| Climate change and human activities caused serious damage to the ecological environment and grassland degradation.In order to recover the degradated grassland and control desertification in ecologically fragile areas,a number of national environmental restoration projects had been launched in China.An effective method for grassland recovering is to plant shrub,which not only improves ecological environment but also produces carbon sink and thus makes great benefits to the national carbon sequestration and emission reduction.However,the carbon storage of artificial shrubs in degraded grassland have not been calculated accurately and habitat factors?e.g.climate,topography,and soil?affecting shrubs carbon stock were not well quantified.In this paper,the Siziwangqi of Inner Mongolia is selected as the research area.The shrub carbon storage were calculated by sample survey,the influences of habitat factors on the shrub carbon storage were analyzed,and the explanatory power of driving factors of spatial difference distribution of the shrub carbon storage were quantitatively identified by using the Geodetector model.The main results were as follows:?1?The total carbon storage of 9935.33 ha artificial shrubbery plots in Siziwangqi were 86470.50 t from 2005 to 2018.The shrub carbon storage per hectare varied with stand ages,and the shrub carbon storage of 10-year,8-year,and 5-year artificial shrubbery were 11.65±6.45 t ha-1,16.35±5.80 t ha-1,1.17±0.66 t ha-1,respectively.?2?The shrub carbon storage per hectare in the degraded grassland of Siziwangqi area showed obvious difference in spatial distribution.The shrub carbon storage per hectare varied from 0.13 to25.08 t ha-1and the southern regions had a significantly higher shrub carbon storage in unit area than northern regions?p<0.05?.?3?The habitat factors showed different effects on the shrub carbon storage.The annual average precipitation and annual average temperature showed a significant positive correlation with the shrub carbon storage,respectively?p<0.01?.The impact of annual average precipitation on the carbon storage of shrubs was higher than the annual average temperature.The effects of topographical factors on shrub carbon storage was different,among them,slope had no significant effect on shrub carbon storage,and shrub carbon storage under semi-sunny slope was significantly higher than that on semi-shady slope and sunny slope.The carbon storage of shrubs under chestnut soil was higher than that of meadow soil and gray-brow soil,but it was not significant.There is no linear correlation between soil organic carbon and shrub carbon storage.?4?The effect intensity of driving factors on the spatial difference of shrub carbon storage were as follows:meteorological factor>stand age>soil type>topographical factor.The ranking of explanatory power was:average annual precipitation?26.97%?,stand age?13.85%?,average annual temperature?8.77%?,soil type?8.27%?,soil organic carbon storage?3.71%?,slope direction?3.27%?,slope?0.76%?.Therefore,precipitation was the main factor affecting the spatial difference of shrub carbon storage in Siziwangqi area,which had a higher effect intensity than shrub stand age and average annual temperature.?5?The interaction of two factors can increase the explanatory power of the difference of shrub carbon storage,which were manifested by nonlinear enhancement and two-factor enhancement.The interaction of average annual precipitation and stand age,average annual precipitation and soil organic carbon exerted leading role to explain the spatial distribution of shrub carbon storage.Average annual temperature greatly enhanced the explanatory power of other factors on the spatial distribution of shrub carbon storage.In summary,the complex habitat factors should be carefully considered when calculating the carbon storage of shrubbery in large areas and multi plots.The validity of carbon sink calculation will be improved by exploring the main driving forces of spatial difference distribution.The results provide a theoretical basis for the reasonable layout of the construction of artificial shrubs,and also provide a reference for promoting the supply of ecological services and carbon trading. |
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