Interactive effects of soil warming and nitrogen addition on fine root production of Chinese fir seedlings

doi:10.17521/cjpe.2016.0274

Abstract

Abstract:

Aims There have been a large number of studies on the independent separate responses of fine roots to warming and nitrogen deposition, but with contradictory reporting. Fine root production plays a critical role in ecosystem carbon, nutrient and water cycling, yet how it responds to the interactive warming and nitrogen addition is not well understood. In the present study, we aimed to examine the interactive effects of soil warming and nitrogen addition on fine root growth of 1-year-old Chinese fir (Cunninghamia lanceolata) seedlings in subtropical China.
Methods A mesocosm experiment, with a factorial design of soil warming (ambient, +5 °C) and nitrogen addition (ambient, ambient + 40 kg·hm^-2·a^-1, ambient + 80 kg·hm^-2·a^-1), was carried out in the Chenda State-owned Forest Farm in Sanming City, Fujian Province, China. Fine root production (indexed by the number of fine roots emerged per tube of one year) was measured biweekly using minirhizotrons from March of 2014 to February of 2015.
Important findings (1) The two-way ANOVA showed that soil warming had a significant effect on fine root production, while nitrogen addition and soil warming × nitrogen addition had no effect. (2) The three-way ANOVA (soil warming, nitrogen addition and diameter class) showed that soil warming, diameter class and soil warming × diameter class had significant effects on fine root production, especially for the number of fine roots in 0-1 mm diameter class that had been significantly increased by soil warming. Compared with the 1-2 mm roots, the 0-1 mm roots seemed more flexible. (3) Repeated measures of ANOVA (soil warming, nitrogen addition and season) showed that soil warming, season, soil warming × season, and soil warming × nitrogen addition × season had significant effects on fine root production. In spring, the number of fine roots was significantly increased both by soil warming and soil warming × season, while soil warming, nitrogen addition, soil warming × nitrogen addition significantly decreased fine root production in the summer. (4) Soil warming, soil layer, soil warming × soil layer had significant effects on fine root production. The number of in-growth fine roots was significantly increased by soil warming at the 20-30 cm depth only. It seemed that warming forced fine roots to grow deeper in the soil. In conclusion, soil warming significantly increased fine root production, but they had different responses and were dependent of different diameter classes, seasons and soil layers. Nitrogen addition had no effect on fine root production. Only in spring and summer, soil warming and nitrogen addition had significant interactive effects.

Key words: soil warming, nitrogen addition, Cunninghamia lanceolata, minirhizotron, fine root production

Shun-Zeng SHI, De-Cheng XIONG, Fei DENG, Jian-Xin FENG, Chen-Sen XU, Bo-Yuan ZHONG, Yun-Yu CHEN, Guang-Shui CHEN, Yu-Sheng YANG. Interactive effects of soil warming and nitrogen addition on fine root production of Chinese fir seedlings[J]. Chin J Plan Ecolo, 2017, 41(2): 186-195.

Add to citation manager EndNote|Ris|BibTeX

URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2016.0274

https://www.plant-ecology.com/EN/Y2017/V41/I2/186

Figures/Tables 12

Fig. 1 Annual changes of soil (0-10 cm) temperature (A) and moisture (B) under different treatments (mean ± SD). ▲, control treatment (ambient, ambient); ■, soil warming treatment (+5 °C, ambient).

Fig. 2 Soil (0-20 cm) nitrogen availability under different treatments (mean ± SD). NH4+, ammonium nitrogen. NO3- + NO2-, nitrate nitrogen. CT, control treatment (ambient, ambient); HN, high nitrogen addition (ambient, ambient + 80 kg·hm-2·a-1); LN, low nitrogen addition (ambient, ambient + 40 kg·hm-2·a-1); W, soil warming (+5 °C, ambient); WHN, soil warming plus high nitrogen addition (+5 °C, ambient + 80 kg·hm-2·a-1); WLN, soil warming plus low nitrogen addition (+5 °C, ambient + 40 kg·hm-2·a-1). Different capital letters indicate significant differences among treatments (p < 0.05).

