青藏高原高寒草甸植物群落生物量对氮、磷添加的响应

doi:10.3724/SP.J.1258.2014.00014

摘要/Abstract

摘要：

青藏高原正经历着明显的温暖化过程, 由此引起的土壤温度的升高促进了土壤中微生物的活性, 同时青藏高原东缘地区大气氮沉降十分明显, 并呈逐年增加的趋势, 这些环境变化均促使土壤中可利用营养元素增加, 因此深入了解青藏高原高寒草甸植物生物量对可利用营养元素增加的响应, 是准确预测未来全球变化背景下青藏高原高寒草甸碳循环过程的重要基础。该研究基于在青藏高原高寒草甸连续4年(2009-2012年)氮、磷添加后对不同功能群植物地上生物量、群落地上和地下生物量的测定, 探讨高寒草甸生态系统碳输入对氮、磷添加的响应。结果表明: (1)氮、磷添加均极显著增加了禾草的地上绝对生物量及其在群落总生物量中所占的比例, 同时均显著降低了杂类草在群落总生物量中的比例, 此外磷添加极显著降低了莎草地上绝对生物量及其在群落总生物量中所占的比例。(2)氮、磷添加均显著促进了青藏高原高寒草甸的地上生物量增加, 分别增加了24%和52%。(3)氮添加对高寒草甸地下生物量无显著影响, 而磷添加后地下生物量有增加的趋势。(4)氮添加对高寒草甸植物总生物量无显著影响, 而磷添加后植物总生物量显著增加。研究表明, 氮、磷添加可缓解青藏高原高寒草甸植物生长的营养限制, 促进植物地上部分的生长, 然而高寒草甸植物的生长极有可能更受土壤中可利用磷含量的限制。

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关键词: 高寒草甸, 生物量, 功能群, 氮添加, 磷添加, 青藏高原

Abstract:

Aims Rising soil temperature under the warming process stimulates microbial activity in soils on the Qinghai- Xizang Plateau. Moreover, the eastern edge of Qinghai-Xizang Plateau has been experiencing distinct atmospheric nitrogen deposition with an increasing trend. All of these have led to an increase in the available nutrients in soils. This study was aimed to determine the responses of carbon fixation in the alpine meadow to nitrogen and phosphorus additions on the Qinghai-Xizang Plateau.
Methods The study was conducted in an alpine meadow ecosystem at the Haibei National Field Research Station of Alpine Grassland Ecosystem, Northwest Institute of Plateau Biology, Chinese Academy of Sciences. Four treatments were set up in 2009, including control, nitrogen addition only (N), phosphorus addition only (P), and combined nitrogen and phosphorus additions (NP). Nutrients were added in June or July each year. The aboveground biomass of functional groups and the above- and belowground biomass of plant communities were measured by harvesting in 2012.
Important findings (1) N and P additions increased the aboveground biomass of grass, and the proportion of grass biomass in the community, but decreased the proportion of forb biomass in the community. Only P addition decreased the aboveground biomass of sedge, and the proportion of sedge biomass in the community. (2) N and P additions increased the aboveground biomass by 24% and 52%, respectively, compared with the control. (3) N addition had no effect on the belowground biomass, whereas P addition slightly increased the belowground biomass. (4) N addition had no effect on the total biomass, whereas P addition significantly increased the total biomass. Therefore, N and P additions could relieve the nutrient limitation and stimulate plant growth. Furthermore, the results suggest that the Qinghai-Xizang Plateau could be more limited by P than N on plant growth.

