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Rock outcrops are unique habitats in terms of their geological and ecological specializations, soil availability, water seasonality, and environmental extremes. These habitats have attracted the attention of many researchers worldwide in the last few decades. Indian rock outcrops spread throughout the country with more concentration in the Western Ghats region, supporting many endemic and unique habitat specialist species. Despite Indian outcrops having become hotspots for novel species discoveries in recent times, ecological studies on them are still in their infancy. In the present review, we discuss studies, research gaps, and the scope for future investigations on Indian outcrops. We also compare outcrop studies across the world with the Indian systems in order to understand their uniqueness and peculiarities. Literature and observations revealed the presence of 390 taxa on rock outcrops of the Western Ghats with various adaptive traits such as desiccation tolerance, succulence, carnivory, and geophytism, a trend common to most of the tropical outcrops. The dominance of Poaceae endemics, large extents of monocotyledonous mats, and underrepresentation of succulence are unique features of Indian rock outcrops. In the light of various disturbances, faced by Indian outcrops, further studies that would lay a foundation on which conservation strategies can be formulated are a want of time. [ABSTRACT FROM AUTHOR]

Rock outcrops are geologically and ecologically unique ecosystems that harbour threatened and endemic biodiversity. These underappreciated, open ecosystems are undergoing rapid land-use changes and the impacts of these changes on the threatened and endemic biodiversity are poorly understood, compared to the forested ecosystems. The unprotected, low-elevation lateritic plateaus of the northern Western Ghats of India are a case in point; they have high levels of endemism but are experiencing agricultural land-use change to orchards on the one hand and abandonment of traditional paddy cultivation on the other. We compared 1) the availability of loose rocks, a critical microhabitat for saxicolous animals, 2) the prevalence of an endemic caecilian (Gegeneophis seschachari), an endemic gecko (Hemidactylus albofasciatus), and a widespread snake (Echis carinatus), and 3) the composition and abundance of other rock-dwelling animals across 12 less-disturbed natural rock outcrop sites and 10 sites each in agroforestry plantations and abandoned paddies using time-constrained searches. By surveying 7179 surface rocks, we encountered 5738 individuals from 38 animal taxa. We found that the abundance of large rocks, which were the most-preferred size class of rocks by animals, was higher in abandoned paddy compared to plateaus and orchards. However, the prevalence of the reptiles H. albofasciatus and E. carinatus was highest on undisturbed plateaus. Contrastingly, the prevalence of G. seshachari, a caecilian, was significantly higher under rocks in abandoned paddy than in less-disturbed plateau or orchards. We also found significant differences between the rock-dwelling faunal assemblages across the three agricultural land-use types. Despite being adapted to persist in extremely variable climates on lateritic plateaus, multiple species/groups are vulnerable to land-use changes. However, G. seshachari and a few other taxa appear to benefit from certain kinds of agricultural land-use change, highlighting the context-specificity in species responses. This is one of the first studies to determine the impacts of the agricultural conversion of rock outcrops, thereby highlighting the conservation value of habitats that are often classified as wastelands.

The freshwater rockpools support high endemic biodiversity but are poorly studied habitats in the Western Ghats biodiversity hotspot. These freshwater rock pools are situated on outcrops at various elevations in the Western Ghats and are composed of different bedrocks such as laterite and basalt. We aimed to analyze the water quality, geographical position based differences in the water chemistry and the role of bedrock in determining the water chemistry of the rock pools. Our study showed a wide range of water quality variables such as pH, conductivity, and ionic contents that attributed to the natural variation. We observed a drastic variation in the anions and cations at low elevation pools. Rock type and precipitation are influencing the ionic concentration; for example, Calcium and Bromide could be attributed to the seasonal precipitation and geomorphology. This documentation of physicochemical properties of the Western Ghats rock pools can form a baseline for further detailed studies. HIGHLIGHTS The water quality across rock outcrops of Western Ghats is documented.; 80 different rockpools show high variation in the physicochemical composition.; Water quality of the rock outcrops is suitable for supporting aquatic life.; Rock type and precipitation influence the ionic concentration of water.;

