不同氮添加量和添加方式对南亚热带4个主要树种幼苗生长的影响

doi:10.17521/cjpe.2015.0092

摘要/Abstract

摘要：

为阐明南亚热带4个主要树种——海南红豆(Ormosia pinnata)、马占相思(Acacia mangium)、木荷(Schima superba)和马尾松(Pinus massoniana)幼苗生长对不同氮添加量和添加方式的响应差异, 进行了幼苗模拟氮添加实验。实验设置3个氮添加水平(对照: 背景大气氮沉降量5.6 g N·m^-2·a^-1, 中氮: 15.6 g N·m^-2·a^-1, 高氮: 20.6 g N·m^-2·a^-1), 每个水平分两种添加方式(幼苗冠层施氮和土壤表层施氮), 共6个处理: (1)土壤对照(S-CK); (2)土壤中氮(S-MN); (3)土壤高氮(S-HN); (4)冠层对照(C-CK); (5)冠层中氮(C-MN); (6)冠层高氮(C-HN), 每个处理设置6个重复。研究结果表明: 不同氮添加量下, 土壤施氮和冠层施氮对植物幼苗生长的影响不同, 氮添加量、氮添加方式和物种3个因子之间存在显著的交互效应。与对照相比, S-MN增加了马占相思和木荷幼苗的生物量, 降低了马尾松的株高和生物量, 而C-MN仅增加了马占相思的生物量, 对其他3个树种没有影响; S-HN增加了马占相思的生物量, 显著降低了马尾松的基径、株高和生物量(p < 0.01), C-HN增加了马占相思、木荷和马尾松的基径、株高和生物量(p < 0.01)。不同氮添加量和氮添加方式对幼苗生长的影响因物种而异, 所有氮处理下海南红豆和马占相思的生长均明显快于木荷和马尾松; 木荷和马尾松幼苗的生长在两种氮添加方式间差异显著, 冠层施氮比土壤施氮对其幼苗生长的促进作用更大。由此可见: 在氮沉降背景下, 阔叶豆科植物(海南红豆、马占相思)比阔叶非豆科植物(木荷)生长快; 阔叶树种(海南红豆、马占相思和木荷)比针叶树种(马尾松)生长快。在长期氮沉降环境下, 不同物种生长的差异响应有可能导致亚热带森林物种组成发生变化。

关键词: 生物量, 高氮, 豆科植物, 冠层加氮

Abstract: Aims

Numerous studies have been carried out concerning the effects of atmospheric nitrogen (N) deposition on forest ecosystems. However, most of previous experiments were conducted by adding N fertilizer to the surface soil directly. Realistically simulated canopy N deposition and comparison of the effects of soil N addition and canopy N addition on ecosystems were rare. Our purpose is to better understand the effects of two N addition regimes at different N addition levels on seeding growth in major tree species of subtropical China.

Methods

A 2-year pot experiment was conducted, with seedlings of four species (Ormosia pinnata, Acacia mangium, Schima superba, Pinus massoniana) grown in pots subjected to treatments of three levels (ambient, medium, and high) and two regimes (in soil vs. on canopy) of N addition, specifically including S-CK (ambient N addition in soil), S-MN (medium N addition in soil), S-HN (high N addition in soil), C-CK (ambient N addition on canopy), C-MN (medium N addition on canopy), and C-HN (high N addition on canopy). The total amounts of added N in the three N levels were 5.6, 15.6 and 20.6 g·m^-2·a^-1, respectively. Tree basal diameter and tree height were measured in June and December 2012, and November 2013. All trees were harvested in November 2013, and then the biomass was calculated according to the dry-mass of roots, shoots and leaves; the root-shoot ratios were calculated.

Important findings

N treatments affected seeding growth, along with significant interactive effects among N addition level, N addition regime and species. Compared to CK, S-MN stimulated the biomass in seedlings of A. mangium and S. superba, but decreased the tree height and biomass in seedlings of P. massoniana; C-MN increased the biomass in seedlings of A. mangium; S-HN promoted the biomass in seedlings of A. mangium, but significantly decreased the biomass, basal diameter and tree height in seedlings of P. massoniana (p < 0.01); C-HN led to the greater growth in seedlings of A. mangium, S. superba and P. massoniana (p < 0.01). N addition responses were dependent upon plant species: while seedlings in O. pinnata and A. mangium grew faster than S. superba and P. massoniana under all N treatments, the differences in the growth of S. superba and P. massoniana seedlings between the two N addition regimes were more pronounced than in O. pinnata and A. mangium seedlings. We concluded that legumes (O. pinnata and A. mangium) grew faster than non-legumes (S. superba). And growth stimulation in broadleaved trees (O. pinnata, A. mangium, and S. superba) by N addition was significantly greater than in coniferous trees (P. massoniana). Our findings suggest that the relatively high and chronic atmospheric N deposition in subtropical forest ecosystems may lead to changes in species composition.

