Badland Areas Research Articles

Detecting soil hydrological connectivity in a badland area by fast field cycling nuclear magnetic resonance relaxometry

AbstractThe ‘hydrological connectivity inside the soil’ refers to both the spatial pattern inside the soil (structural component) and the physical–chemical process at a molecular level (functional component). Fast field cycling (FFC) nuclear magnetic resonance (NMR) relaxometry allows for measuring structural and functional connectivity by two suitable indexes named structural connectivity index (SCI) and functional connectivity index (FCI). In this study, FFC NMR relaxometry was applied to soils sampled in a very degraded environment (i.e., a badland area) to detect the capability of the measurement technique to distinguish the hydrological connectivity of these samples having different conditions (layer explored by roots, sparsely‐vegetated and bare soil). The relaxograms measured by the FFC NMR, using Proton Larmor frequencies in the range 0.01–10 MHz, were integrated and the resulting S‐shaped curves were analysed to obtain the connectivity indexes. Results showed that the ‘Sparsely vegetated’ sample is characterized by more small‐sized pores than the ‘Rooted’ one. The comparison between the ‘Sparsely vegetated’ and ‘Bare’ conditions pointed out that the presence of vegetation reduces the measured relaxation times and, as a consequence, the corresponding pore sizes and modifies the structural connectivity. The analysis also revealed that the three samples are characterized by similar values of SCI, which are independent of the proton Larmor frequency, while the FCI values of the ‘Bare’ soil are the lowest. Conversely, samples from soil with vegetation (‘Rooted’ and ‘Sparsely vegetated’) present comparable functional connectivity. Finally, the analysis of the frequency distribution of the ratio of each connectivity index and its mean value (SCI/m(SCI) and FCI/m(FCI)) allowed to establish its normal distribution. For the investigated samples, this result established that FCI and SCI can be represented by their mean value.

STUDIES OF THE AREA AROUND SINGRAULI COAL FIELD & ENERGY BELT, DISTRICT SIGRAULI, MADHYA PRADESH INDIA

STUDIES OF THE AREA AROUND SINGRAULI COAL FIELD & ENERGY BELT, DISTRICT SIGRAULI, MADHYA PRADESH INDIA

A New Model for Solving Hydrological Connectivity Inside Soils by Fast Field Cycling NMR Relaxometry

In this paper, a new quantitative approach for estimating the structural and functional connectivity inside soil by Fast Field Cycling (FFC) NMR relaxometry is presented, tested by measurements carried out in three samples with different texture characteristics. Measurements by FFC NMR relaxometry have been carried out using water-suspended samples and Proton Larmor frequencies (νL) ranging in the 0.015–35 MHz interval. Two non-degraded soil samples, with different textural characteristics, and a degraded soil collected in a badland area, were analyzed. For a given soil and any applied Proton Larmor frequency, the distribution of the longitudinal relaxation times, T1, (i.e., relaxogram) measured by FFC NMR has been integrated, and the resulting S-shaped curve (i.e., relaxogram integration curve) was represented, for the first time, by Gumbel’s diagram. This new representation of the relaxogram integration curve, transforming the S-shaped curve into a straight line, allowed for distinguishing three linear components, corresponding to three different relaxation time ranges, characterized by three different slopes. Two points, identified by the abrupt slope changes of the relaxogram integration curve plotted in Gumbel’s diagram, are used to identify two characteristic values of relaxation time, T1A and T1B, which define three well-known pore size classes (T1 < T1A micro-pores, T1A < T1 < T1B meso-pores, and T1 > T1B macro-pores). The relaxogram integration curve allowed for calculating the non-exceeding empirical cumulative frequency, F(T1), corresponding to the characteristic T1A and T1B values. The analysis demonstrated that the relaxogram can be used to determine the pore-size ranges of each investigated sample. Finally, using the slope values of the three components of the relaxogram integration curve, a new definition of the Structural Connectivity Index, SCI, and Functional Connectivity Index, FCI, was proposed.

