Calcium-rich Soils Research Articles

Reclaiming Calcicoles: New Insights into Lime Lovers

Calcicoles are never new to the evolutionary life forms in the ecological world. The ramifications of environmental extremes always facilitate the emergence of the functional and structural integrity of plants and calcicoles, which have been exuding through this. The word “calcicole” finds its roots in the writings of Nathaniel Colgan, “The Orchids of Country Dublin,” published in August 1895 in “The Irish Naturalist.” Calcicoles are likely to flourish under calcium-rich soil having a pH of more than five, which otherwise hinders the growth of plant species, causing detrimental effects on their physiology. They are often regarded as lime lovers or acidofuges and are classified based on Ca2+ stress resistance, soluble and insoluble Ca2+ and Mg2+, pH conditions of soil, occurrence, and habitat. There are various variables used to evaluate the calcicoles described in this review, such as the Index of calcifugy, Ellenberg’s indicator values, and Landolt indicator values to predict the influence of environmental factors in determining flora along with changes in vegetation in a particular area considering the ecophysiological or morphological features. Calcicoles have specific in-built mechanisms to cope with stress conditions by producing phytosiderophores (PS) and by involving ecto and ericoid mycorrhizal associations for the absorption of iron and phosphorus, and high control over cytosolic Ca2+ concentrations. Calcicoles are markedly distributed in various plant families like Asteraceae, Brassicaceae, Amaranthaceae, Caryophyllaceae, Ericaceae, Primulaceae, Fabaceae, Gentianaceae, Rubiaceae, Plantaginaceae, Poaceae, Saxifragaceae, etc. The current review focuses on the ecological perspectives, special adaptive features, and phytopharmacological aspects of calcicoles.

Genome-wide identification of Rosa roxburghii CML family genes identifies an RrCML13-RrGGP2 interaction involved in calcium-mediated regulation of ascorbate biosynthesis

Calmodulin-like proteins (CMLs) are an essential family of calcium sensors involved in multiple Ca2+-mediated cellular processes in plants. Rosa roxburghii Tratt, known for the abundance of L-ascorbic acid (AsA) in its fruits, is widely distributed in calcium-rich soil of the karst region in southwestern China. The aim of this study was to identify key CMLs that respond to exogenous Ca2+ levels and regulate AsA biosynthesis in R. roxburghii. A genome-wide scan revealed the presence of 41 RrCML genes with 1–4 EF-hand motif (s) unevenly distributed across the 7 chromosomes of R. roxburghii. qRT-PCR analysis revealed that RrCML13, RrCML10, and RrCML36 responded significantly to exogenous Ca2+ treatment, and RrCML13 was positively correlated with GDP-L-galactose phosphorylase encoding gene (RrGGP2) expression and AsA content in the developing fruit. Overexpression of RrCML13 in fruits and roots significantly promoted the transcription of RrGGP2 and the accumulation of AsA, while virus-induced silencing of RrCML13 reduced the transcription of RrGGP2 and the content of AsA. Furthermore, Moreover, the yeast two-hybrid and bimolecular fluorescence complementation (BiFC) analysis confirmed the interaction between RrCML13 and RrGGP2 proteins, indicating that RrCML13 plays a regulatory role in calcium-mediated AsA biosynthesis. This study enhances our understanding of R. roxburghii CMLs and sheds light on the calcium-mediated regulation of AsA biosynthesis.

Soil inorganic amendments produce safe rice by reducing the transfer of Cd and increasing key amino acids in brown rice

