Effects of nitrogen and phosphorus additions and stand density on soil chemical property in Acacia auriculiformis stands

doi:10.17521/cjpe.2019.0168

Abstract

Abstract:

Aims Due to human activities, nitrogen (N) deposition is increasingly serious, and phosphorous (P) fertility is widely applied in the soils of subtropical forests suffering from P deficiency, but there are relatively few researches of N and P additions on soil characteristics of subtropical forests. Difference in stand density may affect light, temperature, water and litter water holding capacity, which may influence soil characteristics. The effects of external nitrogen and phosphorus and stand density on soil chemical property were investigated in 10 years-old Acacia auriculiformis stands in order to provide a scientific basis for stand density and forest soil management.Methods In this study, five subsample plots were established in the stands with four densities (1 667, 2 500, 4 444 and 10 000 trees·hm ^-2) and treated with N addition, P addition, N+P addition and control from 2013 to 2015. At the end of experiment, soils at 0-10 cm depth with different treatments were collected and pH value, organic matter content, N, P and K contents were analyzed in the A. auriculiformis stands.Important findings The results indicated that soil pH value and available potassium (K) content significantly decreased, whereas soil alkalized N content significantly increased after N and N+P additions in the four density stands, and soil total N content significantly increased after N addition. Soil pH value significantly increased and soil total N content significantly decreased after P addition. Contents of soil organic matter, total P and available P significantly increased after P and N+P additions. With the increase of stand density, the contents of soil organic matter, total N, alkaline N, total P, available P and available K significantly increased. The interactive effects of density and N and P additions on soil pH value, organic matter, N, P and K contents were significant in the stands. Generally, the effects of N and P additions, stand density and the both interaction on soil chemistry property were significant.

Key words: Acacia auriculiformis, stand density, nitrogen addition, phosphorus addition, soil chemical property, interaction

FENG Hui-Fang, LIU Luo-Yu, XUE Li. Effects of nitrogen and phosphorus additions and stand density on soil chemical property in Acacia auriculiformis stands[J]. Chin J Plant Ecol, 2019, 43(11): 1010-1020.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2019.0168

https://www.plant-ecology.com/EN/Y2019/V43/I11/1010

Figures/Tables 10

Table 1 Characteristics of the Acacia auriculiformis stands

林分 Stand	林龄 Stand age (a)	郁闭度 Canopy density	密度 Density (trees·hm^-2)	胸径 Diameter at breast height (cm)	树高 Tree height (m)	坡向 Aspect	坡度 Slope (°)	主要林下植物 Main undergrowth plant
低密度 Low density	10	0.65	1 667	11.4	11.2	SW 43°	28	桃金娘、芒草、玉叶金花、梅叶冬青、了哥王、米碎花、滇牡丹、黑面神 Rhodomyrtus tomentosa, Miscanthus sinensis, Mussaenda pubescens, Ilex asprella, Wikstroemia indica, Eurya chinensis, Paeonia delavayi, Breynia fruticosa
中密度 Medium density	10	0.70	2 500	10.6	10.2	SW 44°	31	玉叶金花、桃金娘、芒草、芒萁、梅叶冬青、米碎花 M. pubescens, R. tomentosa, M. sinensis, Dicranopteris pedata, I. asprella, E. chinensis
较高密度 Relatively high density	10	0.75	4 444	9.8	10.1	SW 44°	30	芒萁、芒草、桃金娘、梅叶冬青、玉叶金花、米碎花 D. pedata, M. sinensis, R. tomentosa, I. asprella, M. pubescens, E. chinensis
高密度 High density	10	0.80	10 000	8.6	11.1	SW 42°	27	玉叶金花、桃金娘、海金沙、芒草、芒萁、梅叶冬青 M. pubescens, R. tomentosa, Lygodium japonicum, M. sinensis, D. pedata, I. asprella

Fig. 1 Soil pH value of the Acacia auriculiformis stands under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05).

Fig. 2 Soil organic matter (SOM) content of Acacia auriculiformis stands under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05).

Fig. 3 Soil total N (TN) content of Acacia auriculiformis stands under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05).

Fig. 4 Soil alkaline N (AN) content of Acacia auriculiformis stands under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05).

Fig. 5 Soil total P (TP) content of Acacia auriculiformis stands under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05).

Fig. 6 Soil available P (AP) content of Acacia auriculiformis stands s under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05).

Fig. 7 Soil total K (TK) content of Acacia auriculiformis stands under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05).

Fig. 8 Soil available K (AK) content of Acacia auriculiformis stands under different treatments and densities (mean ± SE). CK, control; N, N addition; P, P addition; N+P, N and P addition. Different lowercase letters indicate significant differences at 0.05 levels between nitrogen and phosphorus additions (p < 0.05)

Table 2 Interaction between NP treatments and density in soil chemical properties of Acacia auriculiformis stands

指标 Parameter	NP处理 NP treatments		密度 Density		密度与NP处理交互作用 Interaction between density and NP treatments
指标 Parameter	F	p	F	p	F	p
pH	734.716	0.000	52.721	0.000	10.57	0.000
有机质 SOC	379.581	0.000	2 764.643	0.000	36.204	0.000
全氮 TN	81.08	0.000	680.233	0.000	6.732	0.000
全磷 TP	2 445.366	0.000	651.776	0.000	16.592	0.000
全钾 TK	4.887	0.007	189.284	0.000	8.448	0.000
碱解氮 AN	1 734.794	0.000	265.347	0.000	8.02	0.000
有效磷 AP	1 345.668	0.000	322.54	0.000	43.607	0.000
速效钾 AK	412.176	0.000	536.283	0.000	24.536	0.000

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