农牧交错区草地利用方式导致的土壤颗粒组分变化及其对土壤碳氮含量的影响

doi:10.3773/j.issn.1005-264x.2008.03.009

摘要/Abstract

摘要：

以位于农牧交错带的内蒙古多伦县6种主要草地利用方式为研究对象,对0~30 cm土层的土壤颗粒组分、植物地下根系生物量、土壤有机碳(Soil organic carbon, SOC)和土壤全氮(Total nitrogen, TN)含量进行了测定分析。6种草地利用方式分别为自由放牧、刈割、围封禁牧、弃耕、人工牧草(紫花苜蓿(Medicago sativa))和青储作物(玉米(Zea mays))栽培。对土壤粒径分布的分维分析表明,自由放牧样地的土壤分维数明显低于其余5种类型的草地利用样地,表现出较大的土壤质地异质性。在土壤颗粒组分方面,弃耕样地和人工牧草样地的土壤粘粒(<0.005 mm)和粉粒(0.005~0.05 mm)含量要明显高于其它草地利用方式,而自由放牧样地呈现相反的变异趋势。除人工牧草样地和自由放牧样地之外,代表其余4种类型草地利用方式的样地的粘、粉粒含量均随土层加深而降低。6种草地利用方式中,土壤砂粒(0.05~1 mm)含量均与土壤碳氮含量呈负相关关系;除自由放牧样地和人工牧草样地外,其余4种草地利用方式的土壤粘粒与土壤碳氮含量均表现为显著正相关;植物根系生物量与土壤碳氮含量和粘、粉粒含量均呈显著正相关;地上生物量和凋落物仅与粘粒含量存在显著正相关关系。以上差异说明草地利用变化有可能通过影响植被而改变土壤物理性状,同时土壤碳氮含量和土壤颗粒组分的分布特征以及它们之间的相关关系受土地利用方式的影响较大。根系生物量和土壤粘粒含量可以共同解释土壤碳氮含量变异的70%,自变量的独立解释量约为20%。回归方程为:SOC = 1.08×[粘粒含量]+0.01×[根系生物量]-19.45,TN=0.079×[粘粒含量]+0.001×[根系生物量]-1.143。

关键词: 土地利用, 土壤质地, 草地, 分维分析, 相关分析

Abstract:

Aims In this study, variations of soil particle size distribution and correlations with soil C and N were studied on sites representing six different land-use types in the steppe grasslands of Inner Mongolia, Northern China. The six land-use types are grazing exclusion by fencing (GE), mowing (MW), free grazing (FG), fallow (FL), alfalfa pasture (AP), and corn plantation (CP). Our objectives were to: (a) assess variability of soil particle size distribution across different land-use types in the steppe grasslands of northern China and (b) examine correlations of soil particle size distribution with soil C and N as affected by land-uses.

Methods Twenty-four sampling plots, each 30 m×30 m, were established on sites representing the six land-use types. Measurements were made on soil particle size distribution, aboveground biomass, root biomass, litter, soil organic carbon (SOC) and soil total nitrogen (TN) in the 0-10, 10-20 and 20-30 cm soil layers. Data were evaluated by one-way analysis of variance and correlation analysis using SPSS. Fractal dimension of soil particle size distribution was calculated using the method of Yang et al. (1993).

Important findings Fractal dimension of soil particle size distribution was lowest in the FG among the six land-use types. Soil clay (<0.005 mm) and silt (0.005-0.05 mm) content of the FL and AP were consistently higher than the other four land-use types; whereas those of the FG were consistently lower. Clay and silt content decreased with soil depth except for the AP and FG. Soil sand content was significantly negatively correlated withSOC and TN for all land-use types, while soil clay content was significantly positively correlated with SOC and TN except for FG and AP. Regardless of the land-use types, root biomass was found to be significantly positively correlated with SOC, TN and soil clay and silt content. Aboveground biomass and litter were significantly positively correlated with only clay content. Root biomass and clay content together explained 70% of the variance in SOC and soil TN, and separately only 20% of the variance each. The relationships were best described as: SOC = 1.08 × clay% + 0.01 × biomass _roots-19.45,TN=0.079×clay%+0.001×biomass_roots-1.143. Findings indicate that land-use types can have significant effects on soil physical properties as well as SOC and soil TN and consequently alter the relationships of soil particle size distribution with SOC and soil TN.

