Relationships between soil nutrients and plant functional traits in different degradation stages of Leymus chinensis steppe in Nei Mongol, China

doi:10.17521/cjpe.2015.0465

Abstract

Abstract:

Aims Understanding ecological implications of plant functional traits is helpful in exploring community assembly under different environments of nature and human disturbances, and then to reveal the maintenance mechanism of the ecosystem services. By analyzing vegetation and soil data derived from field observations in Leymus chinensis steppe of Xilin River Basin in Nei Mongol, we aimed to explore the responses of plant functional traits to changing soil nutrients at different degradation stages. Methods We observed 69 plots for both plant community structure and soil attributes using quadrat and soil-drilling methods. Five plant functional traits, namely the specific leaf area (SLA), leaf dry matter content (LDMC), leaf carbon to nitrogen ratio (C:N), leaf lignin content (LLC), and maximum height (MH), were measured for each plot. We also tested soil attributes, such as total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), available phosphorus (AP), and organic carbon (OC). The sixty-nine communities were classified into four groups (undegraded L. chinensis + forbs, slightly degraded L. chinensis + Stipa sp., moderately degraded L. chinensis + Cleistogenes squarrosa, and heavily degraded L. chinensis + Artemisia frigida) using TWINSPAN software. The relationships between plant functional traits and soil nutrient variables were analyzed for the four community groups using the Pearson’s correlation test with SPSS 21.0 software. Important findings (1) The soil nutrients decreased with the grassland degradation process and there were significant differences in TN and TP between the undegraded L. chinensis + forbs and heavily degraded L. chinensis + A. frigida communities; (2) plant functional traits also showed strong differences between the degradation stages. MH and C:N decreased with degradation. A significant difference was observed in MH between the undegraded L. chinensis + forbs and slightly degraded L. chinensis + Stipa sp. communities. The difference in C:N was also significant between the undegraded L. chinensis + forbs and heavily degraded L. chinensis + A. frigida communities; (3) the effects of soil nutrients on plant functional traits changed with grassland degradation. AN was negatively correlated with MH, LLC, and C:N in the slightly degraded L. chinensis + Stipa sp. community. In the moderately degraded L. chinensis + C. squarrosa community, those three traits mentioned above showed significantly positive correlations with TP; (4) while analyzing the degraded grassland, different relationships between plant functional traits were found. In the slightly degraded L. chinensis + Stipa sp. community, LLC was positively correlated with all other traits. Moreover, positive correlations also occurred between C:N and MH, C:N and LDMC, and C:N and LLC. In the heavily degraded L. chinensis + A. frigida community, all traits demonstrated the most significantly positive correlations.

http://jtp.cnki.net/bilingual/detail/html/ZWSB201610003

Key words: plant functional traits, soil nutrient, degradation succession, the Leymus chinensis steppe, Xilin River Basin

Dan LI, Saruul KANG, Meng-Ying ZHAO, Qing ZHANG, Hai-Juan REN, Jing REN, Jun-Mei ZHOU, Zhen WANG, Ren-Ji WU, Jian-Ming NIU. Relationships between soil nutrients and plant functional traits in different degradation stages of Leymus chinensis steppe in Nei Mongol, China[J]. Chin J Plant Ecol, 2016, 40(10): 991-1002.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2015.0465

https://www.plant-ecology.com/EN/Y2016/V40/I10/991

Figures/Tables 6

Fig. 1 The distribution map of observation sites.

