Distribution Characteristics And Influencing Factors Of Soil Phosphorus Under Different Vegetation Types In The Qinghai-Tibet Plateau

As an essential nutrient for plant growth,phosphorus?P?plays a crucial role in the process of plant growth and development by participating in cell division,matter and energy synthesis.It is a limiting element of the ecosystem because of the limit of its supply in nature in many situations.The phosphorus content of soil is mainly affected by the parent rock,soil texture,climatic conditions,vegetation cover,geographical position and human activities and so on.The distribution characteristics and circulation rate of phosphorus will change with the change of environment.Understanding that under each environment like vegetation types,soil properties,terrain and climate,the composition,content,distribution and influencing factors of soil phosphorus is an important link to understand the structure and function of region ecosystem.The Qinghai-Tibet Plateau is asensitive area of global climate changes.It is a natural laboratory to study the responses and adaptation mechanisms of ecosystems to climate change.Under the background of global wanning and human activities,the spatial distribution characteristics and influencing factors of soil phosphorus in different vegetation types on the Qinghai-Tibet Plateau have become the focus of the research.Analyzing the content and influencing factors of soil phosphorus in the surface and profile of different vegetation types on the Qinghai-Tibet Plateau occupying geo-statistical methods.The results showed that:?1?Soil TP content in the surface of the Qinghai-Tibet Plateau?0?20 cm?was 0.12?1.11 g·kg^-1,with an average of 0.53 g·kg^-1.Soil IP content ranged from 0.08?0.77 g·kg^-1 with an average of 0.32 g·kg^-1.Soil OP content ranged from 0.01?0.86 g·kg^-1 with an average of 0.21 g·kg^-1.Soil AP content ranged from 1.61?48.17 mg·kg^-1 with an average of 14.80 mg·kg^-1.IP/TP ratio was 11%?96%,with a mean of 62%,OP/TP ratio ranged of 4%?89%,with an average of 38%,and AP/TP ratio varied from 2.65%to 3.55%,with an average of 3.10%.?2?Soil TP content in the profile of the Qinghai-Tibet Plateau?0?70 cm?was 0.29?0.75 g·kg^-1,with an average of 0.48 g·kg^-1.Soil IP content ranged from 0.11 to 0.52 g·kg^-1 with an average of 0.32 g·kg^-1.Soil OP content ranged of 0.02?0.57 g·kg^-1 with a mean of 0.16 g·kg^-1.Soil AP content varied from 6.40 to 39.79 mg·kg^-1 with an average of 20.39 mg·kg^-1.IP/TP ratio was 16%?97%,with a mean of 67%,OP/TP ratio range from 3%to 84%,with a mean of 32%,and AP/TP ratio ranged of 1.00%?12.15%,with an average of 4.71%.?3?The content of soil TP in the surface ranked in order were forest>saline>grassland>shrub grassland>sparse grassland>alpine steppe>alpine meadow>desert.Soil IP were saline>forest>shrub grassland>desert>sparse grassland>grassland>alpine meadow>alpine steppe.Soil OP were alpine steppe>alpine meadow>forest>grassland>sparse grassland>shrub grassland>saline>desert.Soil AP were forest>sparse grassland>saline>grassland>shrub grassland>desert>alpine meadow>alpine steppe.?4?Soil TP content in saline and forest increased with the soil depth,and soil TP content in grassland,shrub grassland,alpine meadow and alpine steppe showed a descending trend with the deepening of soil layer.Soil IP content and IP/TP ratio in grassland,saline,alpine meadow,alpine steppe and forest increased along the soil profiles,and soil IP content reduced along the soil profiles.The vertical distribution of soil OP content and OP/TP ratio was opposite to that of soil IP and IP/TP ratio.Soil AP content and AP/TP ratio in different vegetation types were significantly affected by soil depth and vegetation type in the vertical direction,and the lowest value appeared in 10-20 cm.?5?The content of TP,IP,OP and AP in the Qinghai-Tibet Plateau were influenced by multiple environmental factors.The Monte-Carlo results showed that the impacts of environmental factors on the surface soil phosphorus ranked in order of importance were TOC?soil total organic carbon?>TN?soil total nitrogen?>altitude>pH?soil?>Silt>Clay>growing season temperature>growing season precipitation>annual average precipitation>annual average temperature>C/N>longitude>Sand>EC?soil electric conductance?>Alk?soil total alkalinity?>growing season relative humidity>latitude>SIC?soil inorganic carbon?>growing season relative humidity.The content of soil phosphorus in the profile ranked in order of importance were TN>TOC>pH>Alk>C/N>Silt>Sand>SIC>EC>Clay.