| Chinese fir is one of the important timber species in the south of China,which has 2000 years cultural history.It can not only provide wood and a variety of forest by-products in China's southern forestry production,but also plays an important role in protecting the ecological environment and maintaining the balance of forest ecosystem.Because of expanding scale of Chinese fir plantations,the phenomenon of pure forest,coniferous and multi-generation serialization has become more and more serious,which has caused more serious soil erosion and decline of soil fertility.It directly restricts the sustainable development of Chinese fir plantations.In recent years,there have been many reports on the decline of soil fertility of Chinese fir plantations,but more scholars have also focused on research on the mechanism,and the lack of systematic and in-depth research on the decline and decay technology of Chinese fir plantations.Although some scholars have also put forward some technical measures or countermeasures(such as the cultivation of mixed forest,the interplanting of broad-leaved trees and forest fertilization,etc.),because of these technical measures are difficult to operate,and costing highly.It is difficult to get promoted,most still remain at the theoretical level.Therefore,how to make full use of natural force from the point of the whole ecosystem to construct the management mode of near-natural Chinese fir forest has become an urgent problem to be solved urgently in the current decline of Chinese fir plantation.In this view,the group researchs on various ecological problems of Chinese fir plantation,Chinese fir plantation ecosystem is closed to the near-natural management from the new theory and new methods of plantation management which domestic and foreign scholars put forward.Setting up two near-natural management of Chinese fir plantations:Old-growth Chinese fir forests and Chinese fir sprouting forests,and Second-generation Chinese fir plantation 2(without controlled-buming),Second-generation Chinese fir plantation 1(controlled-burning)and Natural evergreen broad-leaved forest were established in the adjacent area as the research area.This study mainly probing into the impacts of soil microbial functional diversity,soil microbial structural diversity,soil carbon pool and soil nitrogen pool of Chinese fir forest under different management.To reveal the mechanism of Chinese fir forest soil decline mechanism and degradation of Chinese fir plantation ecosystem restoration and reconstruction to provide a scientific theoretical basis for institutional change.The main results are as follows:(1)Using the method of Biolog ecological board,the paper studied impact of soil microbial functional diversity of Chinese fir forest under different management.The results showed that the the highest AWCD values was Chinese fir sprouting forests,and the lowest AWCD values was the Second-generation Chinese fir plantation 1,the results showed that the Chinese fir sprouting forests of the soil microbial community was the highest in the five different management patterns,and the Second-generation Chinese fir plantation 1 was the smallest one.The ability of soil microbial community for using multi-polymers,carboxylic acids and amino acids were higher than the other three carbon sources on 0 to 10 cm and 10 to 20 cm soil layers.On the 0 to 10 cm soil layer Chinese fir forest under different management of the six types of carbon source utilization is greater than 10 to 20 cm soil layer.The Shannon-wiener index of the Second-generation Chinese fir plantation 1 was the smallest on 0 to 10 cm and 10 to 20 cm soil layers,indicating that the soil microbial carbon species used in the Second generation Chinese fir plantation was less and less uniform.(2)The results showed that the phospholipid fatty acid biomarkers of 17 kinds of microbial communities were detected from different Chinese fir forest management by using PLFA technique,and the soil phospholipid fatty acid content of various types of microbial communities was different from different management Chinese fir forest management.The content of bacterial phospholipid fatty acid was the highest and the actinomycete was the lowest in all flora.Atinomycete was Only fouldnt in natural evergreen broad-leaved forest(0.51 nmol·g-1).Different Chinese fir forest management patter of soil fungi phospholipid fatty acid content exist significant different(P<0.05).Soil total phospholipid fatty acid content exist significant different(P<0.05).Different Chinese fir forest management patter of soil other phospholipid fatty acid content don't exist significant different(P>0.05).Soil total phospholipid fatty acid content presented a range from 33.15 to 10.48 nmol·g-1,and the content order:Natural evergreen broad-leaved forest>Second-generation Chinese fir plantation 2>Chinese fir sprouting forest>Old-growth Chinese fir forest>Second-generation Chinese fir plantation 1.