Using fallout 137Cs and OSL as sediment tracers in badlands: a case study of Tepezalá volcano (Central Mexico)

ABSTRACT Badlands are dynamic landforms that cause soil loss over extensive areas. In this study, we analyze recent sediment mobilization in a badland area by using a novel approach that integrates fallout 137Cs and optically stimulated luminescence (OSL). We assess how erosion and sediment storage operate over the Tepezalá volcano, a tephra cone located in central Mexico. We analyzed a set of sediment samples extracted from the surface of an altitudinal sequence with different land uses to explore how landscape management practices relate to erosion and, depth profiles from local sinks, to detect patterns of sediment mobilization and sedimentation. We compared 137Cs and OSL results with reference values to evaluate whether erosion or deposition is predominant and to assess how deep the erosive processes in the landscape are. Results from fallout 137Cs values indicate that in those badlands with implemented actions to mitigate erosion, sediment is retained. The high luminescence values show that the edaphic soil has been flushed away, and subsoil crops out in some of the sampled sites. For the case of depth profiles, maximum values of 137Cs coincide with high luminescence values, suggesting that in such sites, the sediment was mobilized during rapid incision episodes that caused widespread erosion of the landscape. We detected at least three episodes of rapid incision in 10 years of sediment record. We propose that using 137Cs and OSL together can provide valuable information of the sediment transport in settings dominated by fast erosion as do occur for the case of badlands.

Effects of cropland abandonment and afforestation on soil redistribution in a small Mediterranean mountain catchment

In slopes of Mediterranean mid-mountain areas, land use and land cover changes linked to the abandonment of cropland activity affect soil quality and degradation and soil redistribution; however, limited attention has been paid to this issue at catchment scale. This paper evaluates the effects of cropland abandonment and post-land abandonment management (through natural revegetation and afforestation) on soil redistribution rates using fallout 137Cs measurements in the Araguás catchment (0.45 km2, Central Spanish Pyrenees). A total of 52 soil core samples, distributed in a regular grid, from the first 30–40 cm and 9 sectioned reference samples were collected across the catchment and soil properties were analysed. Fallout 137Cs was measured in a 5 cm sectioned references samples and in bulk grid samples. 137Cs inventories were used to estimate soil erosion and deposition rates across the catchment. Results show that the highest erosion rates were recorded under sparsely vegetated sites in the badland area, while the lowest rates were found in the afforested area, but no significant differences were observed between the different uses and covers in soil redistribution rates likely due to a long history of human intervention through cultivation in steep slopes and afforestation practices. However, the recovery of the soil organic matter in afforested areas suggest that afforestation can reduce soil degradation at long-term scale. The information gained achieve a better understanding of soil redistribution dynamics and provide knowledge for effective land management after cropland abandonment of agroecosystems in Mediterranean mountain areas.

Regional distribution and characteristics of major badland landscapes in Turkey

Badlands are extremely rugged, outstanding landscapes that can be seen in all ice-free climate regions over erosion-susceptible unconsolidated materials, and they have drawn attention with their spectacular and iconic forms. Unlike nearly all badlands researches conducted at the experimental site and watershed scale, so far, the broader-scale evaluation has been neglected in the analysis of badland distribution, characteristics, and dynamics. Our study provides an integrative new insight into badland landscapes by investigating the distribution, characteristics and controlling factors of Turkish badlands on a broad, regional scale. We inventoried Turkish badlands using aerial imagery and studied their distribution using K-means clustering, an unsupervised machine learning algorithm, based on a set of major conditional geo-environmental factors that control the regional distribution and characteristics of badlands, including tectonics, lithology, topography, climate, and vegetation. Here, we identified, a total of 4494 km2 of badland areas which are non-uniformly distributed across Turkey, substantially clustered in the Central Anatolian Plateau (CAP). According to our regional analyses, we have determined a total of five badland regions comprising three major types classified as Semi-arid, Mediterranean, and Montane (humid), together with two transitional types in-between the Semi-arid and Montane badland regions. Our results indicate that temperature seasonality (0.83), mean annual precipitation (0.83), and precipitation seasonality (0.76) are predominantly assigned to the badlands clusters. The clastic rocks are revealed as the most crucial and inevitable factor for the development of Turkish badlands, which are represented in a wide geologic time-scale (Cretaceous to Quaternary) and diverse lithological units (i.e., lacustrine, volcaniclastics, and terrestrial). Neogene and Paleogene terrestrial clastics (77 %) constitute the majority of the lithologic settings of these badland landscapes. The active and complex tectonic history of Turkey has portrayed the fundamental frame of the identified badland regions, by providing a susceptible environment (i.e., development of sedimentary basins) and promoting badland development through successive base-level changes. Furthermore, tectonically-modulated (i.e., formation of orogenic belts, and uplifting of CAP) climate dynamics outline the distribution pattern and differentiation of the regional characteristics of badlands in Turkey. Overall, our regional-scale approach to badland mapping and regional synthesis may decipher not only the tectonic and climatic conditions of the identified badlands regions, but it may also contribute to the implementation of future effective strategies for the detection and mapping of erosion susceptible and high sediment flux areas in very broad spatial contexts of similar unexplored territories.

