Soil phosphorus availability regulates the response of soil enzyme activity and enzymatic stoichiometry to litter addition in a subtropical forest

doi:10.17521/cjpe.2022.0430

Abstract

Abstract:

Aims It is of great significance to explore soil extracellular enzyme activity and its stoichiometry to understand soil nutrient availability and changes in the nutrient requirements of microorganisms. Subtropical forest ecosystems have high net primary productivity, but the availability of phosphorus (P) in soil is low due to severe soil weathering. Under climate change (i.e., warming, elevated CO₂ concentration), plant productivity is predicted to increase, which would increase the input of leaf litter. However, it is still unclear whether the effect of increasing litter input on soil enzyme activity and its stoichiometry is affected by soil P availability in the future.

Methods This study investigated the effects of the addition of three kinds of litters (Pinus massoniana, Michelia macclurei and Liquidambar formosa) with different quality (characterized by different leaf C:N or C:P) and P on soil properties and enzyme activities in subtropical low-P soils. By analyzing the stoichiometric ratio of soil enzymes, vector length (VL), and vector angle (VA), the relative nutrient limitation to soil microorganisms and the key regulatory factors were explored.

Important findings The results showed that litter addition increased β-N-acetyl-glucosaminidase and acid phosphatase (ACP) activities. The addition of litter significantly increased VL and VA in the order of M. macclurei > L. formosana > P. massoniana. Litter addition could change the status of nutrient limitation to soil microorganisms, with the degree of changes being related to the quality of litter. Compared with the addition of litter alone, the addition of both litter and P significantly increased the content of available P, and reduced ACP activity and VA, suggesting that P addition could help alleviate P limitation to soil microorganisms under the input of litter. Redundancy analysis results showed that the soil carbon/nitrogen ratio, dissolved organic carbon content, and available P content were the main factors affecting enzyme activities and their stoichiometry. In conclusion, our study found that the response of soil microbial nutrient limitation to litter input in subtropical forest was not only affected by litter quality, but also regulated by soil P availability. This study provides a theoretical reference for the response of microbial nutrient acquisition strategies to different litter inputs and P additions in subtropical forests under future climate change, and is conducive to improving our understanding of the soil biogeochemical cycling in subtropical low P forest ecosystems.

Key words: litter, phosphorus addition, soil enzyme activity, enzymatic stoichiometry, phosphorus limitation

WU Jun-Mei, ZENG Quan-Xin, MEI Kong-Can, LIN Hui-Ying, XIE Huan, LIU Yuan-Yuan, XU Jian-Guo, CHEN Yue-Min. Soil phosphorus availability regulates the response of soil enzyme activity and enzymatic stoichiometry to litter addition in a subtropical forest[J]. Chin J Plant Ecol, 2024, 48(2): 242-253.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2022.0430

https://www.plant-ecology.com/EN/Y2024/V48/I2/242

Figures/Tables 8

Table 1 Basic properties of three kinds of litters (mean ± SD, n = 3)

	全碳(C)含量 Total carbon (C) content (g·kg^-1)	全氮(N)含量 Total nitrogen (N) content (g·kg^-1)	C:N	全磷(P)含量 Total phosphorus (P) content (g·kg^-1)	C:P
马尾松 Pinus massoniana	458.37 ± 9.84^ab	12.07 ± 0.41^a	37.98 ± 0.53^c	2.03 ± 0.01^a	225.58 ± 5.24^c
醉香含笑 Michelia macclurei	475.18 ± 1.89^a	10.38 ± 0.25^b	45.81 ± 1.23^b	0.96 ± 0.02^c	496.57 ± 13.45^a
枫香树 Liquidambar formosana	454.87 ± 1.01^b	9.44 ± 0.14^c	48.17 ± 0.78^a	1.41 ± 0.01^b	323.38 ± 2.36^b
p	0.011	<0.001	<0.001	<0.001	<0.001

Fig. 1 Effects of litter and phosphorus (P) addition on soil physical and chemical properties in a subtropical forest (mean ± SD, n = 3). CK, control; LF, Liquidambar formosana litter addition; LF+PA, L. formosana litter and P addition; MM, Michelia macclurei litter addition; MM+PA, M. macclurei litter and P addition; PA, P addition; PM, Pinus massoniana litter addition; PM+PA, P. massoniana litter and P addition. L, PA and L×PA respectively represent the main effects of litter addition and P addition and their interactions respectively following a two-way ANOVA. AP, available P; DOC, dissolved organic carbon; DON, dissolved organic nitrogen; TC, total carbon; TN, total nitrogen; TP, total P. Different lowercase letters meant significant difference at 0.05 level among treatments.

Fig. 2 Effects of litter and phosphorus (P) addition on soil microbial biomass nutrient content in a subtropical forest (mean ± SD, n = 3). CK, control; LF, Liquidambar formosana litter addition; LF+PA, L. formosana litter and P addition; MM, Michelia macclurei litter addition; MM+PA, M. macclurei litter and P addition; PA, P addition; PM, Pinus massoniana litter addition; PM+PA, P. massoniana litter and P addition. L, PA and L×PA represent the main effects of litter addition and P addition, and their interactions, respectively following a two-way ANOVA. MBC, microbial biomass carbon; MBN, microbial biomass nitrogen; MBP, microbial biomass P. Different lowercase letters meant significant difference at 0.05 level among treatments.