Key words: biomass, high N addition levels, legumes, N addition on the canopy

刘双娥, 李义勇, 方熊, 黄文娟, 龙凤玲, 刘菊秀. 不同氮添加量和添加方式对南亚热带4个主要树种幼苗生长的影响. 植物生态学报, 2015, 39(10): 950-961. DOI: 10.17521/cjpe.2015.0092

LIU Shuang-E,LI Yi-Yong,FANG Xiong,HUANG Wen-Juan,LONG Feng-Ling,LIU Ju-Xiu. Effects of the level and regime of nitrogen addition on seedling growth of four major tree species in subtropical China. Chinese Journal of Plant Ecology, 2015, 39(10): 950-961. DOI: 10.17521/cjpe.2015.0092

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2015.0092

https://www.plant-ecology.com/CN/Y2015/V39/I10/950

图/表 10

表1 氮添加处理前土壤理化参数背景值(平均值±标准偏差, n = 12)

Table 1 Background values of soil physicochemical properties at beginning of the experiment (mean ± SD, n = 12)

土壤深度 Soil depth (cm)	pH值 pH value	有效磷 Available phosphorus (mg·kg^-1)	硝态氮 Nitrate nitrogen (mg·kg^-1)	铵态氮 Ammonium nitrogen (mg·kg^-1)	有机质 Organic matter (g·kg^-1)
0-20	3.99 ± 0.096	0.84 ± 0.072	17.39 ± 1.34	6.01 ± 0.69	22.72 ± 1.20

附录I 两种氮添加方式下土壤含水量(平均值±标准偏差)

Supplement I Soil water content (%) under two N addition regimes (mean ± SD)

物种 Species	对照 Ambient N addition		中氮 Medium N addition		高氮 High N addition
物种 Species	土壤施氮 SN	冠层施氮 CN	土壤施氮 SN	冠层施氮 CN	土壤施氮 SN	冠层施氮 CN
海南红豆 Ormosia pinnata	17.11 ± 1.68	14.07 ± 1.40	18.28 ± 1.08	15.74 ± 1.99	17.06 ± 1.25	16.67 ± 1.01
马占相思 Acacia mangium	17.63 ± 2.17	13.87 ± 2.48	19.69 ± 0.39^a	13.83 ± 2.74^b	16.65 ± 1.12	14.33 ± 3.51
木荷 Schima superba	18.14 ± 1.13	16.73 ± 1.61	19.18 ± 0.80^a	16.03 ± 1.68^b	17.22 ± 0.81	15.70 ± 0.60
马尾松 Pinus massoniana	17.39 ± 2.49	15.52 ± 1.72	18.03 ± 1.18	17.28 ± 0.33	17.60 ± 0.74	15.85 ± 0.93

表2 氮添加量和氮添加方式对4种树种幼苗生长的影响(三因素方差分析)

Table 2 Effects of N addition level and regime on seedling growth in four major tree species (three-way ANOVA)

主要因素及相互作用 Main factors and interactions	基径 Basal diameter		株高 Tree height		生物量 Biomass		土壤pH Soil pH
主要因素及相互作用 Main factors and interactions	F and p values	d.f.	F and p values	d.f.	F and p values	d.f.	F and p values	d.f.
处理水平 Level	6.721 0.002	2	4.013 0.021	2	3.608 0.039	2	70.555 <0.001	2
施氮方式 Regime	0.906 0.344	1	0.544 0.463	1	6.421 0.017	2	107.545 <0.001	1
物种 Species	48.661 <0.001	3	386.887 <0.001	3	122.901 <0.001	3	31.299 <0.001	3
水平×施氮方式 Level × regime	19.591 <0.001	2	1.799 0.171	2	12.949 <0.001	2	7.314 0.002	3
水平×物种 Level × species	5.293 <0.001	6	2.088 0.062	6	12.266 <0.001	6	1.681 0.146	6
施氮方式×物种 Regime × species	7.207 <0.001	3	8.017 <0.001	3	11.592 <0.001	3	3.458 0.023	3
水平×施氮方式×物种 Level × regime × species	9.227 <0.001	6	1.673 0.136	6	10.981 <0.001	6	5.313 <0.001	6
误差 Error		95		95		103		48