The Influences of Climatic and Lithological Factors on Weathering of Sediments in Humid Badland Areas

Climate variables including temperature, rainfall intensity, rainfall acidity, and lithological properties are among the most important factors affecting rock weathering. However, the relative contribution of these four factors on rock weathering, especially on chemical weathering, is still unclear. In this study, we carried out a series of weathering-leaching rainfall simulations on four types of badland sediments under controlled conditions of two levels of temperature, rainfall intensity, and rainfall acidity based on the real field data from representative weather scenarios. The main objectives are 1) to explore the progressive change of sample surface and leachate characteristics and 2) to reveal the independent effects of temperature, rainfall intensity, rainfall acidity, and lithology and their relative contribution as well, on both mechanical and chemical weathering. Qualitative analysis on crack development and fragmentation of sample surface and quantitative analysis on the leachate volume, pH, electrical conductivity, and total cation and anion releases of sample leachate together demonstrated that for the investigated sediments, under the conditions of temperature, intensity, and acidity of rain that can be achieved in nature, high drying temperature obviously increases mechanical disintegration by promoting the rate and magnitude of moisture variations (wetting–drying alterations), while high rainfall intensity and acid rain have no obvious effect. Impact and importance of the drying process caused by high temperature between wetting events need more attention, rather than high rainfall intensity. Low temperature, high rainfall intensity, and acid rain contributing more hydrogen ions required for cation exchanges, rock type with more soluble minerals, all promote chemical weathering, and the influence of climatic and lithological factors on chemical weathering decreases in the following order: mineral composition> rainfall intensity > temperature > rainfall acidity. Climatic variations on temperature can modify weathering processes and in that way conditioned hydro-geomorphological processes in badland areas. Such changes should be considered for direct and indirect implications on badland dynamics.

Multifractal approach to gully network interpretation of an alluvial badland terrain

Badlands are intensely gullied lands, undergoing heavy soil losses, bereft of sustainability and are degenerative to the verdant ecosystem. This paper aims at using multifractal and lacunarity analysis to badlands systems, with the objective of offering geomorphic correlation and interpretation of multifractal parameters to understand the nature of patterns and the operative processes in badlands. Interpretability of the parameters, namely generalised dimension (Dq) versus exponent (Q), multifractal function of the component (f(α)) versus Holder’s exponent (α), (Δα), Δf (α) and lacunarity (Ʌ or λ), provides an efficient approach to comprehend and resolve the dynamic problem of badlands patterns. Four badlands sites were selected in the study area and the analysis was done using ImageJ software. The analysis showed that the sigmoidal curves of Dq versus Q decreasing towards higher values of Q (Q > 0) and the high values of Dq indicate that the badlands are typical multifractal patterns and have been densely dissected. The graphs of f(α) versus (α) are hump-shaped and are right-skewed with negative values of Δf (α), which suggests that erosion processes are active on a finer scale in the area. The greater values (Δα) show greater complexity in the study area, while the decrease in (Δα) may be indicative of adjustment of forms. The lacunarity values are very low, suggesting high intensity of dissection and homogeneity of the pattern of the system. This study may provide a basis for priority ranking for land conservation measures and in monitoring thereof in the badland areas.

