广西平果县石漠化地区立地划分与生态恢复试验初报

以石漠化严重和扩展趋势明显的平果县果化镇布尧村龙何屯为例,在现有土地利用类型的基础上,综合坡度、土层厚度、裸岩率、植被盖度等因子,将该屯土地划分为8个立地类型。根据不同立地类型采取相应的生态恢复模式,设计构建不同的植物群落,生态环境治理与农村经济发展兼顾,构筑以木本农业为主的复合农林经营体系。通过两年多的综合治理,试验区农业产业结构调整、封山育林与人工诱导促进植被恢复以及生态苗圃基地建设等方面取得了初步成效。      

Relating groundwater to seasonal wetlands in southeastern Wisconsin, USA

Historically, drier types of wetlands have been difficult to characterize and are not well researched. Nonetheless, they are considered to reflect the precipitation history with little, if any, regard for possible relation to groundwater. Two seasonal coastal wetland types (wet prairie, sedge meadow) were investigated during three growing seasons at three sites in the Lake Michigan Basin, Wisconsin, USA. The six seasonal wetlands were characterized using standard soil and vegetation techniques and groundwater measurements from the shallow and deep systems. They all met wetland hydrology criteria (e.g., water within 30 cm of land surface for 5% of the growing season) during the early portion of the growing season despite the lack of appreciable regional groundwater discharge into the wetland root zones. Although root-zone duration analyses did not fit a lognormal distribution previously noted in groundwater-dominated wetlands, they were able to discriminate between the plant communities and showed that wet prairie communities had shorter durations of continuous soil saturation than sedge meadow communities. These results demonstrate that the relative rates of groundwater outflows can be important for wetland hydrology and resulting wetland type. Thus, regional stresses to the shallow groundwater system such as pumping or low Great Lake levels can be expected to affect even drier wetland types.     

The Darfur Dome,western Sudan: the product of a subcontinental mantle plume

Field investigations, K-Ar age determinations and chemical data were used to describe the development of an intraplate volcanic province, the Darfur Dome, Sudan. Magmatism started 36 Ma ago at a small subvolcanic complex (Jebel Kussa) in the center of the dome and was active in the same area between 26 and 23 Ma. Two major volcanic fields (Marra Mountains and Tagabo Hills) developed between 16 and 10 Ma. Volcanism started again at 6.8 Ma with a third volcanic field (Meidob Hills) and at 4.3 Ma in the Marra Mountains and with the reactivation of the center. Activity then continued until the late Quaternary. Having started in the center of the Darfur Dome, volcanism moved in 36 Ma 200 km towards the NNE and 100 km SSW No essential difference in the alkaline magma types (basanitic to phonolitic-trachytic, with different amounts of assimilation of crustal material) in the different fields, was observed. Magmatism is thought to have been produced by a rising mantle plume and volcanism was triggered by stress resolution along the Central African Fault Zone.     

黔桂喀斯特山地NDVI的垂直分布特征

黔桂喀斯特山地地形复杂,植被覆盖度垂直特征分异显著,以往研究多从气候因子响应方面探讨其垂直分布差异,而研究区人地矛盾尖锐,人类活动对植被分布有重要的影响。文章以黔桂喀斯特山地为例,利用2010年MODIS13Q1 NDVI数据表征植被覆盖度,结合高程、坡度和坡向等地形特征,不同土地利用类型的分布情况,叠置分析研究区的NDVI垂直分布特征。结果表明:黔桂喀斯特山地以林地、耕地和草地为主,不同土地利用类型随海拔、坡度和坡向的变化呈现不同的分布特征。研究区NDVI平均值为0.59,其中林地NDVI最大,达到0.63,草地为0.58,耕地最小为0.54。空间分布上,贵州境内NDVI值大部分为0.5~0.6,广西境内自西北向东南NDVI值由0.8逐渐降低至0.4,以0.6~0.7为主。NDVI在垂直梯度上分布特征显著,与植被垂直地带性分布以及不同地类的垂直分布特征有密切关系。海拔分布上,NDVI在海拔小于200 m区间最小,400~600 m的区间最大;北部贵州整体海拔较高,但植被覆盖度较低;南部广西海拔较低,但植被覆盖度较高。坡度分布上,在坡度小于35°范围,随坡度增大,耕地、水域、建设用地面积迅速减少,林草地面积逐步增加,使得NDVI随坡度增大逐渐增大。坡向分布上,NDVI不随坡向变化呈现明显变化,仅偏东坡向稍大于偏西坡向。研究表明应根据海拔和坡度等地形特征,并考虑土地利用情况,因地制宜进行生态建设。      