• Petroplinthite morphology provides clear clues to its genesis. • Morphological facies of petroplinthites describe the way soil components relate. • Morphological facies reveal evolutionary degrees of petroplinthites. • Processes lead to the formation, transformation or degradation of petroplinthites. Morphological facies of petroplinthites describe how soil components such as the soil matrix, nodules, pores, and coatings relate to each other in space. French scientists have extensively used such descriptions to interpret evolutionary processes and stages of petroplinthites (laterites, ferruginous duricrusts, ironstones) in Central and Western Africa. However, there has been little progress using the interpretation of petroplinthite facies in other parts of the world. This study explores the protocol in Brazilian petroplinthites with the aim of defining processes and identifying evolutionary stages based on analysis of the morphological differences in the petroplinthites from a pedogenetic perspective. The studies were concentrated in the Southern Espinhaço Range, southeast Brazil, and covered Petric or Pisoplinthic Plinthosol (Petroferric Oxisols) profiles with a wide morphological variety of petroplinthites. Based on a literature review, the aim was to standardize concepts and define the different morphological facies , before applying them to the petroplinthites of the study area. Geochemical and mineralogical analyses were added to the description of the facies to interpret the main pedogenetic processes and evolutionary sequences among the profiles. As such, macro and micro morphological descriptions were carried out in association with geochemical maps using SEM-EDS, and specific mineralogical characterization was performed using an electronic microprobe to characterize the main morphological facies. XRD, XRF, and magnetic susceptibility analyses were used to interpret the main formation, transformation, and degradation processes of the petroplinthites. The integration of these analyses enabled the association of the morphological facies with the petroplinthite evolutionary processes. Thus, while lamellar facies are shown to be directly associated with saprolitization processes, nodular and massive facies generally represent intense lateritization. Protopisolithic facies are commonly associated with transformation processes, with goethite precipitation and re-cementation of the matrix, while pisolithic facies are formed through degradation processes with intense mineral dissolution. Recovering the protocol for associating macro and micro morphological facies with geochemistry and mineralogy enabled improved interpretation of the genesis of petroplinthites, with clearer and more objective identification of the evolutionary stages, as well as their relationship with the landscape and the hydrological systems and environmental conditions. [ABSTRACT FROM AUTHOR]

The northern section of the Western Ghats is a biodiversity hotspot with a predominance of rock outcrops. Although these outcrops are characterized by environmental extremes, they support a large diversity of species, many of which are endemics. High-elevation rock outcrops of the Western Ghats exhibit two lithotypes of distinct geological origins, namely basalt mesa (BM) and high-level ferricrete (HLF). We examined the interrelation between environmental factors, lithotypes and functional type abundance. We recorded 265,447 individuals belonging to 127 taxa categorized under seven plant functional types in 128 quadrats from sixteen high-elevation rock outcrops. Cluster analysis separated the sites based on the lithotypes. Graminoids and Therophytes were the dominant functional types across both the lithotypes. Latitude, seasonality, soil carbon and nitrogen were the influential environmental factors. Multivariate analysis of variance (MANOVA) showed that based on environmental characteristics, the two lithotypes are significantly different from each other. Different plant functional types were associated with different environmental variables, as shown by canonical correspondence analysis (CCA). Lithotype and levels of soil carbon and nitrogen together seem to shape the functional type abundance. Overall, we observed that there is a marginal difference in the vegetation across the two lithotypes of outcrops. The abundance of each plant functional type was deferentially associated with the seasonal environment and soil nutrients. [ABSTRACT FROM AUTHOR]

