黄土丘陵区退耕地土壤可溶性氮组分季节变化与水热关系
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摘要
为探究黄土丘陵区退耕地植被恢复土壤有效氮素养分累积的季节动态变化特征及水热驱动效应,以邻近坡耕地为对照,分析了植被恢复15 a的刺槐、柠条、荒草地土壤可溶性氮组分密度、分布比例在4—10月份内的动态变化状况及其与土壤温度和含水量间的关系。结果表明,整个采样期间,0—30 cm土层土壤硝态氮、可溶性有机氮和可溶性全氮动态变化显著,且各可溶性氮组分中仅硝态氮随土层变化差异显著。其中土壤硝态氮变化幅度整体为0.13—1.71 g/m~2,占可溶性全氮的5.1%—52.1%,其最大值出现在4月份,最小值出现在10月份;可溶性有机氮整体变化幅度为0.29—2.92 g/m~2,占可溶性全氮的30.9%—85.3%,在4月份和8月份分别达最小值和最大值;铵态氮动态变化不显著,4—10月份整体变化幅度为0.17—0.74 g/m~2,占6.4%—21.4%,其最小值出现在10月份,最大值出现在4月份;可溶性全氮整体变化幅度为1.25—3.52 g/m~2。可溶性氮组分中,各组分所占比例为可溶性有机氮>硝态氮>铵态氮,并且可溶性有机氮与硝态氮所占比例动态变化趋势相反。刺槐、柠条林和荒草地0—30 cm土壤硝态氮平均约为耕地的3.42倍、2.54倍和1.26倍,铵态氮平均为耕地的1.71倍、1.37倍和1.30倍,可溶性有机氮约为1.64倍、1.31倍和1.23倍。可溶性氮组分受土壤含水量的影响大于土壤温度,硝态氮对土壤含水量的变化最为敏感,而可溶性全氮则对土壤温度变化最为敏感。综上所述,人工林植被恢复有利于提高土壤可溶性氮组分,增加氮的有效性,同时除铵态氮外,土壤可溶性氮组分随季节变化显著。
Soil soluble and available nitrogen are considered to be limiting nutritional factors for the productivity of plants in terrestrial ecosystems.Land-use change has a significant impact on the physical and chemical properties of soil,particularlynitrogen pools.Furthermore,although the amounts of soil soluble nitrogen are generally very small,they can change rapidly during the plant growing season.However,the changes in soil soluble nitrogen dynamics associated with different vegetation restoration patterns are still poorly understood.Therefore,more information is essential to gain a better understanding of the changes in ecosystems dynamics that occur following the conversion of farmland to forest in the Loess Hilly Region.We studied the dynamic changes in soil soluble nitrogen from April to October,and their relation to soil moisture and temperature under three converted land types in the Loess Hilly Region[Robinia pseudoacacia(RP),Caragana korshinskii(CK),and abandoned farmland(AF)],which have undergone conversion from slope farmland(SF)for 15 years.The average densities of nitrate nitrogen(NO~-_3-N),soluble organic nitrogen(SON),and soluble total nitrogen(STN)changed significantly from April to October in the 0-30 cm soil layer(P<0.05),although only NO~-_3-N varied significantly with soil depth(P<0.05).During the sampling period(April to October),the average NO~-_3-N density accounted for 5.1%-52.1%of STN,ranging from 0.13 g/m~2(in April)to 1.71 g/m~2(in October).The average density of SON varied significantly from0.29 g/m~2(in April)to 2.92 g/m~2(in August),which accounted for 30.9%-85.3%of STN.Although the variation in ammonium nitrogen(NH~+_4-N)was not significant,it ranged from 0.17 g/m~2(in October)to 0.74 g/m~2(in April)and accounted for 6.4%-21.4%of STN.After long-term vegetation restoration,the average densities of NO~-_3-N in RP,CK,and AF were 3.42,2.54,and 1.26 times higher,respectively,than that of SF in the 0-30 cm soil layer,whereas those of NH~+_4-N in RP,CK,and AF were increased by 1.71,1.37,and 1.30 times,respectively,and those of SON were increased by 1.64,1.31,and 1.23 times,respectively,compared to SF.Correlation analyses indicated that the dynamic change in soil soluble nitrogen was affected by soil moisture and temperature,and that soluble nitrogen was more sensitive to soil moisture than to temperature.Moreover,NO~-_3-N was more sensitive than SON and STN to soil moisture changes,whereas STN was the most sensitive to soil temperature.Collectively,these findings indicate that converting farm to forest can improve the density of soil soluble nitrogen,and increase the availability of soil nitrogen.It was also observed that the amounts of soil soluble nitrogen change significantly with different seasons.