The digestibility of cadmium (Cd) in brown rice is directly related to amino acid metabolism in rice and human health. In our field study, three kinds of alkaline calcium-rich soil inorganic amendments (SIAs) at three dosages were applied to produce safe rice and improve the quality of rice in Cd-contaminated paddy. With the increased application of SIA, Cd content in iron plaque on rice root significantly increased, the transfer of Cd from rice root to grain significantly decreased, and then Cd content in brown rice decreased synchronously. The vitro digestibility of Cd in brown rice was estimated by a physiologically based extraction test. Results showed that more than 70% of Cd in brown rice could be digested by simulated gastrointestinal juice. Based on the total and digestible Cd contents in brown rice to evaluate the health risk, the application of 2.25 ton SIA/ha could produce safe rice in acidic slightly Cd-contaminated paddy soils. The amino acids (AAs) in brown rice were determined by high-performance liquid chromatography. The contents of 5 key AAs (KAAs) that actively respond to environmental changes increased significantly with the increased application of SIA. The structural equation model indicated that KAAs could be affected by the Cd translocation capacity from rice root to grain, and consequently altered the ratio of indigestible Cd in brown rice. The formation of indigestible KAAs-Cd complexes by combining KAAs (phenylalanine, leucine, histidine, glutamine, and asparagine) with Cd in brown rice could be considered a potential mechanism for reducing the digestibility of Cd.

Radiocarbon age offsets, ontogenetic effects, and potential old carbon contributions from soil organic matter for pre-bomb and modern detritivorous gastropods from central Texas, USA

Carbon isotopes of terrestrial gastropod yield insights on age and paleoenvironments for many depositional settings, but questions remain on the carbon source for gastropod carbonate and the climatic significance. This study documented for four terrestrial gastropod species ( Rabdotus dealbatus, A. alternata, V. indentata, and Rumina decollata) from central Texas 14 C age offsets between shell‑carbonate and corresponding atmosphere values that lived on carbonate- and kerogen-rich Cretaceous bedrock in the 20th and 21st centuries. Also, the ontogenetic variations in 14 C content were assessed to better understand carbon cycling between gastropods and the associated reservoirs. The carbon sources were partitioned based on 13 C isotopic values to evaluate the possible causes for age anomalies using initially a three-component model that includes contributions from atmosphere, vegetation, and limestone pools, with a new added fourth component, for soil organic carbon. The average ( n = 4) of the outer and inner shell samples yielded the respective 14 C ages of 550 ± 325 and 1520 ± 525 yr B.P. The apparent linearized 14 C distance-age anomaly for an individual gastropod whorl is 4–26 mm/yr calculate from shell 14 C ages on apex and aperture material. The smallest gastropod dated, a single V. indentata test (3.9 mg) yielded the oldest 14 C age of 2340 yr B.P. The four-component model for the oldest 14 C ages indicates that 50–85% of shell carbon may be from ingestion, with a smaller pool from respiration. Up to 30% of the organic carbon in gastropod shell may be derived from soil organic carbon. Terrestrial gastropods that yield anomalously old 14 C ages of >500 years may be detritivores and live in soils with sources of labile old carbon either inherited from the bedrock and/or the older pool of soil organic matter common in well-developed calcium-rich soils. • Modern and prebomb terrestrial gastropods from Texas gave 14 C ages 300–2400 yr old. • Gastropod shells show ontogenetic effect with older ages at apex by 100–1700 yr. • Identify new old carbon source for snails from kerogen-rich soil organic matter (SOM) • Develop new four component model (air, rock, SOM and plants) to explain old 14 C ages • Up to 30% of carbon in gastropod shell may be derived from SOM.

In situ transformations of bonechar and tri-poly phosphate amendments in phosphorus-limited subsurface soils

