摘要
土壤无机氮作为植物可直接吸收和利用的氮源,其含量变化反映了土壤供氮能力。大量研究表明荒漠生态系统中土壤无机氮含量受到灌木种类和空间位置的影响。然而,有关采样方向对土壤无机氮含量的影响,目前仍所知甚少。基于此,本研究以准噶尔荒漠西北缘两种广泛分布的优势灌木为对象-梭梭和里海盐爪爪,通过测定和计算两物种个体大小(大、中、小和较小个体)在4个空间位置(主根周围、冠幅中央、冠幅边缘和株间空地)和4个采样方向(东、南、西和北)上0~10 cm和10~20 cm土层中土壤铵态氮、硝态氮含量和铵硝比,分析了灌木个体大小、空间位置和采样方向主效应及其交互效应对各土层无机氮含量的影响。研究结果发现:1)梭梭和里海盐爪爪冠下土壤无机氮含量均受到个体大小主效应的影响。两物种大个体冠下硝态氮含量均显著高于较小个体,梭梭大个体冠下铵态氮含量和铵硝比最低,而里海盐爪爪大个体冠下则拥有最高的铵态氮含量和铵硝比,表明土壤无机氮含量变化存在灌木个体大小依赖性。2)两物种冠下0~10 cm土层中硝态氮和铵态氮含量都显著高于10~20 cm,意味着灌木对表层土壤无机氮的影响幅度更大。3)梭梭冠下土壤无机氮含量还受到个体大小与采样方向交互作用的影响,且在冠幅东侧和南侧存在无机氮富集特征。4)空间位置和采样方向对里海盐爪爪冠下土壤无机氮存在显著交互作用,在里海盐爪爪冠下东侧和南侧,主根周围无机氮含量普遍高于其他3个空间位置。这些结果表明荒漠生态系统中土壤无机氮的变化特征因物种而异,同时受到个体大小、空间位置和采样方向等多种因素的影响。
As a direct nitrogen source for plant absorption and utilization,the soil inorganic nitrogen content(SINC)reflects the nitrogen-supply capacity of soil.Many studies have revealed that in desert ecosystems,SINC is significantly affected by the shrub species,but also by the position of the sampling site.However,there is still limited knowledge about the impact of sampling direction on SINC.In this study,we selected two dominant shrubs(Haloxylon ammodendron and Kalidium caspicum)that are widely distributed in the Junggar Desert,and collected soil samples at 0-10 cm and 10-20 cm soil depths under plants in four size classes(large,medium,small,and very small)at four spatial positions(shrub center,shrub middle,shrub edge,and shrub outside)and for four sampling directions(east,south,west and north).We then measured the nitrate nitrogen content(NNC)and ammonium nitrogen content(ANC)in the soil samples,and calculated the ratio of ammonium nitrogen content(RAN)to nitrate nitrogen.These analyses allowed us to determine the main and interactive effects of shrub size,spatial position,and sampling direction on SINC.It was found that:1)Shrub size significantly affected SINC.In particular,NNC was higher under canopies of large individuals than under canopies of smaller individuals of both H.ammodendron and K.caspicum.However,ANC and RAN were lowest under canopies of large individuals of H.ammodendron but highest under canopies of large individuals of K.caspicum,suggesting that the variation in SINC was dependent on shrub size.2)NNC and ANC were significantly higher in the 0-10 cm soil depth than in the 10-20 cm soil depth under canopies of H.ammodendron and K.caspicum,indicating that shrubs had a stronger effect on SINC in the topsoil layer.3)SINC under canopies of H.ammodendron was affected by interactive effects between shrub size and sampling direction,and a SINC enrichment phenomenon was observed at the east and south directions under canopies of H.ammodendron.4)SINC under canopies of K.caspicum was influenced by the interactive effect between spatial position and sampling direction.SINC was generally higher at the shrub center that at the other three positions at the east and south directions.These findings demonstrate that in desert ecosystems,SINC under shrub canopies varies among shrub species and is affected by shrub size,spatial position,and sampling direction.
作者
潘斯瑶
宋渝川
袁如薏
候圣彤
蔡俊歌
陈冰
程军回
PAN Si-yao;SONG Yu-chuan;YUAN Ru-yi;HOU Sheng-tong;CAI Jun-ge;CHEN Bing;CHENG Jun-hui(College of Resources and Environment of Xinjiang Agricultural University,Xinjiang Key Laboratory of Soil and Plant Ecological Processes,Urumqi 830052,China)
出处
《草业学报》
CSCD
北大核心
2024年第5期183-195,共13页
Acta Prataculturae Sinica
基金
国家自然科学基金项目(32260280)资助。
关键词
土壤无机氮
灌木个体大小
空间位置
采样方向
荒漠生态系统
soil inorganic nitrogen
individual sizes of shrubs
spatial positions
sampling direction
desert ecosystem