【作者】 袁红；

【导师】 袁道先；

【作者基本信息】 西南大学 ， 自然地理学， 2009， 博士

【摘要】 岩溶生态系统是一种脆弱的生态系统,具有环境因子的利弊兼容性、生境的多样性和严酷性、水分亏缺的异质性和派生性、环境的脆弱性和改造的艰难性。因此岩溶区土壤退化和土壤的养分保持能力研究是一项非常重要和有意义的工作。本文系统分析了岩溶区不同石漠化程度下土壤的指纹电荷特征,及其所表征的土壤养分保持能力和土壤退化程度:选择三个岩溶区域进行对比,探讨岩溶区土壤在自然生态恢复、人为生态重建、人类无规划利用等方式下的养分保持能力,得出人为生态重建能有效恢复岩溶区土壤的养分保持能力;同时通过对人为生态重建区一年前后的土壤进行分析,提出运用土壤指纹电荷方法对某一研究区域的土壤养分保持能力进行研究,制作图谱,后期研究则只需取少量土壤测定pH值后查询前期土壤指纹电荷图谱即可得出某时段内土壤养分保持能力的变化趋势;最后对南平镇石庆村西南坡退耕樟树林坡地不同坡位处土壤的营养元素进行分析,进一步验证了岩溶区坡地土壤流失的双重性,即不仅存在地表流失,而且还有地下漏失。土壤pH值是土壤重要的基本性质之一,对土壤的理化性质、微生物活动以及植物生长发育都有很大的影响,因此在一定区域,根据土壤pH值的变异可以评估土壤的养分保持能力。土壤指纹电荷特征是通过土壤pH值获得的一系列特征值,由于任何区域、类型土壤所含可变电荷特征都不一样,如同人类指纹般具有唯一的特征性,因而被称为指纹电荷。它能表征岩溶区土壤退化中的养分保持能力,且与非岩溶区土壤对比,土壤指纹电荷特征对岩溶区土壤的养分保持能力和土壤退化能力有更明显的指示作用:通过对缙云山非岩溶区与南平岩溶区旱地、撂荒地的土壤指纹电荷特征进行对比分析,得出无论是旱地还是撂荒草地,非岩溶区土壤实际pH值所对应的指纹电荷都处于中等水平,这说明在非岩溶区,旱地由于一定量的施肥使土壤养分保持能力处于中等水平,撂荒草地由于少有人类活动干扰,土壤养分保持能力也处于中等水平。但岩溶区撂荒草地土壤B层实测pH值所对应的指纹电荷处于低值,表明岩溶区土壤退化后恢复较慢,指纹电荷特征更能表征岩溶区土壤的养分保持能力。岩溶区土壤剖面中,碱性界面处与远离基岩处土壤pH值变异较大,因此,岩溶区土壤样品的采集不同于非岩溶区土壤样品的常规采集,应具有岩溶的特殊性:本研究在岩溶区这一特定地域,通过对碱性界面处与远离基岩处土壤pH值进行变异分析,发现在同一土壤剖面中,土壤pH值变异系数竟然＞2%,由此可见岩溶区碱性基岩对界面附近土壤pH值的影响较大。尤其在碱性基岩面上20cm范围内,土壤pH值变化最大,如在退耕樟树林土壤地质剖面中,碱性基岩面上20cm范围内土壤pH值比20cm范围外土壤高出0.14个pH值单位,比土壤表层土壤高出0.24个pH值单位。在马尾松土壤地质剖面中,基岩表面20cm范围内土壤pH值与土壤表层pH值的差值更大,达到0.5个pH值单位,变异系数为5.11%。金银花种植地土壤地质剖面中,碱性基岩表明20cm范围内土壤pH值为7.15,基岩表面20cm～40cm土壤的pH值为7.05,差值为0.1个pH值单位。因此,在对岩溶区域范围内土壤的环境质量、肥力质量、健康质量进行整体性、综合性分析和评价时,其土壤样品的采集应避免碱性基岩界面对土壤理化等一系列性质的影响。而在对岩溶区小范围内土壤的异质性进行分析和评价时,要注意基岩、岩石裂隙对土壤发生、发育的影响。在研究方法上,根据岩溶区土壤pH值特征,对土壤指纹电荷的测定进行了参数修正,将pH值梯度范围修正为（8.0、7.2、6.4、5.6、4.8、4.0）,使之更适合岩溶区土壤特征:土壤pH值与土壤发生密切相关,岩溶区发育于碱性母岩上的土壤,由于Ca²⁺的大量存在常使土壤呈碱性反应,一般石灰土的pH值为中性到微碱性,如安徽省石灰岩风化物发育土壤的pH值在6.15～8.06之间,重庆北碚鸡公山石灰土的pH值在5.98～8.00之间,重庆巫山地区石灰土pH值在5.68～8.51之间,重庆黔江地区石灰土pH值在5.18～7.69之间,广东阳山黑色石灰土pH值在7.00～8.06之间,重庆金佛山岩溶石灰土pH值在4.25～6.95之间。因此,在对研究区岩溶土壤样品进行分析时,对pH值的上限做了扩展,pH值设定区域为4.0～8.0,具体的梯度值分别为（8.0、7.2、6.4、5.6、4.8、4.0）。得出不同石漠化程度下土壤指纹电荷特征,把金佛山土壤样品根据分析划分为无石漠化阶段、轻度石漠化阶段、中度石漠化、强度石漠化阶段,并对不同石漠化程度下土壤样品进行土壤指纹电荷特征和土壤有机质及其组分关系分析,得出在不同石漠化程度下,土壤指纹电荷有明显变化,且呈衔接式——阶梯状发展,即:在无石漠化的山顶,土壤A、B层土壤保持养分能力最强的pH值范围与土壤实测pH值较为吻合;轻度石漠化条件下,土壤B层养分保持能力与无石漠化的土壤A层较为一致,土壤A层养分保持能力受到明显扰动;中、强度石漠化条件下,土壤A、B保持养分能力的相对平衡点的pH值明显偏酸,这在A层表现尤为明显,主要是人为施肥的结果。土壤有机质对土壤指纹电荷即土壤保持能力有重要作用,其中富里酸的正相关作用较大,而胡敏酸的负相关作用较大。通过区域对比分析,得出三种生态恢复与重建模式下土壤的养分保持能力,并通过土壤指纹电荷特征予以验证:选择重庆北碚鸡公山槽上,重庆南川区南平镇,重庆南川区东胜镇分别作为三种生态恢复与重建模式（自然生态恢复、人为生态重建、人类无规划利用区）的研究区作对比分析,从土壤结构退化、土壤水分退化、土壤微生物退化、土壤养分退化四个方面得出鸡公山自然生态恢复区基本无退化;南平镇人为生态恢复区主要处于轻度退化阶段;而东胜镇人类无规划利用区则处于退化中度阶段。这与基于土壤指纹电荷特征得到的三区域土壤退化趋势是相一致的。通过时间对比分析,得出不同土壤利用方式下土壤养分保持能力和土壤退化的变化趋势,提出运用土壤指纹电荷方法对某一研究区域的土壤养分保持能力进行研究,可以减少研究区土壤的破坏程度,只要前期充分展开相关指纹电荷工作研究,制作图谱,后期研究则只需取少量土壤测定土壤pH值后查询前期土壤指纹电荷图谱即可得出某时段内土壤养分保持能力的变化趋势:通过对重庆南平镇石庆村人为生态恢复区不同土壤利用方式下前后一年土壤样品的分析,得出退耕后撂荒草地土壤的各项养分保持指标含量增长最快,对恢复土壤退化程度最为有利,其次是杉树林和樟树林;而从人为生态恢复的各种利用方式来看,花椒林土壤的养分保持能力最好,土壤退化恢复的程度最快,其次是金银花和桃林。结合岩溶区的环境效益、生态效益和社会经济效益,岩溶贫困山区栽种花椒、金银花的措施,能够在短时期内有效改善土壤养分保持能力,有利于土壤的稳定培肥,同时有效改善石漠化状况,阻止水土流失。通过对南平镇石庆村西南坡退耕樟树林坡地采样分析,以坡地土壤中营养元素为媒介,对岩溶区坡体的地表流失和地下漏失有了更深一步的了解:从Ca、Mg、Cu、zn、Mn、Mo、Si、Fe八个营养元素在岩溶区坡体中的含量分析得出,从坡顶到坡底都有不同程度的流失过程,然而在坡底却没有明显的堆积过程,这说明岩溶区坡体中由于地上和地下的双层结构,使坡体土壤的流失形式异于其他红黄壤区,不仅存在着地表土壤流失,还有地下岩溶裂缝、落水洞的土壤漏失,其中Cu、Mn、Zn、Mg、Mo五个营养元素在坡体的坡腰部位开始出现拐点,因而可以看做是地表流失和地下漏失双重作用的结果,Fe、Ca、Si则是在坡麓处就出现转折点,地表土壤流失与地下土壤漏失在此处得到明显表现。更多还原

