on resident soil and root mycobiomes in beech forests

2021 ◽  
Author(s):  
S. Clausing ◽  
L. E. Likulunga ◽  
D. Janz ◽  
H. Y. Feng ◽  
D. Schneider ◽  
...  
Keyword(s):  
Ectomycorrhizal Fungi ◽  
N Fertilization ◽  
Fungal Communities ◽  
P Availability ◽  
Nitrogen And Phosphorus ◽  
Saprotrophic Fungi ◽  
Phosphorus Addition ◽  
Different Response ◽  
P Addition ◽  
Total P

AbstractN and P are essential macronutrients for all organisms. How shifts in the availability of N or P affect fungal communities in temperate forests is not well understood. Here, we conducted a factorial P × N fertilization experiment to disentangle the effects of nutrient availability on soil-residing, root-associated, and ectomycorrhizal fungi in beech (Fagus sylvatica) forests differing in P availability. We tested the hypotheses that in P-poor forests, P fertilization leads to enhanced fungal diversity in soil and roots, resulting in enhanced P nutrition of beech, and that N fertilization aggravates P shortages, shifting the fungal communities toward nitrophilic species. In response to fertilizer treatments (1 × 50 kg ha−1 P and 5 × 30 kg ha−1 N within 2 years), the labile P fractions increased in soil and roots, regardless of plant-available P in soil. Root total P decreased in response to N fertilization and root total P increased in response to P addition at the low P site. Ectomycorrhizal species richness was unaffected by fertilizer treatments, but the relative abundances of ectomycorrhizal fungi increased in response to P or N addition. At the taxon level, fungal assemblages were unaffected by fertilizer treatments, but at the order level, different response patterns for saprotrophic fungi among soil and ectomycorrhizal fungi on roots were found. Boletales increased in response to P, and Russulales decreased under N + P addition. Our results suggest that trait conservatism in related species afforded resistance of the resident mycobiome composition to nutritional imbalances.

scholarly journals Impact of nitrogen and phosphorus addition on resident soil and root mycobiomes in beech forests

2020 ◽  
Author(s):  
S. Clausing ◽  
L.E. Likulunga ◽  
D. Janz ◽  
H.Y. Feng ◽  
D. Schneider ◽  
...  
Keyword(s):  
Ectomycorrhizal Fungi ◽  
N Fertilization ◽  
P Availability ◽  
N Addition ◽  
P Fertilization ◽  
Nutrient Inputs ◽  
Nitrogen And Phosphorus ◽  
Saprotrophic Fungi ◽  
Phosphorus Addition ◽  
Total P

AbstractIn forest soils, the pools of N and P available for microbes and plants are strongly dependent on soil properties. Here, we conducted a P and N fertilization experiment to disentangle the effects of nutrient availability on soil-residing, root-associated and ectomycorrhizal fungi in beech (Fagus sylvativa) forests differing in P availability. We tested the hypothesis that in P-poor forests, P fertilization leads to enhanced fungal diversity in soil and roots, resulting in enhanced P nutrition of beech and that N fertilization aggravates P shortage, shifting the fungal communities towards nitrophilic species. In response to fertilizer treatments (1x 50 kg ha−1 P, 5x 30 kg ha−1 N within 2 years), the labile P fractions increased in soil and roots, regardless of plant-available P in soil. Root total P decreased in response to N fertilization and root total P increased at the low P site in response to P addition. The relative abundances of ectomycorrhizal fungi, but not their species richness, increased in response to P or N addition in comparison with that of saprotrophic fungi. While some fungal orders (Trechisporales, Atheliales, Cantharellales) were moderately decreased in response to fertilizer treatments, Boletales increased in response to P and Russulaes to N addition. N or P fertilization resulted in functional trade-off, shifting away from saprotrophic towards symbiotrophic potential. Our results suggest that chronic exposure of forest ecosystems to increased nutrient inputs may overcome the resistance of the resident mycobiome structures resulting in nutritional imbalance and loss of forest ecosystem services.

