Soil nutrient stoichiometric ratios and their influencing factors in mountainous areas of the Ili River Valley
Studying the soil stoichiometric ratios and the influencing factors of different altitude gradients in mountain ecosystems in arid zones is significant in revealing the soil nutrient status and maintaining the sustainable development of mountain ecosystems.In this paper,13 sample plots were established along the elevation gradient in the mountains of the southern Ili River Valley,and soil in the depth of 0-20 cm was studied to investigate nutrient stoichiometric ratios and their influencing factors.The results showed that:(1)Soil acidity gradually increased with elevation.Organic carbon and total nitrogen contents are significantly higher in the middle and high mountain belts than in the low mountain belts,while total phosphorus and total potassium contents are opposite.(2)Due to altitudinal differences,the carbon-to-nitrogen ratio is significantly higher in the mid-alpine belt than in the low and alpine belts;carbon and phosphorus ratios are significantly higher in the middle and high mountain belts than in the middle and low mountain belts;carbon and potassium ratios are significantly higher in the middle and high mountain belts than in the low mountain belts;nitrogen-phosphorus ratios are higher in the alpine zone,but there is no major difference between the transition zone and the low mountain zone;nitrogen-potassium ratios are much higher in the alpine zone,whereas there is no significant difference between the mid-alpine zone and the transition zone;the differences of phosphorus/potassium ratios between altitudinal gradients are ignorable.(3)The dominant factors affecting the stoichiometric ratios of soil physicochemical indicators are soil organic carbon(62.4%),total phosphorus(15.9%),and total carbon(13.7%);while the major environmental factors are mean annual soil temperature(27.1%),vegetation index(11.2%),elevation(12.3%),and mean annual atmo-spheric temperature(3.4%).The study showed that the physicochemical indicators have an important influence on the soil stoichiometric ratio,further verified that the altitude is still the dominant factor affecting the stoichiometric ratio,and revealed that the influence of microenvironmental factors on the soil stoichiometric ratio should not be neglected,which provides a scientific basis for the in-depth study of the nutrient status of soils in mountainous areas of the Ili River Valley.
stoichiometric ratioimpact factorsoil nutrientsIli River valley mountains
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