Key words: land-use, soil texture, grassland, fractal dimension analysis, correlation analysis

田佳倩, 周志勇, 包彬, 孙建新. 农牧交错区草地利用方式导致的土壤颗粒组分变化及其对土壤碳氮含量的影响. 植物生态学报, 2008, 32(3): 601-610. DOI: 10.3773/j.issn.1005-264x.2008.03.009

TIAN Jia-Qian, ZHOU Zhi-Yong, BAO Bin, SUN Jian-Xin. VARIATIONS OF SOIL PARTICLE SIZE DISTRIBUTION WITH LAND-USE TYPES AND INFLUENCES ON SOIL ORGANIC CARBON AND NITROGEN. Chinese Journal of Plant Ecology, 2008, 32(3): 601-610. DOI: 10.3773/j.issn.1005-264x.2008.03.009

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链接本文: https://www.plant-ecology.com/CN/10.3773/j.issn.1005-264x.2008.03.009

https://www.plant-ecology.com/CN/Y2008/V32/I3/601

图/表 7

图1 不同土地利用方式下的土壤粒径分维 FG: 自由放牧Free grazing MW:刈割Mowing GE:围封禁牧Grazing exclusion FL:弃耕Fallow AP:人工牧草Alfalfa pasture CP:青储作物 Corn plantation

Fig.1 Fractal dimension of soil particle by land-use types

图2 不同土地利用方式下各土层土壤颗粒组分的变化相同字母表示在0.05水平下差异不显著

Fig.2 Soil particle size distribution of three soil layers for six land-use types Same letters indicate no significant differences at 5% level among land-use types

表1 不同土地利用方式各土层(0~10,10~20和20~30 cm)土壤粘粒含量(%)和土壤粉粒含量(%)的方差分析

Table 1 One-way ANOVA in soil clay and silt content among three soil layers (0~10,10~20 and 20~30 cm) for six different land-use types

土地利用方式 Land-use types	土壤粘粒含量 Soil clay content (%)		土壤粉粒含量 Soil silt content (%)
土地利用方式 Land-use types	F	p	F	p
自由放牧Free grazing	1.701	0.260	0.108	0.900
刈割Mowing	30.901	0.001	95.781	0.000
围封禁牧Grazing exclusion	45.810	0.000	7.931	0.021
弃耕地 Fallow	6.646	0.030	11.176	0.009
人工牧草地 Alfalfa pasture	2.636	0.151	7.152	0.052
青储作物Corn plantation	4.861	0.056	2.516	0.161

表2 不同土地利用方式植物地上生物量、凋落物、根系生物量,0~30 cm土层土壤有机碳含量、全氮含量、碳氮比和土壤容重(平均值±标准误差)

Table 2 Plant aboveground biomass, litter, root biomass, along with soil organic carbon content, total nitrogen content, C∶N ratio and soil bulk density of three soil layers (0~10 cm, 10~20 cm, 20~30 cm) in six land-use types (Mean±SE)

土地利用方式 Land-use type	地上生物量 Aboveground biomass (g·m^-2)	凋落物 Litter (g·m^-2)	土壤剖面深度 Soil depth (cm)	根系生物量 Root biomass (g·m^-2)	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	碳氮比 C∶N	容重 Bulk density (g·cm^-3)
自由放牧 Free grazing	71.32±21.81	-	0~10	656.15±268.45	7.153±2.169	0.449±0.140	15.961±1.053	1.644
			10~20	169.50±31.00	5.379±1.964	0.413±0.137	12.952±0.942	1.544
			20~30	68.92±19.58	5.176±1.732	0.429±0.099	11.970±2.042	1.552
刈割 Mowing	173.08±23.93	38.47±5.99	0~10	755.96±216.31	22.182±0.720	1.631±0.040	13.604±0.319	1.435
			10~20	168.05±38.97	10.686±1.865	0.850±0.163	12.713±1.849	1.494
			20~30	81.56±21.32	6.427±1.955	0.516±0.098	12.421±2.770	1.559
围封禁牧 Grazing exclusion	251.61±24.18	30.12±15.43	0~10	779.70±53.41	19.073±0.678	1.339±0.064	14.273±0.831	1.414
			10~20	189.25±19.38	12.217±1.075	0.956±0.089	12.809±0.843	1.542
			20~30	71.65±26.86	7.273±1.038	0.533±0.100	13.856±2.018	1.589
弃耕 Fallow	350.96±81.76	29.46±8.76	0~10	751.20±60.13	20.686±3.573	1.596±0.075	12.996±2.420	1.258
			10~20	256.30±57.23	16.740±0.736	1.290±0.034	12.985±0.647	1.535
			20~30	56.14±9.64	11.883±2.813	0.623±0.055	19.209±5.265	1.621
人工牧草 Alfalfa pasture	289.69±87.5	77.58±7.17	0~10	612.29±84.20	16.120±1.144	1.169±0.083	13.821±0.94	1.509
			10~20	258.12±60.60	14.151±0.737	1.107±0.110	12.916±1.687	1.560
			20~30	133.37±26.00	11.830±1.643	0.853±0.187	14.704±4.584	1.581
青储作物 Corn plantation	2197.087±209.43	—	0~10	521.24±173.0	14.486±2.539	0.942±0.066	15.436±2.793	1.478
			10~20	204.27±68.00	15.603±1.112	0.988±0019	15.796±1.078	1.629
			20~30	78.75±54.19	6.526±1.547	0.529±0.091	12.371±1.696	1.640

