Pedological Factors Research Articles

Forms and Extent of Ferrugination in Soils of Georgia

Ferruginization as one of the most characteristic processes in soils of Georgia, has been investigated both qualitatively and quantitatively mainly micropedologically, by polarizing microscopy on thin sections. A study was undertaken to determine some of pedological factors affecting the genesis of Fe-formations in soils series of West and East Georgia. This process is diagnosed by the presence of different forms of ferrous formations, concentration level or iron crystallization, ferruginized micro-zones of plasma impregnation with ferric hydroxides, etc. A map showing the distribution of the ferrugination process in the soils of Georgia was created.

Storage and depth distribution of organic carbon in volcanic soils as affected by environmental and pedological factors

It has been recognised that volcanic soils, particularly Andosols, can store large amounts of soil organic carbon (SOC). This study investigates the factors controlling the regional and vertical distributions of SOC in soils of volcanic origin. To this aim, we investigated the vertical distribution of SOC in a total of 212 soil profiles representing all combinations of soil-forming factors in a volcanic area with a high diversity of ecosystems and soil types. We analysed the SOC contents in relation to intrinsic (soil type and relevant soil properties: texture and pH) and extrinsic factors (climate, parent material, relief), and we studied the patterns of SOC distribution with depth by fitting the SOC contents to different curve models. Furthermore, we selected ten soil profiles for a more detailed study to assess the effect of vegetation by examining the relationships of the SOC storage and depth distribution to the amount and allocation of plant roots and litterfall.SOC storage was controlled by the interaction of climatic (rainfall), time (substrate age), topographic (slope) and biotic (plant-mediated) factors. Our results indicate that under humid conditions, large organic inputs and the inhibition of microbial degradation due to low pH, Al-toxicity and persistent anaerobiosis within soil microaggregates largely contributed to SOC accumulation. Soil type was a poor predictor of SOC storage, most likely due to the co-occurrence of young and evolved Andosols and a certain andic character in many soils that did not qualify as Andosols. The distributions of root carbon and SOC appeared to be closely interrelated, suggesting a major role of roots in the supply of organic matter and the lack of significant bioturbation. The depth distribution of SOC was best fitted by the quadratic, cubic and power models, the latter being a feasible alternative that should be used to this aim in volcanic soils rather than the widely used exponential model.

Three-dimensional interpolation of soil data: fertility and pedomorphological features in southern Brazil

The graphical representation of spatial soil properties in a digital environment is complex because it requires a conversion of data collected in a discrete form onto a continuous surface. The objective of this study was to apply three-dimension techniques of interpolation and visualization on soil texture and fertility properties and establish relationships with pedogenetic factors and processes in a slope area. The GRASS Geographic Information System was used to generate three-dimensional models and ParaView software to visualize soil volumes. Samples of the A, AB, BA, and B horizons were collected in a regular 122-point grid in an area of 13 ha, in Pinhais, PR, in southern Brazil. Geoprocessing and graphic computing techniques were effective in identifying and delimiting soil volumes of distinct ranges of fertility properties confined within the soil matrix. Both three-dimensional interpolation and the visualization tool facilitated interpretation in a continuous space (volumes) of the cause-effect relationships between soil texture and fertility properties and pedological factors and processes, such as higher clay contents following the drainage lines of the area. The flattest part with more weathered soils (Oxisols) had the highest pH values and lower Al3+ concentrations. These techniques of data interpolation and visualization have great potential for use in diverse areas of soil science, such as identification of soil volumes occurring side-by-side but that exhibit different physical, chemical, and mineralogical conditions for plant root growth, and monitoring of plumes of organic and inorganic pollutants in soils and sediments, among other applications. The methodological details for interpolation and a three-dimensional view of soil data are presented here.

