| Four broad leaved-coniferous mixed forest land of Pinus massoniana have been selected in Dashan forest farm,Zongyang County(Al:Pure Forest;A2:mixed forest with 80%-90% of Pinus massoniana; A3:mixed forest with 70%-80% of Pinus massoniana;A4: mixed forest with 60%-70% of Pinus massoniana),12 piece of sample plots were set,each forest respectively set up 3 piece of repetition,and each plot is at the same area 20m×20m.Research on the ecological effects which contain the soil physical and chemical properties,water conservation capacity,micro-climate understory biomass allocation pattern of understory and fuel characteristics of understory has been conducted by the methods of sample collection,Soil sampling,Measure mented at a Location and Laboratory analysis. The results are as follows:The soil organic matter of four broad leaved-coniferous mixed forest land of Pinus massoniana (A1,A2,A3,A4,Hereinafter) were 15.45g/kg,16.11g/kg,17.42g/kg and 19.50g/kg,total N were 1.04g/kg,1.10g/kg,1.39g/kg and 1.63g/kg, Hydrolysable N were 123.66mg/kg,124.42mg/kg,125.84mg/kg and 131.31mg/kg, Available P were 8.71mg/kg,9.04mg/kg,9.27mg/kg and 9.55mg/kg, available k were 65.03mg/kg,65.66mg/kg,68.03mg/kg and 69.42mg/kg, bulk density were 1.26g/cm3,1.24g/cm3,1.11g/cm3 and 1.11g/cm3,>0.25mm water-stable aggregate were 66.24%,66.42%,69.10% and 69.53%, soil water content were 16.06%,16.18%,23.64% and 23.68%. The result of correlation analysis showed that there were closer significantly positive relationships between the soil organic matter,Total N,Available P,Available K, water-stable aggregate with the broadleaved mixed forest proportion(the correlation coefficient were 0.973*,0.973*,0.998**,0.979* and-0.934*).The accumulation capacity of dead wood and defoliation of four broad leaved-coniferous mixed forest land of Pinus massoniana were 8.29t·hm-2,6.42t·hm-2,5.79t·hm-2 and 5.65 t·hm-2.The maximum water-holding ratio of dead wood and defoliation of the four mixed of Pinus massoniana were 269.60%,345.34%,371.89% and 342.87%, The maximum water-holding capacity were 22.35t·hm-2,22.17t·hm-2,21.54t·hm-2 and 19.36t·hm-2, the maximum comprehensive water conservation capacity of soil were 1758.6t·hm-2,1806.8t·hm-2,2499.2t·hm-2 and 2614.3t·hm-2,comprehensive maximum water conservation capacity of four forest types were 1780.95t·hm-2,1828.97t·hm-2,2520.74t·hm-2 and 2633.66t·hm-2. Compared with A1, the maximum water conservation capacity(A1,A2 and A3) were respectively increased to 22.06%,41.54% and 47.88%. As can be seen,the water conservation capacity was increased by the increase of the broadleaved mixed forest proportion.The beginning infiltration rate of water infiltration situation of four broad leaved-coniferous mixed forest land of Pinus massoniana were 19.8mm·min-1,20.3mm·min’’,27.7mm·min-1 and 28.1mm·min-1, The steady Infiltration rate were 2.2mm·min-1,2.3mm·min-1 and 2.7mm·min-1 å'Œ 2.8mm·min-1, the time to reach steady infiltration were 17.3min,18.0min,19.5min and 20.0min. The beginning infiltration rate,the steady infiltration rate and the time to reach steady infiltration were increased by the increase of the broadleaved mixed forest proportion of the broad Leaved-coniferous Mixed Forest land of Pinus massoniana.Understory biomass of four broad leaved-coniferous mixed forest land of Pinus massoniana were 1632.55g/m2,1329.67g/m2,838.95g/m2 and 550.55g/m2,the Root Biomass of shrub were 854.06g/m2,736.81g/m2,423.14g/m2 and 251.80g/m2,the Stem Biomass of shrub were 854.06g/m2,736.81g/m2,423.14g/m2 and 251.80g/m2,the Leaf Biomass of shrub were 218.84g/m2,207.21g/m2,130.59g/m2 and 96.65g/m2,the underground Biomass of herb layer were 218.84g/m2,207.21g/m2,130.59g/m2 and 96.65g/m2, the aboveground Biomass of herb layer were 42.67g/m2,45.54g/m2,59.02g/m2 and 69.05g/m2.The proportion of the underground part of the understory vegetation biomass decreased by the increase of the broadleaved mixed forest proportion of the broad Leaved-coniferous Mixed Forest land of Pinus massoniana. The result of correlation analysis showed that there were closer negative relationships between the underground biomass with the soil bulk density and the soil water content(R=-0.826*--0.958*).The amount of combustible matter of four broad leaved-coniferous mixed forest land of Pinus massoniana were 8.29t·hm-2,6.42t·hm-2,5.79t·hm-2 and 5.65t·hm-2,with the increase proportion of broadleaf,the amount of combustible matter were decreased. The ignition time of 50g combustibles at those woodland were 17.00s,21.33s,36.33s and 40.67s.thus,with the increase proportion of broadleaf, woodland combustibles burn harder,enhancing the fire resistant ability,reduce the rate of spread of fire,forest-fire probability and the hazard degree were reduce. |
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