Soil soluble and available nitrogen are considered to be limiting nutritional factors for the productivity of plants in terrestrial ecosystems.Land-use change has a significant impact on the physical and chemical properties of soil,particularlynitrogen pools.Furthermore,although the amounts of soil soluble nitrogen are generally very small,they can change rapidly during the plant growing season.However,the changes in soil soluble nitrogen dynamics associated with different vegetation restoration patterns are still poorly understood.Therefore,more information is essential to gain a better understanding of the changes in ecosystems dynamics that occur following the conversion of farmland to forest in the Loess Hilly Region.We studied the dynamic changes in soil soluble nitrogen from April to October,and their relation to soil moisture and temperature under three converted land types in the Loess Hilly Region[Robinia pseudoacacia(RP),Caragana korshinskii(CK),and abandoned farmland(AF)],which have undergone conversion from slope farmland(SF)for 15 years.The average densities of nitrate nitrogen(NO~-_3-N),soluble organic nitrogen(SON),and soluble total nitrogen(STN)changed significantly from April to October in the 0-30 cm soil layer(P<0.05),although only NO~-_3-N varied significantly with soil depth(P<0.05).During the sampling period(April to October),the average NO~-_3-N density accounted for 5.1%-52.1%of STN,ranging from 0.13 g/m~2(in April)to 1.71 g/m~2(in October).The average density of SON varied significantly from0.29 g/m~2(in April)to 2.92 g/m~2(in August),which accounted for 30.9%-85.3%of STN.Although the variation in ammonium nitrogen(NH~+_4-N)was not significant,it ranged from 0.17 g/m~2(in October)to 0.74 g/m~2(in April)and accounted for 6.4%-21.4%of STN.After long-term vegetation restoration,the average densities of NO~-_3-N in RP,CK,and AF were 3.42,2.54,and 1.26 times higher,respectively,than that of SF in the 0-30 cm soil layer,whereas those of NH~+_4-N in RP,CK,and AF were increased by 1.71,1.37,and 1.30 times,respectively,and those of SON were increased by 1.64,1.31,and 1.23 times,respectively,compared to SF.Correlation analyses indicated that the dynamic change in soil soluble nitrogen was affected by soil moisture and temperature,and that soluble nitrogen was more sensitive to soil moisture than to temperature.Moreover,NO~-_3-N was more sensitive than SON and STN to soil moisture changes,whereas STN was the most sensitive to soil temperature.Collectively,these findings indicate that converting farm to forest can improve the density of soil soluble nitrogen,and increase the availability of soil nitrogen.It was also observed that the amounts of soil soluble nitrogen change significantly with different seasons.
引文
[1]邢肖毅,黄懿梅,安韶山,张宏.黄土高原沟壑区森林带不同植物群落土壤氮素含量及其转化.生态学报,2013,33(22):7181-7189.
[2]殷睿,徐振锋,吴福忠,杨万勤,熊莉,肖洒,马志良,李志萍.川西亚高山不同海拔森林土壤活性氮库及净氮矿化的季节动态.应用生态学报,2013,24(12):3347-3353.
[3]Murphy D V,Macdonald A J,Stockdale E A,Goulding K W T,Fortune S,Gaunt J L,Poulton P R,Wakefield J A,Webster C P,Wilmer W S.Soluble organic nitrogen in agricultural soils.Biology and Fertility of Soils,2000,30(5/6):374-387.
[4]张宏威,康凌云,梁斌,陈清,李俊良,严正娟.长期大量施肥增加设施菜田土壤可溶性有机氮淋溶风险.农业工程学报,2013,29(21):99-107.
