| The quality of the ecological environment has been significantly improved after years of vegetation restoration in the abandoned land of Xiangtan manganese mine.However,the changes of the main nutrient(phosphorus)and phoD-harboring bacterial community under different vegetation restoration models are still unclear.Therefore,three typical vegetation restoration patterns including Lespedeza cuneata,Juniperus chinensis and Koelreuteria paniculata were selected to investigate the effect of different vegetation restoration patterns on soil phosphorus,phosphorus forms and phosphorus transformation microorganisms.The mineral waste residue was collected as the control.Combining traditional soil nutrients detection and modern high-throughput sequencing techniques,the soil properties,enzyme activity,phosphorus forms and phosphorus transformation microorganisms in vegetated soils and residues were analyzed.The relationships of soil phosphomonoesterases activity,phosphorus forms and phoD-harboring bacterial community were discussed to clarify the change characteristics of soil phosphorus form and availability in different vegetation restoration models,as well as the main driving factors affecting the changes of phoD bacterial community.The results will provide theoretical references for vegetation restoration management and sustainable development of ecosystems in mining areas.The main findings were as follows:(1)The soil pH was in the order of Koelreuteria panicwulata(6.4)>Lespedeza cuneata(5.7)>Juniperus chinensis(5.6),which were significantly higher than that in mineral waste residue(2.66)(p<0.05).The content of dissolved organic carbon(DOC),microbial biomass carbon(MBC)and total phosphorus(TP)in the vegetation restoration area was significantly higher than those in the mineral waste residue(p<0.05).The highest contents of soil organic carbon(SOC),DOC and MBC were detected in Juniperus chinensis,with values of 11.9 g kg-1,66.9 mg kg-1 and 219.9 mg kg-1,respectively.TP and available phosphorus(Olsen-P)were 1.09 g kg-1 and 8.37 mg kg-1 in Koelreuteria paniculata,which were higher than other two vegetation restoration models.(2)The soil alkaline phosphomonoesterases(ALP)activity of the three vegetation restoration models in the manganese mine wasteland was significantly higher than that of mineral waste residue(4.2 ?g PNP g-1 hr-1)(p<0.05).There is significant difference in ALP activity in different vegetation restoration modes(p<0.05),and the highest was found in Koelreuteria paniculata(110.7 ?g PNP g-1 hr-1),followed by Juniperus chinensis(72.2 ?g PNP g-1 hr-1),and the lowest was in Lespedeza cuneata(35.8 ?g PNP g-1 hr-1).The soil acid phosphomonoesterases(ACP)activity of the three vegetation restoration models in the manganese mine wasteland was higher than that of mineral waste residue(26.2 ?g PNP g-1 hr-1).There is significant difference in ACP activity in different vegetation restoration modes(p<0.05),and the highest was found in Juniperus chinensis(315.3 ?g PNP g-1 hr-1),followed by Lespedeza cuneata(29.9 ?g PNP g-1 hr-1),and the lowest was in Koelreuteria paniculata(9.7 ?g PNP g-1 hr-1).(3)ALP,ACP and SOC were selected as the minimum data set for soil quality evaluation based on principal component analysis and Pearson correlation analysis,and the weight of each indicator was in the order of ACP>SOC>ACP.The calculated soil quality index of three vegetation restoration models were significantly higher than that of the mineral waste residue(0.13)(p<0.05).SQI of Juniperus chinensis(0.69)was significantly higher than that of and Lespedeza cuneata(0.45)and Koelreuteria paniculate(0.33)vegetation restoration modes(p<0.05),indicating that Juniperus chinensi had the best improvement of SQI.(4)The residual phosphorus(Residual-P)and NaOH-extracted organic phosphorus(NaOH-Po)were the main soil phosphorus forms in the mineral waste residue and three vegetation restoration models.The contents of Residual-P and NaOH-Po ranged from 284.5?829.9 mg kg-1 and 91.7-170.6 mg kg-1,respectively.The content of labile phosphorus were 27.1 mg kg-1,36.7 mg kg-1 and 55.0 mg kg-1 in Lespedeza cuneata,Juniperus chinensis and Koelreuteria paniculate,which were significantly higher than that of mineral waste residue(18.1 mg kg-1)(p<0.05).The content of moderately liable phosphorus were 236.4 mg kg-1,192.91 mg kg-1 and 235.4 mg kg-1 in Lespedeza cuneata,Juniperus chinensis,Koelreuteria paniculate,which were all significantly higher than that of mineral waste residue(141.8 mg kg-1)(p<0.05).The content of stable phosphorus were 399.2 mg kg-1,728.2 mg kg-1 and 837.1 mg kg-1 in Lespedeza cuneata,Juniperus chinensis,Koelreuteria paniculate,and the soil stable phosphorus content in Juniperus chinensis and Koelreuteria paniculate were significantly higher than that of mineral waste residue(296.2 mg kg-1)(p<0.05).The labile phosphorus and moderately liable phosphorus content were both significantly positively correlated with ALP(p<0.01,p<0.05),which indicated that the improvement of soil quality after vegetation restoration was related to the increase of the available phosphorus content.(5)Compared with mineral waste residue,the diversity of phoD-harboring bacterial community was significantly increased following vegetation restoration(p<0.05).Proteobacteria was the dominated phoD-harboring bacterial community in mineral waste residue and vegetation restoration areas,accounting for 86.56%to 91.01%of the total phoD-harboring bacterial community.The relative abundance of Firmicutes decreased after vegetation restoration.Rhodobacterales was significantly positively correlated with key SQI indicators such as SOC and ACP,and Methylococcales was significantly positively correlated with ACP,which was also one of the key SQI indicators.These results indicated that the improvement of soil quality after vegetation restoration was related to the increase of the phosphorus transforming microorganisms. |
PDF Full Text Request