科尔沁沙地4种典型灌木灌丛下土壤碳、氮、磷化学计量特征

Stoichiometric Characteristics of Soil Carbon,Nitrogen and Phosphorus of Four Typical Shrubs in Horqin Sandy Land

该研究以科尔沁沙地半流动沙地4种典型灌木(小叶锦鸡儿、东北木蓼、黄柳、差巴嘎蒿)灌丛下的土壤为研究对象,分析不同灌木类型各土层碳、氮、磷含量及其生态化学计量比的垂直分布特征以及各指标间的相关关系,以阐明同一环境条件下不同灌木类型组成的植被对土壤营养元素的影响与反馈能力,为沙漠化治理和生态恢复提供指导。结果表明:(1)4种典型植物灌丛下0～80cm土层SOC、TN、TP平均含量分别在0.90～2.18g/kg、0.19～0.32g/kg、0.27～0.32g/kg之间,其中东北木蓼灌丛下0～80cm土壤SOC、TN、TP平均含量最高,且土壤SOC、TN含量与小叶锦鸡儿的差异不显著,但两者均显著高于其他植物灌丛;土壤TP平均含量在不同灌木类型间均不显著。(2)4种植物灌丛下土壤SOC、TN、TP含量随土壤深度增加而下降,表层(0～10cm)土层受植被类型影响显著(P<0.05),同一灌丛0～10cm土层与其他各土层间差异显著(P<0.05),且随着土层深度的增加土层间的差异减弱。(3)各灌木类型下的土壤SOC、TN呈"倒金字塔"的分布模式,但TP含量随土壤深度变化相对不明显,呈"圆柱体"的分布模式。(4)小叶锦鸡儿下各土层C∶N、C∶P平均比值最高,其次是东北木蓼、黄柳,差巴嘎蒿最低;C∶N、C∶P、N∶P的比值均随土壤深度增加而下降,不同灌木类型之间的差异也随土壤深度增加而减弱;其中各灌丛下土壤C∶P随着土壤深度呈急剧减小趋势,且土壤C∶P、N∶P垂直递减的速率比C∶N快。(5)相关分析表明,土壤SOC、TN、TP相互之间呈显著正相关关系,C∶N、C∶P比值主要受土壤SOC含量的影响,N∶P比值主要受到土壤SOC、TN含量的影响,C∶P比值对土壤C∶N、N∶P比值影响显著。研究发现,不同灌木对半流动沙地的土壤质量的改善修复作用差异显著,且东北木蓼和小叶锦鸡儿的适应性强、对土壤养分的积累更加明显。

Shrub type plays an essential role in ecosystem recovery and affects soil quality,especially soil carbon (C),nitrogen (N) and phosphorus (P) contents.Studies on the effects of different shrub types on soil C,N and P stoichiometry are beneficial to understand the processes and functions of the ecological system.C,N and P stoichiometry are estimated in four typical shrubs:Caragana microphylla ,Atraphaxis manshurica ,Salix flavida and Artemisia halodendron .In order to elucidate the effect on ability of different shrub types on soil nutrient elements under the same environmental conditions and provide guidance for desertification control and ecological restoration,we measured soil organic carbon (SOC),total nitrogen (TN) and total phosphorus (TP) contents in depth of 0-80 cm,compared ecological stoichiometry characteristics in different shrubs and soil depths and explored the correlation between indicators.Results showed that:(1)the mean contents of SOC,TN and TP were 0.90-2.18 g/kg,0.19-0.32 g/kg and 0.27 -0.32 g/kg.The average concentrations of SOC,TN and TP in 0-80 cm soil layer of A.manshurica is the highest in all of them.SOC and TN of C.microphylla and A.manshurica were significantly higher than that in others,but there were no significant differences between C.microphylla and A.manshurica .The average concentrations of TP in these four shrubs were no significant differences.(2)The contents of SOC,TN and TP in the surface layer (0-10 cm) of each shrub type were significantly affected by vegetation type.The surface layer (0-10 cm) of four shrubs was significantly higher than other layers.And they significantly declined with increasing soil depth.(3)The concentrations of SOC and TN decreased with the increase of soil depth in four shrubs,showed“inverted Pyramid”distribution pattern.However,the content of TP was no obviously change with the increase of soil depth,appeared“cylinder”distribution pattern.(4)The average ratios of C∶N,C∶P of A.manshurica were the highest,followed by A.manshurica and S.flavida ,the lowest was found in A.halodendron .The ratios of C∶N,C∶P,N∶P and their differences decreased with the increase of soil depth.Both soil N∶P and C∶P ratios significantly declined with increasing soil depth,whereas the vertical pattern of soil C∶N ratio has high stability.(5)The correlations between SOC,TN and TP were significant,the ratios of C∶N,C∶P were mostly influenced by the content of SOC,the N∶P ratio was mostly influenced by the content of SOC,TN,and the ratios of C∶N,N∶P were significantly influenced by the ratio of C∶P.In summary,the difference of the adaptability of the 4 kinds of planting species was significant. A.manshurica and C.microphylla take effects in increasing soil nutrients obviously.