【Abstract】 The ecosystem of karst is vulnerable.She is of compatibility of advantages and disadvantages of environmental factors,diversity and rigor of habitat,inhomogeneity and accompanying attributes of water’s deficit,vulnerability of environment and hard to improve.So,it would be an important and significative work to study soil degradation and capability of nutrient’s holding in karst area.This paper analyzed characteristics of the soil fingerprint charge and soil nutrient retention capacity in different karst rocky desertification;and chose three karst regions（that is natural ecologic rehabilitation region,man-made ecologic rehabilitation region and region had not project） to compare soil nutrient retention capacity;at the same time,analyzed soil physical and chemical properties which sampled in man-made ecologic rehabilitation region one year later,put forward that if we work out atlases of soil fingerprint charge in prior period,we can query soil nutrient retention capacity just through soil pH;finally,this paper sampled soil in a camphor slope,through analyzed on soil nutritive elements,like that Ca,Mg,Cu,Zn,Mn,Mo,Si,Fe,we had a deeper understanding with soil ground erosion and underground soil leaks.pH is the main soil variable,and it also is the main impact factor to symbol and quantity of soil varying charge.At the same time,pH is a crucial property of soil,and soil physical and chemical properties,activity of microbe,growth of plants would be change when pH varied.So,we can evaluate soil capability of nutrient’s holding.Soil fingerprint Charge（SFC） is a method to measure charge characteristics of soil surface which is determined by ion strength of soil.i.e.measure maximum capability of keeping ion in different pH and ion concentration.SFC has its special characters in different area,or soil types,like as people’s fingerprint,so we called it soil fingerprint charge.Compared to non-karst area,SFC was more efficiency in illustrated soil capability of nutrient’s holding:We had many dates about SFC in different land use in karst area and non-karst area, like that dry land,wasteland,and woodland.And found that in all of land use in both area,the SFC which corresponded by its intrinsic pH was in moderate standard.The reason was fertilization in dry land.In wasteland,compared with non-karst area,B soil layer had a low SFC corresponded