| Precious tree species have always been the focus of attention in China and the world.Under the current market environment where there is a shortage of precious tree species,it has become an inevitable trend to cultivate precious tree species resources.Traditional tending forestry measures have occupied an important position in China's forestry development,and also showed good forestry effects.To create a complete set of precious tree species tending measures can also obtain theoretical guidance and experience from traditional tending measures.In order to screen out the tending measures suitable for the cultivation of precious tree species,this paper selects the mixed plantation of Dalbergia odoratum and sandalwood in the southern region to carry out the weeeding and fertilization experiment,and set up four treatments of CK?control?,weeding,fertilization,weeding and fertilization to study the soil of mixed forest.Quick-acting nutrient content,soil nit rogen process?mineralization,nitrification,ammoniumification,leaching?,soil respiration and isoxic respiration in response to weeding fertilization and tending measures,in order to initially screen the effective combination of Dalbergia odoratum and sandalwood Tending measures provide practical reference and theoretical guidance for the establishment of a complete breeding system for precious tree species.The main research results are as follows:?1?The application of weeding and fertilization increased the p H value of the soil,enhanced the acid-base buffering performance of the soil,and slowed the seasonal fluctuation of soil p H.The average p H of the soil increased by 0.15 compared with CK.The soil available nutrient content was significantly affected by the seasonal and tending measures.The content of nitrogen and nitrate nitrogen peaked in autumn and winter.The annual ammonium content of soil nitrogen,weeding,fertilization,weeding+fertilization increased by 16.87%,8.17%and20.25%,respectively.The weeding and weeding+fertilization application increased by 12.69%and 21.45%compared with CK,and the fertilization decreased by 1.81%compared with CK.The soil available phosphorus content increased by 50.63%and 19.58%compared with CK,and the weeding decreased by 2.53%compared with CK.The soil available potassium content The amount of weeding,fertilization and weedng+fertilization increased by 117.18%,57.91%and 142.54%respectively compared with CK.?2?CK,weeding,fertilization,weeding+fertilization application 4 treatment 0?10 cm soil layer in spring and autumn have the maximum net nitrogen mineralization rate,the value is18.92mg·kg-1·month-1,18.13 mg·kg-1·month-1;At the same time,the four treatment 0?10cm soil layer has the maximum nitrification rate in spring and autumn,the value is 20.35mg·kg-1·month-1,18.85 mg·kg-1·month-1;The maximum ammoniumation rate in winter is 0.22mg·kg-1·month-1,0.26 mg·kg-1·month-1;the nitrogen leaching is the most serious in autumn,the value is 15.98 mg·kg-1·month-1·the maximum leaching for the year was 86.69mg·kg-1.weeding,fertilization,weeding+fertilization all inhibited the net mineralization and nitrification rate of soil nitrogen to some extent.The annual nitrogen mineralization of weeding,fertilizing,weeding+fertilization treatment decreased by 26.27%and 16.07%,respectively.At6.29%,the annual nitrogen nitrification decreased by 17.10%,16.58%,and 1.42%,respectively,and also inhibited the accumulation of ammonium nitrogen in the soil.The annual nitrogen leaching amount of weeding,fertilization,weeding+fertilization treatment decreased by25.24%,8.65%and 6.09%.Compared with weeding,fertilization,weeding+fertilization and tending measures,seasonal factors have a more significant impact on soil nitrogen processes.Weeding,fertilization,weeding+fertilization inhibited the mineralization,ammoniumification and nitrification of soil nitrogen,and reduced the leaching loss of soil nitrogen,which was conducive to soil fertility preservation and nitrogen accumulation.It can alleviate the environmental pollution caused by nitrogen leaching and has certain ecological benefits.?3?The monthly dynamic changes of soil respiration rate were obvious,and the soil respiration rate was significantly different in different months.There was no significant difference in the low-peak period of respiration rate between treatments,and the difference in respiratory peak was significant.The respiration rate of CK soil ranged from2.09-7.89?mol·m-2·s-1,and the range of soil respiration rate was 2.80-102.24?mol·m-2·s-1.The range of soil respiration rate under fertilization treatment was 2.81-8.07?mol·m-2·s-1,the soil respiration rate ranged from 2.89-10.50?mol·m-2·s-1,and the heterotrophic respiration rate ranged from 1.55-5.79?mol·m-2·s-1,the average annual respiratory rate of each treatment was19.02%,8.79%,and 39.26%higher than that of CK.The soil respiratory temperature sensitivity coefficients were CK?1.71?,weeding?1.73?,fertilization?1.79?,and weeding+fertilization?2.03?,and the soil isoxia respiratory temperature sensitivity coefficient was 1.94.The annual flux of CK,weeding,fertilization,weeding+fertilization and isoxic soil respiration was 19.98,21.27,20.91,24.96 and 13.81 t C.hm-2a-1,and the annual flux of each treatment was 6.46%higher than that of CK.4.65%and 24.92%. |
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