松嫩平原典型黑土分布区土壤呼吸研究

在松嫩平原典型黑土分布区,选择耕地、休耕地、自然荒地3种土地利用方式进行土壤CO₂呼吸研究。采用壕沟隔断法,探讨了植物根系呼吸在不同土地利用方式下的差异,采用温度敏感系数Q10分析了不同土地利用方式下土壤呼吸对温度的敏感性。结果表明: 土壤呼吸受多方面因素影响,包括土壤温度、湿度、植被类型、农业生产活动等。土壤呼吸日变化过程中,温度是影响土壤呼吸速率的决定性因素。在夏季植物根系呼吸所占的比例最大,超过了50％,春秋两季根系呼吸所占的比例相对较少。受植物种类及植物根系呼吸在土壤呼吸中所占比例大小的影响,在3种不同的土地利用方式下根系自养呼吸所占的比例大小顺序依次为荒地>休耕地>耕地。有根系的土壤呼吸对土壤温度升高的反应要敏感些。     

The relations between land use and karst rocky desertification in a typical karst area,China

Karst rocky desertification (KRD) is one major type of desertification which is under irrational human impact on the vulnerable eco-geo-environment. In this study, Zhudong fengcong rocky desertification landscape was selected to investigate the land use types distribution law in different rock types and the KRD land in different land use types. KRD data was determined by user–computer interactive interpreting method from Aster images in 2004, according to the exposed ratio of rock, the coverage of vegetation and soil in 0.2 km² unit, integrating with land utilizing present situation map, hydrogeology map, relief map, vegetation map, soil distribution map, as well as the practical investigation and the population census datum in 2002. Results showed that the occurrence ratio of KRD land is different in land use types and rocky assemblages obviously; land cover has a strong impact upon KRD. The sloping cropland distributed in homogenous limestone has a higher occurrence ratio of light KRD, secondly, is in the limestone interbedded with clastic rock. Light KRD land was dominated by shrubland, and sloping cropland accounts for 11.67% of it, moderate KRD land was dominated by moderate coverage grass slopes, strong and extremely strong KRD was dominated by rocky dry land which is difficult to use.     

城市土地利用对植被特征影响的研究

城市土地利用对植被的影响是城市生态学中研究的重要问题。简单综述了国内外在该领域中的研究现状。通过在北京市进行的研究，对城市植被的特点及其与土地利用的关系进行了分析，结论为：①藜科（Chenpodiac eae）和蓼科（Polygonac eae）植物种类数量相对增加，归化植物占的比例大是城市植物区系的特征；②与非城市区域相比，生活型谱中一二年生植物比例增高，属的区系地理成分构成中世界分布属所占比例也明显提高；③城市土地利用类型对生境和植物群落特征的影响明显；④生境多样化对维持城市植物物种多样性而言，比面积大小具有更为显著的作用。     