表2 不同土地利用方式植物地上生物量、凋落物、根系生物量,0~30 cm土层土壤有机碳含量、全氮含量、碳氮比和土壤容重(平均值±标准误差)

土地利用方式 Land-use type	地上生物量 Aboveground biomass (g·m^-2)	凋落物 Litter (g·m^-2)	土壤剖面深度 Soil depth (cm)	根系生物量 Root biomass (g·m^-2)	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	碳氮比 C∶N	容重 Bulk density (g·cm^-3)
自由放牧 Free grazing	71.32±21.81	-	0~10	656.15±268.45	7.153±2.169	0.449±0.140	15.961±1.053	1.644
			10~20	169.50±31.00	5.379±1.964	0.413±0.137	12.952±0.942	1.544
			20~30	68.92±19.58	5.176±1.732	0.429±0.099	11.970±2.042	1.552
刈割 Mowing	173.08±23.93	38.47±5.99	0~10	755.96±216.31	22.182±0.720	1.631±0.040	13.604±0.319	1.435
			10~20	168.05±38.97	10.686±1.865	0.850±0.163	12.713±1.849	1.494
			20~30	81.56±21.32	6.427±1.955	0.516±0.098	12.421±2.770	1.559
围封禁牧 Grazing exclusion	251.61±24.18	30.12±15.43	0~10	779.70±53.41	19.073±0.678	1.339±0.064	14.273±0.831	1.414
			10~20	189.25±19.38	12.217±1.075	0.956±0.089	12.809±0.843	1.542
			20~30	71.65±26.86	7.273±1.038	0.533±0.100	13.856±2.018	1.589
弃耕 Fallow	350.96±81.76	29.46±8.76	0~10	751.20±60.13	20.686±3.573	1.596±0.075	12.996±2.420	1.258
			10~20	256.30±57.23	16.740±0.736	1.290±0.034	12.985±0.647	1.535
			20~30	56.14±9.64	11.883±2.813	0.623±0.055	19.209±5.265	1.621
人工牧草 Alfalfa pasture	289.69±87.5	77.58±7.17	0~10	612.29±84.20	16.120±1.144	1.169±0.083	13.821±0.94	1.509
			10~20	258.12±60.60	14.151±0.737	1.107±0.110	12.916±1.687	1.560
			20~30	133.37±26.00	11.830±1.643	0.853±0.187	14.704±4.584	1.581
青储作物 Corn plantation	2197.087±209.43	—	0~10	521.24±173.0	14.486±2.539	0.942±0.066	15.436±2.793	1.478
			10~20	204.27±68.00	15.603±1.112	0.988±0019	15.796±1.078	1.629
			20~30	78.75±54.19	6.526±1.547	0.529±0.091	12.371±1.696	1.640

表3 不同利用方式下土壤颗粒组分与土壤有机碳(SOC)及全氮(TN)含量之间的Pearson相关性分析

Table 3 Pearson correlation analysis for relationships of soil particle size distribution with soil organic carbon (SOC) and total nitrogen (TN) content in six land-use types