[5]安韶山,黄懿梅.黄土丘陵区柠条林改良土壤作用的研究.林业科学,2006,42(1):70-74.
[6]于洋,贾志清,朱雅娟,赵淑伶,刘艳书,刘海涛,李清雪.高寒沙地植被恢复区乌柳人工防护林对土壤的影响.林业科学,2013,49(11):9-15.
[7]漆良华,张旭东,周金星,彭镇华,岳祥华,黄玲玲.湘西北小流域不同植被恢复区土壤微生物数量、生物量碳氮及其分形特征.林业科学,2009,45(8):14-20.
[8]王风芹,田丽青,宋安东,桑玉强,张劲松,高峻.华北刺槐林与自然恢复植被土壤微生物量碳、氮含量四季动态.林业科学,2015,51(3):16-24.
[9]刘纯,刘延坤,金光泽.小兴安岭6种森林类型土壤微生物量的季节变化特征.生态学报,2014,34(2):451-459.
[10]赵溪,李君剑,李洪建.关帝山不同植被恢复类型对土壤碳、氮含量及微生物数量的影响.生态学杂志,2010,29(11):2102-2110.
[11]翁伯琦,郑祥洲,丁洪,王煌平.植被恢复对土壤碳氮循环的影响研究进展.应用生态学报,2013,24(12):3610-3616.
[12]Vestgarden L S,Kjonaas O J.Potential nitrogen transformations in mineral soils of two coniferous forests exposed to different N inputs.Forest Ecology and Management,2003,174(1/3):191-202.
[13]刘苑秋,王芳,柯国庆,王迎迎,郭圣茂,范承芳.江西瑞昌石灰岩山区退耕还林对土壤有机碳的影响.生态学报,2015,22(4):885-890.
[14]Loreau M,Naeem S,Inchausti P,Bengtsson J,Grime J P,Hector A,Hooper D U,Huston M A,Raffaelli D,Schmid B,Tilman D,Wardle D A.Biodiversity and ecosystem functioning:current knowledge and future challenges.Science,2001,294(5534):804-808.
[15]Maithani K,Arunachalam A,Tripathib R S,Pandey H N.Nitrogen mineralization as influenced by climate,soil and vegetation in a subtropical humid forest in northeast India.Forest Ecology and Management,1998,109(1/3):91-101.
[16]金发会,李世清,卢红玲,李生秀.石灰性土壤微生物量碳、氮与土壤颗粒组成和氮矿化势的关系.应用生态学报,2007,18(12):2739-2746.
[17]徐李亚,杨万勤,李晗,倪祥银,何洁,吴福忠.雪被覆盖对高山森林凋落物分解过程中水溶性和有机溶性组分含量的影响.应用生态学报,2014,25(11):3067-3075.
[18]王春阳,周建斌,董燕婕,陈兴丽,李婧.黄土区六种植物凋落物与不同形态氮素对土壤微生物量碳氮含量的影响.生态学报,2010,30(24):7092-7100.
[19]陈哲,杨世琦,张晴雯,周华坤,井新,张爱平,韩瑞芸,杨正礼.冻融对土壤氮素损失及有效性的影响.生态学报,2016,36(4):1083-1094.
[20]Pajuste K,Frey J.Nitrogen mineralisation in podzol soils under boreal Scots pine and Norway spruce stands.Plant and Soil,2003,257(1):237-247.
[21]Wei X R,Shao M A,Fu X L,Agren G I,Yin X Q.The effects of land use on soil N mineralization during the growing season on the northern Loess Plateau of China.Geoderma,2011,160(3/4):590-598.
[22]Uri V,Lohmus K,Kund M,Tullus H.The effect of land use type on net nitrogen mineralization on abandoned agricultural land:silver birch stand versus grassland.Forest Ecology and Management,2008,255(1):226-233.
[23]Mc Kinley D C,Rice C W,Blair J M.Conversion of grassland to coniferous woodland has limited effects on soil nitrogen cycle processes.Soil Biology and Biochemistry,2008,40(10):2627-2633.
