Effects of thinning on hydrological characteristics of litters in Cunninghamia lanceolata plantation in moun-tainous area of Fujian Province
Analyzing the effects of thinning on litter storage and hydrological characteristics can provide a scientific support for the establishment of Chinese fir(Cunninghamia lanceolata)plantation and the improvement of its water-conserving function.A randomized block experiment was designed in a 13-year-old Chinese fir plantation in the Yangkou State-owned Forest Farm in Fujian Province,with four thinning intensities:no thinning(control),light,moderate,and high thinning intensity.We analyzed the litter storage capacity,water absorption characteris-tics,and interception capacity of each decomposition layer of the Chinese fir plantation under the four thinning in-tensities using field investigation and indoor immersion methods.The litter stock under the four treatments ranged from 4150 kg·hm-2 to 7148 kg·hm-2.The litter accumulation under the moderate thinning was 21.06％and 75.06％higher than that under light and high thinning,respectively,and the litter stock in the half-decomposed layer was 3.38 times of that in the undecomposed layer.The relationship between water capacity(W),water absorption rate(V)and immersion time of undecomposed and half-decomposed litters was described with the func-tion models of W=a+blnt and V=ktn,respectively.The former increased rapidly before 4 h,while the latter decreased rapidly from 0 to 4 h.The water holding capacity and water absorption rate of the half-decomposed layer were higher than those of the undecomposed layer,and were higher in the moderate thinning treatment than in the other three treatments.Thinning significantly changed the maximum water holding capacity(14011-23600 kg·hm-2),maximum storage capacity(10450-17840 kg·hm-2)and effective storage capacity(8340-14310 kg·hm-2)of litter layer,with the strongest effect of the moderate thinning.The values of the hydrological charac-teristics of litter were greater in the half-decomposed layer than in the undecomposed layer.It is suggested that mod-erate thinning should be adopted in the management of Chinese fir plantations in this area to maximize the benefit of forest water conservation.
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