土壤增溫對幼齡杉木細根化學計量學特征的影響
首發時間:2018-03-19
摘要:為了揭示我國最重要人工林樹種杉木(Cunninghamia lanceolata)對全球變暖的地下響應及其適應性,通過在福建省三明市陳大國有林場設置杉木幼苗土壤增溫實驗(增溫5 ℃和不增溫兩個處理,各5個重復),采用內生長環法,在增溫后的第二年和第三年進行4次(2015年1月、7月,2016年1月、7月)細根(分0-1 mm和1-2 mm兩個分級)取樣,研究土壤增溫對杉木幼苗細根化學計量學特征(C、N、P濃度,C/N比和N/P比)的影響。結果表明:(1)增溫處理使2015年1月0-1mm細根C濃度顯著降低,但在2016年的兩次取樣中則顯著降低了1-2mm細根C濃度。增溫使前兩次取樣中0-1mm細根和前三次取樣中1-2mm細根N濃度顯著提高、C/N比降低;但此后由于增溫對土壤N有效性的促進作用減弱,增溫對細根N濃度的影響不顯著甚至降低,細根C/N比提高。(2)增溫使第三次、第四次取樣中0-1mm細根和第四次取樣中1-2mm細根的P濃度顯著降低;同時在大部分取樣時間中增溫提高了細根的N/P比。(3)隨著苗木的生長,細根呈現出C濃度和C/N比升高、N濃度和N/P比降低的趨勢;而P濃度則僅在對照0-1mm細根表現出上升的趨勢??梢?,土壤增溫引起了細根N富集,細根P濃度降低,N/P比升高,從而杉木生長可能受P限制。
關鍵詞: 生態學;細根;化學計量學;杉木;稀釋效應
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Effects of soil warming on fine root stoichiometry of young Chinese fir seedlings
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
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土壤增溫對幼齡杉木細根化學計量學特征的影響
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