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Objective The study of the relationship between climate proxies and climate factors in sandy surface sediments is highly significant when determining the reliability and applicability of climate proxies. Methods In this study， 32 samples of surface sediments were collected over a large spatial scale in Otindag sandy land. By analyzing correlations between chroma， Hm/Gt， magnetic susceptibility and modern climate factors （average annual precipitation and average annual temperature）， the relationships between each index and climate factors and their environmental significance are discussed. Results The results show that the variation range of a* and b* is small， and that the overall trend from east to west is increasing： the minimum value of a* is 3.87， the maximum value is 8.26， and the average value is 6.09. The minimum value of b* is 9.49， the maximum is 17.44， and the average is 14.24. a* and b* were negatively correlated with precipitation （correlation coefficients -0.88 and -0.77， P < 0.01）， and positively correlated with temperature （correlation coefficients 0.89 and 0.82， P < 0.01）， indicating that both a* and b* could be used as effective proxy indicators of climate change， with a* being the more sensitive to climate factors. The variation range of L* was small， and no obvious change rule from east to west was evident. The maximum value was 59.54， minimum value 48.80， and the average value was 54.69. The relationship between L* and climate factors is not obvious， and its change is mainly directly affected by vegetation； it does not appear to have any obvious indicative significance for climate. The peak value of the first derivative of hematite ranges from 0.08 to 0.19， with an average of 0.14. The peak value of the first derivative of goethite ranges from 0.06 to 0.09， with an average of 0.07. The value of hematite/goethite （Hm/Gt） ranged from 1.20 to 2.73 （average 1.88）， and showed an increasing trend from east to west. The correlation between hematite and climate factors is higher than it is for goethite. The ratio of Hm/Gt is negatively correlated with average annual precipitation （correlation coefficient -0.85， P < 0.01）， and positively correlated with average annual temperature （correlation coefficient 0.84， P < 0.01）， which reveals the sensitivity of both hematite and Hm/Gt to precipitation and temperature. It effectively reflects changes of hydrothermal conditions in sandy land. In low-frequency magnetic susceptibility （χlf） and high-frequency magnetic susceptibility （χhf）， the variation direction of hf amplitude shows a constantly increasing trend from east to west. The percentage frequency magnetic susceptibility does not change significantly from east to west. The magnetic susceptibility of the region does not correlate well with climate factors. The source of the sand material may be the main factor in its variation， emphasizing the complexity and specificity of sand magnetic susceptibility changes. Conclusions a*， b*， and b*/a* are all effective alternative indicators for studying regional climate， whereas L* is influenced by vegetation， resulting in ambiguous climate information. Hematite and Hm/Gt values correlate well with climate parameters and are ideal indicators of moisture and heat changes in sandy land. The surface magnetic susceptibility of sandy land is less affected by climate， reflecting the complexity and specificity of magnetic susceptibility changes in sandy land.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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