Table 1 p-value of two-way ANOVA on the effects of soil warming, nitrogen addition and their interaction on soil temperature, soil moisture and soil nitrogen availability

因子 Factor	土壤温度 Soil temperature (℃)	土壤湿度 Soil moisture (%)	铵态氮 Ammonium nitrogen	硝态氮 Nitrate nitrogen	土壤有效氮(铵态氮和硝态氮) Soil nitrogen availability (ammonium nitrogen and nitrate nitrogen)
W	<0.001	0.005	<0.001	<0.001	<0.001
N			<0.001	<0.001	<0.001
W × N			<0.001	0.317	<0.001

Table 2 p-value of two-way ANOVA on the effects of soil warming, nitrogen addition and their interaction on total number of fine roots emerged per tube of one year

指标 Index	因子 Factor
指标 Index	W	N	W × N
每根管细根一年总出生数量 Total number of fine roots emerged per tube of one year (No.·tube^-1·a^-1)	0.005	0.616	0.483

Fig. 3 Total number of fine roots emerged of one year (A) under different treatments and number of different diameter class (B) (mean ± SD). Different capital letters indicate significant differences among treatments (p < 0.05). Different lowercase letters indicate significant differences among diameters (p < 0.05). CT, control treatment (ambient, ambient); HN, high nitrogen addition (ambient, ambient + 80 kg·hm-2·a-1); LN, low nitrogen addition (ambient, ambient + 40 kg·hm-2·a-1); W, soil warming (+5 °C, ambient); WHN, soil warming plus high nitrogen addition (+5 °C, ambient + 80 kg·hm-2·a-1); WLN, soil warming plus low nitrogen addition (+5 °C, ambient + 40 kg·hm-2·a-1).

Table 3 p-value of ANOVA on the effects of soil warming, nitrogen addition and diameter class on total number of fine roots emerged per tube of one year

指标 Index	因子 Factor
指标 Index	W	N	D	W × N	W × D	N × D	W × N × D
每根管细根一年总出生数量 Total number of fine roots emerged per tube of one year (No.·tube^-1·a^-1)	0.004	0.624	<0.001	0.491	0.002	0.44	0.431

Table 4 p-value of two-way ANOVA on the effects of soil warming, nitrogen addition and their interaction on total number of fine roots emerged per tube of one year in different diameter classes, seasons and soil layers

指标 Index	因子 Factor		W	N	W × N
每根管细根一年总出生数量 Total mumber of fine roots emerged per tube of one year (No.·tube^-1·a^-1)	径级 Diameter class	0-1 mm	0.004	0.535	0.465
	径级 Diameter class	1-2 mm	0.137	0.182	0.505
	季节 Season	春季 Spring	<0.001	0.529	0.010
		夏季 Summer	0.003	0.001	0.041
		秋季 Autumn	0.226	0.555	0.971
		冬季 Winter	0.702	0.175	0.313
	土层 Soil layer	0-10 cm	0.547	0.488	0.423
		10-20 cm	0.158	0.114	0.052
		20-30 cm	0.005	0.424	0.892
		30-40 cm	0.124	0.379	0.892

Table 5 p-value of repeated measures ANOVA on the effects of soil warming, nitrogen addition and season on total number of fine roots emerged per tube of one year

指标 Index	因子 Factor
指标 Index	W	N	S	W × N	W × S	N × S	W × N × S
每根管细根一年总出生数量 Total number of fine roots emerged per tube of one year (No.·tube^-1·a^-1)	0.005	0.616	<0.001	0.483	<0.001	0.193	0.025

Fig. 4 Total number of fine roots emerged per tube of one year under different seasons (mean ± SD). Different capital letters indicate significant differences among treatments in the same season (p < 0.05). Different lowercase letters indicate significant differences among seasons in the same treatment (p < 0.05). CT, control treatment (ambient, ambient); HN, high nitrogen addition (ambient, ambient + 80 kg·hm-2·a-1); LN, low nitrogen addition (ambient, ambient + 40 kg·hm-2·a-1); W, soil warming (+5 °C, ambient); WHN, soil warming plus high nitrogen addition (+5 °C, ambient + 80 kg·hm-2·a-1); WLN, soil warming plus low nitrogen addition (+5 °C, ambient + 40 kg·hm-2·a-1).

