| Pinus massoniana and Castanopsis hystrix are important native species or precious species in Guangxi,respectively.They all have the advantages of wide adaptability,fast growth rate and excellent wood material,and have broad development prospects.In this study,we set different mixing ratio modes [P.massoniana and C.hystrix according to 9?1(A),8?2(B),7?3(C),6?4(D),pure forest of P.massoniana(E)and pure forest of C.hystrix(F)] and did standard survey and biomass measurement,for 8 consecutive years of positional monitoring of different mixed proportions of P.massoniana-C.hystrix mixed forests,and measuring 8 years of mixed forests.The biomass and productivity were used to reveal the effects of different mixing ratios on the growth and biomass productivity of P.massoniana and C.hystrixmixed forest,which provide a scientific basis for the selection of the mixed model of P.massonianaC.hystrix mixed forest.The main results are as follows:(1)With the increase of stand age,the height,DBH and single plant volume of P.massoniana and C.hystrixmixed increased in each mixed mode and the difference in growth effect between mixed forest and pure forest gradually became obvious.The growth effects of the four mixed modes(A,B,C,D)were better than those of pure forests.Among them,the A-type P.massoniana had the best growth effect,and the average DBH,tree height and individual volume of P.massoniana inthe mixed forest.Compared with the pure forest(E)of P.massoniana(E),they increased by 5.80%,8.33% and 23.31%;the B-type C.hystrixmixed had the best growth effect,and the average DBH,tree height and single volume volume of the mixed forest mixed cone were respectively higher than that of the C.hystrixmixed pure forest(F mode)increased by 8.57%,18.18% and 49.16%.(2)After 8 years of afforestation,the ratio of different mixed proportions to the average wood biomass of the trees was different.Among them,the biomass of the single-planted P.massoniana was the largest,reaching 56.26 kg/plant,which was better than the pure forest of P.massoniana(E-mode).48.54 kg/plant increased by 15.90%;B-mode C.hystrix had the largest biomass per plant,reaching 44.79 kg/plant,which was 25.25% higher than that of C.hystrix pure forest(F model)(35.76 kg/plant).(3)There are differences in biomass of P.massoniana and C.hystrix mixed forests with different mixed proportions,among which A is the largest,83.18t·hm-2,followed by B,C,E and D mode,which are 80.91? 79.91?77.67 and74.57 t·hm-2,respectively.the minimum is F mode,which is 56.86 t·hm-2.(4)There are differences in the net productivity of the arbor layer of the mixed forest of different ages of 8-year-old,which are ranked A(10.40t/(hm2·a))and B(10.11 t/(hm2·a)),C(9.99 t/(hm2·a)),E(9.71 t/(hm2·a)),D(9.32 t/(hm2·a)),F(7.11 t/(hm2·a))).The net productivity of each organ of P.massoniana-C.hystrix in different mixed modes was dry material>tree branch>root>bark>leaf.In summary,the mixed forest of P.massoniana and C.hystrix promotes the growth and development of two tree species,which increase the growth rate of trees and the biomass productivity of stands... |
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