岩溶地区不同利用方式土壤土力学特性垂直变化特征

以黔中岩溶地区不同利用方式的土壤为研究对象,采用野外调查和室内试验相结合的方法,研究了土壤黏聚力c、内摩擦角φ及紧实度随不同土壤利用方式、不同土层深度的变化特征。结果表明:土壤黏聚力c总体随土层深度不断增大,在0-35 cm内受不同土壤利用方式的影响比较明显;土壤内摩擦角φ在0-50 cm土层内,呈“S”形变化,受母质影响显著,三种不同土壤利用方式总体变化趋势基本一致;林地、灌草地、坡耕地土壤在垂直剖面上都存在着上松下紧的状况,在0-20 cm内,坡耕地土壤紧实度均小于林地和灌草地,20 cm以下坡耕地和灌草地土壤紧实度基本一致,但均大于林地,三者均保持着不断增大的趋势。研究表明:植被生长对于改善土壤力学性能具有一定的影响。因而通过加强植被保护与管理和调整坡耕地利用方式是改善土壤力学性能,防治土壤侵蚀和控制石漠化的主要手段。      

土地利用结构与生态过程

本文从土地利用与土壤水分、土地利用与土壤养分、土地利用与水土流失3个方面系统讨论了土地利用结构与生态过程研究的现状和特征,指出:1)土地利用结构对土壤水分的影响涉及生态系统、坡面、小流域和区域等系列尺度,土地利用的分布及景观特点影响土壤水分的时空变异;2)土地利用对土壤养分的影响表现在土地利用的镶嵌格局影响土壤养分的分布和迁移,土地利用的变化可以引起土壤养分的变化;3)土地利用与水土流失关系密切,土地利用的改变能够减少或增加径流和土壤侵蚀.尺度不同,土地利用与水土流失的机制也不尽相同.土地利用结构与生态过程的研究,还需要注重大尺度和多尺度上的综合研究.     

吉林西部不同土地利用类型的土壤有机碳垂向分布和碳密度

土壤碳库在陆地生态系统碳循环中起着关键性的作用。在对吉林西部进行为期6年（2004－2009年）的环境调查基础上,采集了217个土壤剖面,获取了2 170个土壤样品的平均容重、含水率和有机碳含量,分析了不同土地利用类型下土壤有机碳（SOC）的垂向分布特征、原因和机理。结果表明：不同土地利用类型的土壤有机碳垂向分布表现出截然不同的特征,大致可分为“下降型”、“上升型”和“不变型”3种。呈下降型的草地、农田、湿地等SOC含量主要富集在0~30 cm耕作层,并随深度增加而快速下降;滩地为上升型,良好的水文条件和相对茂盛的植物为有机质提供了有利条件;不变型包括盐碱地、林地和沙地,SOC含量处于全区最低水平。不同土地利用类型的土壤有机碳密度差异很大,从大到小依次为水田、草地、旱田、湿地、退化草地、滩地、林地、沙地、盐碱地,其中水田为（169.25±17.70） t/hm²,盐碱地为 （26.50±10.00） t/hm²。植被生物量和土壤理化性质是影响土壤有机碳含量的主要因素。     

黄土高原西部地区现代植被及其表土正构烷烃分布模式研究

由于现代木本、草本植物正构烷烃主峰分布的研究结果存在一定的差异,从而导致黄土沉积中利用正构烷烃主峰分布进行古植被恢复时存在较大争议,尤其是松科植物主峰分布的不同。因此,采集黄土高原西部地区常见木本和草本植物及其表土,包括研究区常见松科植物,利用GC分析,开展现代植物及其表土正构烷烃主峰分布的研究。结果发现,黄土高原西部地区常见10种木本植物正构烷烃的主峰分布均以C27或C29为主峰,3种草本植物以C31为主峰,与分子有机地球化学研究结果一致,研究区3种常见松科植物均以C29为主峰,并无C31为主峰的分布; 研究区现代表土正构烷烃的结果显示,表土正构烷烃主峰分布与上覆植被输入量有直接关系,对于不同景观的采样点,由于其木本、草本植物输入量的差异而导致正构烷烃分布存在差异,对于有机质来源较为多元化的地区,分析要十分慎重。同一种植物腐叶与新鲜叶片正构烷烃主峰分布是一致的,说明植物叶片的腐烂过程对其正构烷烃主峰分布没有产生影响。对同一种植物不同地区的对比分析发现,木本植物正构烷烃主峰分布特征受生长环境影响较小,主峰分布不变,但是对于草本植物受生长环境影响较大,主峰分布会产生变化。因此,对于黄土沉积中利用正构烷烃主峰分布特征进行的古植被恢复在开展现代过程研究的基础上是较为可靠准确的。     