[24]寇萌,焦菊英,尹秋龙,杜华栋,王东丽.黄土丘陵沟壑区主要草种枯落物的持水能力与养分潜在归还能力.生态学报,2015,35(5):1337-1349.
[25]马红亮,闫聪微,高人,尹云锋,杨玉盛,陈仕东.林下凋落物去除与施氮对针叶林和阔叶林土壤氮的影响.环境科学研究,2013,26(12):1316-1324.
[26]Gelfand I,Yakir D.Influence of nitrite accumulation in association with seasonal patterns and mineralization of soil nitrogen in a semi-arid pine forest.Soil Biology and Biochemistry,2008,40(2):415-424.
[27]李贵才,韩兴国,黄建辉,唐建维.森林生态系统土壤氮矿化影响因素研究进展.生态学报,2001,21(7):1187-1195.
[28]王常慧,邢雪荣,韩兴国.草地生态系统中土壤氮素矿化影响因素的研究进展.应用生态学报,2004,15(11):2184-2188.
[29]陈永川,杨春霞,赵志平,李春丽,汤利.不同管理方式下橡胶林土壤氮动态特征.生态学杂志,2012,31(4):954-960.
[30]周才平,欧阳华.温度和湿度对暖温带落叶阔叶林土壤氮矿化的影响.植物生态学报,2001,25(2):204-209.
[31]宋飘,张乃莉,马克平,郭继勋.全球气候变暖对凋落物分解的影响.生态学报,2014,34(6):1327-1339.
[32]王新源,赵学勇,李玉霖,连杰,曲浩,岳祥飞.环境因素对干旱半干旱区凋落物分解的影响研究进展.应用生态学报,2013,24(11):3300-3310.
[2]殷睿,徐振锋,吴福忠,杨万勤,熊莉,肖洒,马志良,李志萍.川西亚高山不同海拔森林土壤活性氮库及净氮矿化的季节动态.应用生态学报,2013,24(12):3347-3353.
[3]Murphy D V,Macdonald A J,Stockdale E A,Goulding K W T,Fortune S,Gaunt J L,Poulton P R,Wakefield J A,Webster C P,Wilmer W S.Soluble organic nitrogen in agricultural soils.Biology and Fertility of Soils,2000,30(5/6):374-387.
[4]张宏威,康凌云,梁斌,陈清,李俊良,严正娟.长期大量施肥增加设施菜田土壤可溶性有机氮淋溶风险.农业工程学报,2013,29(21):99-107.
[5]安韶山,黄懿梅.黄土丘陵区柠条林改良土壤作用的研究.林业科学,2006,42(1):70-74.
[6]于洋,贾志清,朱雅娟,赵淑伶,刘艳书,刘海涛,李清雪.高寒沙地植被恢复区乌柳人工防护林对土壤的影响.林业科学,2013,49(11):9-15.
[7]漆良华,张旭东,周金星,彭镇华,岳祥华,黄玲玲.湘西北小流域不同植被恢复区土壤微生物数量、生物量碳氮及其分形特征.林业科学,2009,45(8):14-20.
[8]王风芹,田丽青,宋安东,桑玉强,张劲松,高峻.华北刺槐林与自然恢复植被土壤微生物量碳、氮含量四季动态.林业科学,2015,51(3):16-24.
[9]刘纯,刘延坤,金光泽.小兴安岭6种森林类型土壤微生物量的季节变化特征.生态学报,2014,34(2):451-459.
[10]赵溪,李君剑,李洪建.关帝山不同植被恢复类型对土壤碳、氮含量及微生物数量的影响.生态学杂志,2010,29(11):2102-2110.
[11]翁伯琦,郑祥洲,丁洪,王煌平.植被恢复对土壤碳氮循环的影响研究进展.应用生态学报,2013,24(12):3610-3616.
[12]Vestgarden L S,Kjonaas O J.Potential nitrogen transformations in mineral soils of two coniferous forests exposed to different N inputs.Forest Ecology and Management,2003,174(1/3):191-202.