Assessment of Badlands Erosion Dynamics in the Adriatic Side of Central Italy

Badlands are unique soil erosion landforms distributed in numerous geological, geomorphological, and climate contexts in several Mediterranean countries. The aim of this study was to map, classify, and analyze the temporal evolution of the badlands that crop out between the Tesino and Tronto Rivers in the Marche region, Central Apennines (Italy). In this study, 328 badlands landforms were mapped through Google Earth, orthophoto analysis (year 2016), and field surveys. Moreover, badlands were classified from a morphological point of view based on the active processes detected in the field. Additionally, badlands were studied from a lithological point of view, meaning they were strictly related to the soft sedimentary formations of the study area. Subsequently, through the analysis of a 10 × 10 m DEM, the most significant morphometric indices were extrapolated and badlands were classified. Finally, through the orthophotos from 1988, another badlands dataset was created and the area of each landform was compared with respect to the orthophotos from 2016. The multi-temporal air photo analysis, combined with the NDVI results, identified a general reduction trend in badlands areas, with increases in green cover and dense vegetation and changes in badlands morphotypes.

Surface Environmental Evolution Monitoring in Coal Mining Subsidence Area Based on Multi-Source Remote Sensing Data

The exploitation of mineral resources is crucial for cost-effective construction but has also led to severe damage to the ecological environment in mining areas. Therefore, it is particularly important to effectively monitor surface environmental problems in the mining subsidence area caused by the exploitation of mineral resources. Herein, the Huinong coal mining subsidence area, Shizuishan city, Ningxia, China, was taken as the study area. The remote sensing image features of various environmental elements were investigated through field investigations, the measured spectra, and image spectrum contrast analysis. On this basis, an object-oriented random forest classification method was used to classify images from different time phases and sources in coal mining subsidence areas. Next, the man–machine interactive interpretation was confirmed by referring to the pre-classification results. By overlaying the interpretation result map and analyzing the land-use class changes, the spatial–temporal evolution monitoring of the surface environment in the coal mining subsidence area from 1979 to 2018 was carried out. The results show that the surface environment in the coal mining subsidence area has undergone significant changes over the past 40 years, among which—from 1979 to 2003—the environment of the coal mining area was severely damaged by the intensive mining activities. The area of cultivated land and vegetation coverage decreased sharply, while the area of other land-use classes, such as coal heaps, water bodies, and coal gangue, exhibited a trend of rapid growth. From 2003 to 2018, after more than 10 years of mine geological environment renovation and management, the surface environment of the coal mining subsidence area greatly improved, among which the vegetation coverage has shown the fastest growth rate, while the area of coal gangue, badlands, and other land-use classes have significantly reduced. The hidden dangers of geological disasters have been drastically mitigated. In addition, the residential area continued to decrease in the early stages and then rebounded to a certain extent, indicating that urbanization was carried out at the same time as the ecological environment began to improve. The surface environment before and after the renovation is consistent with the results from remote sensing monitoring.

Investigating the sources and dynamics of naturally occurring radioactive material (NORM) in the Red Deer River, Alberta, Canada.

Distinguishing between natural and anthropogenic controls on the proportions of naturally occurring radioactive materials (NORMs) in the environment is important for water resource management. In this study, the dynamics of uranium (U) and thorium (Th), two of the most prominent NORM elements, were investigated in the Red Deer River basin using monitoring data collected from 2015 to 2018. More than twofold increases in median proportions of total U (from 0.73 to 1.53µg/L) and Th (from 0.008 to 0.104µg/L) were observed for sites located downstream of the Steveville badlands, an area of highly erodible bedrock that a ~ 300km section of the river flows through. Input is highly variable, coinciding mainly with increases in total suspended solids during intense rainstorms in the late summer. In-depth examination of monitoring data through factor analysis, multiple linear regression, mass balance calculations, and land use analysis highlights the importance of erosion and subsequent particle transport along river banks in the badlands area on the distribution of total U and Th, while also revealing that groundwater-surface water interaction affects proportions of dissolved U throughout the river. No significant influence from industry or land use on U and Th export was found, and proportions of U and Th in water and suspended sediment are within the natural ranges expected for surface waters and sediments/soils. Methodology employed in this study provides a basic framework for analysis of environmental monitoring datasets, which can be employed in the absence of radiochemical data to study the fate, transport, and sources of NORMs.

