摘要: 目的研究茂兰喀斯特森林植被自然恢复过程中不同演替阶段土壤养分与化学计量的动态变化规律，探讨两者间的相互关系，定量评价各影响因子对其的解释程度，阐明群落演替与土壤性状演变间的内在耦合关系，旨在为该区域植被的恢复与重建提供理论依据、�/sec> 方法以草本群落、灌木灌丛群落、乔林群落和顶极常绿落叶阔叶混交林群落等演替阶段为研究对象，每个演替阶段各设�?个固定样地，样地内根据不同小生境随机布设12个土壤剖面，分层取样，测定土壤有机碳（SOC）、全氮（TN）、全磷（TP）和全钾（TK）含量，并计算其化学计量比、�/sec> 结果研究区土壤的SOC、TN、TP和TK含量均值分别为54.72�?.67�?.73�?.53 g/kg，且SOC、TP和TN含量相互间均存在显著或极显著正相关，表现出相对一致的变化规律；C:N、C:P、C:K、N:P、N:K和P:K分别�?1.95�?9.16�?.50�?.64�?.550 1�?.085 2；从变异系数来看，除TK含量和C:N属弱变异性以外，其余土壤养分含量及化学计量比均属中等变异性。随植被的正向演替，不同演替阶段的SOC、TN和TP含量基本上均呈上升趋势，而TK含量则呈倒“V”字型变化，表现为：乔林阶段 > 顶极阶段 > 灌木灌丛阶段 > 草本阶段；各演替阶段不同土层深度的SOC、TN和TP含量均表现为0 ~ 10 cm要高�?0 ~ 20 cm，而TK含量则无明显变化。土壤化学计量特征随演替的进展其变化趋势差异较大；在土壤剖面层次上，各演替阶段除C:N不同土层深度间无显著差异以外，其余也均表现为0 ~ 10 cm要高�?0 ~ 20 cm。冗余分析结果表明，土层深度和群落演替是调控该区域土壤养分含量和化学计量特征的主要因素，对其解释程度分别�?2.82%�?2.19%、�/sec> 结论研究区土壤有机碳含量相对较高，氮、磷养分含量丰富，植物生长受氮（或磷）素限制的原因可能是土壤养分含量的有效性偏低所致；减少人为干扰、加之适当的保护，促进群落的正向演替，提高喀斯特森林生态系统的稳定性和抗干扰性，有利于土壤养分的积累；研究初步揭示了众多影响因子对土壤养分含量和化学计量特征的解释程度，对喀斯特森林的保护具有重要的指导意义、�/sec>

关键诌�
• 喀斯特森林/
• 自然恢复/
• 土壤/
• 化学计量特征/
• 茂兰自然保护匹�/a>

Abstract: ObjectiveThe dynamics of soil nutrition and stoichiometric characteristics of different successional stages during the process of natural restoration in Maolan karst forest vegetation of southwestern China were studied to explore the relationship between them, and quantitatively evaluate the degree of explanation of impact factors on soil stoichiometric characteristics, and clarify the intrinsic coupling relationship between the vegetation community succession and soil property evolution, in order to provide the theoretical basis for restoration and reconstruction of degraded karst forest. MethodTaking he herb stage, shrub stage, arbor stage and climax stage as the research objects, three fixed sample plots were set up in each succession stage, 12 soil profiles were randomly set up according to different niche conditions and laminated sampling. The contents of SOC, TN, TP and TK were measured and the stoichiometric ratio was calculated. ResultThe mean contents of SOC, TN, TP and TK of soil in the research region were 54.72, 4.67, 0.73 and 8.53 g/kg, respectively. There were significantly or very significantly positive correlations between the contents of SOC, TP and TN, showing relatively consistent law of change. The ratios of C:N, C:P, C:K, N:P, N:K and P:K were 11.95, 79.16, 6.50, 6.64, 0.550 1 and 0.085 2, respectively. In terms of coefficient of variation, except TK content and C:N belonged to weak variability, the soil nutrient content and stoichiometric ratio were all medium variability. With the forward succession of vegetation, the SOC, TN and TP contents in different succession stages basically increased, but the change trend of TK content was reverse V-shape, showed arbor stage > climax stage > shrub stage > herb stage. The contents of SOC, TN and TP of different soil depth at each succession stage showed that 0�?0 cm was higher than 10�?0 cm, but the content of TK had no obvious change. The variation trend of the soil stoichiometric characteristics with the succession was quite different. At the soil profile level, except for no significant difference between the depth of different soil layers in C:N, the others showed that 0�?0 cm was higher than 10�?0 cm. The results of redundancy analysis showed that soil depth and community succession were the main factors to regulate soil nutrition content and stoichiometric characteristics in the region, with the explanatory degree of 32.82% and 32.19%, respectively. ConclusionSoil organic carbon content in the study area was relatively high, N and P contents were rich , plant growth restricted by N (or P) element may be caused by the low effectiveness of soil nutrient content.Reducing human disturbance, and appropriate protection can promote the positive succession of community, improve the stability and anti-interference of the karst forest ecosystem, and conducive to the accumulation of soil nutrients.The results preliminarily reveal the degree to which many influencing factors can explain soil nutrition content and stoichiometric characteristics, which is of important guiding significance to the protection of karst forest.