Pedological and geological relationships with soil lichen and moss distribution in the eastern Mojave Desert, CA, USA

Biological soil crusts (biocrusts) are ubiquitous in drylands globally. Lichens and mosses are essential biocrust components and provide a variety of ecosystem services, making their conservation and management of interest. Accordingly, understanding what factors are correlated with their distribution is important to land managers. We hypothesized that cover would be related to geologic and pedologic factors. We sampled 32 sites throughout the eastern Mojave Desert, stratifying by parent material and the age of the geomorphic surfaces. The cover of lichens and mosses on ‘available ground’ (L + Mav; available ground excludes ground covered by rocks or plant stems) was higher on limestone and quartzite-derived soils than granite-derived soils. Cover was also higher on moderately younger-aged geomorphic surfaces (Qya2, Qya3, Qya4) and cutbanks than on very young (Qya1), older-aged surfaces (Qia1, Qia2), or soils associated with coppice mounds or animal burrowing under Larrea tridentata. When all sites and parent materials were combined, soil texture was the most important factor predicting the occurrence of L + Mav, with cover positively associated with higher silt, very fine sand, and fine sand fractions and negatively associated with the very coarse sand fraction. When parent materials were examined separately, nutrients such as available potassium, iron, and calcium became the most important predictors of L + Mav cover.

Climate and pedological factors of slump development on a Transylvanian example

Abstract Areas endangered by slump formation in the M˘agherani Basin, part of the Nirajului Hills (Romania), are studied in the present paper. Time periods considered dangerous regarding the development of slumps and the degree of risk were determined. Pedological conditions of the model area are assessed based on field and laboratory measurements, self-constructed maps and literature data. These factors could have contributed to the formation of slump phenomena in the model area.

Synergistic application of fuzzy logic and geo-informatics for landslide vulnerability zonation—a case study in Sikkim Himalayas, India

The present study comprises the application of various Fuzzy algebraic functions for assessment of landslide vulnerability in Rumtek-Samdung area of Sikkim, which is a Himalayan state in India. The thematic layers for probable causative factors for landslides were collected from various spatial data sources. The main causative factors identified include pedologic factors viz. soil depth, soil texture, soil drainage behavior, soil stoniness, soil erosion and soil hydraulic conductivity, geologic factors such as lithology and foliation along with land use, slope, existence of road and drainage, etc. Landslide spots for the past few years were identified and detected using Cartosat panchromatic image of 2.5 m resolution and further augmented with Google image and field verification. A relation between the occurrence of landslides and each sub-category of the causative factors was established through their frequency ratio and converted to fuzzy membership values. In addition to the five Fuzzy operators used in previous researches, we have introduced two new operators named as Fuzzy AVERAGE(AR) which is computed as the average of AND, and OR operators, and Fuzzy AVERAGE(SP) which is computed as the average of Fuzzy algebraic SUM and Fuzzy algebraic PRODUCT operators. Landslide Susceptibility Index values were computed employing various Fuzzy operators based on which zonation maps were generated classifying the study area into five zones such as least vulnerable zone, low vulnerable zone, moderate vulnerable zone, highly vulnerable zone and most vulnerable zone. Vulnerability assessment accuracy was then computed based on the occurrences of past landslides in the higher three vulnerability zones. The Fuzzy GAMMA Operator exhibited the highest vulnerability assessment accuracy at Lambda = 0.5. The two newly formulated Fuzzy operators showed significant improvement in the vulnerability assessment accuracy in comparison to the two conventional Fuzzy operators’ namely Fuzzy algebraic PRODUCT and Fuzzy algebraic AND operator. Performance Index for the Fuzzy Operators is computed as the ratio of vulnerability assessment accuracy to the percentage of area in the higher three vulnerability zones. All the three newly formulated Fuzzy Average operators exhibited higher Performance Index compared to Fuzzy OR- and Fuzzy SUM-based operators indicating higher proficiency in landslide vulnerability assessment

Avaliação do ARCMUSLE para estimativa da produção de sedimentos na bacia hidrográfica do alto rio Negro, região sul brasileira

