| At the late growth stage of the artificial pure forests,or after long term continuous planting of them,most of the forest soil exhibited soil impoverishment,self poisoning and soil degradation.Forming mixed forests of coniferous and broad-leaf species shows obvious advantages in the rapid restoration of the ecological environment,effective utilization of nutrients and space,and the improvement of site conditions.Friendly interspecific relationship is of great importance during the forming of mixed forests vegetation.Because the litter plays important roles in the forest ecosystems,whether the species in the litter mixture will affect the decomposition of each other directly affect the nutrient cycling and the balance of soil nutrients of the mixed forest ecosystem.At present,the allelopathy in the mixed litter decomposition process is rarely studied.Therefore,it is necessary to investigate this factor for perfecting the research of interspecific relationship,assessing mixed suitability of different tree species.Five common broad-leaf species(Betula albo-sinensis,Catalpa fargesi,Populus purdomii,Eucommia ulmoides,Acer truncatum)and 5 coniferous species(Pinus tabulaeformis,Platycladus orientalis,Pinus armandii,Larix kaempferi,Picea asperata)in Qinling Mountains were taken as objects for this study.The extracts of coniferous litter was termly added into the decomposition medium to simulate the decomposition and nutrient release of broad-leaf litter under the effects of allelochemicals from coniferous litters.In addition,the alterations of enzymatic activity of the decomposition medium(soil)were detected as well.The main results are as follows:(1)P.tabulaeformis litter extracts significantly inhibited the decomposition and the release of C,P and Cu of B.albo-sinensis litter.P.orientalis litter extracts significantly inhibited the decomposition and the release of C,N,P and K of it,however,promoting the release of Cu and Mn.P.armandii litter extracts significantly inhibited the decomposition and the release of C,P,K and Mn of it,however,promoting the release of N.L.kaempferi litter extracts significantly inhibited the decomposition and the release of C,N,P,K and Zn.P.asperata litter extracts exhibited no effects on the decomposition.While it inhibited the release of K,promoting the release of C,N,P,Cu and Mn.(2)P.tabulaeformis litter extracts significantly inhibited the decomposition and the release of C,P and Zn of C.fargesii litter,however,significantly promoting the release of Mn.P.orientalis litter extracts significantly inhibited the decomposition and the release of C,N,P,K and Zn.P.armandii litter extracts significantly inhibited the decomposition and the release of C,N and P,while it promoted the release of Mn.L.kaempferi litter extracts significantly inhibited the decomposition and the release of C,N,P,K,Cu,Zn and Mn.P.asperata litter extracts showed no effects on the decomposition of C.fargesii,significantly promoting the release of N,K,Cu,Zn and Mn,while it significantly inhibited the release of C and P.(3)P.tabulaeformis litter extracts significantly inhibited the decomposition and the release of C,N,K and Cu of E.ulmoides litter,however,significantly promoting the release of P.P.orientalis litter extracts showed no effects on the decomposition,while it inhibited the release of N,P,K,Cu and Zn.P.armandii litter extracts significantly inhibited the decomposition and the C,N,K,Cu and Zn.L.kaempferi litter extracts significantly inhibited the decomposition and C,N,K and Cu,promoting the release of P.P.asperata litter extracts showed no effects on the decomposition,significantly promoting the release of N and P,while it significantly inhibited the release of K.(4)P.tabulaeformis litter extracts showed no effects on the decomposition of P.purdomii.It significantly promoted the release of Cu,while it significantly inhibited the release of P and Mn.P.orientalis litter extracts significantly inhibited the decomposition of P.purdomii and the release of C.P.armandii litter extracts significantly inhibited the decomposition of P.purdomii and the release of C and P,significantly promoting the release of N.L.kaempferi litter extracts significantly inhibited the decomposition of P.purdomii and the release of C,P,K and Zn.P.asperata litter extracts had no significant effect on the decomposition of P.purdomii,while it significantly promoted the release of N,P,K,Cu and Zn.(5)P.tabulaeformis litter extracts significantly promoted the decomposition of A.truncatum and the release of C and Zn,while it inhibited the release of P.P.orientalis litter extracts significantly promoted the decomposition of A.truncatum and the release of C,K and Zn,while it inhibited the release of P.P.armandii litter extracts significantly promoted the decomposition of A.truncatum and the release of C,N and Zn,while it inhibited the release of P.L.kaempferi litter extracts significantly promoted the decomposition of A.truncatum,while it inhibited the release of P and K.P.asperata litter extracts significantly promoted the decomposition of A.truncatum and the release of C,N and Zn. |