Measuring hydrological connectivity inside soils with different texture by fast field cycling nuclear magnetic resonance relaxometry

The locution “hydrological connectivity inside the soil” is generally used to disclose how the spatial patterns inside the soil affect the physical–chemical processes at a molecular level to influence water transfer into the soil, the surface runoff and related sediment transport. Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometry has been used to measure both structural and functional connectivity by two indexes indicated as structural (SCI) and functional (FCI) connectivity index. Here, FFC-NMR relaxometry has been applied to analyze three samples: two non-degraded soils, having different grain-size distribution, and a degraded soil sampled in a badland area. Proton Larmor frequencies (νL) ranging in the 0.015–35 MHz interval were used on water suspended samples. The relaxograms (i.e., the distributions of the longitudinal relaxation times, T1) obtained by the FFC-NMR investigations were integrated. The resulting S-shaped curves were handled to obtain the aforementioned FCI and SCI parameters. Results showed that the empirical frequency distribution of the SCI index is related to soil texture and structure, while soils having similar SCI revealed different functional connectivity values. This approach allowed (i) to distinguish SCI values of degraded soils from those of non-degraded ones and (ii) to verify whether the structural connectivity index is related to soil texture and structure. The analysis also showed that the variation coefficient of SCI and FCI, achieved from the measurements done at different νL values, is minimum in the measurement range 0.015–1 MHz. The frequency of 1 MHz can be considered the optimal value to have accurate measured connectivity indexes. For the investigated samples, the obtained relationship between FCI and SCI allowed to conclude that high structural connectivity values correspond to a better functional connectivity. Finally, the hydrological connectivity inside a soil was defined as the sum of the two components representing structural and functional perspective.

Controlling Factors of Badland Morphological Changes in the Emilia Apennines (Northern Italy)

Badlands are typical erosional landforms of the Apennines (Northern Italy) that form on Plio-Pleistocene clayey bedrock and rapidly evolve. The present study aimed at identification and assessment of the areal and temporal changes of badlands within a pilot area of the Modena Province (Emilia Apennines), where no previous detailed investigation has been carried out. For this purpose, a diachronic investigation was carried out to map the drainage basin and the drainage networks of the linear erosion features in the study area during the last 40 years, and to evaluate changes in badlands drainage basins morphometry and surface, land use and pluviometry. The investigation carried out indicated a general stabilisation trend of the badlands in the study area. In fact, a reduction in the bare surface area from 6187.1 m2 in 1973 to 4214.1 m2 in 2014 (31%), due to an intensified revegetation process around the badland areas, has been recorded. This trend, in line with the results of research carried out in other sector of the Northern Apennines, is mainly due to intensive land use changes, mostly the increase in forest cover and the reduction of agricultural land, that occurred in the study area from the 1970s onwards.

Long-term temporal structure of catchment sediment response to precipitation in a humid mountain badland area