Modelling soil moisture under different land covers in a sub-humid environment of Western Ghats,India

The objective of this study is to apply and test a simple parametric water balance model for prediction of soil moisture regime in the presence of vegetation. The intention was to evaluate the differences in model parameterization and performance when applied to small watersheds under three different types of land covers (Acacia, degraded forest and natural forest). The watersheds selected for this purpose are located in the sub-humid climate within the Western Ghats, Karnataka, India. Model calibration and validation were performed using a dataset comprising depth-averaged soil moisture content measurements made at weekly time steps from October 2004 to December 2008. In addition to this, a sensitivity analysis was carried out with respect to the water-holding capacity of the soils with the aim of explaining the suitability and adaptation of exotic vegetation types under the prevailing climatic conditions. Results indicated reasonably good performance of the model in simulating the pattern and magnitude of weekly average soil moisture content in 150 cm deep soil layer under all three land covers. This study demonstrates that a simple, robust and parametrically parsimonious model is capable of simulating the temporal dynamics of soil moisture content under distinctly different land covers. Also, results of sensitivity analysis revealed that exotic plant species such as Acacia have adapted themselves effectively to the local climate.     

Weed vegetation and land use of upland maize fields in north-west Vietnam

Agriculture in upland Vietnam changes more and more from short cultivation-long fallow periods to short cultivation-short fallow periods or even permanent cropping. Soil degradation and high weed infestation are often the consequences. Thus, the objective of this study was to survey the weed vegetation and to investigate if certain species can be related to soil degradation parameters or land use intensity. Weed vegetation on 12 upland maize fields in Son La Province, a mountainous region of north-western Vietnam was investigated in 1998. The maize fields analysed had a maximum inclination of 35° and belonged to Black Thai farmers of three villages. Vegetation surveys covered only eight maize fields, whereas plant species collection included all 12 maize fields. In addition, analysis of different soil parameters took place. Two weed communities could be distinguished within the area for the surveys conducted. This differentiation was supported by differences in soil parameters (pH, CEC, content of organic matter and nitrogen) and land use intensity. In general, weed infestation did not seem to be yet at a crucial stage as reported for other fields in the study region. Land use intensity on the higher altitude fields was low as fields were cleared only a few years ago. Besides the negative aspects of weeds, their importance for soil conservation on steep slopes has to be taken into consideration. Therefore, the development of an integrated weed management - soil conservation strategy is needed. This revised version was published online in July 2006 with corrections to the Cover Date.     

断陷盆地区不同土地利用方式土壤钙形态分布特征

选择云南省蒙自市西北勒乡碧色寨村具有典型岩溶地貌特征的草地、人工林地、玉米地（由草地开垦种植玉米2年）和火龙果地（由草地开垦种植火龙果5年）作为研究对象,采用连续浸提（BCR）提取方法测定不同形态钙含量,以探讨岩溶区不同土地利用方式下石灰性土壤钙形态特征及其影响因素。结果表明:土地利用方式显著影响了土壤全钙含量及其形态分布;草地土壤全钙和各形态钙含量均高于其他土地利用类型,玉米地最低;４种土地利用方式土壤钙的赋存形态主要为交换态（占总量的59.4%~74.8%）,有机结合态钙含量最低（占总量的0.5%~1.0%）;全钙和各形态钙与有机碳、全氮、全镁、阳离子交换量（CEC）、pH呈显著正相关,说明全钙和各形态钙与土壤物理化学性质是互相影响的。      

Phytolith reference study for identifying vegetation changes in the forest−grassland region of northeast China

