The study was aimed to investigate the soil-microbial carbon, nitrogen and phosphorus characteristics of Eucalyptus plantations at different altitude gradients in Hainan Tropical Rainforest National Park. Typical Eucalyptus plantation forests at different altitudes (500 m, 700 m and 900 m) in Wuzhishan were used as the study object, and natural secondary forests at the same altitude were used as the control. Soil organic carbon (SOC) and total nitrogen (TN) content showed a gradual increase with elevation, and total phosphorus (TP) showed a gradual decrease. The range of variation was 13.16-13.58, 0.93-1.15, 0.17-0.19 g/kg, respectively, which was lower than the SOC and TN contents of natural secondary forests, and lower than the national average values of SOC, TN and TP contents of forests. The microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) showed a trend of gradual increase with elevation, and the microbial biomass phosphorus (MBP) content overall showed a decreasing trend with elevation, with the range of 237.46-398.26, 23.04-30.74, 4.77-9.59 mg/kg, respectively, and with the TP contents. TP showed highly significant positive correlation (P<0.01). The differences were not significant compared with those of natural secondary forests at the same elevation. MBC/MBN, MBC/MBP and MBN/MBP all tended to increase with elevation, with ratios ranging from 9.05-13.17, 24.73-80.99 and 2.76-6.60. At 500 m, the MBC/MBP and MBN/MBP of the Eucalyptus plantation were significantly different from those of the natural secondary forest.. The variation of microbial quotient carbon (qMBC), microbial quotient nitrogen (qMBN) and microbial quotient phosphorus (qMBP) at different elevations was 1.89%-3.34%,2.90%-3.23% and 1.33%-5.41%, respectively. qMBC showed a gradual increase in elevation, and qMBP declined with the elevation. qMBC and qMBP were higher than those of natural secondary forests. qMBC and qMBP were higher than those of natural secondary forests. Soil organic carbon and total nitrogen were the key factors affecting the changes. In conclusion, the elevation gradient has a significant impact on the content and stoichiometric ratio of soil-microbial carbon, nitrogen, and phosphorus in Eucalyptus plantations. Compared with natural secondary forests at the same elevation, the soil of Eucalyptus plantations exhibited a deficiency in carbon and phosphorus contents, but enhanced the conversion efficiency of soil carbon and phosphorus to microbial biomass carbon and phosphorus. Based on this, the Eucalyptus plantations in the park should be conserved, and attention should be paid to the influence of carbon and phosphorus elements in the subsequent management.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |