Soil organic carbon mineralization, microbial biomass carbon and metabolic quotient in soils were determined to understand the effects of litter on soils in natural evergreen broadleaved forest, Sassafras tzumu planta...Soil organic carbon mineralization, microbial biomass carbon and metabolic quotient in soils were determined to understand the effects of litter on soils in natural evergreen broadleaved forest, Sassafras tzumu plantation and Cryptomeria fortunei plantation. Soils were collected in the 0～20 cm layer and incubated for 15, 30, 45, 60, 75 and 90 days in the laboratory at 25 ℃ with natural water content and different litters. The results indicated that organic carbon mineralization rate, microbial biomass carbon and metabolic quotient in soils showed the ranked order of natural evergreen broadleaved forest > Sassafras tzumu plantation > Cryptomeria fortunei plantation when the forest litter was not added to the soil. The added forest litter increased the organic carbon mineralization rate, microbial biomass carbon and metabolic quotient in soils regardless of the forests. Comparing with the litter from the Sassafras tzumu plantation and Cryptomeria fortunei plantation, the litter from the natural evergreen broadleaved forest led to higher organic carbon mineralization rate, microbial biomass carbon and metabolic quotient in soils. The results suggested that the artificial regeneration of the natural evergreen broadleaved forest into the Sassafras tzumu plantation and Cryptomeria fortunei plantation might lead to the low organic carbon mineralization, microbial biomass carbon and metabolic quotient in soils.展开更多
Public welfare forest is the most important model of vegetation restoration in the Conversion of farmland to forests in Sichuan Province. It can well represent and reflect the characteristics and laws of vegetation re...Public welfare forest is the most important model of vegetation restoration in the Conversion of farmland to forests in Sichuan Province. It can well represent and reflect the characteristics and laws of vegetation restoration in hillside fields. Therefore an Alnus cremastogyne forest community developed via converting hillside fields to forest, was investigated by contrast with a weed community on abandoned hillside fields. The results indicated that: 1) In Sichuan Basin and surrounding regions of it, vegetations restored so rapid that the average DBH (diameter at breast height), tree height of A.cremastogyne tree crown density, ground vegetation coverage respectively reached 5.2 cm, 6.1 m, 0.7 and 100 percent for 3 years and after converting hillside fields to forest. 2) With vegetation restoring, community gradually developed mosaic spatial pattern and vertical stratification, simultaneously distribution of plant population changed from regular to clumped, and spatial heterogeneity of community increased. 3) Community biodiversity remarkably increased in the process of vegetation restoration in hillside fields. During the period, species richness of both commnuities changed from 20 to 39, Shannon-Wiener diversity index was 4.205 and 5.021 respectively, while Pielou equitability index dropped little. 4) Plant species frequently and dramatically altered, which mainly showed that therophytes declined rapidly from 16 to 10, while perennial ones dramatically increased from 2 to 26, and 8 of them are phanerophytes. 5) The pathway of community development approximately was from annual herbs to shrubs + perennial herbs to trees + shrubs and herbs + perennial herbs, finally to natural mixed forests, such driving force was mainly from interspecific competition.展开更多
文摘Soil organic carbon mineralization, microbial biomass carbon and metabolic quotient in soils were determined to understand the effects of litter on soils in natural evergreen broadleaved forest, Sassafras tzumu plantation and Cryptomeria fortunei plantation. Soils were collected in the 0～20 cm layer and incubated for 15, 30, 45, 60, 75 and 90 days in the laboratory at 25 ℃ with natural water content and different litters. The results indicated that organic carbon mineralization rate, microbial biomass carbon and metabolic quotient in soils showed the ranked order of natural evergreen broadleaved forest > Sassafras tzumu plantation > Cryptomeria fortunei plantation when the forest litter was not added to the soil. The added forest litter increased the organic carbon mineralization rate, microbial biomass carbon and metabolic quotient in soils regardless of the forests. Comparing with the litter from the Sassafras tzumu plantation and Cryptomeria fortunei plantation, the litter from the natural evergreen broadleaved forest led to higher organic carbon mineralization rate, microbial biomass carbon and metabolic quotient in soils. The results suggested that the artificial regeneration of the natural evergreen broadleaved forest into the Sassafras tzumu plantation and Cryptomeria fortunei plantation might lead to the low organic carbon mineralization, microbial biomass carbon and metabolic quotient in soils.
文摘Public welfare forest is the most important model of vegetation restoration in the Conversion of farmland to forests in Sichuan Province. It can well represent and reflect the characteristics and laws of vegetation restoration in hillside fields. Therefore an Alnus cremastogyne forest community developed via converting hillside fields to forest, was investigated by contrast with a weed community on abandoned hillside fields. The results indicated that: 1) In Sichuan Basin and surrounding regions of it, vegetations restored so rapid that the average DBH (diameter at breast height), tree height of A.cremastogyne tree crown density, ground vegetation coverage respectively reached 5.2 cm, 6.1 m, 0.7 and 100 percent for 3 years and after converting hillside fields to forest. 2) With vegetation restoring, community gradually developed mosaic spatial pattern and vertical stratification, simultaneously distribution of plant population changed from regular to clumped, and spatial heterogeneity of community increased. 3) Community biodiversity remarkably increased in the process of vegetation restoration in hillside fields. During the period, species richness of both commnuities changed from 20 to 39, Shannon-Wiener diversity index was 4.205 and 5.021 respectively, while Pielou equitability index dropped little. 4) Plant species frequently and dramatically altered, which mainly showed that therophytes declined rapidly from 16 to 10, while perennial ones dramatically increased from 2 to 26, and 8 of them are phanerophytes. 5) The pathway of community development approximately was from annual herbs to shrubs + perennial herbs to trees + shrubs and herbs + perennial herbs, finally to natural mixed forests, such driving force was mainly from interspecific competition.
