Evidence of the early stage weathering pedogenesis by carbonate rock 碳酸盐岩早期风化成土作用的证据
2.
Setenaly according to the analyses from selected profiles , we know that , it is cold and dry in this region during the early holocene when east asian winter monsoon ' s influence is obvious , so , it is a transition period from sand deposit to sandy soil deposit , when the layers become thinner gradually from north to south . during middle holocene , it is warm and humid , influenced evidently by east asian summer monsoon , so , it is an obivious pedogenesis , when there are generally well - developped holecene palaeosol ( so ) from north to south , and the pedogenesis in the south is better than that in the north , the soil is also thicker than that of the north . from late holocene to now , the climate changes to be dry and cold , but its changing scope is smaller than that of last glacial period 2 、就所选剖面分析来看，本区在全新世早期气候回返，相对较寒冷干燥，东亚冬季风影响较明显，此时为沙层堆积向砂质土壤过渡，自北至南堆积的沙粒渐细；全新世中期气候温暖湿润，东亚夏季风影响显著，此时为明显的成壤期，表现在自北至南普遍可见发育较好的黑垆土层，且南部的成壤作用比北部好，土壤的厚度也要大；全新世晚期至今，气候向干冷方向转化，但变化幅度远小于末次冰期。
3.
The main results are following : ( 1 ) the variation of clay / silt ratio can indicate the secondary clay action of dust depositions ; the variations of magnetic susceptibility and total fe content are inferred to be records of the changeable intensity of bio - pedogenesis ; the variations of sr content and rb / sr ratio can indicate bio - pedogenesis , dissolving and leaching action ; the content of total organic carbon ( toc ) can reflect variation of climate and vegetation during soil formation , it indicates the intensity of weathering and bio - pedogenesis ; the content variation of caco3 can show the intensity of dissolving - leaching action and secondary deposit , which was noted as pseudomycilia in pores and fissures in the sediment , so it can indicate the intensity bio - pedogenesis quite well . these proxy indexes also reflect obvious regional difference of pedogenic environment and the intensity bio - pedogenesis ; namely , secondary clay action , dissolving - leaching action and bio - pedogenesis are all much stronger in south than that in north 实验结果表明：粘粒粉沙比值能很好地指示粉尘堆积物的次生粘化作用；磁化率和全铁很好地指示生物风化成壤作用； sr和rb sr比值能很好的指示生物风化成壤作用和淋溶作用；总有机碳( toc )含量的高低，在一定程度上反应了土壤发育过程中气候和植被状况的变化，指示着成壤过程中腐殖质化的程度； caco3含量的变化，可以反映了黄土古土壤形成时的风化成壤作用的强弱程度，指示成壤过程中的淋溶作用和次生碳酸盐化作用；并且各指标所指示的成壤环境和成壤强度存在明显的区域差异，即渭河流域土壤的生物风化成壤作用、次生粘化作用和淋溶作用均表现出南部强于北部。
4.
Firstly , evidence from depositional pattern suggests that the hsl has experienced an expansion - contraction circle since the late glacial epoch . the expansion and movement of the hsl or desert in early stage were clearly marked by the presence of paleo - aeoline sands . the occurrence of paleosoal characterized the stabilization and contraction of the hsl and also indicated the activity of pedogenesis on the paleo - aeilian sands 通过系列气候代用指标的分析，首次发现该地区粒度、磁化率指标值在两个大的峰值之间有多个小的峰谷出现，表明了在大的气候变化阶段次一级的暖湿?干冷气候波动，值的进一步做年龄的小尺度高分辨率研究。
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This paper summarized the disturbance effect of rodents on soil ( pedogenesis , patch formation , and physical and chemical properties ) and vegetation ( species diversity , productivity , and seed dispersion ) , aimed to illustrate the contributions of rodents activities to desert ecosystem 本文主要从鼠类活动对土壤（包括土壤发生过程、土壤斑块的形成、土壤理化性质）和植物群落（包括物种多样性、生产力、植物种子）的扰动效应做了归纳总结，旨在阐明鼠类在荒漠生态系统中的作用。
