| Taking the 30-year-old Cupressus torulosa plantation in Guangyuan region of Sichuan Province as the research object,this paper studies the content,reserves,distribution characteristics,utilization efficiency,annual net accumulation of nutrients and soil nutrient status of forest nutrients(N,P,K),and clarifies the nutrient elements of Tibetan cypress Plantation(N,P,K)content status,nutrient reserves,distribution characteristics,utilization efficiency,annual net accumulation of nutrients and soil nutrient status,and compared with the site conditions of Sichuan Cypress,in order to implement the scientific intensive management of Tibetan Cypress plantation,fertilization management,maintenance of ground force and improve productivity,improve the level of management to provide a scientific basis.The results of the study show that:(1)Nutrient content:The relationship between nutrient content and size of different organs is not exactly the same,the relationship between the nutrient content of trunk,branches and leaves is K>N>P,and only the cones show K>P>N.According to the average content of 3 nutrient elements,the Arbor layer showed K(3.9680g/kg)>N(1.3776g/kg)>P(0.8714g/kg),the undergrowth shrub layer showed K(7.43g/kg)>N(2.68g/kg)>p(0.51g/kg),The herbaceous layer is represented by K(5.5973g/kg)>P(0.9021g/kg)>N(0.3503g/kg),and the litter layer is represented by K(4.4475g/kg)>N(1.1847g/kg)>p(0.8636g/kg).(2)Nutrient reserves and distribution characteristics:The total reserves of 3kinds of nutrients(N,P,K)of the Cupressus torulosa are 691.30kg/hm~2,the size of each nutrient reserve is sorted into K(71.59%)>N(20.69%)>P(7.72%),and the K element reserves account for more than 70 of the total reserves of 3 elements,There is a great demand for K elements in the Tibetan cypress.The relationship between the nutrient reserves of each organ is not consistent,the trunk,branches and leaves show K>N>P,and the cones show K>P>N,which is consistent with the content of nutrient elements.The relationship between the total reserves of nutrients in each organ is shown as:Trunk>Branches>Cones>leaves.The size of the reserves of various elements of arbor layer,shrub layer and litter layer is consistent,the size relation is K>N>P,and the herbaceous layer is K>P>N.(3)Nutrient utilization efficiency:the total amount of nutrients required for the production of 1t dry matter in planted cypress is 4.92 kg,compared with light birch(6.19 kg),Southwest Birch(8.42 kg),Pinus massoniana(10.87 kg)and Sichuan cypress(6.51 kg),which requires the least nutrients,Nutrient utilization efficiency is high.The utilization efficiency of each nutrient element in Cupressus torulosa has the highest utilization efficiency of p>K and P and the minimum utilization efficiency of K.(4)Annual net accumulation of nutrients:3 kinds of annual net accumulation of nutrients is 25.6kg/(hm~2·a),the relationship between the size of each element is K>N>P,the annual net accumulation of 3 kinds of nutrients in the performance of each organ in the performance of the trunk>Branches>Cones>leaves,The annual net accumulation of trunk is 20.30 kg/(hm~2·a),which accounts for 79.3%of the total annual net accumulation of Arbor layer.(5)Soil nutrient status:The total N content of the Tibetan cypress plantation was0.499~0.761g/kg,with an average of 0.597 g/kg,the total P content was 0.096~0.378g/kg,and the average value was 0.192 g/kg.It is 6.212~8.741 g/kg with an average of7.572 g/kg.According to the soil nutrient grading standards in the hilly area of central Sichuan,the contents of N,P and K in the soil of Tibetan cypress plant were all in a state of deficiency.It is recommended to increase the supply of N,P and K fertilizers during the nurturing process.(6)compared with Tuber,the content of nutrient elements,in terms of the content of each organ,in addition to the content of the trunk K elements of Cupressus torulosa>Tuber,the content of each element of other organs are expressed as Tuber>Tibetan Cypress.In terms of reserves,the nutrient reserves of arbor layer are shown as 691.30kg/hm2>Tuber(633.16 kg/hm~2),and the nutrient reserves of Tibetan cypress are mainly concentrated in the trunk part,Tuber concentrated in the leaf part.The nutrient reserves of the irrigation layer are Tuber(12.67 kg/hm~2)>The Cupressus torulosa(9.53 kg/hm~2).The nutrient reserves of the litter layer are reflected in the Tibetan Berzenberg(144.54 kg/hm~2)>Tuber(19.66 kg/hm~2).Combined with the nutrient reserves of arbor layer,the nutrient reserves on the ground of Cupressus torulosa Plantation are Tuber,which shows that the Tibetan cypress plantation needs to increase soil fertility more than Tuber.The utilization efficiency of nutrient elements was expressed by 4.92 kg/t>Tuber(6.51 kg/t),which showed that the utilization efficiency of soil nutrients in Cupressus torulosa was higher than that of Sichuan Bai,and under the same conditions,the growing cypress trees in Tibet were better than tubers,which illustrated the suitability of Tibetan cypress trees for soil conditions.The demand for K is greater than that of tubers,and the utilization efficiency is low,so it is necessary to improve the use level of potash fertilizer in Tibetan cypress.The annual net accumulation of nutrient elements is manifested in the collection of Cupressus torulosa trees[25.6kg/(hm~2·a)]>Chuan cypress[21.1 kg/(hm~2·a)],which grows faster than tubers and requires more nutrients during growth than the amount of nutrients absorbed by tubers from the soil each year to absorb weight Therefore,under the same conditions,Tibet’s Bobby Chuber needs more soil fertility,and the amount of fertilizer applied in Tibetan cypress plantations will increase in the process of woodland management,and efforts should be intensified.According to the diagnostic and evaluation criteria of soil fertility,T soil nitrogen and phosphorus nutrient in the southern region,the content of nitrogen and phosphorus in cypress soil of Tibet was higher than that of soil nitrogen and phosphorus in Sichuan Cypress.Cupressus torulosa and Sichuan Cypress are in a state,and the supply of nitrogen and phosphorus fertilizers needs to be increased. |
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