Key words: alpine meadow, biomass, functional groups, nitrogen addition, phosphorus addition, Qinghai-Xizang Plateau

杨晓霞, 任飞, 周华坤, 贺金生. 青藏高原高寒草甸植物群落生物量对氮、磷添加的响应. 植物生态学报, 2014, 38(2): 159-166. DOI: 10.3724/SP.J.1258.2014.00014

YANG Xiao-Xia, REN Fei, ZHOU Hua-Kun, HE Jin-Sheng. Responses of plant community biomass to nitrogen and phosphorus additions in an alpine meadow on the Qinghai-Xizang Plateau. Chinese Journal of Plant Ecology, 2014, 38(2): 159-166. DOI: 10.3724/SP.J.1258.2014.00014

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https://www.plant-ecology.com/CN/Y2014/V38/I2/159

图/表 6

图1 氮(A)、磷(B)添加对3种不同功能群地上生物量的影响(平均值±标准误差)。

Fig. 1 Effects of nitrogen addition (A) and phosphorus addition (B) on aboveground biomass of three different functional groups (mean ± SE). **, p < 0.01; ***, p < 0.001.

图2 氮(A)、磷(B)添加对3种不同功能群的地上生物量在群落总生物量中所占比例的影响(平均值±标准误差)。

Fig. 2 Effects of nitrogen addition (A) and phosphorus addition (B) on the proportions of the three different functional groups aboveground biomass of the community biomass (mean ± SE). *, p < 0.05; **, p < 0.01; ***, p < 0.001.

表1 氮、磷添加对不同功能群的地上生物量(g·m-2·a-1)和其在群落总生物量中所占比例(%)的影响的双因素方差分析表

Table 1 Two way ANOVA of the effects of nitrogen and phosphorous additions on aboveground biomass of different functional groups and their proportions of the community biomass

	氮添加 N addition		磷添加 P addition		氮磷交互作用 N × P interaction
	F	p	F	p	F	p
莎草生物量 Sedge biomass	0.28	0.611	15.60	0.006	2.75	0.141
莎草生物量 Sedge biomass (%)	0.01	0.910	17.53	0.004	0.79	0.403
禾本生物量 Grass biomass	15.24	0.006	39.95	<0.001	0.80	0.400
禾本生物量 Grass biomass (%)	12.78	0.009	19.64	0.003	0.19	0.676
杂类草生物量 Forb biomass	1.91	0.210	0.13	0.730	0.97	0.358
杂类草生物量 Forb biomass (%)	9.91	0.016	9.34	0.018	0.04	0.844

表2 氮、磷添加对地上生物量(AGB)、地下生物量(BGB)、总生物量(TB)和地下地上生物量比(R/S)影响的双因素方差分析表

Table 2 Two-way ANOVA of the effects of nitrogen and phosphorus additions on aboveground biomass (AGB), belowground biomass (BGB), total biomass (TB) and the ratio of belowground biomass to aboveground biomass (R/S)

	氮添加 N addition		磷添加 P addition		氮磷交互作用 N × P interaction
	F	p	F	p	F	p
AGB (g·m^-2·a^-1)	13.61	0.008	66.38	< 0.001	0.95	0.363
BGB (g·m^-2·a^-1)	1.80	0.216	4.82	0.060	0.02	0.880
TB (g·m^-2·a^-1)	0.002	0.969	15.22	0.008	1.54	0.260
R/S	3.50	0.086	1.24	0.309	0.07	0.806

图3 氮、磷添加对地上生物量(A)、地下生物量(B)和总生物量(C)的影响(平均值±标准误差)。

Fig. 3 Effects of nitrogen and phosphorus additions on aboveground biomass (A), belowground biomass (B) and total biomass (C) (mean ± SE). **, p < 0.01; ***, p < 0.001.

表3 不同处理下的地上(AGB)、地下(BGB)和总生物量(TB)碳库(平均值±标准误差)

Table 3 Aboveground biomass (AGB), belowground biomass (BGB) and total biomass (TB) carbon stock under different treatments (mean ± SE)

	对照 CK	氮添加 N addition	磷添加 P addition	氮磷添加 N, P addition
AGB (g C·m^-2)	146.5 ± 14.0^a	204.8 ± 7.8^b	250.9 ± 12.7^c	281.5 ± 7.9^d
BGB (g C·m^-2)	558.0 ± 68.4^a	510.5 ± 36.8^a	709.1 ± 49.5^b	598.8 ± 101.3^a
TB (g C·m^-2)	704.6 ± 64.3^a	715.3 ± 40.9^a	960.0 ± 41.8^b	880.3 ± 95.8^ab

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