Bare Sites Research Articles

Arbuscular mycorrhizal fungal communities associated with switchgrass (<i>Panicum virgatum</i> L.) in the acidic, oligotrophic pine barrens ecosystem

Arbuscular mycorrhizal (AM) fungi contribute globally to ecosystem services and play an important role in sustainable crop production. However, it is unclear which factors contribute most to their colonization and community structure at different sites, particularly in understudied ecosystems. This study investigated the AM fungal communities associated with switchgrass (<i>Panicum virgatum</i> L.) in the understudied acidic and oligotrophic pine barrens ecosystem using next-generation sequencing. Switchgrass was also sampled from agroecosystems, as well as, from a native prairie for comparison. The pine barrens switchgrass harbored a distinct AM fungal community − <i>Acaulospora</i> and <i>Ambispora</i> were almost exclusively found in the pine barrens sites, and some of these species may represent undescribed taxa. <i>Glomus</i> was the most ubiquitous AM fungal genus recovered from all sites. This study suggests differences in the AM fungal community structure under different soil properties and land uses. This is the first sequence-based report of the AM fungal communities in the pine barrens ecosystem.

El desafío de reducir la fitotoxicidad de metales en suelos afectados por operaciones históricas de fundición de níquel y cobre en la Península de Kola, Rusia

The topic of vegetative cover rehabilitation of industrial barrens sites has a worldwide significance, especially given the potential of the polluted soils themselves to be “secondary pollution sources.” The goal of this study was to determine the effect of peat addition to the lime + vermiculite-lizardite combined amendment on plant growth in the soils from the vicinity of the Ni/Cu smelter in the Kola Peninsula, Russia. Given the complexity and time-consuming nature of field studies, we decided to test the selected amendments under laboratory conditions first. Surface horizons from two Spodosols (0-20 cm) were collected in the vicinity of the Ni/Cu smelter. Lolium perenne was cultivated in pots for 21 days under controlled conditions. The difference in plant growth with and without peat was not substantial. In other words, the addition of peat did not improve the efficacy of the lime + vermiculite-lizardite combined amendment in promoting plant growth. Therefore, the challenge of reducing ryegrass exposure to soil metals remained unsolved.

Sea urchin mass mortality rapidly restores kelp forest communities

Giant kelp Macrocystis pyrifera is a foundational species that forms a 3-dimensional habitat and supports numerous high-value fisheries species. Constant grazing of kelp holdfasts by overabundant sea urchins causes catastrophic ecological and economic impacts on rocky reefs worldwide. Overgrazing creates urchin barrens that persist for decades in the absence of ecological forcing that would shift the ecosystem back to a kelp-dominated state. Annual surveys of kelp forest and urchin barren sites in the Southern California Bight were performed from 2011 to 2020 to assess changes in kelp forest communities as a result of restoration efforts through sea urchin culling. However, that time period also encompassed a sea urchin mass mortality event. Following drastic reductions of sea urchin densities, rocky reefs returned to a kelp-dominated state within approximately 6 mo and remained stable through the remainder of the study. Benthic cover, fish, and kelp and macroinvertebrate communities inside former urchin barrens became more similar to that of kelp forest reference sites and continued to do so for the next 5 yr. Giant kelp density increased significantly compared to existing kelp forests, while benthic indicators of urchin dominance (i.e. crustose coralline algae and bare rock cover) decreased. Kelp restoration through sea urchin culling essentially mimics sea urchin mass mortality events. If culling can produce similar declines in urchin density, it may be a viable management tool to rapidly restore persistent urchin barrens at moderate spatial scales, while a mass mortality event can drive recovery of kelp forest communities at more extensive spatial scales.

Habitat benefits of restored oyster reefs and aquaculture to fish and invertebrates in a coastal pond in Rhode Island, US.

Oyster habitat restoration seeks to recover lost ecosystem services including increased provisioning of refuge and foraging habitat for fish and invertebrate communities. The goal of this study was to quantify the ecosystem service benefit of habitat provisioning in Ninigret Pond, RI following oyster restoration. We measured four metrics, abundance, biomass, species richness and diversity, as well as isotopic composition in fish and invertebrates collected seasonally from restored oyster, aquaculture, and bare sediment sites, to examine whether the oyster habitat outperformed the bare sediment habitat. Sampling locations were chosen in Foster's Cove north and south, Grassy Point, South Sanctuary, and an Aquaculture lease; each had two restored oyster sites and one bare sediment site. Each site was sampled using a box trap, seine net, shrimp trap, and minnow trap. Oyster habitats had significantly greater metrics than did bare sediment habitats in some comparisons from the box trap and seine net samples. Restored oyster sites at South Sanctuary had lower metric values than the other oyster sites. Metrics from the Aquaculture sites were comparable to the Foster's Cove and Grassy Point restored oyster sites and often outperformed South Sanctuary restored oyster sites. Seasonally, spring and autumn samples tended to have higher abundance and biomass values than summer. Isotopic composition of five species occurring at both restored oyster and bare sediment sites demonstrated some differences in the trophic levels between species but not between habitat types. In Ninigret Pond, fish and invertebrate abundance, biomass, species richness, and diversity benefit from the use of oyster and bare sediment habitats. Coastal zone managers interested in restoring the ecological function of oyster reefs to support fish and invertebrate communities should consider strategically locating restoration projects within the mosaic of structured habitats and monitoring them for selected ecosystem services.

