中国科学院机构知识库网格系统: 陕北黄土高原全新世气候影响下

学位类别

博士

答辩日期

2009

授予单位

中国科学院研究生院

授予地点

陕西

刘普灵; 杨明义

学位专业

土壤学

中文摘要

竹子生长主要是气候,如果温度不至于低到冻死它,都可以长,只是长得好不好是另一回事.比如华北也可以长竹子,只是长不大,冬天也不会死.南方土壤偏酸性,气候温暖湿润,适合它长.至于土壤是什么样的岩石风化的,并无关系,只要有足够的土层. 再问： 我在福建龙岩一带发现，变质岩风化的土壤就有竹子，花岗岩风化的土壤就没有竹子。黄土高原是世界上面积最大黄土沉积最厚的风成（或“风积”）高原，由风的侵蚀、搬运和堆积作用形成。气候制 它的沉积物自下而上分别为河流滞留沉积、河约着河流的水流量和沉积物的供应, 干旱的气 流沉积、河口湾沉积、海相沉积和上部河口湾相候, 导致河流水流量减少, 因而降低了河流的下 沉积及河流相沉积。

选取磁化率、碳酸钙含量、总有机碳含量和0.01~0.05 mm粗粉粒含量作为气候替代指标，利用小波分析方法研究了A、B、D三个剖面全新世以来气候变化情况。结果表明，总体上，A和B剖面10000 a B.P.~8500 a B.P.为变暖期；8500 a B.P.~3000 a B.P.温湿大暖期；3000 a B.P.以来为变冷干期；而D剖面表现为，8000 a B.P.~4000 a B.P.为温湿大暖期，4000 a B.P.以来为变冷干期，其时间差异可能是由于D剖面比A、B剖面相同时期的埋藏土壤年龄偏老而造成的。(3) 运用土壤深度-年龄曲线法，得到各剖面全新世以来不同气候条件下黄土沉积速率，A、B、D剖面全新世平均黄土沉积速率为0.0179 cm/a、0.0153 cm/a、0.0213 cm/a。该研究区黄土沉积速率分布图表明，黄土沉积速率由西北向东南逐渐减小黄土高原气候，并且在中部出现了极低值点。利用磁化率重建历史时期降雨量变化状况，并根据降雨量与土壤侵蚀强度的关系分析了地质时期土壤侵蚀情况，详细讨论了土壤侵蚀对各气候时期的沉积速率的影响黄土高原气候，发现此极低值是由该地区地质时期土壤侵蚀造成的。

与此相关的还有一个概念: 土壤流失 除了以上两种水土保持措施, 山坡出现的凹面比率, 土壤流失比率 slr: soil loss ratio 是有覆 造成的沉积会降低侵蚀。黄土高原是世界上面积最大黄土沉积最厚的风成高原，由风的侵蚀、搬运和堆积作用形成。北部因受地质沉陷和红、黄土层沉积，形成黄土层沉积，形成黄土丘陵地貌。

英文摘要

Soil loss in loess plateau in northern Shaanxi is the most serious all over the world。 The loess deposition rate in this region is the base for determination of soil loss tolerance。 Unstable climate in the Holocene affects on loess deposition and formation。 Meanwhile, the loess formed in this period has the closest relationship with human。 Thus, it is necessary to research the loess deposition rate under influence of climate in the Holocene。 This study could provide theoretical basis and data supporting for determination of soil loss tolerance and assessment of soil erosion risk。

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kelvin tan asked on statalist(see here):"i would like to know if i can stack two correlation matrix tables intoone big correlation matrix ((foreign=1) in lower diagonal and(foreign=0) in upper diagonal of the big correlation matrix table)."maarten buis suggested a solution that works for the coefficients but does notprovide significance stars or p-values(see here).here are some examples for combining correlation coefficients while preserving the p-values. ifyou just want to stack two correlation matrices, you could code:。 ), the time delay is found out which maximizes the plateau region on the local slope (14) for the correlation integral (13) calculated in each embedding dimension。kou, x. y., ferguson, d. k., xu, j. x., wang, y. f. & li, c. s.* 2006. the reconstruction of paleovegetation and paleoclimate in the late pliocene of west yunnan, china. climatic change. 77: 431-448。

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The average loess deposition rate of A, B and D profile in the Holocene was 0。0179 cm/a、0。0153 cm/a、0。0213 cm/a, respectively。 The distribution of loess depostion rate in this region showed that, it decreased from northwest to southeast, and the minimum was in the middle of region。 The soil erosion in the Holocene was analyzed by the annual rainfall which was calculated by magnetic susceptibility。 The influences of soil erosion on soil deposition rate were discussed。 The minimum in the middle of region was caused by soil erosion。

Therefore, the loess deposition rate was comprehensive results of deposition, erosion and other pedogenesis。 The loess depotition rate derived from soil depth and age could show the comprehensive result quantitatively。(4) Soil age, loess accumulation rate and climate indexes of B and C profile were used to reconstruct the landforms on the slope where the C profile on before 12000 a B。P。。 The soil eosion rate was lager than loess deposition rate, and it was proved that this method could be used to research on soil erosion and reconstruct the landforms in geological period。

(5) Soil erosion risk of the research region and a watershed was assessed by the ratio of soil loss to soil deposition。 The soil erosion risk in Luochuan, Yanchang and Heangshan was 14。1、43。3 and 24。8, much larger than critical value 1, so this region should be an important protection and control area。 With the growth of management degree, the soil erosion risk dropped from 28。8 in 1997 to 0。2 in 2007 in Yan’gou watershed。 The soil erosion was under control。This study could provide theoretical basis for determination of soil loss tolerance, soil genesis and development。

It would provide new idea and method for quantificationally research on reconstruct the landforms in geological period。 The application of loess deposition rate on assessment of soil erosion risk could provide theoretical basis for environmental treatment decision。

公开日期

2011-07-01

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水土保持研究所_水保所知识产出(1956-2013)

推荐引用方式

GB/T 7714

. 陕北黄土高原全新世气候影响下的黄土沉积速率[D]. 陕西. 中国科学院研究生院. 2009.