Effect of land use on the characteristics of organic carbon and labile organic carbon in soil aggregates in Karst mountain areas
| Autor: | 陈彩云 Chen Caiyun, 龙健 Long Jian, 李娟 Li Juan, 廖洪凯 Liao Hongkai |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Total organic carbon
geography geography.geographical_feature_category Ecology Soil organic matter chemistry.chemical_element Soil science Soil carbon Karst complex mixtures Humus chemistry Environmental chemistry Soil water Environmental science Orchard Carbon Ecology Evolution Behavior and Systematics |
| Zdroj: | Acta Ecologica Sinica. 33:2147-2156 |
| ISSN: | 1000-0933 |
| Popis: | Soil organic carbon is a dynamic medium of carbon transfer and is a main pathway for the circulation of carbon through soils in Karst systems.Karst systems are typically ecologically fragile areas with limited environmental capacity and resistivity.In addition,the implementation of a state policy encouraging the return of farmland to woodland(grass) and labor output in recent years has led to considerable change in land use patterns over a short period in these areas,which is bound to have far-reaching impacts on the spatial distribution pattern of soil organic carbon.Extensive previous research has investigated the response characteristics of soil organic carbon under different land use patterns.However in general,most of these studies have only investigated the total soil organic carbon in whole soils,and have rarely studied the organic carbon and labile organic carbon in soil aggregates.Organic carbon and labile organic carbon in aggregates are largely isolated from microbial activity because of the physical protection of the aggregates,and this may have a major impact on their function as soil carbon sinks.Therefore,the purpose of this study was to explore the distribution and accumulation characteristics of organic carbon and labile organic carbon in aggregates through survey,sampling,and analysis of soils in selected Karst mountain areas in China. The experiment was conducted in a small watershed in Huajiang Karst areas in southwestern Guizhou(25° 38.988′—25° 41.322′N latitude and 105° 38.031′—106° 40.505′E longitude).Samples of topsoils(0—15 cm) were collected from five kinds of typical land use patterns(Pitaya orchard,grassland,Chinese prickly ash orchard,forest and shrub-grassland).Soil aggregates were separated by dry sieving.Aggregate composition was dominated by particles 0.5 mm which accounted for 82.57% to 94.79% of the whole soil under the different land use patterns.In all size classes of aggregate particles,forest had the highest values of organic carbon and labile organic carbon,followed by Chinese prickly ash orchard,while grassland and shrub-grassland were relatively lower.With decreasing aggregate particle size,the peak of organic carbon and labile organic carbon basically appeared in particles 0.25 mm in size.However,these aggregate particles contributed less than 6% and 4%,respectively,to the contents of soil organic carbon and soil labile organic carbon.The accumulation of soil organic carbon and soil labile organic carbon were influenced by increasing aggregate size,with 5—1 mm aggregates contributing 28.70%—49.47% and 34.13%—47.47% of the organic carbon and labile organic carbon contents,respectively.Therefore,it can be assumed that particles of aggregate size 5—1 mm hold the majority of soil carbon fixed in Karst mountain areas.In addition,the labile organic carbon content and total organic carbon content in soil aggregates were highly significantly positively correlated(r=0.8768),which suggests that labile organic carbon may be a sensitive index for measuring the dynamics of organic carbon in soil aggregates in Karst mountain areas.Our results will help to reveal the regional soil organic carbon sequestration in Karst mountain areas in China. |
| Databáze: | OpenAIRE |
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