title: [Impact of Land Utilization Pattern on Distributing Characters of Labile Organic Carbon in Soil Aggregates in Jinyun Mountain].
abstract: Four land utilization patterns were selected for this study in Jinyun mountain, including subtropical evergreen broad-leaved forest (abbreviation: forest), sloping farmland, orchard and abandoned land. Soil samples were taken every 10 cm in the depth of 60 cm soil and proportions of large macroaggregates (> 2 mm), small macroaggregates (0. 25-2 mm), microaggregates (0. 053 - 0. 25 mm) and silt + clay (<0. 053 mm) were obtained by wet sieving method to measure the content of organic carbon and labile organic carbon in each aggregate fraction and analyze impacts of land uses on organic carbon and labile organic carbon of soil aggregates. LOC content of four soil aggregates were significantly reduced with the increase of soil depth; in layers of 0-60 cm soil depth, our results showed that LOC contents of forest and abandoned land were higher than orchard and sloping farmland. Reserves of labile organic carbon were estimated by the same soil quality, it revealed that forest (3. 68 Mg.hm-2) > abandoned land (1. 73 Mg.hm-2) > orchard (1. 43 Mg.hm-2) >sloping farmland (0.54 Mg.hm-2) in large macroaggregates, abandoned land (7.77, 5. 01 Mg.hm-2) > forest (4. 96, 2.71 Mg.hm-2) > orchard (3. 33, 21. 10 Mg.hm-2) > sloping farmland (1. 68, 1. 35 Mg.hm-2) in small macroaggregates and microaggregates, and abandoned land(4. 32 Mg.hm-2) > orchard(4. 00 Mg.hm-2) > forest(3. 22 Mg.hm-2) > sloping farmland (2.37 Mg.hm-2) in silt + clay, forest and abandoned land were higher than orchard and sloping farmland in other three soil aggregates except silt + clay. It was observed that the level of organic carbon and labile organic carbon were decreased when bringing forest under cultivation to orchard or farmland, and augments on organic carbon and labile organic carbon were found after exchanging farmland to abandoned land. The most reverses of forest and abandoned land emerged in small macroaggregates, orchard and sloping farmland were in microaggregates. That was, during the transformations of land utilization pattern, soil aggregates with bigger size were easier to accumulate or lose labile organic carbon. Allocation ratios of labile organic carbon to soil organic carbon under four land uses were decreased as the soil depth added. Allocation ratios of orchard and sloping farmland were a bit higher than forest and abandoned land, which indicated that organic carbon of forest and abandoned land were more steady and available for soil as a carbon sink, meanwhile, the forest and abandoned land would avoid more CO2 diffusing to the atmosphere from the decomposition of soil organic carbon.
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.forename: Chang-sheng
authors.initials: CS
authors.lastname: Jiang
authors.forename: Qing-ju
authors.initials: QJ
authors.lastname: Hao
mesh_terms: D000383:Agriculture; D000538:Aluminum Silicates; D002244:Carbon / Q000032:analysis*; D057965:Carbon Sequestration; D002681:China; D000077215:Clay; D065928:Forests; D012987:Soil / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D012987:Soil; D002244:Carbon; D000077215:Clay