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Effects of snowpack on early foliar litter humification during winter in a subalpine forest of western Sichuan |
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| Affiliation: | Key Laboratory of Ecological Forestry Engineering of Sichuan Province, Institute of Ecology & Forestry, Sichuan Agricultural University, Chengdu 611130, China |
| Abstract: | Aims Foliar litter humification is an important ecological process relating to soil carbon and nutrient budget in subalpine forest ecosystems, and the process of foliar litter humification can be affected by various snowpacks with different thicknesses in winter. However, little is known on the effects of snowpack on foliar litter humification. The objective of this study is to explore the effects of snowpack on early foliar litter humification during the first winter in subalpine forest. Methods A field litterbag experiment was conducted in a subalpine forest in southwestern China from November 2012 to April 2013. Air-dried foliar litter of fir (Abies faxoniana), cypress (Sabina saltuaria), larch (Larix mastersiana), birch (Betula albo-sinensis), willow (Salix paraplesia), and azalea (Rhododendron lapponicum) were incubated under snowpacks with varying thicknesses (deep snowpack, medium snowpack, thin snowpack, and no snowpack) due to variations in the canopy openness. Net accumulation of humus carbon, humification degrees, and humification rates were measured at snow formation, snow cover, and snow melt stage as foliar litter humification proceeded. Important findings Significant humification was observed in the six foliar litter types during the first winter regardless of the condition of snowpacks. The highest humification degree was observed in birch foliar litter (4.45%-5.67%), and the humification degrees were 1.91%-2.15%, 1.14%-2.03%, 1.06%-1.97%, 0.01%-1.25%, and 0.39%-1.21%, respectively, for fir, azalea, willow, larch, and cypress foliar litter under varying snowpacks. The net accumulation of humus carbon of all foliar litters increased at the snow formation, snow melt stage, and the whole winter, which exhibited an increasing tendency with the decrease of snow cover thickness. In contrast, net accumulation of humus carbon showed a declining trend at the snow cover stage, and significantly increased with the decrease of snow cover thickness. In addition, correlation analysis results indicated that the humification degree was positively correlated with total nitrogen and acid-insoluble residues and negatively related to the organic carbon, total phosphorus, and water- and organic-soluble components. These results clearly suggest that foliar litter humification in subalpine forest can be enhanced by reduced snow cover in a scenario of climate warming, although the humification degree is controlled by snowpack and litter qualities at different stages of snow cover in winter. |
| Keywords: | foliar litter humification humus carbon snowpack |
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