Water erosion is one of the main processes which cause soil degradation in tropical environments. This process occurs by the interactions between hydrological, geomorphological and pedological factors that cause the detachment and transport of particles. Through process understanding it is possible to make use of mathematical models in order to estimate the sediment yield in watersheds. The main objective of this paper is to apply the Modified Universal Soil Loss Equations (MUSLE) to simulate a rainfall event and evaluate the fit of this simulation to the measured data of sediment transport. MUSLE is a deterministic, empiric and originally lumped model that replaces the rainfall erosivity factor by the overland flow factor to simulate sediment yield in individual rainfall events. In addition to overland flow effects, the model considers the soil erodibility factor (K), hillslope length and steepness (LS), crop and management factor (P) and the erosion control practice factor (C) to perform simulations. The ArcMUSLE model was used integrated with a Geographical Information System (GIS) allowing an estimate, entirely for isolated events, of the overland flow and the sediment yield through a spatially distributed form. The model was applied to the Upper Negro River watershed, located between the geographic coordinates 25°55’S and 26°14’S, 48°56’W and 49°23’W, and drains an area of 788km². For the simulated event, with total rainfall of 60mm, results showed that both, overland flow and sediment transport, were overestimated by the model. Although the overland flow and the sediment yield simulated were, respectively, 8,81% and 30,02% higher than measured data, the results allowed analysis of the spatial variability of sediment yield and to locate sediment source areas in the watershed.

Patterns of floristic composition of Mediterranean meadows and mesophytic grasslands in eastern Continental Portugal

It is becoming increasingly necessary to gain a deeper understanding of the ecological gradients underlying the floristic pattern of meadows and grasslands, because their distribution area and dynamics may be affected by the increased dryness resulting from climate change. Thus, the objectives are (1) to identify community types in Molinio–Arrhenatheretea meadows and Stipo giganteae–Agrostietea castellanae grasslands in Eastern Continental Portugal; (2) to recognize those communities that configure habitat types of the European Union Habitats Directive; (3) to establish environmental gradients underlying their spatial variation. Combining the Braun–Blanquet approach with numerical analysis, 292 relevés and 448 species were classified and ordered using two-way indicator species analysis (Twinspan classification) and canonical correspondence analysis (CCA). Partial CCA was applied to assess the relative influence of land use factors. About 17 community types were identified and those floristic patterns were mainly related to environmental gradients linked to pedological factors and humidity gradients. Based on biogeography and the determination of diagnostic species, four new phytosociological associations were proposed: Mentho pulegii–Cyperetum badii ass. nova hoc loco; Trifolio resupinati–Menthetum suaveolentis ass. nova hoc loco; Mentho suaveolentis–Holcetum lanati ass. nova hoc loco and Festuco amplae–Brachypodietum phoenicoidis ass. nova hoc loco.

Carbon and Water in Upper Montane Soils and Their Influences on Vegetation in Southern Brazil

Considering the many environmental functions of the upper montane soils, the aims of this study were (1) to verify if the soils of upper montane forests and grasslands of Caratuva Peak (1850 m a.s.l.) have similar characteristics to those found in other highlands in southern and southeastern Brazil; (2) to reinforce the geomorphological and pedological factors that impose the establishment of each type of vegetation in these highlands; and (3) to estimate potential soil carbon stocks and potential soil water retention. Folic and haplic histosols were found in the grasslands, and dystrophic regosols were found in the forests. The soils were dystrophic, extremely acidic, and saturated with Al and total organic carbon. In contrast to the grasslands, the upper montane forests were prevalent in valleys and subjected to morphogenetic processes resulting in soils that contained thicker mineral horizons. The grasslands occupied ridges and divergent convex ramps, and the pedogenetic processes in these regions promoted thicker histic horizons. The potential water retention capacities were high and strongly related to the high porosities of histic horizons associated with the gleyic horizons. In particularly, the carbon stocks were two- to three-fold higher than those found in soil ecosystems from the same latitude but lower altitude.