scholarly journals Responses of Soil C-, N-, and P-Hydrolyzing Enzyme Activities to N and P Addition in an Evergreen Broad-Leaved Forest in Southwest China

2021 ◽  
Author(s):  
Xing Liu ◽  
Shixing Zhou ◽  
Liehua Tie ◽  
Shengzhao Wei ◽  
Junxi Hu ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Enzyme Activities ◽  
Urease Activity ◽  
P Availability ◽  
N Addition ◽  
Soil C ◽  
Broad Leaved Forest ◽  
N Treatment ◽  
P Addition ◽  
Leaved Forest

Abstract Background and Aims Human activities-mediated input of nitrogen (N) and phosphorus (P) to ecosystem may significantly affect soil hydrolyzing enzyme activities (Hy-EAs). However, the mechanisms underlying the responses of soil Hy-EAs to change in N and P availability remains unclear. Methods Here, a two-year field N and P addition experiment was conducted in a subtropical evergreen broad-leaved forest to elucidate the effects of N addition, P addition, and NP co-additions on soil Hy-EAs and biochemistry properties. Results The invertase, cellulase, and acid phosphatase activities were increased in N treatment but reduced in P treatment. The urease activity was reduced in N treatment but did not alter in P treatment. NP treatment significantly increased the invertase and cellulase activities. Furthermore, the cellulase activity was positively correlated with soil organic carbon concentration. The acid phosphatase activity was negatively correlated with microbial biomass carbon (MBC), total P, and available P concentrations. Whereas the urease activity was not strongly dependent on total N concentrations, but positively correlated with soil pH and MBC. These Hy-EAs were significantly correlated with C-to-P and N-to-P ratios, while no significantly correlation with C-to-N ratio. Conclusions Overall, our results indicated that N and P addition significantly affected the soil C-, N-, and P-hydrolyzing enzyme activities. With ongoing imbalanced N and P input in our studied subtropical evergreen broad-leaved forest, N addition may exacerbate the limitation of soil C and P availability, while the exogenous P addition may improve the soil C and P availability.

scholarly journals Contrasting effects of nitrogen and phosphorus addition on soil respiration in an alpine grassland on the Qinghai-Tibetan Plateau

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Fei Ren ◽  
Xiaoxia Yang ◽  
Huakun Zhou ◽  
Wenyan Zhu ◽  
Zhenhua Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Soil Respiration ◽  
Heterotrophic Respiration ◽  
Interactive Effects ◽  
Alpine Grassland ◽  
Organic Carbon Content ◽  
N Addition ◽  
Alpine Grasslands ◽  
Nitrogen And Phosphorus ◽  
P Addition

Abstract High soil organic carbon content, extensive root biomass, and low nutrient availability make alpine grasslands an important ecosystem for assessing the influence of nutrient enrichment on soil respiration (SR). We conducted a four-year (2009–2012) field experiment in an alpine grassland on the Qinghai-Tibetan Plateau to examine the individual and combined effects of nitrogen (N, 100 kg ha−1year−1) and phosphorus (P, 50 kg ha−1year−1) addition on SR. We found that both N and P addition did not affect the overall growing-season SR but effects varied by year: with N addition SR increased in the first year but decreased during the last two years. However, while P addition did not affect SR during the first two years, SR increased during the last two years. No interactive effects of N and P addition were observed, and both N addition and P addition reduced heterotrophic respiration during the last year of the experiment. N and P addition affected SR via different processes: N mainly affected heterotrophic respiration, whereas P largely influenced autotrophic respiration. Our results highlight the divergent effects of N and P addition on SR and address the important potential of P enrichment for regulating SR and the carbon balance in alpine grasslands.

scholarly journals Increased phosphorus availability mitigates the inhibition of nitrogen deposition on CH<sub>4</sub> uptake in an old-growth tropical forest, southern China