by its intrinsic pH,and indicated in karst area,after soil degradation,the speed of soil renew was slowly.To sum up,SFC was more efficiency in illustrated soil capability of nutrient’ s holding.In karst area,it was different to obtain soil samples between karst area and non-karst area.In karst area,because of the influences from the alkali rocks,we must avoid when sampling:We analyzed coefficient of variation（CV） of soil pH where soil was in round of or away from alkali rocks.It was indicated that in a one soil vertical section,the CV of pH was greater than 2%,and alkali rocks had big influence to soil pH,especially in 20 centimeters to alkali rocks.For example,in soil geologic section of camphor woods, surface soil pH of alkali rocks was higher about 0.14 pH units to 20 centimeters offscale of alkali rocks,and compared to topsoil,was higher about 0.24 pH units.In pinus massoniana soil vertical section,there were more differences,like that o.5 pH units,and the CV was 5.11%.In honeysuckle soil vertical section,soil pH of in 20 centimeters of alkali rocks was 7.15,and 7.05 in 20 to 40 centimeters,so there were a difference about 0.1 pH units.Due to the method of SFC mainly applied to non-karst area,and had different characters about pH to karst area,so we must modify the pH grads.Analyzed by dates, and founded that:In China karst area,soil pH mainly focused between 5.0 and 8.0.So, we amended soil pH grads to（8.0,7.2,6.4,5.6,4.8,and 4.0）,the reasons as follows:Soil pH and soil growth were on speaking terms.In karst area,due to abound of Ca²⁺,and soil pH show to neutral or tiny alkalescence,like that:in Anhui karst area,the pH was 6.15 to 8.06;in Chongqing,in Beibei Jigong Mountain,the pH was 5.98 to 8.00; in Wushan,the pH was 5.68 to 8.51;in Qianjiang,was 5.18 to 7.69;in Jifo mountain, was 4.25 to 6.95;in Yangshang in Guangdong,the pH was between 7.0 and 8.06,and so on.So,I expanded the upper limit of soil pH.In Jinfo Mountain,according to soil features,the soil section can be divided into no karste rocky desertification,week karst rocky desertification,middle karst rocky desertification,and strong karst rocky desertification.It was found that under different degree of karst rocky desertification（KRD）,it shows clear change about SFC,i.e., under no KRD,the range of soil pH,which keeps nutrient,is consistent with real pH. Under week KRD,the capacity of keeping nutrient in layer B is similar to layer A under no KRD,and the capacity of layer A was disturbed.Under middle and strong KRD,pH of layers A and B is decreased to be acid,which is possibly due to fertilization by land use.The fulvic acid contained more active functions groups compared with humic acid, and therefore had more positive correlation on SFC,and humic acid had more