Fig. 5 Total number of fine roots emerged per tube of one year under different soil layer (mean ± SD). Different capital letters indicate significant differences among treatments in the same soil layer (p < 0.05). Different lowercase letters indicate significant differences among soil layers in the same treatment (p < 0.05). CT, control treatment (ambient, ambient); HN, high nitrogen addition (ambient, ambient + 80 kg·hm-2·a-1); LN, low nitrogen addition (ambient, ambient + 40 kg·hm-2·a-1); W, soil warming (+5 °C, ambient); WHN, soil warming plus high nitrogen addition (+5 °C, ambient + 80 kg·hm-2·a-1); WLN, soil warming plus low nitrogen addition (+5 °C, ambient + 40 kg·hm-2·a-1).

Table 6 p-value of ANOVA on the effects of soil warming, nitrogen addition and soil layer on total number of fine roots emerged per tube of one year

指标 Index	因子 Factor
指标 Index	W	N	L	W × N	W × L	N × L	W × N × L
每根管细根一年总出生数量 Total number of fine roots emerged per tube of one year (No.·tube^-1·a^-1)	0.001	0.563	0.06	0.419	0.025	0.256	0.765

Fig. 6 Proposed mechanism on the effects of soil warming and nitrogen addition on fine root production. “+” means increase; “-” means decrease; “NS” means have no significant effect. The red arrows mean effects by soil warming; while the black arrows mean effects by nitrogen addition.