2011 ◽  
Vol 8 (9) ◽  
pp. 2805-2813 ◽  
Author(s):  
T. Zhang ◽  
W. Zhu ◽  
J. Mo ◽  
L. Liu ◽  
S. Dong
Keyword(s):  
Tropical Forest ◽  
Uptake Rate ◽  
Southern China ◽  
N Deposition ◽  
P Availability ◽  
N Addition ◽  
Old Growth ◽  
P Limitation ◽  
Ch4 Uptake ◽  
P Addition

Abstract. It is well established that tropical forest ecosystems are often limited by phosphorus (P) availability, and elevated atmospheric nitrogen (N) deposition may further enhance such P limitation. However, it is uncertain whether P availability would affect soil fluxes of greenhouse gases, such as methane (CH4) uptake, and how P interacts with N deposition. We examine the effects of N and P additions on soil CH4 uptake in an N saturated old-growth tropical forest in southern China to test the following hypotheses: (1) P addition would increase CH4 uptake; (2) N addition would decrease CH4 uptake; and (3) P addition would mitigate the inhibitive effect of N addition on soil CH4 uptake. Four treatments were conducted at the following levels from February 2007 to October 2009: 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). Static chamber and gas chromatography techniques were used to quantify soil CH4 uptake every month throughout the study period. Average CH4 uptake rate was 31.2 ± 1.1 μg CH4-C m−2 h−1 in the control plots. The mean CH4 uptake rate in the N-addition plots was 23.6 ± 0.9 μg CH4-C m−2 h−1, significantly lower than that in the controls. P-addition however, significantly increased CH4 uptake by 24% (38.8 ± 1.3 μg CH4-C m−2 h−1), whereas NP-addition (33.6 ± 1.0 μg CH4-C m−2 h−1) was not statistically different from the control. Our results suggest that increased P availability may enhance soil mathanotrophic activity and root growth, resulting in potentially mitigating the inhibitive effect of N deposition on CH4 uptake in tropical forests.

scholarly journals Foliar N:P Stoichiometry in Aralia elata Distributed on Different Slope Degrees

2019 ◽  
Vol 47 (3) ◽  
Author(s):  
Hongxu WEI ◽  
Hengtian ZHAO ◽  
Xin CHEN
Keyword(s):  
Nitrogen Availability ◽  
Plant Density ◽  
N Uptake ◽  
N:P Ratio ◽  
Individual Growth ◽  
Digital Object Identifier ◽  
N Availability ◽  
P Availability ◽  
Aralia Elata ◽  
Degree Slope

Plant nitrogen (N) to phosphorus (P) stoichiometry is of essentially ecological meaning to non-wood forest production (NWFP) plant community in the temperate forest ecosystem. In this study, natural Aralia elata (Miq.) Seem. communities in montane areas of southern Heilongjiang Province, Northeast China were investigated for plant density, vegetative growth, and soil and leaf parameters on slopes in 5°, 9°, and 14° degrees. We found that individual height was greater in sites on 5°- (1.6 m) and 9°-degree slopes (1.9 m) than on the 14°-degree slope (0.8 m), but soil available P content was highest on the steepest slope (5.5, 4.0, and 16 mg kg-1, respectively). The foliar N:P ratio ranged 6–13. Nitrogen availability tended to promote community density and individual growth; while P availability tended to depress density but promote foliar biomass accumulation. By the diagnosis of plant nutritional monogram, the better growth and high foliar N:P ratio of about 13:1 in A. elata individuals on 9°-degree slope were generated by both deficiency-driving N uptake and excessive P depletion. We recommend the 9°-degree slope to develop A. elata community which can be fed by higher N availability if higher density was achieved.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

scholarly journals Enhanced Community Production rather than Structure Improvement under Nitrogen and Phosphorus Addition in Severely Degraded Alpine Meadows