Nutrient availability is a key factor for the in situ bioremediation of petroleum hydrocarbon contaminated (PHC) soils. Phosphorus deficiencies in calcium rich PHC soils can often be challenging, as amendment P rapidly forms new mineral phases. In situ bioreactors were used to determine the chemical fate of several P amendments (ortho-P, tripolyphosphate, fishmeal and bonemeal biochar), which are currently under consideration to address P nutrient deficiencies during PHC remediation. Contaminated and uncontaminated soil from the study site were treated with the P amendments then suspended in onsite bioreactors (contaminated and uncontaminated). Amendment fate and transformation was determined utilizing a combination of bulk and micro-focused X-ray diffraction (XRD), P X-ray absorption near edge structure (XANES), and X-ray fluorescence imaging (XFI). The ortho-P amendment was found to rapidly precipitate as a Mg-brushite species, proposed as a surface precipitate on dolomite mineral surfaces. Tripolyphosphate increased the adsorbed P fraction through direct adsorption to mineral surfaces and displayed evidence of surface hydrolysis over time with subsequent formation of surface precipitated Mg-brushite. Both P rich biochars demonstrated a potential for dissolution and incorporation of Mg ions, resulting in increased fractions of Mg-brushite and newberyite on the edges of the biochar particles. Tripolyphosphate is an effective short-term P amendment; as there was an increased adsorbed P fraction without the formation of precipitate species until after hydrolysis. In contrast, biochars are potentially an effective long-term amendment, as significant time is required for mineral dissolution to occur and increase the P nutrient status of subsurface soils.

Experimental Study of Soil and Aspect on American Ginseng in an Appalachian Cove Ecosystem

Panax quinquefolius, American ginseng, is one of the most valuable non-timber forest products providing provisioning and cultural ecosystem services in eastern temperate forests. Although ginseng has a broad distribution range, populations are declining due to several factors including overharvesting and habitat degradation. We designed experiments to study the effects of soil and aspect on ginseng to better identify potential reintroduction sites. We hypothesized soil and aspect would have a significant effect on ginseng performance. Performance included growth (leaf area, height, number of prongs) and reproduction (inflorescence presence). We predicted ginseng would have greatest performance in calcium-rich loam soil, on north-facing slopes. After four growing seasons, we found only soil had a significant effect on growth. This was a consistent result over four growing seasons. On average, ginseng grown in limed loam soil were 55-mm taller with 20,000 mm2 more leaf area and more prongs than ginseng grown in soils lower in calcium. Aspect did not affect any measured variables. Given these results, we suggest identifying soils with higher levels of calcium regardless of aspect as potential ginseng habitat. This experimental study contributes to a more complete understanding of the ecology of ginseng. Further, these results can be incorporated into developing strategies for restoration and management of this valuable species.

Soil diversity and major soil processes in the Kalahari basin, Botswana

The study area of the Chobe Enclave (northern Botswana) is defined as mostly covered by Arenosols in available maps. However, recent explorations of the area showed that soils are more diverse than expected. This is because of complex interactions between current alluvial deposition processes, paleo-environmental effects (ancient alluvial deposition, ancient wind-blown sand deposits) and ongoing hydrological effects and colluvial effects on topographic gradients. An in-depth exploration of both soils and vegetation in the area was conducted with the aim (i) to survey the soil diversity at the Chobe Enclave, (ii) to study soil dynamics and identify the key factors of this diversity, and (iii) to create a soil map based on the analysis of the soil-vegetation relationship. For this purpose, thirty-six soil profiles were extensively described according to the World Reference Base for soil resources. In order to better classify these soils, physicochemical parameters, such as pHH2O, exchangeable cations, and particle size distributions, were measured for a specific set of soils (n = 16), representative of their diversity. To assess Soil Organic Matter (SOM) dynamics, samples were studied using Rock Eval pyrolysis. Results show a high soil diversity and heterogeneity with the presence of (i) Arenosols, as expected, but also of (ii) organic-rich soils, such as Chernozems, Phaeozems, and Kastanozems, (iii) salty/sodic soils, such as Solonchaks and Solonetz, and finally (iv) calcium-rich soils, such as Calcisols. Analyses of the different actors driving the soil diversity emphasized the importance of the surficial geology, composed of different sand deposits (red sands/white sands), carbonate and diatomite beds, as well as ancient salt deposits, in which high proportions of exchangeable Na+ were found, associated with high pHH2O (up to 11.3). In addition, as a parameter, the topography creates a complex hydrological system in the Chobe Enclave and therefore, induces a notable soil moisture gradient. Moreover, this study stressed the key role of termites: not only do they modify physicochemical patterns of soils, but they also decay and incorporate large quantities of fresh plant materials into soils. Finally, the analysis of Organic Matter (OM) showed that the Soil Organic Carbon (SOC) is composed essentially by recalcitrant Organic Carbon (OC) substances, such as charcoal, a common carbon type of tropical soils.