To provide a basis for tracing changes in vegetation and tree cover density, we studied the phytoliths of 129 common temperate plant species, and extracted the phytoliths from 75 surface soil samples from sites in grassland, forest−grassland ecotone and forest habitats in northeast China. From the analysis of shapes and morphological parameters of the plant samples, we developed a reference data set of herbaceous and woody phytoliths, and subsequently identified 21 herbaceous and 13 woody phytolith types in the surface soil samples. To test the reliability of soil phytolith analysis for distinguishing forest, grassland and the forest−grassland ecotone, we used principal components analysis (PCA) and discriminant analysis (DA) to summarize the soil phytolith assemblage characteristics of the different ecosystems. The results show that the grassland and forest samples are characterized by abundant herbaceous and woody phytoliths, respectively; and that forest−grassland ecotone habitats are characterized by low abundances of blocky polyhedral, multifaceted epidermal and sclereid phytoliths. In general, the surface soil phytolith assemblages can reliably differentiate samples from forest, grassland and the forest−grassland ecotone, with up to 92% of the samples classified correctly. We also tested the reliability of phytolith indices (W/G (1), W/G (2), W/G (3)) for discriminating different vegetation types in our study area, and found that W/G (2) was the most reliable index and corresponded well with the species inventory data. The W/G values for grassland ranged from 0 to 0.3, from 0.3 to 0.6 for the forest−grassland ecotone, and exceeded 0.6 for forest. We conclude that our study provides reliable analogues for phytolith assemblages from palaeoecological contexts, which can be used to reconstruct shifts in forest−grassland ecotones and vegetation succession in temperate areas.     

马卡山不同植被群落下非饱和带大孔隙流路径示踪试验

为辨识在天然降雨条件下,植被发育斜坡非饱和带中具有优先流效应的大孔隙流路径,不包括死端大孔隙,分析两种植被群落下非饱和带大孔隙流路径分布模式差异及植被根系、有机质含量、土壤颗粒尺寸分布对大孔隙流路径分布模式的影响;选择亚甲基蓝作为染色示踪剂,结合降雨入渗模拟试验,在马卡山草本植被群落斜坡和木本植被群落斜坡开展染色示踪渗透试验。基于垂直开挖剖面采用图像处理技术获得大孔隙流路径分布模式图像。采用非参数检验分析大孔隙流路径差异。采用差方分析、回归分析法分析根系质量分数、有机质含量和颗粒尺寸分布对大孔隙流路径分布模式的影响。结果显示：木本植被群落斜坡大孔隙流路径分布模式更复杂,尺度更大;根系显著影响大孔隙流路径数量、尺度和分布特征,尤其是垂直向下和顺坡向下的根系,当根系尺寸增大时,其对大孔隙流路径影响更显著;有机质有利于团聚体间大孔隙的形成;黏粒、粉粒和砂粒对大孔隙流路径形成没有积极功效,但砾粒有利于大孔隙路径形成,尤其是在表土层;根-土界面和砾-土界面也是重要的大孔隙流路径。研究表明,可以通过根系分布形态、规模,有机质含量和砾粒含量综合评价植被发育斜坡大孔隙流路径分布模式。     

云南小江流域不同土地利用类型土壤微量元素的对比分析

文章对云南小江流域不同土地利用类型（耕地、林地、园地、建设用地、裸地）土壤的微量元素进行空间插值、方差分析和相关性研究,旨在探讨云南小江流域不同土地利用类型微量元素的分布和迁移规律。结果表明:除Mo的含量较低外,小江流域土壤中Cu、Mn、Ni和Zn的含量普遍较高。各微量元素含量在不同土地利用类型中具有明显的差异性,园地土壤微量元素含量最高。微量元素的变异程度均属于中等变异。Cu、Mn、Mo、Ni、Zn的空间分布具有一定的相似性,高值区主要集中在海拔较低的岩溶河谷区右侧和盆底沉积平坝区,主要土壤类型为碳酸盐岩红壤;低值区集中在海拔较高的河谷区左侧和中山区,主要土壤类型为碎屑岩。地貌、土壤母岩和人为活动是影响微量元素分布和迁移的重要因素。      

