| In order to explore the seasonal dynamic evolution characteristics of nutrients in soil and litters of Phoebe bournei,Cunninghamia lanceolata and its mixed plantation,improve the soil nutrient status of Phoebe bournei plantation and achieve sustainable management of forest..In this paper,three standard plots were set up for each of the 3 stands of Phoebe bournei plantation,Cunninghamia lanceolata plantation and Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation,Soil and litters samples were collected in January(winter),April(spring),August(summer)and November(autumn)of 2018 respectively,and 16 nutrient indexes of soil and 9 nutrient indexes of litters in the sample plots were determined.The seasonal dynamics of soil and litter nutrients under three stand types in hunan province were studied by using correlation analysis and typical correlation analysis.The main res-earch results are as follows(1)Different forest types of soil nutrient index:contents of organic matter,dissolved organic nitrogen,dissolved organic phosphorus,total nitrogen,total phosphorus,hydrolyzed nitrogen,available phosphorus,total calcium,total magnesium,total sulfur,total iron,total manganese,total copper and total zinc all showed significant differences(p?0.05).while the content of dissolved organic carbon and total potassium there was no significant difference.The contents of soil organic matter,total nitrogen,total phosphorus,hydrolyzed nitrogen,total calcium,total magnesium and total zinc in Phoebe bournei plantation were significantly higher than that of Cunninghamia lanceolata plantation.The contents of dissolved organic nitrogen and dissolved organic phosphorus in Cunninghamia lanceolata plantation and Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation were significantly higher than that of Cunninghamia lanceolata plantation.The content of total sulfur and manganese in Cunninghamia lanceolata plantation was higher than that of Phoebe bournei plantation.The content of total manganese in Cunninghamia lanceolata plantation and total copper in Phoebe bournei plantation were significantly higher than that in Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation.The content of available phosphorus was only significantly different in the soil layer of 0?10cm.With the increase of soil depth,the stand of soil organic matter,dissolved organic nitrogen carbon,dissolved organic nitrogen nitrogen,dissolved organic nitrogen,zinc and copper were significantly lower,and the total phosphorus,total potassium,available phosphorus,iron and magnesium content of no significant difference between different layers(2)The contents of soil organic matter,dissolved organic phosphorus,total phosphorus available phosphorus,total calcium,total sulfur,total iron,total manganese,total copper and total zinc in three stand types all showed significant differences with seasonal dynamic changes(p?0.05),while the contents of total magnesium showed no significant differences with seasonal dynamic changes.The content of soil nutrient index in each stand is not consistent with seasonal variation.Among them,the contents of soil organic matter,dissolved organic phosphorus,total phosphorus hydrolyzed nitrogen,total copper and total manganese were the highest in Phoebe bournei plantation in autumn.The contents of soil dissolved organic carbon,total sulfur,total and iron were the highest in winter.The contents of dissolved organic nitrogen and total calcium were the highest in summer.The amount of available phosphorus was the highest in spring.The contents of dissolved organic nitrogen,total nitrogen,total phosphorus,hydrolyzed nitrogen and total copper in soil were the highest in Cunninghamia lanceolata plantation in autumn.The contents of dissolved organic phosphorus,available phosphorus,total sulflur and total iron were the highest in winter.The contents of soil organic matter,total potassium,total calcium and total manganese are the highest in spring.The contents of organic matter and dissolved organic phosphorus were the highest in the Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation in autumn.The contents of available phosphorus,total sulfur,total iron,total manganese and total zinc are the highest in winter.The contents of dissolved organic carbon,total calcium and total copper are the highest in spring.With the increase of soil depth,soil organic matter,dissolved organic carbon,dissolved organic nitrogen,dissolved organic phosphorus,total nitrogen,hydrolyze nitrogen,total calcium,total sulfur,total iron,manganese,zinc and copper levels were significantly reduced in three forest types in each season,and the content of total phosphorus,total potassium and total magnesium there was no significant difference between different layers.