土地利用方式 Land-use types	粘粒含量 Clay (%)			粉粒含量Silt (%)			砂粒含量 Sand (%)
土地利用方式 Land-use types	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	碳氮比 C∶N ratio	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	碳氮比 C∶N ratio	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	碳氮比 C∶N ratio
自由放牧 Free grazing	0.653 2	0.792 7^*	0.060 9	0.305 1	-0.005 0	0.551 0	-0.788 6^*	-0.913 8^**	-0.119 7
刈割 Mowing	0.862 2^**	0.891 5^**	0.090 6	0.946 0^**	0.958 0^**	0.080 2	-0.940 7^**	-0.957 4^**	-0.037 0
围封禁牧 Grazing exclusion	0.957 1^**	0.917 8^**	0.494 0	-0.144 1	-0.001 0	-0.351 6	-0.880 9^**	-0.881 6^**	-0.263 2
弃耕Fallow	0.854 6^**	0.828 0^**	0.449 7	0.927 0^**	0.884 8^**	-0.497 0	-0.937 6^**	-0.900 0^**	0.499 2
人工牧草Alfalfa pasture	0.037 3	0.200 3	0.229 0	0.416 0	0.755 9^*	-0.466 9	-0.388 9	-0.869 5^**	0.601 0
青储作物 Corn plantation	0.677 3^*	0.791 7^*	0.489 2	0.376 2	0.577 5	0.128 7	-0.517 9	-0.687 2^*	-0.289 2

表4 不同土层植物生物量与(地上、根系以及凋落物)土壤碳氮含量及土壤颗粒组分之间的秩相关分析

Table 4 Rank correlation analysis between plant biomass (aboveground, root and litter) and soil nutrient content, as well as soil particle size distribution in different soil layers

植物生物量 Plant biomass (g·m^-2)	土壤剖面深度 Soil depth (cm)	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	碳氮比 C∶N ratio	粘粒 Clay content (%)	粉粒 Silt content (%)
地上生物量 Aboveground biomass	0~30	0.426	0.232	0.302	0.561^*	0.410
		(-0.078)	(-0.354)	(-0.223)	(-0.015 3)	(-0.091)
凋落物 Litter	0~30	-0.161	-0.035	-0.056	0.599^*	0.315
		(-0.618)	(-0.914)	(-0.863)	(-0.040)	(-0.318)
根系生物量 Root biomass	0~10	0.657	0.657	-0.371	-0.371	0.406
		(-0.156)	(-0.156)	(-0.468)	(-0.468)	(-0.425)
	10~20	0.771	0.886^*	0.314	0.829^*	0.886^*
		(-0.072)	(-0.019)	(-0.554)	(-0.042)	(-0.019)
	20~30	0.200	0.200	-0.029	-0.029	-0.086
		(-0.704)	(-0.704)	(-0.957)	(-0.957)	(-0.872)
	0~30	0.750^**	0.701^**	0.302	0.505^*	0.700^**
		(0.000)	(-0.001)	(-0.223)	(-0.033)	(-0.001)

表5 土壤粘粒含量及根系生物量对土壤碳氮含量影响的线性回归分析

Table 5 Statistics of regression for SOC and total N content with given factors by stepwise elimination

因变量 Dependent variable	自变量 Independent variable	(复)相关系数 (Multiple) correlation coefficient (R)	判定系数 Determination coefficient (R²)	调整的判定系数 Adjusted determination coefficient ( $R a 2$ )	p	自变量独立解释量 Independent explanation (%)
土壤有机碳含量 Soil organic carbon content (g·kg^-1)	粘粒含量 Clay content (%)	0.839	0.703	0.664	0.000	20.79
	根系生物量 Root biomass (g·m^-2)					20.70
土壤全氮含量 Soil total nitrogen content (g·kg^-1)	粘粒含量 Silt content (%)	0.823	0.678	0.635	0.000	20.61
	根系生物量 Root biomass (g·m^-2)					19.54

表5 土壤粘粒含量及根系生物量对土壤碳氮含量影响的线性回归分析

Table 5 Statistics of regression for SOC and total N content with given factors by stepwise elimination

因变量 Dependent variable	自变量 Independent variable	(复)相关系数 (Multiple) correlation coefficient (R)	判定系数 Determination coefficient (R²)	调整的判定系数 Adjusted determination coefficient ( $R a 2$ )	p	自变量独立解释量 Independent explanation (%)
土壤有机碳含量 Soil organic carbon content (g·kg^-1)	粘粒含量 Clay content (%)	0.839	0.703	0.664	0.000	20.79
	根系生物量 Root biomass (g·m^-2)					20.70
土壤全氮含量 Soil total nitrogen content (g·kg^-1)	粘粒含量 Silt content (%)	0.823	0.678	0.635	0.000	20.61
	根系生物量 Root biomass (g·m^-2)					19.54

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