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Effects of soil warming on fine root stoichiometry of young Chinese fir seedlings

• 1、State key laboratory of humid subtropical ecology,Fuzhou 35007
• 2、School of geographical sciences,Fuzhou 350007

Abstract：In this paper a field soil cable warming experiment was conducted in Chenda State-Own Forest Farm, Sanming, Fujian Province.limited information regarding how warming affects root processes has restricted our ability to predict how roots will respond to elevated temperatures. The experiment included two treatments: soil warming (W, ambient+5℃) and non-warming (CT, ambient), and each had 5 replicate 2m×2m mini-plots.Four Chinese fir (Cunninghamia lanceolata) seedlings were planted in each mini-plot.We measured changes in fine root stoichiometry (C, N, P,C/N和N/P) of Chinese fir seedlings using soil ingrowth donut methods during the second (January and July 2015) and the third year (January and July 2016) after soil warming. The results showed that:(1)with soil warming, C concentration in the 0~1 mm fine roots decreased significantly in January 2015,whereas C concentration in the 1~2mm fine roots decreased significantly in 2016. Soil warming significantly decreased N concentrations in the 0~1 mm fine roots in the first two samplings and decreased N concentrations in the 1~2 mm fine roots in the first three samplings, which hence reduced the C/N ratios in fine roots. In the late sampling, however, soil warming had no effect on or even reduced fine root N concentrations, which in turn increased fine root C/N ratios. (2)Soil warming had no effect on fine root P concentration during the early samplings, but had decreased fine root P concentration during the late samplings; the N/P ratios in fine roots had been increased by soil warming in most of the samplings; (4)Along with seedling growth, the fine roots showed the trends of increased C concentrations and C/N ratios and decreased N concentration and N/P ratios, mainly indicating the dilution effect of seedling growth on fine root N concentrations. P concentrations of the 0~1mm fine roots in the CT showed a increasing trend with seedling growth, which might be a result of developing capacity of fine roots to uptake soil P.

Keywords： Ecology soil warming, fine roots stoichiometry Chinese fir (Cunninghamia lanceolata), dilution effect