图1 不同氮添加量和氮添加方式对幼苗基径的影响(平均值±标准偏差)。不同小写字母(a, b)和大写字母(A, B)分别表示土壤氮添加和冠层氮添加下低氮、中氮、高氮处理间差异显著(p < 0.05); *表示两种施氮方式间有差异(Duncan多重比较; * p < 0.05, ** p < 0.01)。CK, 对照处理; HN, 高氮处理; MN, 中氮处理。CN, 冠层氮添加; SN, 土壤氮添加。AM, 马占相思; OP, 海南红豆; PM, 马尾松; SS, 木荷。

Fig. 1 Effects of N addition level and regime on tree basal diameter in four tree species (mean ± SD). Different lowercase letters (a, b) and capital letters (A, B) above the error bars indicate significant differences among N addition levels in soil and on canopy, respectively, in each species (p < 0.05); * above the error bars indicate significant difference between two N addition regimes (Duncan multiple range test; * p < 0.05, ** p < 0.01). CK, ambient N addition; HN, high N addition; MN, medium N addition. CN, N addition on canopy; SN, N addition in soil. AM, Acacia mangium; OP, Ormosia pinnata; PM, Pinus massoniana; SS, Schima superba.

图2 不同氮添加量和氮添加方式对幼苗株高的影响(平均值±标准偏差)。不同小写字母(a, b)和大写字母(A, B)分别表示土壤氮添加和冠层氮添加下低氮、中氮、高氮处理间差异显著(p < 0.05); *表示两种施氮方式间有差异(Duncan多重比较; * p < 0.05, ** p < 0.01)。CK, 对照处理; HN, 高氮处理; MN, 中氮处理。CN, 冠层氮添加; SN, 土壤氮添加。AM, 马占相思; OP, 海南红豆; PM, 马尾松; SS, 木荷。

Fig. 2 Effects of N addition level and regime on tree height in four tree species (mean ± SD). Different lowercase letters (a, b) and capital letters (A, B) above the error bars indicate significant differences among N addition levels in soil and on canopy, respectively, in each species (p < 0.05); * above the error bars indicate significant differences between two N addition regimes (Duncan multiple range test; * p < 0.05, ** p < 0.01). CK, ambient N addition; HN, high N addition; MN, medium N addition. CN, N addition on canopy; SN, N addition in soil. AM, Acacia mangium; OP, Ormosia pinnata; PM, Pinus massoniana; SS, Schima superba.

图3 不同氮添加量和氮添加方式对幼苗生物量的影响(平均值±标准偏差)。不同小写字母(a, b)和大写字母(A, B)分别表示土壤氮添加和冠层氮添加下低氮、中氮、高氮处理间差异显著(p < 0.05); *表示两种施氮方式间有差异(Duncan多重比较; * p < 0.05, ** p < 0.01)。CK, 对照处理; HN, 高氮处理; MN, 中氮处理。CN, 冠层氮添加; SN, 土壤氮添加。AM, 马占相思; OP, 海南红豆; PM, 马尾松; SS, 木荷。

Fig. 3 Effects of N addition level and regime on biomass in four tree species (mean ± SD). Different lowercase letters (a, b) and capital letters (A, B) above the error bars indicate significant differences among N addition levels in soil and on canopy, respectively, in each species (p < 0.05); * above the error bars indicate significant differences between two N addition regimes (Duncan multiple range test; * p < 0.05, ** p < 0.01). CK, ambient N addition; HN, high N addition; MN, medium N addition. CN, N addition on canopy; SN, N addition in soil. AM, Acacia mangium; OP, Ormosia pinnata; PM, Pinus massoniana; SS, Schima superba.