A long-term database with information on precipitation, discharge and sediment yield dynamics was analyzed to characterize the temporal structure response of a catchment in a humid mountain badland area. Due to the non-linearity and non-stationary nature of the data, a combination of frequency analysis and wavelet reconstruction techniques were initially used to determine the dominant time scales of the precipitation, discharge and sediment yield. Within the full spectrum of time scales, the spectral frequency analysis could distinguish the dominant ones governing the overall trend of the time-series. Furthermore, the temporal multiresolution wavelet technique enabled accurate de-noising of the hydrometric and sediment time-series, by filtering out the high frequency intermittent processes superimposed on the main signal. Geomorphological metrics were subsequently applied to the filtered data and link to the temporal structure of the catchment response. The combined frequency-geomorphological analysis provides a physical explanation of the complete temporal structure of the catchment response to precipitation. This analysis features components from intra-annual, annual and multi-year scales. Intra-annual and annual time scales are led by climatological characteristics of the catchment site (seasonal rainfall patterns of a mountain Pyrenean catchment). The multi-year response related to the sediment yield reveals the importance of the sediment storage/depletion cycle in the catchment: although the main driver of the sediment yield is the discharge, weathering processes and sediment storage are also major control factors. Therefore, correct management of the catchment requires the combined multi-temporal response of water and sediment fluxes to be controlled. The temporal spectral analysis herein outlined provides a detailed analysis of the long-term temporal structure of databases and can be accepted as an adequate tool for catchment management in terms of flood forecasting or reservoir operation.

Calanchi badlands reconstructions and long-term change detection analysis from historical aerial and UAS image processing

In Italy, highly dissected badlands may be found widespread (over the entire Apennine region) and are locally described as “calanchi” (singular: “calanco”). Accelerated geomorphic processes led to the rapid evolution of these erosional landunits with intense drawbacks on agriculture, infrastructure and society. Historical aerial photographs (HAP) of such badland areas exist worldwide. To reconstruct the past surface and related topographic changes offers high potential for the assessment of long-term topographic changes of many interesting landscapes. Due to technical and conceptual demands of traditional photogrammetry those photographs have been used comparable little in long-term geomorphology. Processing them with user-friendly SfM-MVS photogrammetry would provide a new perspective on the assessment of long-term erosion rates on the catchment and slope scale and the related badland evolution. Therefore, this multi-temporal approach focusses on the appliance of SfM-MVS photogrammetry in order to reconstruct the past landscape and to calculate the related long-term surface changes of a badland located in the upper Val d’Orcia (Tuscany, Italy). The analysis is based on a set of high-resolution UAV images (2016) and two sets of historical aerial images of varying quality and scale (1976 and 1994). Digital elevation models (DEMs), shaded relief raster, several morphometric parameters and DEMs of difference (DoD) (resolution: 1 m) were used to obtain overall terrain changes and to calculate sediment balances and annual surface change rates on catchment and slope scale. Change detection analysis revealed a mean surface lowering of 0.01 m*a–1 (1976–2016) on the catchment scale and 0.03 m*a–1 (1976–1994) to 0.06 m*a–1 (1994–2016) on the slope scale. Our results further show a reduced activity of fluvial erosion processes from the mid 90s’ on while mass movements dominating the topographic changes in the second half of the 40 years observation period. Erosion processes are enhanced near the tear-off edges of the lateral valleys. Deposition mainly occurs in the main valley floor which can be classified as a temporary sediment sink/store. The geomorphic development of the catchment indicates a self-stabilizing behaviour towards an equilibrium state. A reduction of the mean slope gradient in the main valley from 25° in 1976 to 14° in 2016 confirms the self-stabilizing theory. The study also revealed the potential and limitations of historical aerial images for long-term geomorphic change detection and showed that SfM-MVS algorithms operate less reliable when applied to only a few images (n=3) of a singular flightline. Nevertheless, the good agreement of our results with the long term rates obtained by other authors with different methods/techniques and different time scales proof the great potential of historical aerial photographs for 3D surface reconstructions (SfM-MVS) of semi-arid badlands when ceratin quality parameters, mainly high image overlaps and entropy, are fulfilled.

Geomorphology of the Anversa degli Abruzzi badlands area (Central Apennines, Italy)

ABSTRACT This work presents the geomorphology of the Anversa degli Abruzzi badlands (also called calanchi, a typical italian landform) area, located in the Abruzzo Region (Central Apennines, Italy). The map is the result of morphometric and geomorphological analyses, performed at the badland scale, and incorporates three main sections including orography and hydrography, main geomorphological map, and multi-temporal photogeological analysis. The aim of this work is to provide the basis for the recognition of geomorphological features linked to the fluvial environment. Specifically, the study is focused on the Anversa degli Abruzzi calanchi system and it contributes to improving the understanding of this landscape evaluating the geomorphological processes that control its morphometric features and its spatial and temporal evolution.