[13]刘苑秋,王芳,柯国庆,王迎迎,郭圣茂,范承芳.江西瑞昌石灰岩山区退耕还林对土壤有机碳的影响.生态学报,2015,22(4):885-890.
[14]Loreau M,Naeem S,Inchausti P,Bengtsson J,Grime J P,Hector A,Hooper D U,Huston M A,Raffaelli D,Schmid B,Tilman D,Wardle D A.Biodiversity and ecosystem functioning:current knowledge and future challenges.Science,2001,294(5534):804-808.
[15]Maithani K,Arunachalam A,Tripathib R S,Pandey H N.Nitrogen mineralization as influenced by climate,soil and vegetation in a subtropical humid forest in northeast India.Forest Ecology and Management,1998,109(1/3):91-101.
[16]金发会,李世清,卢红玲,李生秀.石灰性土壤微生物量碳、氮与土壤颗粒组成和氮矿化势的关系.应用生态学报,2007,18(12):2739-2746.
[17]徐李亚,杨万勤,李晗,倪祥银,何洁,吴福忠.雪被覆盖对高山森林凋落物分解过程中水溶性和有机溶性组分含量的影响.应用生态学报,2014,25(11):3067-3075.
[18]王春阳,周建斌,董燕婕,陈兴丽,李婧.黄土区六种植物凋落物与不同形态氮素对土壤微生物量碳氮含量的影响.生态学报,2010,30(24):7092-7100.
[19]陈哲,杨世琦,张晴雯,周华坤,井新,张爱平,韩瑞芸,杨正礼.冻融对土壤氮素损失及有效性的影响.生态学报,2016,36(4):1083-1094.
[20]Pajuste K,Frey J.Nitrogen mineralisation in podzol soils under boreal Scots pine and Norway spruce stands.Plant and Soil,2003,257(1):237-247.
[21]Wei X R,Shao M A,Fu X L,Agren G I,Yin X Q.The effects of land use on soil N mineralization during the growing season on the northern Loess Plateau of China.Geoderma,2011,160(3/4):590-598.
[22]Uri V,Lohmus K,Kund M,Tullus H.The effect of land use type on net nitrogen mineralization on abandoned agricultural land:silver birch stand versus grassland.Forest Ecology and Management,2008,255(1):226-233.
[23]Mc Kinley D C,Rice C W,Blair J M.Conversion of grassland to coniferous woodland has limited effects on soil nitrogen cycle processes.Soil Biology and Biochemistry,2008,40(10):2627-2633.
[24]寇萌,焦菊英,尹秋龙,杜华栋,王东丽.黄土丘陵沟壑区主要草种枯落物的持水能力与养分潜在归还能力.生态学报,2015,35(5):1337-1349.
[25]马红亮,闫聪微,高人,尹云锋,杨玉盛,陈仕东.林下凋落物去除与施氮对针叶林和阔叶林土壤氮的影响.环境科学研究,2013,26(12):1316-1324.
[26]Gelfand I,Yakir D.Influence of nitrite accumulation in association with seasonal patterns and mineralization of soil nitrogen in a semi-arid pine forest.Soil Biology and Biochemistry,2008,40(2):415-424.
[27]李贵才,韩兴国,黄建辉,唐建维.森林生态系统土壤氮矿化影响因素研究进展.生态学报,2001,21(7):1187-1195.
[28]王常慧,邢雪荣,韩兴国.草地生态系统中土壤氮素矿化影响因素的研究进展.应用生态学报,2004,15(11):2184-2188.
[29]陈永川,杨春霞,赵志平,李春丽,汤利.不同管理方式下橡胶林土壤氮动态特征.生态学杂志,2012,31(4):954-960.
[30]周才平,欧阳华.温度和湿度对暖温带落叶阔叶林土壤氮矿化的影响.植物生态学报,2001,25(2):204-209.
[31]宋飘,张乃莉,马克平,郭继勋.全球气候变暖对凋落物分解的影响.生态学报,2014,34(6):1327-1339.
[32]王新源,赵学勇,李玉霖,连杰,曲浩,岳祥飞.环境因素对干旱半干旱区凋落物分解的影响研究进展.应用生态学报,2013,24(11):3300-3310.