黄河中下游典型河岸带土壤性质空间变异及其对环境的响应

Spatial variation in riparian soil properties and its response to environmental factors in typical reach of the middle and lower reaches of the Yellow River

土壤和植被作为河岸带生态系统服务维持的根基,其空间分布与变异对河岸带生态功能的发挥起着决定性作用.本研究以黄河中下游典型河段河岸带为研究对象,采用野外调查、实验分析与冗余分析(RDA)相结合的方法,研究了河岸带土壤理化性质空间分异特征及其对环境的响应.结果表明:研究区土壤物理性质的横向梯度效应较为明显,随缓冲距离增大土壤容重呈现先增后减的趋势,而土壤含水量呈相反趋势;不同缓冲区土壤的全磷(TP)、有效磷(AP)、全碳(TC)、有机碳(TOC)、全氮(TN)、铵态氮(NH_4^+-N)和硝态氮(NO_3^--N)含量差异均不显著;不同植被类型(杨树人工林和柳树人工林)的土壤化学性质差异均不显著.相关性分析表明,石开究区土壤TOC与TN、NO_3^--N含量均呈极显著正相关、与NH_4^+-N含量显著正相关土壤TC和TOC含量均与砂粒呈极显著负相关与粘粒极显著正相关.RDA结果显示土壤TOC和NH_4^+-N含量随乔木层高度和盖度的增加而增加,土壤TP与NO_3^--N随乔木层树木胸径和草本层植物盖度的增加而增加,而NH_4^+-N含量随海拔升高呈递增的趋势,说明黄河中下游河岸带土壤性质受群落结构和海拔梯度的影响显著.

Soil and vegetation are the foundation of maintaining riparian ecosystem services,and their spatial distribution and variations can determine the effects of ecological functions.In the present study,selecting the typical reach of the middle and lower reaches of the Yellow River as the study area,the spatial distributions of riparian soil physicochemical properties and their response to environmental factors were analyzed by employing methods of field investigation,experimental analysis,and redundancy analysis（RDA）.The results showed that soil particle was composed significantly of silt in the study area,with the increase of riparian buffer distance,soil bulk density increased initially and then decreased,whereas soil moisture showed the opposite pattern.Changes in total soil phosphorus（TP）,available phosphorus（AP）,total carbon（TC）,total organic carbon（TOC）,total nitrogen（TN）,ammonium nitrogen（NH4^＋-N） and nitrate nitrogen（NO3^--N） contents under different riparian buffer distance showed no statistically significant differences.The spatial distribution of soil chemical properties was generally insignificantly different through changes between two vegetation types.Pearson correlation analysis showed that there was close relationship between soil physical and chemical properties,therein,TOC content in the study area was positively and significantly related to TN（P〈0.01）,NO3^--N（P〈0.01）,and NH4^＋-N（P〈0.05） contents,respectively.Both the TN and TOC contents were significantly negatively related to sand content（P0.01）,while was significantly positively related to clay content（P〈0.01）,indicating that high sand content could promote porosity and permeability of soil and then accelerate the degradation rate of organic matters in soils.In addition,the results of RDA indicated that TOC and NH4^＋-N contents increased with increasing the height and coverage of the tree layer.Soil TP and NO3^--N contents increased with increasing the plant diameter at breast height（DBH） of the tree layer and coverage of the herb layer.Meanwhile,with the increase of elevation gradient,the content of soil NH4^＋-N presented an increasing trend,indicating that soil properties were significantly influenced by the effects of community structure and elevation gradient in the study area.