杉木纯林转化为杉楠复层林后的凋落物水文效应

[Objective]To investigate the hydrological effects of litter after the conversion of pure Cunninghamia lanceolata forests to Cunninghamia lanceolata-Phoebe bournei complex forests,and to provide a theoretical basis for elucidating the ecological functions of Cunninghamia lanceolata complex forests and the near-natural management of Cunninghamia lanceolata.[Method]Four kinds of Cunninghamia lanceolata pure forests in Shunchang County with different intercrop retention densities were selected to set seeding of Phoebe bournei to be converted into Cunninghamia lanceolata-Phoebe complex forests,and the Cunninghamia lanceolata pure forests were used as the control.Litter were investigated and collected on the forest floor,and hydrological characteristics such as litter layer litter accumulation,water holding rate,storage capacity,water holding capacity,and so on,were determined to analyze the water effects of litter in Cunninghamia lanceolata-Phoebe complex complex forests with different Cunninghamia lanceolata retention densities.[Result]The results showed that(1)the total volume of litter was D65＞D55＞CK＞D35＞D23.Under the same density of heather,the cedar retention density had a significant effect on the volume of litter in Cunninghamia lanceolata-Phoebe dipterocarp forests,and with the increase of cedar retention density,the volume of litter in dipterocarp forests increased,and the ratio of the volume of litter in the semi-decomposed layer to the total volume was higher than that of the non-decomposed layer;(2)Under different soaking times,the water holding capacity of apomictic litter in the semi-decomposed layer was D65＞D55＞Ck＞D35＞D23,and that in the undecomposed layer was D65＞D55＞Ck＞D35＞D23.Apomictic litter in the understorey of compound-storey forests with different retention densities of cedar trees had the fastest rate of water absorption from 0 to 4h,and the maximal water holding capacity and the maximal rate of water holding were greater in the semi-decomposed than the undecomposed layer,which increased with increasing Cunninghamia lanceolata densities.The maximum water holding capacity and maximum water holding rate were greater in the semi-decomposed layer than in the undecomposed layer,and both increased with the increase of Cunninghamia lanceolata density;(3)The maximum retention rate varied from 188.12%to 233.54%,and the effective retention amount ranged from 24.39 t·hm-2 to 48.54 t·hm-2,all of which were the highest in the compound forest with the highest density of cedar trees.The litterr storage volume in the density of 55 cedar trees/mu and 65 cedar trees/mu was 1.37 and 1.38 times higher than that of the Cunninghamia lanceolata in the pure forest,respectively.The increase in litter water holding capacity,the maximum storage capacity and effective storage capacity were significantly higher,indicating that the litter layer of Cunninghamia lanceolata-Phoebe complex forests has a stronger capacity to store precipitation compared with Cunninghamia lanceolata pure forests.[Conclusion]There were some differences in the initial hydrological effects after the conversion of Cunninghamia lanceolata pure forest to Cunninghamia lanceolata-Phoebe complex complex forest,and the hydrological function of cedar-heath complex forest with high Cunninghamia lanceolata retention density was better than that of Cunninghamia lanceolata pure forest.Compared with the Cunninghamia lanceolata forest,the volume of apomictic storage was 1.37 and 1.38 times higher than that of the Cunninghamia lanceolata forest in D55 and D65 densities,respectively,and the water holding rate of apomictic storage increased,and the maximum storage capacity and effective storage capacity were significantly higher,indicating that the apomictic layer of mixed coniferous and broadleaf forests had a stronger ability to store precipitation compared with the pure Cunninghamia lanceolata forest.The volume of apomictic storage,the water holding capacity and the water holding ability of D65 densities were the most advantageous ones among the five densities.The storage capacity,water holding performance and water holding capacity of D65 density were the most favorable among the five densities.In future afforestation management,it is recommended to realize the enhancement of ecohydrological function by creating suitable density of mixed forests and cooperating with corresponding forest management measures.Meanwhile,in future management of plantation forests,we should try to avoid the creation of pure forests,and consider the benefits brought by the planting of multi-species trees.