Ca and Sr isotope compositions of rainwater from Guiyang city, Southwest China: Implication for the sources of atmospheric aerosols and their seasonal variations

Rainwater samples collected from Guiyang city in southwestern China between May 2009 and December 2010 were analyzed to measure their calcium and strontium isotope compositions. The results show that Ca2+ is the most abundant cation in these rainwater samples, while SO42− is the most abundant anion. Most rainwater samples are alkaline, with a volume-weighted mean (VWM) pH value of ~6.2 (a 1.2-unit increase since 2008). This can be explained by the neutralization of rainwater acidity by the dissolution of atmospheric aerosols in the form of calcium-rich soil and other anthropogenic dust, which are increasing because of rapid urbanization. Both stable (δ44/40Ca and δ88/86Sr) and radiogenic (87Sr/86Sr) isotope compositions of rainwater show variations correlating with each other and with the inverse of Sr or Ca concentrations. They also correlated with the concentration ratio of (NH4++K+)/(Ca2++Mg2+) ―an index reflecting the anthropogenic input relative to soil dust. Based on our results, three major reservoirs can be inferred to have contributed to rainwater chemistry in Guiyang city: (1) a carbonate aerosol source characterized by low 87Sr/86Sr (≤~0.708), δ88/86Sr (≤~0.32‰) and δ44/40Ca (~0.5‰), very low (NH4++ K+)/(Ca2++Mg2+), and low 1/Ca2+ and 1/Sr2+; (2) a silicate aerosol source characterized by relatively high 87Sr/86Sr (≥0.717), δ88/86Sr (≥~0.34‰) and δ44/40Ca (~0.8‰), very low (NH4++K+)/(Ca2++Mg2+), low 1/Ca2+ and 1/Sr2+; and (3) an anthropogenic component containing low 87Sr/86Sr (~0.708), δ88/86Sr (~0.30‰) and high δ44/40Ca (~0.8‰), and high (NH4++K+)/(Ca2++Mg2+). The chemistry of solutes in Guiyang rainwater can be explained by (1) dissolution of carbonate and silicate aerosols, as well as the anthropogenic inputs including seasonal farming activities; (2) tightened environmental protection regulations; (3) higher precipitation volumes in 2010; and possibly (4) the increased combustion of coal for heating and electricity in winter. This study demonstrated that a combination of elemental compositions, stable Ca and Sr, and radiogenic Sr isotope compositions in rainwater can be used to trace the sources of atmospheric aerosols.

Seasonal Timing of Consumption of Calcium-Rich Caliche in the Sonoran Desert Tortoise (Gopherus morafkai) in Central Arizona

Abstract Mohave Desert Tortoises (Gopherus agassizii) actively consume calcium-rich soil, bones, and stones, but this “mining” behavior is not well described for Sonoran Desert Tortoises (Gopherus ...