Desertification and land degradation are worldwide problems affecting soil, vegetation and the livelihoods of rural populations. Bowal (plural bowé ) is a particular form of degraded land that occurs in tropical regions and leads to the exposure of ferricretes, which are unsuitable for farming. Bowé are more common on farmland and degraded savanna. Changes in land use/land cover were used to map a region of 6.7 million ha in northern Benin, West Africa in 1975, 1990 and 2010. The changes observed during these periods (1975–1990, 1990–2010 and 1975–2010) were used to predict the occurrence of bowé in the period up to 2050 using Markovian chain analysis. The results showed a considerable change in land use/land cover during the three periods. The types of land on which bowé occur (farmland and degraded savanna) increased in northern Benin by 5.4% per year during the period 1975–1990 and 9.5% per year during the periods 1990–2010, while the natural vegetation (forest, woodland and tree savanna) decreased by the same amount. The future scenarios also predicted the same trend. In the period 1975–1990, 1.28 million ha (26%) of natural vegetation was converted to degraded savanna and farmland while 2.23 million ha (53%) of natural vegetation was converted to degraded savanna and farmland in the period 1990–2010. Based on the dynamics recorded during the period 1975–1990 and 1990–2010 respectively, a total of 1.28 million ha (26% of the natural vegetation that was present in 1975) and 1.29 million ha (31% of the natural vegetation that was present in 1990) will be converted to farmland and degraded savanna in the study area by 2050.Thus bowalization will persist and increase in the period up to 2050. The natural vegetation could disappear if protection and restoration measures are not taken. It is thus important to take measures to stop the degradation and to implement programs to restore soils on bowé based on the soil and water conservation techniques used on highly degraded West African soils, such as zaï pit and stone rows with grass strips. Some native plants species adapted to bowalization and resistant to climate change in northern Benin (e.g. Asparagus africanus , Andropogon pseudapricus and Combretum nigricans ) should be used in association with soil and water conservation techniques on bowé . [ABSTRACT FROM AUTHOR]

Abstract: Some of the weathering deposits that formed during the emersive phase, which in Sardinia lasted from Late Cretaceous to Palaeocene–Early Eocene, consist today of ferruginous palaeosols (ferricretes), sometimes overlain by palustrine limestones. In this article, the two outcrops at Nuxis and Guardia Pisano, containing a ferricrete composed of subspherical goethitic-hematitic concretions, are studied in detail. The main components are Fe, Al, Si, along with Ba, which is very abundant in the Nuxis outcrop. With the exception of the barite, the pisolithic ferricretes of Sardinia can be compared, for their chemical and mineralogical composition, with the pisoplinthites that form in modern tropical soils. They are also comparable with the pisolithic ferricretes cropping out in southern France, that formed around the K/T boundary. The pisolithic ferricretes of southern France and Sardinia can be interpreted as the weathering product of identical warm and humid climatic conditions and, reasonably, of the same climatic event. Therefore, they provide further evidence that Sardinia and southern France formed part of the same palaeogeographic province. A tropical environment is, on the other hand, consistent with the barite leaching from the Palaeozoic substratum and with its reprecipitation into the iron pisoliths. Micro- and nanostructures, observed using SEM analysis within and between the concentric layers of the pisoliths, are consistent with biological processes involving bacteria during their deposition. [Copyright &y& Elsevier]

In this paper we present Quaternary stratigraphy of the area around Chennai based on archaeological findings on the ferricrete surface, geomorphological observations supplemented by radiocarbon dating. The coastal landscape around Chennai, Tamil Nadu, has preserved ferruginised boulder gravel deposits, ferricretes and fluvial deposits of varying thickness. The area studied is approximately 150 km east to west and 180 km north to south with a broad continental shelf towards the seaward. Several rivers enter the Bay of Bengal along its shores like the Koratallaiyar, Cooum and the Adyar. Precambrian charnockite and Upper Gondwana sandstone and shale bedrock rim the shelf margin. For the most part, the Upper Pleistocene-Holocene fluvial sediments overlie an erosion surface that has cut into older Pleistocene sediments and ferricrete surface. Incised valleys that cut into this erosion surface are up to 5–6 km wide and have a relief of at least 30 m. The largest valley is that cut by the Koratallaiyar River. Holocene sediments deposited in the incised valleys include fluvial gravels, early transgressive channel sands and floodplain silts. Older Pleistocene sediments are deposited before and during the 120-ka high stand (Marine isotope stage 5). They consist of ferricretes and ferricrete gravel formed in nearshore humid environments. Muddy and sandy clastic sediments dated to the ca. 5 ka highstand suggest that the climate was semi arid at this time with less fluvial transport. The coarsening up sequence indicates deposition by high intensity channel processes. Pedogenic mottled, clayey silt unit represents an important tectonic event when the channel was temporarily drained and sediment were sub aerially exposed. Uplift of the region has caused the local rivers to incise into the landscape, forming degradation terraces. [ABSTRACT FROM AUTHOR]