References 25

[1]	Bai WM, Wan SQ, Niu SL, Liu WX, Chen QS, Wang QB, Zhang WH, Han XG, Li LH (2010). Increased temperature and precipitation interact to affect root production, mortality, and turnover in a temperate steppe: Implications for ecosystem C cycling.Global Change Biology, 16, 1306-1316.
[2]	Chen GS, Yang YS, Robinson D (2013). Allocation of gross primary production in forest ecosystems: Allometric constraints and environmental responses.New Phytologist, 200, 1176-1186.
[3]	Chen SD, Liu XF, Xiong DC, Lin WS, Lin CF, Xie L, Yang YS (2013). A preliminary study on effects of continuous active warming on soil respiration rates in central sub-tropical forests.Journal of Subtropical Resources and Environment, 4, 1-8. (in Chinese with English abstract)[陈仕东, 刘小飞, 熊德成, 林伟盛, 林成芳, 谢麟, 杨玉盛 (2013). 持续性主动增温对中亚热带森林土壤呼吸影响研究初报. 亚热带资源与环境学报, 4, 1-8.]
[4]	Davidson EA (2009). The contribution of manure and fertilizer nitrogen to atmospheric nitrous oxide since 1860.Nature Geoscience, 2, 659-662.
[5]	Fitter AH, Self GK, Brown TK, Bogie DS, Graves JD, Benham D, Ineson P (1999). Root production and turnover in an upland grassland subjected to artificial soil warming respond to radiation flux and nutrients, not temperature.Oecologia, 120, 575-581.
[6]	Hendricks JJ, Nadelhoffer KJ, Aber JD (1993). Assessing the role of fine roots in carbon and nutrient cycling.Trends in Ecology & Evolution, 8(5), 174-178.
[7]	Huang JX, Chen GS, Yang ZJ, Xiong DC, Guo JF, Xie JS, Robinson D, Yang YS (2016). Understory fine roots are more ephemeral than those of trees in subtropical Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) stands.Annals of Forest Science, 73, 657-667.
[8]	Huang JX, Ling H, Yang ZJ, Lu ZL, Xiong DC, Chen GS,Yang YS, Xie JS (2012). Estimating fine root production and mortality in subtropical Altingia grlilipes and Castanopsis carlesii forests.Acta Ecologica Sinica, 32, 4472-4480. (in Chinese with English abstract)[黄锦学, 凌华, 杨智杰, 卢正立, 熊德成, 陈光水, 杨玉盛, 谢锦升 (2012). 中亚热带细柄阿丁枫和米槠群落细根的生产和死亡动态. 生态学报, 32, 4472-4480.]
[9]	IPCC (Intergovernmental Panel on Climate Change) (2013). Contribution of working group 1 to the fifth assessment report of the intergovernmental panel on climate change. In: Stocker TF, Qin DH, Plattner GK, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM eds. Climate Change in 2013: The Physical Science Basis. Cambridge University Press, Cambridge, UK.
[10]	Johnson MG, Rygiewicz PT, Tingey DT, Phillips DL (2006). Elevated CO2 and elevated temperature have no effect on Douglas-fir fine-root dynamics in nitrogen-poor soil.New Phytologist, 170, 345-356.
[11]	Lamarque JF, Kiehl JT, Brasseur GP, Butler T, Cameron-Smith P, Collins WD, Collins WJ, Granier C, Hauglustaine D, Hess PG, Holland EA, Horowitz L, Lawrence MG, McKenna D, Merilees P, Prather MJ, Rasch PJ, Rotman D, Shindell D, Thornton P (2005). Assessing future nitrogen deposition and carbon cycle feedback using a multimodel approach: Analysis of nitrogen deposition.Journal of Geo- physical Research Atmospheres, 110(D19), 2657-2677.
[12]	Leppälammi-Kujansuu J, Ostonen I, Strömgren M, Nilsson LO, Kleja DB, Sah SP, Helmisaari HS (2013). Effects of long-term temperature and nutrient manipulation on Norway spruce fine roots and mycelia production.Plant and Soil, 366, 287-303.
[13]	Leppälammi-Kujansuu J, Salemaa M, Kleja DB, Linder S, Helmisaari HS (2014). Fine root turnover and litter production of Norway spruce in a long-term temperature and nutrient manipulation experiment.Plant and Soil, 374, 73-88.
[14]	Li WB, Jin CJ, Guan DX, Wang QK, Wang AZ, Yuan FH, Wu JB (2015). The effects of simulated nitrogen deposition on plant root traits: A meta-analysis.Soil Biology & Biochemistry, 82, 112-118.
[15]	Liu LL, Greaver TL (2010). A global perspective on belowground carbon dynamics under nitrogen enrichment.Ecology Letters, 13, 819-828.
[16]	Liu XJ, Duan L, Mo JM, Du EZ, Shen JL, Lu XK, Zhang Y, Zhou XB, He CE, Zhang FS (2011). Nitrogen deposition and its ecological impact in China: An overview.Environmental Pollution, 159, 2251-2264.
[17]	Majdi H, Öhrvik J (2004). Interactive effects of soil warming and fertilization on root production, mortality, and longevity in a Norway spruce stand in Northern Sweden.Global Change Biology, 10, 182-188.
[18]	Nadelhoffer KJ (2000). The potential effects of nitrogen deposition on fine-root production in forest ecosystems.New Phytologist, 147, 131-139.
[19]	Ostertag R (2001). Effects of nitrogen and phosphorus availability on fine-root dynamics in Hawaiian montane forests.Ecology, 82, 485-499.
[20]	State Forestry Administration of the People’s Republic of China (2005). The National Forest Resources Statistics (1999-2003). China Forestry Publishing House, Beijing. (in Chinese)[中华人民共和国国家林业局 (2005). 全国森林资源统计(1999-2003). 中国林业出版社, 北京.]
[21]	Wan SQ, Hui DF, Wallace L, Luo YQ (2005). Direct and indi- rect effects of experimental warming on ecosystem carbon processes in a tallgrass prairie. Global Biogeochemical Cycles, 19, GB2014, doi:10.1029/2004GB002315.
[22]	Wan SQ, Norby RJ, Pregitzer KS, Ledford J, O’Neill EG (2004). CO2 enrichment and warming of the atmosphere enhance both productivity and mortality of maple tree fine roots.New Phytologist, 162, 437-446.
[23]	Way DA, Oren R (2010). Differential responses to changes in growth temperature between trees from different functional groups and biomes: A review and synthesis of data.Tree Physiology, 30, 669-688.
[24]	Wu YB, Zhang J, Deng YC, Wu J, Wang SP, Tang YH, Cui XY (2014). Effects of warming on root diameter, distribution, and longevity in an alpine meadow. Plant Ecology, 215, 1057-1066.
[25]	Zhang X, Liu XF, Chen SD, Xiong DC, Lin WS, Lin TW, Lin CF (2014). Effects of soil warming on the temperature of soil in different depths.Journal of Subtropical Resources and Environment, 9, 89-91. (in Chinese with English abstract)[章宪, 刘小飞, 陈仕东, 熊德成, 林伟盛, 林廷武,林成芳 (2014). 土壤增温对不同深度土壤温度的影响. 亚热带资源与环境学报, 9, 89-91.]