Key words:
• karst forest/
• natural restoration/
• soil/
• stoichiometric characteristics/
• Maolan Natural Reserve

�?nbsp; 1样地点位置图

Figure 1.Location of the sample plots

下载: 全尺寸图牆�/a> 幻灯牆�/a>

�?nbsp; 2不同演替阶段土壤有机碳、全氮、全磷和全钾含量

数据为“平均� ± 标准差”；不同小写字母的表示同一土层深度不同演替阶段间差异显著（P< 0.05）；不同大写字母的表示同一演替阶段不同土层深度间差异显著（P< 0.05）。下同。The values are “mean ± SD�? Different lowercase indicates significant differences between different successional stages of the same soil depth (P< 0.05), and different capital letters indicate significant differences between different soil depths of the same successional stage (P< 0.05). The same below.

Figure 2.Contents of soil organic carbon, total nitrogen, total phosphorus and total potassium in the soils for different successional stages

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�?nbsp; 3不同演替阶段各土层土壤的C:N、C:P、C:K、N:P、N:K和P:K

Figure 3.Ratios of C:N, C:P, C:K, N:P, N:K and P:K of the various soil layers at different successional stages

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�?nbsp; 4群落演替、土层深度、群落多样性指数等与土壤化学计量特征的RDA排序

数字1 ~ 23分别代表土层深度、群落演替、凋落物现存量、物种丰富度Margalef指数、生态优势度Simpson指数、信息多样性Shannon-Wiener指数、均匀度Pielou指数、比叶面积、土壤pH值、土壤密度、土壤体积含水量、土壤非毛管孔隙度、土壤毛管孔隙度、植物叶片C、N、P、K含量、凋落物的C、N、P、K含量和N、P重吸收率�??23 are the abbreviation of soil depth, community succession, biomass of forest litter, Margalef index, Simpson index, Shannon-Wiener index, Pielou index, specific leaf area, soil pH value, soil bulk density, soil volumetric water content, soil non-capillary porosity, soil capillary porosity, the content of carbon, nitrogen, phosphorus and potassium of leaves, the content of carbon, nitrogen, phosphorus and potassium of litter, nitrogen and phosphorus resorption rate, respectively.

Figure 4.RDA ordination of community succession, soil depth, community diversity indices and soil stoichiometric characteristics

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�?nbsp; 1样地基本概况

Table 1.Basic situation of sample plots

演替阶段 Successional stage	样地叶�br/>Plot No.	海拔 Altitude/m	坡度 Slope degree/（°）	坡位 Slope position	裸岩玆�br/>Bare rock ratio/%	优势秌�br/>Dominant species	土壤 Soil
HS	2	626	25 ~ 30	中坡 Middle slope	65	马唐Digitaria sanguinalis 白茅Imperata cylindrical �Pteridium aquilinum 芒草Miscanthussp.	石灰土Calcareous soil
	10	706	25 ~ 30	中坡 Middle slope	55
	11	692	20 ~ 25	中坡 Middle slope	75
SS	7	789	25 ~ 30	中坡 Middle slope	85	瓜木Alangium platanifolium 火棘Pyracantha fortuneana 南天�Nandina domestica 香叶�Lindera communis 青篱�Tirpitzia sinensis	石灰土Calcareous soil
	8	775	20 ~ 25	中坡 Middle slope	85
	12	779	25 ~ 30	中坡 Middle slope	80
AS	1	770	20 ~ 25	下坡 Lower slope	75	卵果海桐Pittosporum lenticellatum 圆果化香Platycarya longipes 木姜润楠Machilus litseifolia 光皮梾木Cornus wilsoniana 香叶�Lindera communis 牛耳枫Ficus microcarpa	石灰土Calcareous soil
	3	800	20 ~ 25	中坡 Middle slope	70
	6	769	20 ~ 25	下坡 Lower slope	80
CS	4	741	30 ~ 35	中坡 Middle slope	75	多脉青岗Cyclobalanopsis multinervis 云贵鹅耳枥Carpinus pubescens 粗柄�Phoebe crassipedicella 光皮梾木Cornus wilsoniana 丝栗�castanopsis fargesii 天峨�Acer wangchii	石灰土Calcareous soil
	5	744	30 ~ 35	下坡 Lower slope	85
	9	779	15 ~ 20	下坡 Lower slope	80
注：HS、SS、AS和CS分别为草本阶段、灌木灌丛阶段、乔林阶段和顶极阶段。下同� Notes: HS, SS, AS and CS represent herb stage, shrub stage, arbor stage and climax stage, respectively. The same below.