Influence of archaeological environment factors in alteration processes of copper alloy artifacts

The article presents the experimental results obtained by combining noninvasive techniques (OM, SEM/EDX, XRF) to analyze three artifacts made of copper alloys discovered in a inhumation tomb (2) and in the soil profile (1) in archaeological sites from Neamt County Romania. To uncover the mechanism of alteration thereof during their longtime underground stay in specific chemical conditions and under the influence of other pedological factors, the corrosion products must be identified. The excess of the chloride ion, from burial site, disturbs the Liesegang effect, transforming the bulk in a stratified sponge structure with chlorapatite and hydroxyapatite. Some of the compounds from primary and secondary patina can be found on the surface of the bulk, as color stains. The presence of alloy components (Cu, Sn, Pb, Zn, Fe, etc.) and of the underground contamination components, allowed us to establish the origin of the ore, the manufacture technology and we identified other materials which affected the artifacts after abandonment.

Fractal dimension and anisotropy of soil CO2 emission in a mechanically harvested sugarcane production area

Soil CO2 emissions (FCO2) are spatially dependent, and their spatial structure varies in different directions along the soil surface (anisotropy). This anisotropy, which can result from several pedological factors that are directly related to soil carbon dynamics, is affected by soil management. In this study, the anisotropies of the spatial variability of soil CO2 emissions and of other soil properties were determined for a sugarcane production area under mechanical harvest, when crop residues are left on soil surface, located in the northeastern part of the state of São Paulo, Brazil. The anisotropic characterization of variables was performed by deriving the fractal dimension (DF) from experimental semivariograms calculated at angles of 0°, 45°, 90° and 135° from the between crop line direction (0°). The mean FCO2 was 2.19μmolm−2s−1, and values were significantly lower in the 0° direction. A principal component analysis was applied to study soil properties and the first principal component was mainly related to soil physical properties and FCO2. A multiple regression analysis indicated that air-filled pore space (AFPS) was the main factor affecting the spatial variability of FCO2 in all directions. The AFPS DF values were significantly lower in the direction in which sugarcane crops were planted, indicating anisotropy of this property and greater homogeneity in this direction. Even after rainfall, there was no change in the structure of spatial variability as expressed by the values of DF. The results indicate that in sugarcane areas, several factors inherent to soil forming processes and management practices during harvest and seeding were responsible for the observed anisotropy, which affected soil CO2 emissions.

BIOGEOCHEMISTRY OF WETLANDS IN BARRAGE LACUL ROSU CATCHMENT (HAGHIMAS - EASTERN CARPATHIAN)

Lake Rosu is the best-known natural barrage lake in Romania. It was formed in 1837 following a landslide which blocked the course of the Bicaz River. There are no studies on the delimitation and typology of the wetlands surrounding the lake and its affluent brooks. The wetlands around Lake Rosu cover large areas because of the morphological changes induced by the landslides, lithological slopes, as well as the reduction in depth next to the river mouths. The typical lacustrine and palustrine wetlands developing in the lake's basin also extend along the lower courses of the main rivers, creating a unified structure from a hydro-morphological point of view. The delimitation and typology of the wetlands were carried out according to international standards, and taking into consideration four defining factors: hydrological, geomorphological, pedological, and biological. For the geomorphological and pedological factors, the wetlands are delimited according to the inclination and exposure of the slopes from the proper lacustrine cuvette, but also by taking into account the amount of humus and organic carbon present in the limnosoil alluvial deposit. The associated vegetation preferred humidity, and created the background of the fields with excess humidity. Compact areas of wetland preserve a high level of protection. In the same way the riparian wetlands have been preserved. Changes in the area induced by human activity are negligible, and the large areas of the slopes are covered with compact forests. For a better preservation of the wetlands and the lake's basin, the area studied was included into the Bicaz Gorges Hasmas Mountains National Park. This is the first such study performed in Romania.