图4 不同氮添加量和氮添加方式下对幼苗各部位(粗根、细根、茎和叶)生物量积累的影响(平均值±标准差)。不同小写字母(a, b)和大写字母(A, B)分别表示土壤氮添加和冠层氮添加下低氮、中氮、高氮处理间差异显著(p < 0.05); *表示两种施氮方式间有差异(Duncan多重比较; * p < 0.05, ** p < 0.01)。CK, 对照处理; HN, 高氮处理; MN, 中氮处理。CN, 冠层氮添加; SN, 土壤氮添加。AM, 马占相思; OP, 海南红豆; PM, 马尾松; SS, 木荷。

Fig. 4 Effects of N addition level and regime on biomass accumulation in leaves, stem and coarse-roots and fine-roots (mean ± SD). Different lowercase letters (a, b) and capital letters (A, B) above the error bars indicate significant differences among N addition levels in soil and on canopy, respectively, in each species (p < 0.05); * above the error bars indicate significant differences between two N addition regimes (Duncan multiple range test; * p < 0.05, ** p < 0.01). CK, ambient N addition; HN, high N addition; MN, medium N addition. CN, N addition on canopy; SN, N addition in soil. AM, Acacia mangium; OP, Ormosia pinnata; PM, Pinus massoniana; SS, Schima superba.

表3 不同氮添加量和氮添加方式下幼苗的根冠比(平均值±标准偏差)

Table 3 Root-shoot ratios under different nitrogen (N) treatments (mean ± SD)

物种 Species	冠层施N N addition on canopy			土壤施N N addition in soil
物种 Species	CK	MN	HN	CK	MN	HN
海南红豆 Ormosia pinnata	0.275 ± 0.029	0.307 ± 0.003	0.315 ± 0.067	0.453 ± 0.103^a	0.332 ± 0.018^ab	0.253 ± 0.009^b
马占相思 Acacia mangium	0.251 ± 0.071	0.222 ± 0.039	0.317 ± 0.059	0.262 ± 0.059	0.235 ± 0.005	0.391 ± 0.175
木荷 Schima superba	0.514 ± 0.128	0.489 ± 0.021	0.754 ± 0.241	0.575 ± 0.055	0.544 ± 0.124	0.608 ± 0.008
马尾松 Pinus massoniana	0.336 ± 0.119	0.277 ± 0.021	0.223 ± 0.070	0.170 ± 0.035^b	0.299 ± 0.075^ab	0.343 ± 0.003^a

表4 不同树种幼苗生长对氮添加方式和氮添加量响应差异(Duncan多重比较)

Table 4 Differential responses of seedling growth to N addition regime and level among different tree seedlings (Duncan multiple range test)

		土壤施N N addition in soil			冠层施N N addition on canopy
		CK	MN	HN	CK	MN	HN
豆科与非豆科相比 Legumes versus non-legumes	基径 Base diameter	18.450 0.001	36.161 <0.001	5.461 0.038	5.747 0.03	15.424 0.002	3.38 0.087
	株高 Tree height	46.039 <0.001	32.859 <0.001	8.979 0.011	16.937 0.001	9.629 0.008	9.111 0.009
	生物量 Biomass	9.126 0.029	21.174 0.006	30.829 0.002	0.932 0.379	11.908 0.026	6.263 0.046
阔叶与针叶相比 Broadleaf versus conifers	基径 Basal diameter	0.679 0.338	1.262 0.276	24.355 <0.001	23.799 <0.001	32.911 <0.001	1.297 0.269
	株高 Tree height	2.516 0.129	6.264 0.022	7.065 0.018	11.620 0.003	17.643 <0.001	10.767 0.004
	生物量 Biomass	0.110 0.750	10.299 0.013	8.170 0.017	16.323 0.004	33.324 0.001	1.11 0.323

图5 不同氮添加量和氮添加方式对土壤pH值的影响(平均值±标准偏差)。不同小写字母(a, b)和大写字母(A, B)分别表示土壤氮添加和冠层氮添加下低氮、中氮、高氮处理间差异显著(p < 0.05); *表示两种施氮方式间有差异(Duncan多重比较; * p < 0.05, ** p < 0.01)。CK, 对照处理; HN, 高氮处理; MN, 中氮处理。CN, 冠层氮添加; SN, 土壤氮添加。AM, 马占相思; OP, 海南红豆; PM, 马尾松; SS, 木荷。

Fig. 5 Effects of N addition level and regime on soil pH value (mean ± SD). Different lowercase letters (a, b) and capital letters (A, B) above the error bars indicate significant differences among N addition levels in soil and on canopy, respectively, in each species (p < 0.05); * above the error bars indicate significant differences between two N addition regimes (Duncan multiple range test; * p < 0.05, ** p < 0.01). CK, ambient N addition; HN, high N addition; MN, medium N addition. CN, N addition on canopy; SN, N addition in soil. AM, Acacia mangium; OP, Ormosia pinnata; PM, Pinus massoniana; SS, Schima superba.

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