Sensory attributes of wines made from vines of differing phosphorus status

Aim: The implications of water and nutrient deficiencies for photosynthesis, dry matter production, and yield have been well documented. However, whereas multiple studies show that water deficits affect grape and wine quality as well as wine sensory characteristics, the corresponding implications of manipulating vine nutrient status through fertilizer additions remain largely unexplored.Methods and results: In this study, phosphorus (P) fertilizers were applied to P-deficient vineyards of Cabernet Sauvignon, Chardonnay, and Chenin blanc growing in rhyolite, granite, and schist derived soils. Bloomtime leaf lamina P levels, basic soil chemical characteristics, juice P, and wine chemical parameters were measured after harvest. A highly sensitive protocol for sensory evaluation was used to test the wines made from the treated and untreated grapes for differences in wine appearance, flavor, aroma, and taste.
 All P additions were effective in rapidly increasing both vine P status and P in the harvested juice. In Cabernet Sauvignon vines growing on rhyolite, juice P was linearly related to vine P status compared to a non-linear accumulation of juice P in Chenin blanc vines growing on an calcium-rich schist soil. Soil CEC and Ca levels were both higher in the schist derived soil than in the rhyolite or granite soils, indicating a possible association of P release with soil parent material. Differences were detected in appearance, flavor, aroma, and taste in wines made from all three varieties on all three sites. Also, increasing vine P status increased the concentration of anthocyanins and soluble phenolics in the wines, and reduced fermentation time in the Cabernet Sauvignon.Conclusions: The results of this study show that vine P nutrient status can be manipulated by the grower across different soil types. Vine nutrient status has also been shown to significantly affect vine bud fertility, photosynthesis, dry matter and fruit production, and grape and wine chemical parameters. However, there is a lack of data describing the effect of manipulating vine nutrient status through fertilizer additions on the resulting wine sensory profile. Our results show that vine P status can influence the sensory attributes of wines.Significance and impact of the study: The results of this study and earlier work with vine water status identify two vineyard sources of variation in wine sensory attributes that occur both naturally and can be manipulated by the grower across different soil types.

Identifying plant and environmental indicators of ancient and recent calcareous grasslands

Dry calcareous grasslands are among the most species-rich habitats in Central Europe, harbouring numerous threatened species. Because of their strong decline, they are being protected under the European Habitats Directive. However, apart from this general decline, new grasslands developed after the abandonment of arable fields on marginal land over the course of the last few centuries or even decades. The main question of this study was which species may indicate the age of a dry calcareous grassland habitat in the Franconian Jurassic mountains near Kallmünz. We compared the diversity parameters and nature conservation value of both grassland types. Additionally, we searched for differences in habitat and soil parameters. Furthermore, we asked if there is a general pattern of indicator species among available studies on ancient (i.e. those continuously used as pastures at least since 1830) and recent (i.e. those temporarily farmed as arable fields after 1830) calcareous grasslands. We compiled a list of indicator species of both ancient and recent grasslands in the study region. Comparison with other studies leads to the conclusion that there are not many species that clearly indicate grassland age across different regions (the best indicators are Carex caryophyllea, Cirsium acaule and Hippocrepis comosa for ancient grasslands, and Agrimonia eupatoria and Astragalus glyciplyllos for recent grasslands). Ancient grasslands harbour a somewhat greater number of threatened species than recent grasslands. Many species of the ancient grasslands under study can be considered relict species of steppic grasslands or open pine forests (e.g. Hippocrepis comosa, Pulsatilla vulgaris, Teucrium chamaedrys, Teucrium montanum and Thymus praecox). Recent grasslands also harbour rare and endangered species, especially disturbance-tolerant relicts of former arable use (e.g. Melampyrum arvense) and may therefore be of high conservation value, too. The average number of species per plot is greater in ancient grasslands. However, the most species-rich plot (46 species of vascular plants within a 4-m2 quadrat) was found in a 60 years old grassland. Arable cultivation in the past has altered the physical and chemical properties of the soil of recent grasslands. In general, ancient grasslands occur on nutrient-poorer and less calcium-rich soils with high water holding capacity. High water holding capacity is connected with high humus content, which increases the importance of ancient grasslands for carbon storage. The challenges and benefits of differentiating grasslands of different age in the management of protected areas and landscape planning (e.g. the identification of High Nature Value farmland) are discussed.

Polymer-enhanced bentonite–sand to cover calcium-rich soil

The hydraulic and chemical properties of a polymer-enhanced bentonite–sand mixture (PEBSM) used as cover over calcium (Ca)-rich soil for 4 years is evaluated based on a series of isothermal laboratory-scale experiments. A 0·5 m thick calcium-rich soil (porewater with 1500 mg/l calcium ion (Ca2+)) was compacted into a laboratory column and then covered by a 0·07 m thick PEBSM layer. The PEBSM either was covered by an intact geomembrane (GMB) to mimic a composite liner or was in direct contact with the overlying soil (to simulate the case of a single-liner system). The hydraulic conductivity (k) and exchangeable cations of PEBSM were measured after 9, 21 and 48 months of exposure. The test results show that when PEBSM is used as a barrier over calcium-rich soil, there is only a small difference between the k of PEBSM covered with GMB (2·7 × 10−10 m/s) compared to the case without GMB (7·8 × 10−10 m/s) after 4 years in service. For both cases, k values after 48 months are considered low.