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�?nbsp; 2土壤养分与化学计量特征的统计分析�?/p>

Table 2.Statistical analysis of soil nutrients and stoichiometric characteristics

指标 Index	样本� Sample number	最大� Max./(g·kg� 1)	最小� Min./(g·kg� 1)	平均� Mean/(g·kg� 1)	标准� SD/(g·kg� 1)	偏度系数 Skewness coefficient	峰度系数 Kurtosis coefficient	变异系数 CV/%
SOC	24	82.45	28.61	54.72	14.12	0.35	� 0.44	25.80
TN	24	7.83	2.25	4.67	1.41	0.68	� 0.22	30.28
TP	24	1.08	0.36	0.73	0.22	� 0.27	� 0.95	30.12
TK	24	10.82	5.16	8.53	1.47	� 0.47	0.17	17.21
C:N	24	15.37	9.76	11.95	1.62	0.40	� 0.59	13.59
C:P	24	130.41	40.35	79.16	20.13	0.65	0.86	25.43
C:K	24	10.09	3.89	6.50	1.63	0.44	� 0.45	25.12
N:P	24	9.63	3.90	6.64	1.48	0.50	� 0.37	22.37
N:K	24	0.857 1	0.339 5	0.550 1	0.142 6	0.47	� 0.50	25.92
P:K	24	0.118 8	0.041 5	0.085 2	0.021 6	� 0.35	� 0.54	25.38
注：CV � 20.0%属弱变异性，20.0% < CV < 50.0%属中等变异性，CV � 50.0%属强变异性。Notes: CV � 20.0%, weak variability; 20.0% < CV < 50.0%, medium variability; CV � 50.0%, strong variability.

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�?nbsp; 3土壤养分与化学计量特征的相关分析

Table 3.Correlation analysis between soil nutrients and soil stoichiometric characteristics

土层深度 Soil depth/cm	指标 Index	对数转换 Log transformation ln(x+ 1)
		SOC	TN	TP	TK	C:N	C:P	C:K	N:P	N:K	P:K
0 ~ 10	ln(SOC + 1)	1.000	0.877**	0.854**	0.529	�	�	�	� 0.348	0.720**	0.700*
	ln(TN + 1)		1.000	0.916**	0.676*	�	� 0.670*	0.265	�	�	0.658*
	ln(TP + 1)			1.000	0.544	� 0.610*	�	0.373	�	0.749**	�
	ln(TK + 1)				1.000	� 0.593*	� 0.380	�	0.014	�	�
10 ~ 20	ln(SOC + 1)	1.000	0.795**	0.666*	0.661*	�	�	�	� 0.206	0.299	0.360
	ln(TN + 1)		1.000	0.739**	0.597*	�	� 0.378	0.195	�	�	0.494
	ln(TP + 1)			1.000	0.585*	� 0.324	�	0.064	�	0.303	�
	ln(TK + 1)				1.000	� 0.120	� 0.293	�	� 0.238	�	�
0 ~ 20	ln(SOC + 1)	1.000	0.875**	0.839**	0.656*	�	�	�	� 0.410	0.495	0.593*
	ln(TN + 1)		1.000	0.867**	0.672*	�	� 0.629*	0.177	�	�	0.607*
	ln(TP + 1)			1.000	0.576*	� 0.503	�	0.256	�	0.558	�
	ln(TK + 1)				1.000	� 0.395	� 0.365	�	� 0.166	�	�
注：*相关性显著（P< 0.05），**相关性极显著＇�i>P< 0.01），� 表示存在自相关关系，不宜进行相关分析� Notes:*and**indicate significant correlations at the 0.05 and 0.01 probability levels, respectively. � indicates that autocorrelation exists and no analysis is conducted.