(3)Different types of forest litter nutrient indexes,organic carbon,dissolved organic nitrogen,dissolved organic phosphorus,total phosphorus and calcium content have significant difference(p?0.05),The contents of soluble organic carbon,total potassium and total magnesium were only significantly different in undecomposed layer litters,total nitrogen content was significantly different only in the semi-decomposed layer.The contents of organic carbon,dissolved organic nitrogen,dissolved organic phosphorus,total phosphorus,calcium and magnesium were the highest in Phoebe bournei plantation.Among the litters in undecomposed layer,the total potassium was the largest in the Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation,which was significantly higher than that of the Phoebe bournei plantation,and the magnesium was the largest in the Phoebe bournei plantation,which was significantly higher than that of the Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation;The total nitrogen content of Phoebe bournei plantation plantation in semi-decomposed layer was significantly higher than that of Cunninghamia lanceolata plantation.In addition,with the increase of decomposition degree,the contents of organic carbon,dissolved organic carbon,dissolved organic nitrogen,dissolved organic phosphorus,total nitrogen,total phosphorus,total potassium,calcium and magnesium in litters in each stand all decreased significantly(4)The contents of organic carbon,dissolved organic carbon,dissolved organic nitrogen,total nitrogen,total phosphorus,total potassium and calcium in litters of three stand types all showed significant differences with seasonal dynamic changes(p?0.05).The content of litter nutrient index in each stand was not consistent with seasonal variation.The contents of organic carbon,dissolved organic carbon,dissolved organic phosphorus and total nitrogen were the highest in Phoebe bournei plantation in winter.The content of total phosphorus and total potassium is the highest in autumn.The content of dissolved organic nitrogen was the highest in spring Calcium is most abundant in summer.The contents of organic carbon,total nitrogen and total potassium were the highest in Cunninghamia lanceolata plantation in autumn.The content of total phosphorus and calcium is the highest in summer.The contents of dissolved organic carbon and dissolved organic phosphorus were the highest in winter.The content of dissolved organic nitrogen was the highest in spring.The contents of organic carbon,total nitrogen,total phosphorus and total potassium were the largest in the Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation in autumn.The contents of dissolved organic carbon,dissolved organic nitrogen and dissolved organic phosphorus were the highest in winter.Calcium content in summer is the largest;Magnesium is most abundant in the spring.In addition,the content of magnesium in Phoebe bournei plantation and Cunninghamia lanceolata plantation was only significantly different with the seasons in the undecomposed layer.With the increase of decomposition degree,the contents of organic carbon,dissolved organic carbon,dissolved organic nitrogen,dissolved organic phosphorus,total nitrogen,total phosphorus,total potassium and calcium in litters of the three stand types decreased significantly with the deepening of decomposition degree(5)Litter and soil stoichiometric characteristics of different stand types C/N,C/P,N/P and DOC/DON all showed significant differences(p?0.05),while DOC/DOP and DON/DOP only showed significant differences in litter layer,but no significant differences in soil layer.The stoichiometric ratios of C/N and DOC/DON in Cunninghamia lanceolata plantation were significantly higher than those in Phoebe bournei plantation,and the stoichiometric ratios of C/P and N/P in the Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation were significantly higher than those in Phoebe bournei plantation.DOC/DOP and DON/DOP are the largest in the Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation in litter layer,In addition,the stoichiometric ratios of C/N,DOC/DOP and DON/DOP in litters layer were significantly higher than that in the soil layer,while the stoichiometric ratios of N/P and DOC/DON in litters layer were significantly higher than that in the soil layer.(6)The litter and soil stoichiometric characteristics of the three stand types all showed significant differences with seasonal dynamic changes(p?0.05).Among them,the stoichiometric ratios of C/N,C/P,N/P and DOC/DON in Phoebe bournei plantation and Cunninghamia lanceolata plantation were the largest in winter,and the stoichiometric ratios of DOC/DOP and DON/DOP were the largest in summer.ln the Phoebe bournei-Cunninghamia lanceolata artificial mixed plantation,the stoichiometric ratios of C/N,C/P and N/P were the largest in winter,and the stoichiometric ratios of DOC/DON,DOC/DOP and DON/DOP were the largest in summer.In addition,the stoichiometric ratios of soil C/N,C/P,N/P and DOC/DON are the sensitivity factors affecting the stoichiometric characteristics of litters(7)There was a significant correlation between litter nutrients and soil nutrients in undecomposed layer and semi-decomposed layer(p<0.05).Among them,organic carbon,dissolved organic phosphorus and calcium in undecomposed layer had a greater correlation with total nitrogen,hydrolyzed nitrogen and total magnesium in soil.Dissolved organic nitrogen,dissolved organic phosphorus,total potassium and calcium in the semi-decomposed layer were significantly correlated with total nitrogen,hydrolyzed nitrogen and total zinc in the soil. |
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