Phytocénose à Mallotus oppositifolius et Macrosphyra longistyla dans le sous—bois des plantations privées de teck (Tectona grandis) de la commune d'Abomey-Calavi, Sud-Bénin

A study has been undertaken in the natural undergrowth of private teak plantations in Abomey—Calavi using the synusial approach to phytosociology. Pedological and topographical factors and private teak plantation production within plant communities have been studied. Mallotus oppositifolius and Macrosphyra longistyla community is identified on acid clayey—sandy soils. It is composed of eight vegetal synusia and represents the fourth stage growth of the vegetation succession in the study area. Mean diameter of teak in this plant community varied between 5.7 cm and 15.8 cm while the mean height is between 6.5 m and 13 m and, the basal area between 10.7 m2/ha and 18.9 m2/ha. This community is indicative of the most productive forest sites of the municipality.

<b>Relações de epífitos vasculares com fatores ambientais nas florestas do Rio Tibagi, Paraná, Brasil</b><br>doi: 10.5007/2175-7925.2010v23n3p37

The aim of this work was to evaluate the relationships of vascular epiphyte richness with climatic, geomorphologic, pedologic and forest structural factors, that change along the Tibagi River. The floristic turnover of the 188 registered species was high, indicating the singularity and importance of the communities to the conservation of epiphytes in the river basin. The similarity was greater between geographically closer areas, which made possible the creation of three groups of epiphytic communities distributed along the river. The greatest richness of epiphytes was registered in the medium Tibagi, where the phytogeographic units are in liaison and the forests present the best conservation status. The increase of epiphytic richness is only significantly and positively related to the maximal diameter of trees, an important environmental factor of the enlargement of alpha diversity. The beta diversity results, probably, from environmental heterogeneity which is principally represented by distinctive geomorphologic patterns and climatic conditions between study areas and different environmental regions of the river.

Soil properties at the tree limits of the coniferous forest in response to varying environmental conditions in the Tianshan Mountains, Northwest China

The continuous coniferous forest in the Tianshan Mountains primarily consists of Picea schrenkiana. The forest forms an unbroken 1,000 km forest zone extending from west to east on the northern slope of the Tianshan Mountains, where environmental conditions such as precipitation, temperature and terrain vary greatly. To gain insight into the differences between soil properties at the upper and lower limits of P. schrenkiana, soil underlying the forests was studied along 4 transects located at Jinghe, Manasi, Fukang, and Balikun, where the natural conditions are typical and therefore representative of western, mid-western, mid-eastern and eastern portions of the Tianshan Mountains. The soil type under the coniferous forest on the northern slope of the Tianshan Mountains is gray cinnamon forest soil. For each transect, soil samples were collected from three different depths (0–5, 5–30 and 30–70 cm) in the area near the upper and lower limits of P. schrenkiana. A total of 48 soil samples were collected from 16 soil profiles and analyzed in two different laboratories. The soil pH, organic matter (OM), total N, total P, CaCO3, and electrical conductivity (EC) were analyzed using common pedological methods. The continuous distribution of P. schrenkiana on the northern slope of the Tianshan Mountains was caused by combined water-heat conditions and pedological factors. At the upper and lower tree limits, where differences existed in the soil parent materials, precipitation, topography, combined water-heat conditions, and local atmospheric pattern, the soil properties showed a close relationship with the local environmental conditions. Due to the presence of high precipitation over the Manasi transect, the soil was fertile and had a low CaCO3 content. In contrast, low soil fertility with high CaCO3 was observed in the soil along the Jinghe and Balikun transects, where there was low precipitation. Although the soil properties varied on the northern slope of the Tianshan Mountains due to the presence of different environmental conditions across the 1,000-km forest zone, this region was suitable for the growth of P. schrenkiana. Taken together, the results of this study indicated that soil played an important role in controlling the continuous distribution of the P. schrenkiana along the northern slope of the Tianshan Mountains.

