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Characteristics Of Soil Aggregates And Organic Carbon And Its Component Contents In Three Forest Types In The Mountain Area Of Eastern Liaoning

Posted on:2019-09-08Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y LiuFull Text:PDF
GTID:2370330569996765Subject:Forest management
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Soil organic carbon is an important part of the forest carbon pool.In the study of forest soil,to discuss the differences between soil aggregates,organic carbon and their components in different forest types,which are of great significance to the rational management of forest and the enhancement of carbon sequestration capacity of forest soil.In this paper,three typical forest types in the mountain area of Eastern Liaoning,including the secondary natural forest,planted pure forest and planted mixed forest,were studied.The effects of different forest types on soil aggregate stability,organic carbon and its components,organic carbon and organic matter content of aggregates were investigated.The main conclusions were as follows:?1?Different forest types had a certain influence on the basic physical and chemical properties of soil.There were significant differences between the 020 cm soil water content,total nitrogen,010 cm carbon nitrogen ratio in three forest types?P<0.05?,showing that secondary natural forest>planted mixed forest>planted pure forest.The total phosphorus,ratio of nitrogen to phosphorus and pH were not obviously affected by forest type and soil layer.The soil in this study area was acidic.Forest type had a great influence on the distribution of soil aggregate sizes.The soil aggregates sizes was distributed in the form of"V".which were mainly macroaggregates?>0.25 mm?,the content range was52.7875.78%,and their contents decrease with the deepening of soil depth.The mean weight diameter was 1.532.73 mm,and the geometric mean diameter was between0.541.29 mm.The stability of soil aggregates were the highest in secondary natural forest,followed by planted mixed forest,and planted pure forest was the worst.?2?Soil organic carbon and its components were significantly affected by forest types and soil layers.In 020 cm soil,the total organic carbon content of three forest types were significantly different?P<0.05?,and the order was:secondary natural forest>planted mixed forest>planted pure forest.The content of organic carbon decreased with the deepening of soil depth?P<0.05?.The soil light fraction organic carbon,particulate organic carbon,oxidizable organic carbon and microbial biomass carbon content ranges were 2.5213.51gkg-1,3.5320.18 gkg-1,0.813.54 gkg-11 and 1.319.06 gkg-1,respectively.The proportion of particulate organic carbon to total organic carbon was the highest,while the proportion of easily oxidizable organic carbon was the lowest.Soil aggregate stability evaluation indices were significantly positively correlated with soil organic carbon and its components?P<0.01?.?3?The soil aggregates organic carbon contents were the highest in secondary natural forest,followed by planted mixed forest,and planted pure forest was the lowest,and the surface enrichment phenomenon was obvious,which was similar to the change rule of organic carbon.The organic carbon contents of soil aggregates in secondary natural forest and planted mixed forest were the highest,which appeared in the microaggregates?<0.25mm?,the contents was 55.91 and 43.75 gkg-11 respectively,while the planted pure forest appeared at 2-1 mm aggregates,and the content was 39.06 gkg-1.The contribution rates of soil aggregate organic carbon decreased first and then increased with decreasing aggregate sizes in three kinds of forest types.In 010 cm soil,the maximum contribution rate of organic carbon in secondary natural forest and planted mixed forest aggregates appear in large aggregates,accounted for 35.93%and 34.43%,respectively,and planted pure forest were found in microaggregates,accounted for 41.38%.In addition,the contribution rate of large aggregates to organic carbon decreased with the deepening of soil depth,while the microaggregates showed the opposite rule.?4?Forest types had certain effects on soil organic carbon components,and soil organic carbon components decreased with the increase of soil depth.The light fraction organic carbon in the secondary natural forest soil large aggregates were significantly higher than those in planted pure forest?P<0.05?.In 010 cm soil,excepted the large aggregates,showed that aggregate particulate organic carbon content in secondary natural forest was significantly higher than that in two planted forest types?P<0.05?,the particulate organic carbon in microaggregates was significantly higher than that of other aggregates?P<0.05?.Soil easily oxidizable organic carbon occupied a small proportion of total organic carbon,but the maximum values all appeared in the large aggregates?>2 mm?.In 010 cm planted pure forest soil,the microbial biomass carbon contents in microaggregates were significantly higher than other aggregates?P<0.05?,in the secondary natural forest soil,the content of microbial biomass organic carbon in large aggregates was the highest and soil microbial biomass carbon content in planted mixed forest showed"V"distribution among aggregate sizes.In addition,microbial biomass carbon content of three forest soil decreased with decreasing aggregate sizes in 2030 cm soil.
Keywords/Search Tags:the mountain area of Eastern Liaoning, planted forest, secondary natural forest, soil aggregates, soil organic carbon
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