喀斯特石漠化治理区不同土地利用方式的小气候效应

研究小气候变化对植被恢复的响应机制可为喀斯特地区石漠化综合防治提供理论依据。文章选取喀斯特高原山地和高原峡谷石漠化综合防治示范区4种土地利用类型为研究对象,通过常规的小气候监测方法,在雨季前(4月)、雨季(8月)、雨季后(12月)对4种土地利用类型的大气温度、光照强度、相对湿度、土壤温度日变化进行监测和对比分析。结果表明:（1）4种土地利用方式中,大气温度、光照强度和土壤温度均表现为石漠化裸地>农耕地>灌木林>林地,而相对湿度的变化规律则反之:林地>灌木林>农耕地>石漠化裸地,说明林地的小气候调节作用最优,而石漠化裸地最差,与其石漠化治理和植被恢复效果相对应;（2）高原峡谷的大气温度、光照强度和相对湿度在不同的季节和不同土地利用方式下都显著高于高原山地,不同土层的土壤温度是高原山地显著低于高原峡谷;（3）各土地利用方式的小气候季节差异明显,大气温度、土壤温度均为:雨季(8月)>雨季前(4月)>雨季后(12月),而光照强度、相对湿度为:雨季(8月)>雨季后(12月)>雨季前（4月),8月各小气候指标值最高,且不同土地利用方式和治理区间的差异亦最大,因此,选取8月进行小气候监测以比较各土地利用方式和治理区之间的差异要优于其他两个月份。      

Levels and distribution of total nitrogen and total phosphorous in urban soils of Beijing, China

Urban soil nitrogen and phosphorus have significant implications for the soil and water quality in urban areas. The concentrations of total nitrogen (TN) and total phosphorus (TP) of soil samples collected from six types of land use, which included residential area (RA), business area (BA), classical garden (CG), culture and education area (CEA), public green space (PGS) and roadside area (RSA) of Beijing urban area, were investigated. Results showed that the geometric mean of TP (857 mg/kg) in urban soils was slightly higher than that (745 mg/kg) in rural soils of Beijing. The concentration of soil TP was higher in the center of the city, and showed an increasing trend with the age of the urban area. The TP concentrations in the six types of land use followed the sequence of CG > BA > RSA > RA > CEA > PGS, which were affected by the use and disposal of phosphorus-containing materials in each type of land use. However, the geometric mean of TN (753.8 mg/kg) in urban soils was much lower than that (1,933.3 mg/kg) in rural soils. TN level in urban soils of Beijing had no correlation with the city’s urbanization history, and was influenced by the coverage of natural vegetation and human activities in each type of land use. This study suggested that the city’s urbanization history and land use were the main factors affecting the distribution of nitrogen and phosphorus in urban soils.     

青藏高原多年冻土区活动层土壤入渗特征及机理分析

青藏高原多年冻土区活动层土壤的入渗规律研究是高寒区土壤水循环过程研究的主要内容。以青藏高原多年冻土区高寒沼泽草甸、高寒草甸和高寒草原的活动层土壤为研究对象,裸地为参照对象,分析了不同植被类型土壤的入渗规律及其主要影响因子。结果表明：不同植被类型土壤的入渗能力排序为高寒草原>裸地>高寒草甸>高寒沼泽草甸。高寒草甸土壤中致密的根系对土壤水分的运移具有强烈的阻滞作用,降低了土壤的入渗性能,而高寒草原土壤层根系较为稀疏,对土壤入渗的阻滞作用较弱,土壤水分向深层的渗漏速率较大。通过对比4种土壤入渗模型的模拟结果,发现Horton模型更适用于描述高寒草地土壤水分的入渗过程。另外,不同入渗模型对裸地入渗过程的模拟均优于其他植被类型草地,说明植被类型及植物的生长状况影响土壤入渗过程的模拟效果。全球变暖条件下,多年冻土区土壤入渗研究将为青藏高原多年冻土区陆地水文过程模型提供参数支持,为未来水资源变化研究提供基础数据。