Accumulation characteristics and driving mechanisms of topsoil organic carbon during the restoration of Caragana korshinskii sand-fixing shrublands

doi:10.7522/j.issn.1000-694X.2026.00077

Journal of Desert Research ›› 2026, Vol. 46 ›› Issue (4): 343-353.DOI: 10.7522/j.issn.1000-694X.2026.00077

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Accumulation characteristics and driving mechanisms of topsoil organic carbon during the restoration of Caragana korshinskii sand-fixing shrublands

Zhengqiang Xu¹(), Xingdong Wang², Zhongwu Wan², Ruixia Wang², Xuelong Yang²

^1.Lanzhou Botanic Garden，Lanzhou 730070，China
^2.Ningxia Lingwu Baijitan National Nature Reserve Management Bureau / Ningxia Baijitan Forest Ecological Positioning Observation and Research Station，Lingwu 750400，Ningxia，China

Received:2026-05-23 Revised:2026-06-22 Online:2026-07-20 Published:2026-08-27

Abstract

Abstract:

Vegetation restoration is a critical strategy for enhancing soil carbon sequestration in desertified regions； however， the patterns of soil organic carbon （SOC） accumulation and their underlying driving mechanisms remain insufficiently understood. In this study， a restoration chronosequence （0， 15， 28， 54， and 70 years） of artificial Caragana korshinskii sand-fixing shrublands on the southwestern margin of the Mu Us Sandy Land was selected using a space-for-time substitution approach. We systematically investigated the dynamics of litter accumulation， soil physicochemical properties， ecological stoichiometric characteristics， and SOC storage along the restoration gradient. Multiple linear regression and partial least squares path modeling （PLS-PM） were employed to elucidate the mechanisms driving SOC accumulation during vegetation restoration. The results showed that litter accumulation， soil moisture content （SMC）， pH， and total nitrogen （TN） increased significantly with restoration age （P < 0.05）. Among these variables， litter accumulation and SMC exhibited the largest increases， reaching levels 6.12-fold and 17.92-fold higher， respectively， in the 70-year restoration stage than in the active sand dune （0-year） stage. Soil total phosphorus （TP） exhibited a unimodal pattern， peaking at 28 years of restoration. Both SOC content and SOC storage increased significantly along the restoration chronosequence （P < 0.05）， with the 70-year stage showing 14.56-fold and 14.97-fold increases， respectively， compared with the active sand dune stage. The accumulation rate of SOC storage also followed a unimodal pattern and reached a maximum of 0.0061 kg·m^-2·yr^-1 at 54 years. Soil stoichiometric ratios （C∶N， C∶P， and N∶P） increased significantly with restoration age （P < 0.05）. Linear regression analyses revealed significant positive relationships between SOC storage and litter accumulation， SMC， pH， TN， and soil stoichiometric ratios （P<0.05）. Multiple regression analysis further indicated that the combined effects of soil C∶N， C∶P， and N∶P ratios， TN， and litter accumulation explained 30.06%， 20.09%， and 13.64% of the variation in SOC storage， respectively. PLS-PM demonstrated that vegetation restoration directly increased TN content and indirectly promoted SOC accumulation by regulating soil stoichiometric characteristics through the synergistic effects of TN and litter accumulation. In conclusion， long-term restoration of Caragana korshinskii sand-fixing vegetation substantially enhanced the soil carbon sink capacity of sandy ecosystems. SOC accumulation exhibited clear stage-specific patterns and was jointly regulated by nutrient enrichment and shifts in soil C-N-P stoichiometry. These findings provide new insights into the mechanisms of long-term carbon sequestration in arid sandy ecosystems and offer a theoretical basis for optimizing vegetation restoration and carbon management strategies in desertified regions.

Key words: vegetation restoration, soil organic carbon storage, ecological stoichiometry, Caragana korshinskii shrubland, Mu Us Sandy Land

CLC Number:

Zhengqiang Xu, Xingdong Wang, Zhongwu Wan, Ruixia Wang, Xuelong Yang. Accumulation characteristics and driving mechanisms of topsoil organic carbon during the restoration of Caragana korshinskii sand-fixing shrublands[J]. Journal of Desert Research, 2026, 46(4): 343-353.

Figures/Tables 6

Fig.1 Geographic location of the study area and distribution of sampling plots

Fig.2 Litter accumulation and soil physicochemical properties under different restoration years

Fig.3 Changes in soil organic carbon content， storage and accumulation rate under different restoration years

Table 1 Soil ecological stoichiometric characteristics across different restoration year

土壤化学计量特征	恢复年限/a
土壤化学计量特征	0	15	28	54	70
土壤碳氮比C∶N	3.86±0.67^c	5.83±0.87^c	7.94±0.47^b	10.11±0.43^a	10.10±0.89^a
土壤碳磷比C∶P	2.29±0.32^c	6.06±0.47^c	9.59±1.31^b	25.72±1.14^a	29.73±2.80^a
土壤氮磷比N∶P	0.61±0.02^b	1.17±0.24^b	1.23±0.20^b	2.55±0.12^a	2.97±0.27^a

Fig.4 Regression analysis of soil organic carbon storage and its influencing factors

Fig.5 Mechanistic analysis of soil organic carbon storage accumulation

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Accumulation characteristics and driving mechanisms of topsoil organic carbon during the restoration of Caragana korshinskii sand-fixing shrublands

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