Table 1 Relationships between soil nutrient contents and plant functional traits

类型 Type	指标 Index	全氮 TN	速效氮 AN	全磷 TP	速效磷 AP	有机碳 OC
羊草+杂类草 Leymus chinensis + forbs	SLA	-0.074	-0.208	0.128	-0.247	0.007
	MH	-0.118	0.098	0.031	0.048	-0.167
	LDMC	0.225	0.297	0.208	0.090	0.244
	LLC	-0.361	-0.196	-0.218	-0.316	-0.268
	C:N	-0.275	-0.571^**	-0.043	-0.534^*	-0.126
羊草+针茅 Leymus chinensis + Stipa sp.	SLA	-0.051	-0.305	0.106	0.147	0.019
	MH	-0.398	-0.515^*	-0.037	-0.214	-0.395
	LDMC	0.061	-0.349	0.204	0.142	0.054
	LLC	-0.384	-0.667^**	-0.102	-0.126	-0.382
	C:N	-0.203	-0.697^**	0.068	-0.114	-0.208
羊草+糙隐子草 Leymus chinensis + Cleistogenes squarrosa	SLA	0.052	-0.078	0.034	-0.103	0.144
	MH	0.371	0.210	0.477^*	-0.096	0.222
	LDMC	0.306	-0.257	0.376	0.293	0.049
	LLC	0.509^*	-0.066	0.514^*	0.181	0.286
	C:N	0.223	-0.362	0.562^**	0.262	-0.029
羊草+冷蒿 Leymus chinensis + Artemisia frigida	SLA	0.519	0.127	0.309	0.280	0.416
	MH	0.432	0.140	0.236	0.254	0.332
	LDMC	0.404	0.305	0.202	0.159	0.329
	LLC	0.354	0.144	0.132	0.143	0.250
	C:N	0.608	0.342	0.441	0.260	0.526

Fig. 2 Comparison of soil nutrient among different degradation stages (mean ± SE). I, Leymus chinensis + forbs; II, Leymus chinensis + Stipa sp.; III, Leymus chinensis + Cleistogenes squarrosa; IV, Leymus chinensis + Artemisia frigida. ns refers to no significant difference at p > 0.05. Letters in each subgraph indicate significant differences between stages (p < 0.05). AN, available nitrogen; AP, available phosphorus; OC, organic carbon; TN, total nitrogen; TP, total phosphorus.

Fig. 3 Comparison of plant functional traits among different degradation stages (mean ± SE). I, Leymus chinensis + forbs; II, Leymus chinensis + Stipa sp.; III, Leymus chinensis + Cleistogenes squarrosa; IV, Leymus chinensis + Artemisia frigida. ns refers to no significant difference at p > 0.05. Letters in each subgraph indicate significant differences between stages (p < 0.05). C:N, leaf carbon and nitrogen ratio; LDMC, leaf dry matter content; LLC, leaf lignin content; MH, maximum height; SLA, specific leaf area.

Table 2 Relationships among plant functional traits

类型 Type	指标 Index	比叶面积 SLA	最大高度 MH	叶片干物质含量 LDMC	叶片木质素含量 LLC	叶片碳氮比 C:N
羊草+杂类草 Leymus chinensis + forbs	SLA	1	0.015	-0.435^*	-0.050	0.268
	MH		1	-0.005	0.527^*	0.309
	LDMC			1	0.021	-0.102
	LLC				1	0.575^**
	C:N					1
羊草+针茅 Leymus chinensis + Stipa sp.	SLA	1	0.434	0.425	0.603^**	0.406
	MH		1	0.518^*	0.681^**	0.565^*
	LDMC			1	0.493^*	0.634^**
	LLC				1	0.693^**
	C:N					1
羊草+糙隐子草 Leymus chinensis + Cleistogenes squarrosa	SLA	1	-0.128	-0.080	0.088	0.184
	MH		1	0.330	0.520^*	0.232
	LDMC			1	0.735^**	0.356
	LLC				1	0.388
	C:N					1
羊草+冷蒿 Leymus chinensis + Artemisia frigida	SLA	1	0.961^**	0.838^**	0.935^**	0.944^**
	MH		1	0.854^**	0.919^**	0.892^**
	LDMC			1	0.953^**	0.842^**
	LLC				1	0.906^**
	C:N					1

Fig.4 Appendix I The result of TWINSPAN classification^ Site numbers are shown in vertical sequence (top-down) by the first two lines on the top of the table. The first three sites coded 19, 61, and 25, for example, are at the very beginning on the left, and the last one is site 6 on the right end. Code of plant species is shown on the very left (the first 11 chars, including blanks) for each line. Var is the abbreviation of “variable”. A group of 0 and 1 on the right demonstrates the classification of plant species; Numbers and dashes appeared in the central part of the table indicate the value of species in sites. The number 5 refers to the most important, and the sign of dash illustrates that the value of species in sites can be neglected; Results of site classification are summarized by the last 6 lines at the bottom of the table, 0 and 1 refer to differentiation. At first, all sites are categorized to 2 groups shown in the line 6 from the end. And then, these two groups are classified further into 4 groups (in the line 5 from the end) by means of dichotomy, and so forth.

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