Land degradation effects on composition of pioneering soil communities: An alternative successional sequence for dryland cyanobacterial biocrusts

Abstract In drylands, soil surfaces in interplant spaces are usually covered by biocrusts, which consist of communities of heterotrophic and chemoautotrophic bacteria, cyanobacteria, mosses, lichens, microalgae, fungi and other organisms. Cyanobacteria are of special interest because of their capacity to promote biocrust succession or increase soil fertility and stability. Therefore, some studies have analyzed their communities in different ecosystems, focusing on how different factors, such as temperature or altitude, influence their composition. Nevertheless, to our knowledge, the relationship between ecosystem degradation and cyanobacterial community composition has not yet been studied in depth. This could be determinant for the successful development of tools for restoring degraded biocrusts by cyanobacterial inoculation. Thus, the objective of this study was to analyze the effect of the ecosystem degradation level on cyanobacteria composition from topsoil communities, where they are keystone pioneering organisms. To do this, we analyzed the cyanobacterial diversity by molecular sequencing (16S rRNA gene) of the DNA extracted from biocrusts at different developmental stages, which were collected from three ecosystems in southeastern Spain. The selected ecosystems represent different “land-condition” states as a result of degradation processes. In one of them soil was removed by mining (the Gádor quarry), the second is a natural badland area (El Cautivo) where water erosion is intense, and the third ecosystem is a well-preserved area (Balsa Blanca). Our findings show that cyanobacterial richness decreases (up to 28 OTUs) as degradation increases and biocrust developmental stage decreases. Also, the relative abundances of most of the species were significantly correlated with the degradation state of the sampling site, either showing a positive or negative trend. Two of the species which increased in abundance with site degradation, and were especially abundant in incipient biocrusts, were Leptolyngbya frigida and Trichocoleus desertorum, while other species, also showing an increase in abundance with degradation, but having a higher relative abundance in most developed biocrusts, were Nostoc commune, Tolypothrix distorta and Scytonema sp. The significant correlation of these species with degradation at different biocrusts developmental stages, suggests an alternative developmental sequence for drylands, at least in more degraded ecosystems. In less degraded ones, the composition of the major cyanobacterial groups followed the common pattern of bundle-forming cyanobacteria (54.7%) pertaining to the Microcoleus genus followed by other non-heterocystous filamentous (17.4%), unicellular/colonial (7.5%) and heterocystous cyanobacteria (1.1%). In comparison, the cyanobacterial groups dominating the most incipient biocrusts, colonizing the most degraded soil, were the filamentous non-heterocystous (50.7%) and the bundle-forming cyanobacteria (48.9%). Therefore, our results show that some cyanobacterial species, which do not belong to traditional pioneer genera, are frequent colonizers of degraded soils, and then, they could be potentially used for producing a more efficient inoculum for inducing biocrust formation and restoring degraded soils. Finally, it is also remarkable that L. frigida appears as dominant in some biocrusts from drylands (up to 74.9% of abundance) being therefore demonstrated its wide distribution in nonpolar biomes and its capacity to also inhabit degraded arid soils.