2019 ◽  
Vol 11 (7) ◽  
pp. 2023 ◽  
Author(s):  
Ning Zong ◽  
Peili Shi
Keyword(s):  
Plant Species ◽  
Aboveground Biomass ◽  
Diversity Index ◽  
The Tibetan Plateau ◽  
N Addition ◽  
P Fertilization ◽  
Nitrogen And Phosphorus ◽  
Phosphorus Addition ◽  
Alpine Meadows ◽  
P Fertilizer

Fertilization is a common management measure for the restoration of degraded grasslands. In order to investigate whether fertilization can improve the severely degraded alpine meadows, we conducted a fertilization experiment on the Tibetan Plateau that began in 2008. The treatments were nitrogen (N) addition alone (50 kg N ha−1 year−1, LN; 100 kg N ha−1 year−1, HN) or combined with phosphorus (P) fertilizer [(50 kg N + 50 kg P) ha−1 year−1, LN+P; (100 kg N + 50 kg P) ha−1 year−1, HN + P] in a severely degraded alpine meadow. Eleven consecutive years of N and P fertilization did not significantly change plant species richness, while fertilization reduced the plant species diversity index, with the most significant reduction in HN and HN + P treatments. LN + P and HN + P treatments greatly increased community coverage and aboveground biomass, while N addition alone, especially the HN treatment, significantly reduced community coverage and aboveground biomass. Fertilization had no effect on edible pastures, while N and P fertilization significantly increased the biomass of forbs. The proportion of forbs to total aboveground biomass was more than 90%, and fertilization had no effect on this proportion. This shows that forbs still have an absolute advantage in the community. In addition, HN, LN + P, and HN + P treatments significantly reduced ecosystem stability. Community aboveground biomass was greatly enhanced in the N and P fertilization treatments, and this was beneficial for the ecosystem quality and soil hydrological functioning. However, fertilization treatments did not improve the community structure with either N addition alone or combined with P fertilizer, which was of little significance in providing forages for the sustainable development of livestock husbandry. To improve the structure of severely degraded alpine grasslands, it is necessary to combine other measures such as cutting the roots of forbs, fencing, or reseeding.

scholarly journals Elevated [CO2] concentration and nitrogen addition affects responses of foliar phosphorus fractions in invasive species to increased phosphorus supply

2021 ◽  
Author(s):  
Lingling Zhang ◽  
Xianzhen Luo ◽  
Hans Lambers ◽  
Guihua Zhang ◽  
Nan Liu ◽  
...  
Keyword(s):  
Invasive Species ◽  
Nucleic Acid ◽  
P Availability ◽  
N Addition ◽  
P Fractions ◽  
Total N ◽  
Soil P ◽  
Soil P Availability ◽  
Foliar Phosphorus ◽  
P Addition

AbstractNo studies have explored how the invasive species of Mikania micranatha and Chromolaena odoratan adjust leaf phosphorus (P) among inorganic P (Pi) and organic P fractions to adapt the low soil P availability, especially under elevated CO2 concentrations ([CO2]) and nitrogen (N) deposition. Here, we address this by measuring foliar total N and P concentrations as well as functional P fractions (i.e. Pi, metabolic P, lipid P, nucleic acids P, and residual P) of both invasive species and a native species (Paederia. scandens) growing under different P supplies, N, and N+P addition under both ambient and elevated [CO2]. Phosphorus addition greatly increased plant biomass and foliar P concentrations but did not significantly affect foliar N concentration and leaf mass per unit leaf area (LMA). In response to P addition, the concentration of metabolic P increased the most, followed by that of nucleic acid P, Pi, and lipid P, in all species by an average of 754%, 82%, 53%, and 38%, respectively. However, elevated [CO2] and N addition weakened this positive effect on concentrations of foliar P fractions in the invasive species. Our results indicate that elevated [CO2] and N addition allowed the invasive species to acclimate to a low soil P availability, supporting their successful invasion, through greatly reducing P allocation to non-metabolic foliar P fractions (phospholipids and nucleic acid P) to meet their demand for metabolic P and Pi for photosynthesis, rather than altering LMA.

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