negative correlation.So,it is significant which used SFC to evaluate soil capability of nutrient’s holding and forecast soil degradation.This paper analyzed soil fingerprint charge and the degradation of soil structure, moisture,micro-carbon and fertility,then obtained conclusions in three different research areas,that is Jigong Mountain—natural ecologic rehabilitation 15 years region, Nanping Town -- ecologic rehabilitation by changing land-use region 1 year ago, Dongsheng Town - region had not project.Finally,we can find that:there were no soil degradation in Jigong Mountain;Nanping Town had light soil degradation,and the optimal land-use was vivacious Huajiao Forest.And after period of time by ecologic rehabilitation,soil quality may improve;and Dongsheng Town had medium soil degradation,if it was still in no rule in land-use,all of indexes wound become serious. Base on soil fingerprint charge,the ranking of soil degradation in three areas was: Dongsheng Town＞Nan ping Town＞Jigong Mountain and it held on the line with conclusion one.Exampled on Shiqing village in Nan ping town,relative analyzed soil physical and chemical properties in one year in different land use,then,draw a conclusion:after restoring the reclaimed land,uncultivated wild grassland had an advantage over fir or camphor woods,and in favor of improve soil degradation,because there were a relatively rapid growth of nutrient.In man-made ecological restoration,prickly ash peel woods was the best land use,and had a good capability to hold nutrient.Secondly was honeysuckle and peach tree wood.So,in poor karst area,in order to link environmental benefits,eco-efficiency and social and economic efficiency,it were best measures to plant prickly ash peel or honeysuckle.It can improve capability of holding nutrient in short phase.,also it were beneficial to soil fertility,and hold back soil erosion.Sampled soil in a camphor slope,through analyzed on soil nutritive elements,like that Ca,Mg,Cu,Zn,Mn,Mo,Si,Fe,we had a deeper understanding with soil ground erosion and underground soil leaks.It indicated that:from peak to bottom of slope,there was a varying degrees process about soil erosion.But it was strange that in the bottom of slope,there were not deposit obviously in ground,so it must be existed underground soil leaks.This was different to other red or yellow soil area,because of double deck structure（ground and underground:like as cracks,sinkholes,and so on） in karst area.In studied area,the content of Mg,Cu,Zn,Mn and Mo changed at middle slope, turned up to inflection point,so,we can think that from middle to bottom of slope,there was a function about ground soil erosion and underground soil leaks.And the content of Si,Fe and Ca had an inflection point in foot slope.更多还原