Abstract
Grazing and over-exploitation can severely degrade soil in native forests. Considering that productivity in ecosystems is related to soil organic matter (SOM) content and quality, the objectives of this study were to: (1) determine the influence of degraded (DEF), partly-degraded (PDF), and undisturbed (UNF) Nothofagus forests on the stocks of carbon (C) in tree biomass and SOM; (2) evaluate fractions of SOM as indicators of sustainable management; and (3) use the Century model to determine the potential gains of soil organic C (SOC). The forests are located in the Andes and Coastal mountains of southern Chile. The SOM was fractionated to separate the light fraction (LF), macroaggregates (>212 µm), mesoaggregates (212–53 µm), and microaggregates (<53 µm). In two measurement periods, the SOC stocks at 0–20 cm and 20–40 cm depths in macroaggregates were on average 100% higher in the Andean UNF, and SOC was over twice as much at 20–40 cm depth in Andean DEF. Century simulations showed that improved silvopastoral management would gradually increase total SOC in degraded soils of both sites, especially the Ultisol with a 15% increase between 2016 and 2216 (vs. 7% in the Andisol). Greater SOC in macroaggregates (p < 0.05) of UNF indicate a condition of higher sustainability and better management over the years.
Highlights
Changes in land-uses can modify soil C stocks through changes in the amount and quality of organic residue that are periodically returned to soil, and through their subsequent use by soil macro and microorganisms, which affects the net rate of accumulation of organic matter in soil [1]
The soil organic matter (SOM) can be fractionated in the laboratory according to its “lability” (i.e., the relative ease which it is decomposed by soil microorganisms, thereby releasing nitrogen (N) and other elements that can be used subsequently for plant growth) [2]
Is stock interesting to see that times greater than PDFwere and DEF, In addition, is interesting to and see that aboveground tree biomass overrespectively
Summary
Changes in land-uses can modify soil C stocks through changes in the amount and quality of organic residue that are periodically returned to soil, and through their subsequent use by soil macro and microorganisms, which affects the net rate of accumulation of organic matter in soil [1].Increasing the organic matter content of the soil (SOM) improves the overall quality of the soil by improving cation exchange capacity (CEC), aggregate stability, water retention, and biological activity.Increases in SOM levels favor increased levels of plant growth that protects the soil from erosion and increases the potential organic residues that are returned to the soil. Changes in land-uses can modify soil C stocks through changes in the amount and quality of organic residue that are periodically returned to soil, and through their subsequent use by soil macro and microorganisms, which affects the net rate of accumulation of organic matter in soil [1]. The SOM can be fractionated in the laboratory according to its “lability” (i.e., the relative ease which it is decomposed by soil microorganisms, thereby releasing nitrogen (N) and other elements that can be used subsequently for plant growth) [2]. The more labile fraction has been used as an indicator of sustainable management because its content in the soil changes in the short term (several months to several years) depending on the vegetation, management, and balance between additions of plant residues and their decomposition in soil [3].
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