Z PÓŁNOCY NA POŁUDNIE, CZYLI INWAZYJNY CHARAKTER RÓŻY RDZAWEJ (ROSA RUBIGINOSA L.)

Róża rdzawa (Rosa rubiginosa) charakteryzuje się nietypowym przebiegiem mejozy oraz dużą odpornością na działanie abiotycznych czynników stresowych. Naturalny zasięg tego gatunku obejmuje półkulę północną (cała Europa, Ameryka Północna, azjatycka część Rosji), gdzie tworzy niezbyt liczne populacje. Występuje głównie na nasłonecznionych stanowiskach i glebach zasobnych w wapń. Rosa rubiginosa została także wprowadzona na półkulę południową – do Ameryki Południowej, Australii i Nowej Zelandii, gdzie stała się gatunkiem inwazyjnym zdolnym do wypierania rodzimych roślin. Na półkuli południowej uważana jest za gatunek niepożądany – „chwast”, jednak jest to również roślina pożyteczna. Występuje jako roślina pionierska wkraczająca na obszary zdegradowane przez katastrofy ekologiczne i na skutek działalności człowieka. Może być wykorzystywana do ochrony innych gatunków roślin rozwijających się w jej sąsiedztwie, zapewniając im odpowiednią wilgotność gleby i powietrza, a także właściwe warunki świetlne. W artykule zwraca się uwagę na duże możliwości aklimatyzacji róży rdzawej do stresów środowiskowych.

Linking songbird nest predation to seedling density: Sugar maple masting as a resource pulse in a forest food web.

The ecological literature presents considerable evidence for top‐down forcing on the maintenance of species diversity. Yet, in temperate forests, bottom‐up forces often exert a strong influence on ecosystem functioning. Here, we report on the indirect influence of a pulsed resource, sugar maple (Acer saccharum) seed production, on nest survival in a migratory songbird. We hypothesized that seed production in year t would determine daily nest survival rate in year t + 1 through its effects on seed‐eating rodents. We used the density of sugar maple seedlings (with cotyledons) in year t + 1 as a proxy for seed production in year t and predicted that it would be inversely related to songbird nest survival the same year. We estimated the density of sugar maple seedlings, eastern chipmunk (Tamias striatus) activity, and daily nest survival rate in the ovenbird (Seiurus aurocapilla) over four successive years in a northern hardwood forest of New Brunswick, Canada. Seedling density varied by two orders of magnitude between years, whereas an index of chipmunk activity changed by an order of magnitude. Both variables were positively correlated and negatively correlated to daily nest survival rate. A logistic‐exposure model including only seedling density received the greatest level of support (lowest AICc). Previous studies have reported the effect of sugar maple masting on seed‐eating rodent populations, but the strong link we report between seedling density and songbird nest survival is novel. A nocturnal seed‐eating nest predator, deer mouse (Peromyscus maniculatus), was not considered in our models, which may explain why chipmunk was not the best predictor of daily nest survival rate. The trophic linkages we observed are remarkably strong for a temperate forest ecosystem and might become more prevalent in northeastern North America, at least on calcium‐rich soils, with the loss of large‐diameter beech trees as a result of beech bark disease.