(3)The Second-generation Chinese fir plantation 2 along presented a highest ratio of soil fungi:bacterial,and the Old-growth Chinese fir forest presented a lowest ratio of soil fungi:bacterial,indicating that the Second-generation Chinese fir plantation 2 could effectively increase the content of soil fungi,While the Old-growth Chinese fir forest is relatively improve the content of soil bacteria.The ratio of soil G+:G-presented a range from 2.70 to 0.46,Natural evergreen broad-leaved forest ratio of soil G+:G-was the highest,and Chinese fir sprouting forest ratio of soil G+:G-was the smallest.There was a little difference in phospholipid fatty acid Pielou index of soil microbial community of Chinese fir forest under different management.The results showed that soil microbial phospholipid fatty acid Simposon index of Natural evergreen broad-leaved forest was maximum,and Chinese fir sprouting forest and Old-growth Chinese fir forest were smaller,the results showed that the content of soil some dominant phospholipid fatty acids were higher in Natural evergreen broad-leaved forest,the content of soil some dominant phospholipid fatty acids were lower in Chinese fir sprouting forest and Old-growth Chinese fir forest.(4)There was no significant difference in soil total C content between different Chinese fir forest management patterns(P>0.05).In Chinese fir forest under different management the order of soil C storage:Second generation fir plantation 1>Second generation Chinese fir plantation 2>Natural evergreen broad-leaved forest>Chinese fir sprouting forest>Old-growth Chinese fir forest.There was a significant difference(P>0.05)in the soil C storage between different Chinese fir forest management patterns in 0 to 10 cm soil layer.Soil DOC content was only significant difference(P<0.01)between different Chinese fir forest management patterns in 0 to 10 cm soil layer.Soil DOC content of Chinese fir sprouting forest was highest in different soil layer.Soil MBC contents presented extremely significant difference(P<0.01)between different Chinese fir forest management patterns.Soil MBC contents of Chinese fir sprouting forest and Old-growth Chinese fir forest were the higher,followed by Natural evergreen broad-leaved forest,Soil MBC contents of Second generation fir plantation 1 and Second generation Chinese fir plantation 2 were lower.Suggesting that,Chinese fir sprouting forest and Old-growth Chinese fir forest may ensure more advantageous for soil microbial reproduction and soil fertility.Soil total C,soil C storage,Soil DOC,Soil MBC content discreased along the soil depth.(5)Soil total N content and Soil N storage presented not significant difference(P>0.05)between different Chinese fir forest management patterns.Soil N storage of Second generation fir plantation 1 and Second generation Chinese fir plantation 2 were higher,Chinese fir sprouting forest and Old-growth Chinese fir forest were lower.Soil NH4+-N content presented a range from 20.83 to 10.23 mg/kg,and soil NH4+-N content presented not significant difference(P>0.05).Soil N03--N content presented a range from 18.72 to 2.24 mg·kg-1.Soil DON content presented a range from 16.08 to 1.76 mg·kg-1,Soil DON content presented significant difference(P<0.05)in 20 to 40 cm soil layer.Soil MBN contents presented extremely significant difference(P<0.01)between different Chinese fir forest management patterns.Soil MBN content presented a range from 78.1 to 10.6 mg·kg-1.Soil MBN content of Chinese fir sprouting forest,Old-growth Chinese fir forest and Natural evergreen broad-leaved forest were higher.Soil total N,soil N storage,soil NH4+-N,Soil N03--N,Soil DON,Soil MBN content discreased along the soil depth.(6)The composite score of different fir forest management patter in 0 to 10 cm soil layer:Chinese fir sprouting forest,Old-growth Chinese fir forest and Second generation fir plantation 2 were higher than Second generation Chinese fir plantation 1.The composite score of different fir forest management pattern in 10 to 20 cm soil layer:Chinese fir sprouting forest,Old-growth Chinese fir forest and Second generation Chinese fir plantation 1 were higher than Second generation fir plantation 2.The composite score of different fir forest management pattern in 20 to 40cm soil layer:Chinese fir sprouting forest,Second generation Chinese fir plantation 1 and Second generation fir plantation 2 were higher than Old-growth Chinese fir forest.The composite score of different fir forest management pattern in 40 to 60 cm soil layer:Chinese fir sprouting forest,Second generation Chinese fir plantation 1 and Second generation fir plantation 2 were higher than Old-growth Chinese fir forest.In general,in different soil layers the composite score of Chinese fir sprouting forest was the highest,indicating that the soil fertility and soil restoration ability of the Chinese fir sprouting forest was the best in all management patterns,and the Chinese fir sprouting forest was the most suitable for the sustainable development of Chinese fir plantation development reference. |
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