Ecopedological research for ecological rehabilitation of degraded lands from Eastern Romania

The assessment study of the global ecological impact tries to highlight the main factors and negative ecological determinants, due to a lack or excess, and it also focuses on highlighting the main negative ecological effects with the aim to rehabilitate and restore the ecological balance within degraded ecosystems. The methodology used in the assessment process was based on graphs, tables in the shape of Leopold matrix, considerably improved by authors. In order to assess qualitatively the negative ecological effects, a reliability scale with 3 indicators and 3 graduations was used, designed to underline the importance of the impact (minor, medium, and major), the quality of the impact (neutral, negative, and positive) and the certainty of the appearance of a negative impact (improbable, probable, and certain). Our research was accomplished in the pasture ecosystem degraded by pluvial erosion from the Tutova Hills, located in the Eastern part of Romania. This ecosystem is characterized through active geo-morphological processes in the depth and on the surface and it drew attention to the presence of 8 negative ecological factors grouped in 3 main categories: geo-climatic, pedological, and anthropogenic. 8 main negative effects were identified and quantified by means of 3 qualitative indicators with 3 graduation scales. The analysis of the current state of the effects of the complex ecological impact upon the degraded ecosystem ask for a series of urgent measures elaborated by scientists, researchers, and representatives of the local administration system. The aim of these measures is to improve the ecological balance and to eliminate the negative anthropogenic impact that augments and aggravates the action of the negative geo-climatic and pedological factors, in of with the protection of soil quality.

Role of soil organic matter characteristics in a pedological survey: “Bosco Frattona” natural reserve (Site of Community Importance, Italy) case study

Changes in land use over time impact on soil organic carbon content and turnover. In the present study a pedological survey was carried out in order to determine the evolution of epipedon of forest soils by studying soil organic matter turnover in relation to certain pedogenesis factors. The study area was the “Bosco Frattona” natural reserve, harbouring a relict of the mixed broadleaves woodland that once covered the Apennine hills of the Po Valley in north Italy, and a significant diversification of pedogenetic factors could be found therein despite its limited extent. The aim of the survey was to identify potentially vulnerable sites and to investigate how some parameters used to characterise soil organic matter in the epipedon – such as the living fraction, humification and thermal stability indices – were correlated to pedogenetic factors such as lithology, geomorphology and plant cover, which have contributed most to the differentiation of soils belonging to the Ustepts suborder. Total organic carbon ( C org), soil biomass carbon ( C mic), extractable and humified carbon together with corresponding humification parameters were determined to quantify carbon distribution in different organic matter pools. Stable carbon isotope measurements ( δ 13C) have been used to assess previous vegetation, land use changes and the organic matter turnover rate. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) analyses were applied on soil humified substances in order to highlight differences in their thermal stability and composition. The results showed a correspondence between the diversification of the pedogenetic characteristics of soil and quali-quantitative characteristics of the organic matter of the epipedons. The abundance estimation of the different organic carbon fractions consistently indicated two pedons (both Typic Dyistrustepts) as being potentially vulnerable due to their very low content of C org, the considerable presence of labile fractions versus humified ones and a high C biom/ C org ratio, which suggested that these soils had a poor humification capacity and an energetically non-conservative system insofar as the organic resource is concerned. Statistical treatment of data through Principal Component Analysis (PCA) highlighted the role of pedogenetic substrate and type of plant cover as discriminant pedological factors. Among the TG data relating to the extracted humic substances, weight loss at low temperature, generally attributed to adsorbed water and thermo-labile functional groups, proved to be discriminant vis-à-vis the type of vegetation. This result seemed to confirm the influence of plant cover on the turnover of organic carbon in soil and on the process of humification. In the group of chemical parameters, PCA revealed a cluster made up of the soil samples that had formed upon the stony silty sand alluvial deposits and also referred to the same pedotype ( Typic Calciustepts). They showed higher microbial and humified carbon contents and higher pH values, whereas no differentiation was found in connection with vegetation changes arising from past land use ( δ 13C). From a methodological viewpoint, the study confirmed that the data set of parameters used was able to identify potentially vulnerable sites and thus to act as soil quality indicators.