Studies on the foliage of Myricaria germanica (Tamaricaceae) and their evolutionary and ecological implications

Ancestral halophytic traits such as salt glands and leaf deciduousness have facilitated the adaptation of Myricaria germanica to non-saline calcium-rich soils. Myricaria germanica is a scale-leaved, deciduous shrub from the Tamaricaceae, a salt gland family of halophytes, xerophytes and rheophytes usually from xeric, saline areas. Atypically, the genus Myricaria is usually from mesic, non-saline areas. In this study, we describe the shoot morphology and anatomy of seedlings and adult plants of Myricaria germanica in order to explore its adaptation to the environment. It is a species of montane to subalpine-flooded riverine areas on non-saline limestone and dolomite soils. The adult leaves show strong leaf reduction but no other significant xeromorphic or scleromorphic features. While the salt glands of most Tamaricaceae secrete NaCl, our SEM EDS investigations show that Myricaria germanica secretes large amounts of Ca and Mg, probably as CaSO4 and as Mg-containing CaCO3, rather than NaCl. This suggests that the evolution of salt glands in a halophytic ancestor may have been an enabling trait that facilitated the adaptation of Myricaria germanica to non-saline Ca-rich soils. Because leaf deciduousness can also be an adaptation for reduction of plant NaCl content, the same may apply to this Myricaria germanica trait. Similarly, leaf reduction can evolve as a response to osmotic stress in saline areas. Its persistence in Myricaria germanica may no longer have any adaptational significance. Our work highlights the dichotomy of the stress-tolerant family Tamaricaceae into two types of stressful habitats, one lowland (e.g. Tamarix) and one montane to alpine (Myricaria). Similar range fragmentation is known in Mediterranean taxa like Armeria and Astragalus.

Iron and Pyritization in Wetland Soils of the Florida Coastal Everglades

We explored environmental factors influencing soil pyrite formation within different wetland regions of Everglades National Park. Within the Shark River Slough (SRS) region, soils had higher organic matter (62.65 ± 1.88 %) and lower bulk density (0.19 ± 0.01 g cm−3) than soils within Taylor Slough (TS; 14.35 ± 0.82 % and 0.45 ± 0.01 g cm−3, respectively), Panhandle (Ph; 15.82 ± 1.37 % and 0.34 ± 0.009 g cm−3, respectively), and Florida Bay (FB; 5.63 ± 0.19 % and 0.73 ± 0.02 g cm−3, respectively) regions. Total reactive sulfide and extractable iron (Fe) generally were greatest in soils from the SRS region, and the degree of pyritization (DOP) was higher in soils from both SRS (0.62 ± 0.02) and FB (0.52 ± 0.03) regions relative to TS and Ph regions (0.30 ± 0.02 and 0.31 ± 0.02, respectively). Each region, however, had different potential limits to pyrite formation, with SRS being Fe and sulfide limited and FB being Fe and organic matter limited. Due to the calcium-rich soils of TS and Ph regions, DOP was relatively suppressed. Annual water flow volume was positively correlated with soil DOP. Soil DOP also varied in relation to distance from water management features and soil percent organic matter. We demonstrate the potential use of soil DOP as a proxy for soil oxidation state, thereby facilitating comparisons of wetland soils under different flooding regimes, e.g., spatially or between wet years versus dry years. Despite its low total abundance, Fe plays an important role in sulfur dynamics and other biogeochemical cycles that characterize wetland soils of the Florida coastal Everglades.

A survey on the invasive plants in Kap O Islands, Northeastern Hong Kong

What type of ecosystems more vuinerabie than the others in herms of inpact of invasive species? It is one of the focuses of modern species invasion ecology. Our survey on the invasive plants on 8 islands in northeastern water of Hong Kong(114°15′~114°27′E, 22°30′~22°34′N) was carried out recently. The results shown that the islands(including Island Sai Ap Chau, Island Ap Lo Chun and Island Ap Chau) with calcium-rich soil might be more invasible than other islands (including Island Lam Shuen Pai, Island Fu Wong Chau, Island Ngo Mei Chau, Island Wong Wan Chau) with low calcium soil. Although there are may more species of invasive plants in Island Kap O, the abundance of exotic plants is low and did not cause significant harm to the natural vegetation. Based on comparison of the invasive plants and island area, human disturbance and soil component, the results presented herewith on the relstionship between calcium and the fact that limestone, saline, beach, calcic soil that widely distributed in temperate zone and arid soil formed in Mediterranean Sea Climate was easily invaded by the invasive plants.

