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Effect of plateau pika disturbance and patchiness on ecosystem carbon emissions in alpine meadow in the northeastern part of Qinghai–Tibetan Plateau

Plateau pika (Ochotona curzoniae) disturbanceand patchiness intensify the spatial heterogeneous distributionof vegetation productivity and soil physicochemicalproperties, which may alter the ecosystem carbon emissionprocess. Nevertheless, previous research has mostly focusedon the homogeneous vegetation patches rather than heterogeneousland surface. Thus, this study aims to improve ourunderstanding of the difference in ecosystem respiration (Re)over heterogeneous land surface in an alpine meadow grassland.Six different land surface types, namely large baldpatches, medium bald patches, small bald patches, intactgrassland, above pika tunnel and pika pile, were selected toanalyze the response of Re to pika disturbance and patchinessand the key controlling factors. The results showed that(1) Re in intact grassland was 0.22–1.07 times higher thanpika pile and bald patches, (2) soil moisture (SM) of intactgrassland was 2 %-11% higher than that of pika pile andbald patches, despite the fact that pika disturbance increasedthe water infiltration rate while soil temperature (ST) in intactgrassland was 1-3less than pika pile and bald patches,(3) soil organic carbon (SOC) and total nitrogen (TN) in intactgrassland were approximately 50% and 60% less thanabove pika tunnel, whereas they were 10 %-30% and 22 %-110% higher than pika pile and bald patches, and (4) Re wassignificantly correlated with SM, TN andvegetationbiomass(P < 0.05). Our results suggested that pika disturbance andpatchiness altered the ecosystem carbon emission pattern,which was mainly attributed to the reduction in soil waterand supply of substrates (Figure 1). Given the wide distribution of pikasand the large area of bald patches, the varied Re in heterogeneousland surfaces should not be neglected in the estimationof ecosystem carbon emissions at the plot or regional scale. This work published on the journal of Biogeosciences in 2019: https://www.biogeosciences.net/16/1097/2019/.

Figure 1. Ecosystem respiration of different surface types: (1) large bald patch (LP), (2) medium bald patch (MP), (3) small bald patch (SP),(4) intact grassland patch (IG), (5) above pika tunnel (PT) and (6) old pika pile (PP). The upper solid lines, the bottom solid lines, the boldsolid horizontal line and the empty dot are the maximum value, minimum value, median and abnormal value, respectively. Letters on theerror bars indicate significant differences among different surface types at P < 0.05.

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