Citrus Decline: Soil Fertility and Plant Nutrition

ABSTRACT Soil physical properties related constraints (clay gradient in soil profile, drainage/irrigation/waterlogging) and soil fertility constraints induced by soil pH, salinity (specific ion-and cumulative osmotic pressure effect), calcareousness (pedogenic or non-pedogenic CaCO3), besides increasing menace of nutrient mining, are the important pedological factors contributing to citrus decline. But, the orchards established on later two soil orders confronted with subsurface constraints in form of argillic (clay rich horizon with acidic or alkaline pH and varying intensity/forms of calcareousness) and spodic horizonation (organic hardpan with very acidic pH), in addition to multiple soil fertility constraints. Soil condition-based rootstock alternatives, site specific nutrient management coupled with variable rate application, and integrated soil management systems representing different modules of INM, are the viable means of combating an untimely decline in citrus orchards’ productivity.

Bromide redistribution as influenced by landscape morphology and pedogenic properties in a variable glacial till landscape: A qualitative examination

Redistribution of water and associated solutes in undulating to hummocky landscapes affects crop yield via losses of valuable nutrients and negatively impacts groundwater quality. The objective of this study was to determine the influence of qualitative soil-landscape complexes on vertical and lateral redistribution of solutes in a variable glacial till landscape under zero tillage agricultural management by employing a bromide tracer. Tracer plots were established in the fall of 1999 within three sites comprising three representative soil-slope associations. Values of soil development indicators (A horizon thickness, solum thickness, depth to CaCO3, profile development index and organic carbon) generally increased from crest to midslope to depression. Further to this, the occurrence and thickness of eluvial and illuvial horizons increased from crest to midslope to depression. Well-developed, clay-coated blocky Bt horizons with vertical cracking and overlying Ae horizons in depressions appeared to have favoured rapid, downward vertical bromide redistribution. Crest positions were the least anisotropic and vertical redistribution was more important than lateral redistribution at this position. A combination of topographic and pedologic factors resulted in more lateral redistribution at the midslope position relative to crests and depressions. Bromide recovery rates in the top 60 cm of the soil profile indicated that most of the recovered bromide remained within that depth following spring runoff, but had mostly leached below that depth after the growing season, particularly at the depression position. Low bromide recovery rates in the top 30 cm following spring runoff, indicated that reduced availability of fall-applied nutrients for early crop growth could be expected at crest and depression positions following spring runoff. Bromide redistribution was important during both spring recharge and over the growing season at the depression position. Bromide movement below crop rooting depths and into shallow groundwater sources provides evidence that fall-applied nutrients can enter groundwater following both spring melt and growing season runoff in depressional landscape positions, especially in recharge areas. Management practices to reduce over-application of soluble nutrients and surface water accumulation, or both, in depressional areas may be an effective means to lower the risk of groundwater contamination with soluble nutrients without jeopardizing crop yield potential across the majority of the landscape positions in undulating to hummocky glacial till terrain. Key words: Solute redistribution, bromide tracer, soil properties, topography, landscape

A FLORESTA FLUVIAL EM DOIS COMPARTIMENTOS DO RIO IGUAÇU, PARANÁ, BRASIL

Este trabalho teve por objetivo demonstrar que os fatores geomorfológicos e pedológicos, decorrentes da interação de condições geológicas e climáticas, podem determinar mudanças importantes na composição florística dentro da mesma unidade fitogeográfica. Para tanto, foram efetuadas pesquisas integradas entre as feições geomórficas existentes em superfícies de agradação e de degradação, tipos de solos e seus atributos, com ênfase ao grau de saturação hídrica, além de análises fitossociológicas em dois compartimentos da planície fluvial do rio Iguaçu, próximos a Curitiba e a União da Vitória (PR). Foi verificado que tanto a florística como a estrutura e a ocupação das florestas fluviais estão diretamente condicionadas às características geomorfológicas e pedológicas. Dentre as características geomorfológicas, sobressaem a forma e o grau de alçamento das feições, as quais, combinadas à textura e à permeabilidade saturada dos solos, determinam o nível de saturação hídrica, que, por sua vez, é o principal fator de seletividade à cobertura vegetacional.