Abstract: Placer deposits mark the ultimate stage of mineral separation in clastic sediments by physical processes in an aquatic regime, whereas duricrusts are an example of extreme element separation by chemical processes in continental environments of deposition. In Quaternary sediments in SE Germany such contrasting types of sediments formed on the NE Bavarian Basement which is underlain by metamorphic and pegmatitic rocks reflecting intense primary element differentiation by themselves. The placer deposits were subdivided into trap and bed placers. Together with three types of encrustation they were put into a scheme illustrating six stages of land formation. The first-mentioned group of placer deposits formed from the Late Cretaceous to the Late Tertiary on a vast peneplain under subtropical conditions (stages I–II). Towards the Quaternary its more acidic meteoric fluids turned alkaline and linear erosion gradually replaced peneplanation as the main process of shaping the landscape (stage III). Evidence for these types of alluvial–fluvial Ti and Sn heavy mineral accumulations and the subtropical climatic conditions can only be found in the major placer mineral aggregates nigrine and cassiterite which preserved a great variety of marker minerals in fractures and vugs. Duricrust I consist of aluminum–phosphate (APS)-bearing phoscretes. Bed placer deposition started off with colluvial to alluvial placers passing eventually into fluvial placers (stages IV–V). Type II duricrusts evolved under humid temperate conditions in the aftermaths of the glacial period. Per-descensum fluids provoked the precipitation of these phosphate-bearing ferricretes. The clastic sediments were reworked in a low-sinuosity fluvial drainage system during stage VI. In addition to the ferricretes mentioned above another type of ferrous encrustations was added to the depositional system by man in form of fayalite-bearing slags from blast furnaces. These smelting artifacts were dumped on the floodplain of the modern river system and kilns which they derived from, were fed with phosphorous iron from duricrusts of type II. Age data for the latest stages of placer formation have been obtained from radio-carbon dating of drift wood and luminescence analyses of quartz and feldspar in placer deposits. These data reveal that morphological processes sparking placer deposition have obviously been influenced by the intensive clearing of settlers in the “Oberpfälzer Wald” (=Forest of Upper Palatinate). The results of the present study may be of assistance to geomorphologists dealing with continental placer deposits (Sn, Ti, Ce, Zr) and chemical sediments (ferricretes, phoscretes) which developed in-situ on ancient and modern peneplains. This is true for geomorphologists in academia and consulting companies alike. Archaeometallurgists may benefit from these results as they were investigating smelting residues scattered within alluvial and fluvial deposits of Quaternary age. Commonly they focus their attention on waste disposals and smelting sites and to a lesser extent on reworked smelting residues in drainage systems. The target group number one is among exploration geologists who are in search of continental placer deposits and want to know more about the clastic dispersion haloes around phosphate- and oxide-bearing pegmatites. Alluvial to fluvial placer deposits containing stable and ultrastable heavy minerals may well be preserved as to their mineralogical composition and chemical patterns even through long-lasting periods of shaping the landscape. These mineralogical and chemical patterns can be used to reconstruct the original morphology of a pegmatitic body which today is present only as “pegmatite ruin”. [Copyright &y& Elsevier]