Influence of Thorny Bamboo Plantations on Soil Microbial Biomass and Community Structure in Subtropical Badland Soils

Vegetation in southeastern Taiwan plays an important role in rehabilitating badland soils (high silt and clay content) and maintaining the soil microbial community. The establishment of thorny bamboo (Bambusa stenostachya Hackel) may have had a profound impact on the abundance and community structure of soil microorganisms. However, little is known regarding the influence of bamboo on soil biota in the badland ecosystem. The present study was conducted at three badland sites in southwestern Taiwan and focused on the measurement of phospholipid fatty acids (PLFA) together with soil microbial biomass C (Cmic) and N (Nmic) contents, enzyme activities, and denaturing gradient gel electrophoresis (DGGE) assessments. The abundances of whole soil microbes as well as bacterial and fungal groups—as evident by PLFA, Cmic and Nmic contents—were much higher in the bamboo plantation soils than the bare land soils. The increased soil organic matter in bamboo plantations relative to the control largely explained the enhancement, the abundance and diversity in the soil microbial community. Principal component analysis of individual PLFA peaks separated the bamboo plantation soil from the non-plantation bare land soil. DGGE analysis also revealed a difference in both bacterial and fungal community structures between soil types. Redundancy analysis of PLFA peak abundance and soil properties indicated that microbial community structure was positively correlated with soil organic C and total N and negatively correlated with pH. This differentiation could be attributed to bamboo in suitable habitats providing an essential nutrient source for soil microbes. The pH reduction in these alkaline soils also contributed to the increase in the size of the microbial community in bamboo-regenerated soils. Together, the results of this study indicate that bamboo plantations are beneficial for soil microbial activities and soil quality in badland areas.

Los paisajes áridos abarrancados como recurso turístico

Los paisajes abarrancados, presentes en todo el mundo, en algunos lugares por sus particulares características, constituyen recursos turísticos y algunos de ellos han sido declarados Patrimonio de la Humanidad por la UNESCO. Los objetivos principales de este trabajo han sido: analizar la importancia de las áreas abarrancadas en la Región de Murcia; hacer una selección de los principales paisajes de badland en la Región, mostrar en estas áreas sus valores y proponerlos como recursos turísticos, considerando sus potencialidades y amenazas que sufren o pueden sufrir. En las áreas seleccionadas se han comparado los valores geológicos, geomorfológicos, paisajísticos, educativos y culturales, diferenciando entre las intensamente intervenidas por la actividad agrícola y las que han mantenido una evolución seminatural. Se ha realizado un análisis DAFO de dichas áreas. Y se ha llevado a cabo una evaluación aplicando los criterios específicos de: i) valor científico y educativo; ii) accesibilidad; y iii) valor turístico. Cada criterio se evaluó según una escala de tres puntos y diferente grado. Los resultados muestran que las cinco áreas estudiadas poseen suficientes valores como para convertirse en áreas de gran interés geoturístico. No obstante, es necesario implementar medias de divulgación y concienciación de dichos valores, entre la población regional y las distintas administraciones, que permitan minimizar las amenazas y potencien las fortalezas.

Identification, characterisation and analysis of the Oltrepo Pavese calanchi in the Northern Apennines (Italy)

Badlands are characteristic erosional forms distributed along the entire Apennines. In the Italian context badland areas are called “calanchi”, the plural of the word “calanco”. In this paper we present the first calanchi inventory map of the Oltrepo Pavese area, Northern Apennines (Italy). In total 263 calanchi were mapped using remote sensing techniques like Orthophotos, Google Earth images, as well as field recognition. Moreover, calanchi were characterised from a geomorphologic, geologic and a morphometric point of view. The calanchi of the Oltrepo Pavese have been categorised in two geomorphological classes based on process related morphologies. In the study area calanchi mainly occur in soft sedimentary bedrock materials such as melanges, marls, claystones, and interstratified rocks. The results show that calanchi formations are often related to faults and tectonic lineaments present in the study area. Moreover, we analyse a 5 m cell size Digital Terrain Model to detect correlations between calanchi and morphometric indices. The calanchi, defined and categorised for the first time in the study area, show typical morphometric characteristics of Apennine calanchi forms and features. In particular, they occur on concave south-facing slopes on soft bedrock formations. Finally, a multitemporal air photo interpretation over a 40 years period indicated a general decrease in calanchi areas. The area reduction is mainly correlated to intensive land use changes combined with variations of precipitation pattern. The revegetation trend was also confirmed by NDVI analysis based on Landsat satellites images. The calanchi were digitized and stored in a GIS database providing the information for future quantitative modelling assessments.