The Relationship between Soil Chemistry and the Occurrence ofEchinacea laevigatain Northeast Georgia

ABSTRACT Echinacea laevigata, or smooth coneflower, is a federally listed endangered species found in open woods and human maintained clearings, including roadsides and utility rights of way. The species is disjunctly distributed in the eastern United States, with populations in Virginia, North Carolina, South Carolina, and Georgia, where they are associated with calcium and magnesium rich soils. This research was designed to determine if there is a nonrandom relationship between soil chemistry and the occurrence of E. laevigata along roadsides in northeast Georgia. Soil samples were collected from sites along roadsides with known populations and from arbitrarily selected sites without E. laevigata along the same roadsides. Multiple response permutation procedure (MRPP) found a nonrandom relationship between soil chemistry and occurrence. Sites with E. laevigata had a wider range of pH values but had lower iron values than the set of arbitrarily selected sites, suggesting that the species may be excluded ...

Effect of a Calcium-Rich Soil on the Performance of an Overlying GCL

Changes in geosynthetic clay liner (GCL) properties over time are examined for the case in which the GCL (1) rests directly on a Ca++ rich soil (1,700–1,800 mg/lCa++) and (2) a 30 cm foundation soil (200–300 mg/lCa++) overlying the Ca++ rich soil. Results for a control case in which the GCL rested only on the foundation soil are also reported. The moisture content increased to 108% and then remained constant in the control case. The moisture and calcium uptake from the underlying soil caused the moisture content of GCL to increase to 96 and 86% in the first 279 days of the experiment for the cases with and without foundation soil, respectively. The moisture content then decreased to 80 and 67% after 1,100 days under isothermal condition with and without the foundation layer, respectively. After 1,100 days (three years), the hydraulic conductivity of the GCL increased (attributable to cation exchange) from approximately 3×10-11 m/s initially to approximately 7×10-11 and 2×10-10 m/s with and without the foundation layer. Changes in swell index (SI) and exchangeable cations were measured and correlated to changes in hydraulic conductivity.

Forest composition, leaf litter, and songbird communities in oak- vs. maple-dominated forests in the eastern United States

Within the eastern deciduous forest region, forest composition varies, with some areas dominated by a mix of oaks ( Quercus spp.) and other areas dominated by a mix of sugar maple ( Acer saccharum) and other tree species. Prescribed fire is being used on an experimental basis to assess its effectiveness in restoring and maintaining oak-dominated forests. Maple-dominated forests are susceptible to invasion by non-native earthworms, such as Lumbricus terrestris, given the palatability of leaf litter and suitable soil conditions, especially in northern parts of the region. What are the implications of this variation on leaf litter availability and habitat for ground-nesting songbirds? We investigated this question by comparing forest composition, leaf litter, and songbird communities in maple-dominated forests in west-central Indiana and oak-dominated forests, recently burned and unburned, in southeastern Ohio. We also assessed abundance of earthworms and decomposition rates of different types of leaves in the maple-dominated forests in Indiana. Leaf litter and ground-nesting bird species were abundant in unburned oak-dominated forests, but were absent or nearly absent in recently burned oak-dominated forests and in maple-dominated forests. The lack of leaf litter and absence of ground-nesting bird species in maple-dominated forests may be due to the combination of abundant non-native earthworms, alkaline and calcium-rich soils, palatable leaves, and rapid leaf litter decomposition rates. Effects of burning on leaf litter and ground-nesting bird species in oak-dominated forests are probably temporary, as long as prescribed fires are not applied on a frequent or widespread basis. Our study is the first one to show a correlation between forest composition, leaf litter availability, earthworm abundance, and songbird populations. Many researchers are investigating effects of non-native earthworm invasions on ecosystem properties in eastern deciduous forests. We recommend that researchers should also monitor songbird populations to assess whether declines in ground-nesting bird populations are occurring in response to these changes.