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Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests.

Zhu F, Lu X, Liu L, Mo J - Sci Rep (2015)

Bottom Line: In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K(+)+Ca(2+)+Mg(2+)) in the old-growth and the two younger forests, respectively.These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return.Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests.

View Article: PubMed Central - PubMed

Affiliation: 1] Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China [2] Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China.

ABSTRACT
Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al(3+) replacement of Ca(2+) in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K(+)+Ca(2+)+Mg(2+)) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests.

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Soil pH (a), concentrations of available P (b), available N (c, NH4+-N and NO3−-N), and ammonium to nitrate ratio (d) in the 0–10 cm soil depth in response to 2.5 years of N and P additions in the three forests.Bars indicate +1 SE (N = 5). Different capital letters indicate significant differences among the three study forests (One-way ANOVA, Tukey'b test, P < 0.05). Different lowercase letters indicate significant differences among treatments in each forest (One-way ANOVA, Tukey'b test, P < 0.05).
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f1: Soil pH (a), concentrations of available P (b), available N (c, NH4+-N and NO3−-N), and ammonium to nitrate ratio (d) in the 0–10 cm soil depth in response to 2.5 years of N and P additions in the three forests.Bars indicate +1 SE (N = 5). Different capital letters indicate significant differences among the three study forests (One-way ANOVA, Tukey'b test, P < 0.05). Different lowercase letters indicate significant differences among treatments in each forest (One-way ANOVA, Tukey'b test, P < 0.05).

Mentions: In the control plots, the old-growth forest was lower in pH (Fig. 1a), but higher in soil NO3−-N (Fig. 1c), soil exchangeable base cation nutrients and Al3+ (Table S1) than the two younger forests. Soil pH values in the control plots averaged 3.82, 4.06 and 3.98 in the old-growth, mixed, and pine forests, respectively. Consistent with the low pH values, exchangeable cation pools of all the three forests were predominated by Al3+ (Table S1). Calculated annual litter nutrient input (annual litterfall production × litter concentrations of N, P, K, Ca, Mg; Table 1, S2) of K and Mg were significantly higher in the old-growth forest than in the pine forest (Table 1).


Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests.

Zhu F, Lu X, Liu L, Mo J - Sci Rep (2015)

Soil pH (a), concentrations of available P (b), available N (c, NH4+-N and NO3−-N), and ammonium to nitrate ratio (d) in the 0–10 cm soil depth in response to 2.5 years of N and P additions in the three forests.Bars indicate +1 SE (N = 5). Different capital letters indicate significant differences among the three study forests (One-way ANOVA, Tukey'b test, P < 0.05). Different lowercase letters indicate significant differences among treatments in each forest (One-way ANOVA, Tukey'b test, P < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300498&req=5

f1: Soil pH (a), concentrations of available P (b), available N (c, NH4+-N and NO3−-N), and ammonium to nitrate ratio (d) in the 0–10 cm soil depth in response to 2.5 years of N and P additions in the three forests.Bars indicate +1 SE (N = 5). Different capital letters indicate significant differences among the three study forests (One-way ANOVA, Tukey'b test, P < 0.05). Different lowercase letters indicate significant differences among treatments in each forest (One-way ANOVA, Tukey'b test, P < 0.05).
Mentions: In the control plots, the old-growth forest was lower in pH (Fig. 1a), but higher in soil NO3−-N (Fig. 1c), soil exchangeable base cation nutrients and Al3+ (Table S1) than the two younger forests. Soil pH values in the control plots averaged 3.82, 4.06 and 3.98 in the old-growth, mixed, and pine forests, respectively. Consistent with the low pH values, exchangeable cation pools of all the three forests were predominated by Al3+ (Table S1). Calculated annual litter nutrient input (annual litterfall production × litter concentrations of N, P, K, Ca, Mg; Table 1, S2) of K and Mg were significantly higher in the old-growth forest than in the pine forest (Table 1).

Bottom Line: In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K(+)+Ca(2+)+Mg(2+)) in the old-growth and the two younger forests, respectively.These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return.Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests.

View Article: PubMed Central - PubMed

Affiliation: 1] Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China [2] Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China.

ABSTRACT
Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al(3+) replacement of Ca(2+) in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K(+)+Ca(2+)+Mg(2+)) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests.

Show MeSH