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�?nbsp; 4RDA排序�?轴的基本特征

Table 4.General characteristics of the first two axis of RDA ordination

参数 Parameter	�?� Axis 1	�?� Axis 2
特征� Eigenvalue	0.477	0.317
化学计量特征−影响因子相关系� Stoichiometry-impact factors correlation	0.992	0.975
化学计量数据累计解释� Cumulative percentage variance of stoichiometry/%	47.70	79.50
化学计量特征−影响因子关系累计解释量 Cumulative percentage variance of stoichiometry-impact relation/%	49.40	82.20
土层深度 Soil depth	0.723	0.434
群落演替 Community succession	� 0.570	0.676
凋落物现存量 Biomass of forest litter	0.337	� 0.429
物种丰富度Margalef指数 Species richness Margalef index (R)	� 0.369	0.582
生态优势度Simpson指数 Ecological dominance Simpson index (D)	� 0.296	0.508
信息多样性Shannon-Wiener指数 Information diversity Shannon-Wiener index (H)	� 0.359	0.553
均匀度Pielou指数 Evenness Pielou index (J)	� 0.287	0.480
比叶面积 Specific leaf area	0.395	� 0.556
土壤pH� Soil pH value	� 0.140	0.437
土壤密度 Soil bulk density	0.788	� 0.128
土壤体积含水� Soil volumetric water content	� 0.542	0.098
土壤非毛管孔隙度 Soil non-capillary porosity	� 0.483	� 0.029
土壤毛管孔隙� Soil capillary porosity	� 0.557	0.138
植物叶片C含量 Plant leaf carbon content	0.358	� 0.587
植物叶片N含量 Plant leaf nitrogen content	0.026	0.102
植物叶片P含量 Plant leaf phosphorus content	0.219	� 0.265
植物叶片K含量 Plant leaf potassium content	0.396	� 0.607
凋落物C含量 Litter carbon content	0.312	� 0.249
凋落物N含量 Litter nitrogen content	� 0.410	0.700
凋落物P含量 Litter phosphorus content	� 0.090	0.303
凋落物K含量 Litter potassium content	� 0.280	0.629
N重吸收率 N resorption rate	0.441	� 0.696
P重吸收率 P resorption rate	0.421	� 0.721

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�?nbsp; 5群落演替、土层深度、群落多样性指数等对土壤化学计量特征的解释程度

Table 5.Interpretation degree of soil stoichiometric characteristics in community succession, soil depth, community diversity indices

影响因子 Impact factor	重要性排庎�br/> Importance sequencing	解释程度 Interpretive degree/%	F	P
土层深度 Soil depth	1	32.82	10.215	0.002
群落演替 Community succession	2	32.20	17.578	0.002
凋落物现存量 Biomass of forest litter	12	1.04	1.633	0.240
物种丰富� Margalef 指数 Species richness Margalef index (R)	11	1.14	1.492	0.214
生态优势度 Simpson 指数 Ecological dominance Simpson index (D)	9	1.45	2.058	0.128
均匀� Pielou 指数 Evenness Pielou index (J)	10	1.35	2.239	0.120
比叶面积 Specific leaf area	5	5.07	4.488	0.012
土壤 pH � Soil pH value	16	0.73	0.982	0.324
土壤密度 Soil bulk density	17	0.41	0.710	0.550
土壤体积含水� Soil volumetric water content	15	0.83	1.522	0.224
土壤非毛管孔隙度 Soil non-capillary porosity	6	3.83	4.020	0.014
土壤毛管孔隙� Soil capillary porosity	13	0.93	1.211	0.324
植物叶片 N 含量 Plant leaf nitrogen content	7	2.28	2.605	0.066
植物叶片 P 含量 Plant leaf phosphorus content	14	0.83	1.031	0.378
凋落� C 含量 Litter carbon content	4	5.80	4.388	0.010
凋落� N 含量 Litter nitrogen content	8	1.86	2.234	0.114
凋落� K 含量 Litter potassium content	3	7.45	4.751	0.006

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