Fig. 3 Effects of litter and phosphorus (P) addition on soil enzymes activities in a subtropical forest (mean ± SD, n = 3). CK, control; LF, Liquidambar formosana litter addition; LF+PA, L. formosana litter and P addition; MM, Michelia macclurei litter addition; MM+PA, M. macclurei litter and P addition; PA, P addition; PM, Pinus massoniana litter addition; PM+PA, P. massoniana litter and P addition. L, PA and L×PA represent the main effects of litters addition and P addition, and their interactions, respectively following a two-way ANOVA. ACP, acid phosphatase; βG, β-glucosidase; NAG, β-N-acetyl-glucosaminidase. Different lowercase letters meant significant difference at 0.05 level among treatments.

Table 2 Effects of litter and phosphorus (P) addition on soil enzymatic stoichiometry in a subtropical forest (mean ± SD, n = 3)

处理 Treatment	E_C:N	E_C:P	E_N:P	VL	VA (°)
CT	0.98 ± 0.03^bcd	0.49 ± 0.01^ab	0.507 ± 0.02^ab	1.09 ± 0.03^bcd	63.11 ± 0.73^bc
PA	0.90 ± 0.04^d	0.48 ± 0.01^b	0.533 ± 0.02^a	1.02 ± 0.04^d	61.81 ± 0.99^c
PM	0.95 ± 0.05^cd	0.50 ± 0.02^ab	0.527 ± 0.02^ab	1.07 ± 0.05^cd	62.22 ± 0.73^bc
MM	1.15 ± 0.11^a	0.52 ± 0.02^ab	0.457 ± 0.03^c	1.26 ± 0.10^a	65.49 ± 1.50^a
LF	1.03 ± 0.08^bc	0.51 ± 0.04^ab	0.500 ± 0.01^ab	1.15 ± 0.09^abcd	63.46 ± 0.45^b
PM+PA	0.97 ± 0.05^bcd	0.52 ± 0.04^ab	0.533 ± 0.01^a	1.10 ± 0.06^bcd	61.99 ± 0.65^bc
MM+PA	1.07 ± 0.04^ab	0.54 ± 0.03^a	0.503 ± 0.01^ab	1.20 ± 0.05^ab	63.20 ± 0.43^bc
LF+PA	1.05 ± 0.07^abc	0.52 ± 0.03^ab	0.497 ± 0.01^b	1.17 ± 0.08^abc	63.46 ± 0.58^b
Two-way ANOVA
L	<0.001	0.063	<0.001	<0.001	<0.001
PA	0.323	0.421	0.310	0.422	0.446
L×PA	0.350	0.689	0.104	0.101	0.468

Fig. 4 Response ratio of soil enzyme vector length (A) and vector angle (B) to litter and phosphorus (P) addition in a subtropical forest (mean ± SD, n = 3). LF, Liquidambar formosana litter addition; LF+PA, L. formosana litter and P addition; MM, Michelia macclurei litter addition; MM+PA, M. macclurei litter and P addition; PA, P addition; PM, Pinus massoniana litter addition; PM+PA, P. massoniana litter and P addition. L, PA and L×PA represent the main effects of litter addition and P addition, and their interactions, respectively following a two-way ANOVA. VA, vector angle; VL, vector length. Different lowercase letters mean significant difference at 0.05 level among treatments.

Fig. 5 Redundancy analysis of soil enzyme activity and enzymatic stoichiometry under litter (A) and phosphorus (P) addition (B). ACP, acid phosphatase activity; AP, available P content; βG, β-glucosaminidase activity; CK, control; DOC, dissolved organic carton content; EC:N, the ratio of carbon-acquiring enzyme activity to nitrogen-acquiring enzyme activity; EC:P, the ratio of carbon-acquiring enzyme activity to phosphorus-acquiring enzyme activity; EN:P, the ratio of nitrogen-acquiring enzyme activity to phosphorus-acquiring enzyme activity; LF, Liquidambar formosana litter addition; LF+PA, L. formosana litter and P addition; MM, Michelia macclurei litter addition; MM+PA, M. macclurei litter and P addition; NAG, β-N-acetyl-glucosaminidase activity; PM, Pinus massoniana litter addition; PM+PA, P. massoniana litter and P addition. TC:TN, the ratio of total carbon content to total nitrogen content; TN, total nitrogen content; TP, total P content; VA, vector angle; VL, vector length.

Fig. 6 A conceptual framework of soil enzyme activity and its stoichiometry in response to litter and phosphorus (P) addition in a subtropical forest. CK, control; LF, Liquidambar formosana; MM, Michelia macclurei; PM, Pinus massoniana. ACP, acid phosphatase activity; AP, available P content; βG, β-glucosaminidase activity; DOC, dissolved organic carton content; EC:N, the ratio of carbon-acquiring enzyme activity to nitrogen-acquiring enzyme activity; EC:P, the ratio of carbon-acquiring enzyme activity to phosphorus-acquiring enzyme activity; EN:P, the ratio of nitrogen-acquiring enzyme activity to phosphorus-acquiring enzyme activity; NAG, β-N-acetyl-glucosaminidase activity; TC:TN, the ratio of total carbon content to total nitrogen content; VA, vector angle; VL, vector length. The width of the trapezoid and CK represent the size of the corresponding index value.

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