Spatial Distribution Of Soil Carbon,Nitrogen And Phosphorus Contents And Ecological Stoichiometric Ratios Of Picea Schrenkiana Forests

The spatial variability of terrestrial ecosystems at different scales and their influencing factors are related to the nutrient cycling process of ecosystems and the response of ecosystems to environmental changes,and thus have received extensive attention from ecologists.At present,the increase in the concentration of greenhouse gases such as carbon dioxide in the atmosphere has aggravated the trend of global warming.However,the research on the soil ecological stoichiometry of terrestrial ecosystems mainly focuses on the variability of soil organic carbon content and its influencing factors.For other nutrient elements,such as nitrogen(N),phosphorus(P),etc.,and the understanding of the spatial coupling characteristics between elements and their control mechanisms,there is still a relative lack.In this study,we studied Picea schrenkiana forest on the northern slope of the Tianshan Mountains.Based on the analysis of field sampling and laboratory experiments,we estimated the spatial patterns of concentrations of soil organic carbon(C),total nitrogen(N),total phosphorus(P)and C?N?P ratios in Picea schrenkiana forest in the Tianshan Mountains used multiple linear regression(MLR)model.The results showed as follows:(1)The average values of soil C,N and P in the 0-30 cm soil depth of Picea schrenkiana forest were(85.76± 30.77)g/kg,(6.86± 2.76)g/kg and(0.87± 0.30)g/kg,respectively,The average values of soil C?N,C?P,and N?P ratios were(13.00± 4.94),(104.08± 38.68),and(8.20± 2.57),respectively;The average values of soil C,N and P in the 30-50 cm soil depth were(47.56± 29.05)g/kg,(4.00± 2.14)g/kg and(0.67 ± 0.22)g/kg,respectively,The average values of soil C?N,C?P and N?P ratios were(11.86± 4.43),(72.78± 37.77)and(6.13± 2.33),respectively;The average values of C,N and P in the 50-80 cm soil depth were(32.76± 21.33)g/kg,(2.84± 1.48)g/kg and(0.59± 0.18)g/kg,respectively,The average values of soil C?N,C?P and N?P ratios were(11.48± 4.69),(56.04± 32.66)and(4.86± 2.09),respectively.The soil C,N and P contents and their stoichiometric ratios of Picea schrenkiana forest showed moderately variable.(2)Correlation analysis of soil C,N,P content and stoichiometry of Picea schrenkiana forest showed that the different soil depth C was significantly positive between N,P,C?N ratio,C:P ratio and N?P ratio.There was a very significant positive correlation between the N content of the 0-30 cm depth soil and the P,N?P ratio,and a significant negative correlation with the C?N ratio,and no correlation with the C?P ratio,at 30-50 cm and 50-80 cm depth soil,there was a very significant positive correlation between N content and P,C?P ratio and N?P ratio,and no correlation with C?N ratio;There was a significant negative correlation between P content in 0-30 cm soil and C?P ratio and N?P ratio,and is not related to C?N ratio.Soil P content in 30-50 cm and 50-80 cm soil layers,there was a significant negative correlation with the N?P ratio and no correlation with the C?Nand the C?Pratios.(3)Vertical distribution characteristics: With the increase of soil depth,soil C,N and P contents and stoichiometric ratios decreased.With the increase of altitude,the soil C and C?P ratio,N?P ratio in all soil layers showed an increasing trend;N increased in 0-30 cm soil layer,and the change in 30-80 cm soil layer was not significant;The P content was not significantly changed in the 0-30 cm soil layer,and decreased in the 30-80 cm soil layer;the C?N ratio was not significantly changed in the 0-50 cm soil layer,and increased in the 50-80 cm soil layer.(4)Horizontal distribution characteristics: With the increase of longitude,the contents of C,N and P in the soil with a depth of 0-30 cm decreased,while the stoichiometric ratios did not change significantly;The C and P in the soil with a depth of 30-50 cm decreased,and the C?P decreased,while the content of N,C:Nratio and N?P ratio did not change significantly.In the 50-80 cm soil layer,C decreased,C?N ratio and C?P ratio decreased,and the N,P and N?P ratio did not change significantly.With the increase of latitude,the contents of C,N and P decreased,the N:P ratio decreased,the C?N ratio increased,and the C?P ratio did not change significantly with the depth of 0-30 cm.The C,N,P and their stoichiometric ratios were not significantly changed.(5)The spatial distribution characteristics of C,N and P content and stoichiometric ratios of soil layers in Picea schrenkiana forest distribution area showed some differences and similarities.In general,soil C,N and P and C?P ratio,N?P ratio showed relatively high content in the southwest,and relatively low in the northwest and east.The spatial distribution characteristics of soil C?N ratio were quite different in each soil layer,showed that the 0-30 cm soil layer was relatively high in the northwest and the east,and relatively low in the southwest.In the 50-80 cm soil layer,the west was relatively large and the east was relatively low,showed a trend of decreasing from west to east.The soil P content had no obvious spatial distribution characteristics.Multiple linear regression models(MLR)can be used to estimate the spatial distribution of regional soil elemental content and ecological stoichiometry.In future work,it is possible to better describe the soil carbon,nitrogen,phosphorus and stoichiometric ratios by introducing more independent variables(biological,abiotic and human factors),adjusting the MLR model or using other spatial estimation models.