Restoring open canopy pine barrens from the ground up: Repeated burns correspond with increased soil hydraulic conductivity

Prescribed fire is widely used for ecosystem restoration, yet the mechanisms that determine its effectiveness remain poorly characterized. Because soil hydrology influences ecosystem processes like erosion, runoff, and plant competition, it is important to understand how fire affects soil hydrology. A systematic approach to understanding relationships among vegetation, topography, and fire is needed to advance knowledge of how fire influences soil properties that in turn affect restoration success. Our objective was to characterize relationships among burn severity, vegetation, and soil hydrology in a heterogenous landscape under restoration management. Our study took place in a barrens-forest mosaic with recent prescribed fire history ranging from 0 to 10 burns since 1960, and additional variation in fuel loading, burn severity, vegetation cover, topography, and soils. We measured soil hydraulic conductivity (SHC) during two consecutive years, which represented control, prefire, postfire, and 1-year postfire conditions. Regression tree analysis identified an important threshold effect of antecedent soil moisture on SHC; soils with initial moisture < 13% had lower SHC than soils with initial moisture > 13%. Furthermore, above this threshold, sites with intermediate to high recent burn frequency (4–10 burns) had significantly greater SHC than unburned control sites. High fuel loads associated with brush cutting and piling increased SHC at barrens sites but not brush or pine sites, suggesting an interaction between vegetation cover and fire effects on SHC. At the local hillslope scale, toe-slopes had greater SHC than summits. Our results suggest that repeated prescribed fires of moderate to high frequency may enhance SHC, thereby reducing soil water retention and potentially restoring functional pine barren processes that limit woody plant growth. Prescribed fire may therefore be an important management tool for reversing mesophication and restoring a global array of open canopy ecosystems.

Stable isotope signatures reveal the significant contributions of microphytobenthos and saltmarsh-driven nutrition in the intertidal benthic food webs

A tidal saltmarsh supporting marine ecosystem services becomes more recognized, but an understanding of its trophic dynamics is far limited. We investigated the benthic food-web dynamics in Ganghwa tidal flat, a representative tidal saltmarsh of South Korea. The stable carbon and nitrogen isotope ratio values were analyzed for the sixteen species of macrobenthos and their potential food sources such as microphytobenthos (MPB) and various organic matters. A year-round survey was conducted in the three sites at Ganghwa showing the different types of sediment bottom (sandy mud or mud) and/or vegetation (Phragmites or Suaeda). In general, the isotopic signature fairly well demonstrated that trophic structure is primarily influenced by sediment mud content and/or dominated vegetation. Among the four feeding types of consumers (filter feeder; deposit feeder; omnivore; carnivore), the deposit feeders such as mollusk, arthropod, and annelid showed increased dietary dependency on MPB at bare sites. Whilst they actively utilized 13C-depleted organic matters at vegetated sites. Meantime, significantly enriched stable nitrogen isotopic ratio of macrobenthos was evidenced in fall, which reflected the seasonal variation of food sources and physiological processes in survival strategy. Overall, the stable isotopic approach was useful to address the key factors (in)directly influencing the benthic food web structure and its functioning in a typical tidal saltmarsh of the Yellow Sea.

Symmetry Breaking Induced by Growth Kinetics: One‐Pot Synthesis of Janus Au−AgBr Nanoparticles

AbstractThis study describes a one‐pot synthetic strategy consisting of concerted stabilization and photo and chemical reductions of metal ions to yield precise anisotropic nanostructures. Photoirradiation of an aqueous precursor solution containing Au3+, Ag+, Br−, and polyvinylpyrrolidone (PVP) forms Janus nanoparticles (NPs) composed of Au having a tiny Ag shell and AgBr. The Au NPs are initially generated by photoreduction of Au3+ in the precursor solution, in which the formation of silver halides is strongly inhibited by the coordination bond between Ag+ and the carbonyl groups in PVP. The coordinated PVP chains are adsorbed on the surfaces of the Au NPs, with the concomitant release of free Ag+ ions. The part of the surface of the Au NP is covered with a few Ag atoms via chemical reduction of Ag+ by PVP. AgBr nanocrystals grow at a bare site on the surface of each Au NP, resulting in the formation of nearly monodisperse Janus Au−AgBr NPs in high yield. A characteristic light absorption profile emerges due to the interface formed between Au and AgBr, which is demonstrated by finite‐difference time‐domain simulation. The precise nanostructures may be leveraged to elucidate mechanisms of photoelectrochemical processes and to construct advanced plasmonic photocatalysts.

Microkinetic assessment of electrocatalytic oxygen evolution reaction over iridium oxide in unbuffered conditions

Water electrolysis driven by electrical power generated from renewable energy sources will play a pivotal role in future sustainable societies, which requires adaptation of various reaction conditions as well as electrolyte identities. Regardless, the anodic half-reaction of the oxygen evolution reaction (OER) is considered a kinetic bottleneck. This study provides quantitative description of the OER kinetics based on rigorous microkinetic analyses including Tafel analysis, isotope effects and temperature dependence using an IrOx electrocatalyst in unbuffered solution at varying pH levels. The diffusional constraints of H+/OH− determine three distinctive kinetic regimes in the pH-potential-current relationships: below pH 5, between pH 5 and 10, and above pH 10 at appreciable current densities on the order of 1 mA cm−2. When shifting from alkaline to acidic solution, the complete consumption of local OH− near the electrode surface switches the OER proceeding as the oxidation of OH− to that of the water molecule at pH ~ 11 irrespective of the electrode identity. At pH 5–10, the diffusional constraints of H+ generated via oxidation reaction yield an environment with pH ~ 4 near the electrode surface even prior to the OER, resulting in a bulk pH-independent region for the OER performance. Under this unbuffered near-neutral-pH condition, the isotope effect was diminished for the OER catalysis, which is consistent with the rate-determining step (rds) being the sole electron-transfer step via the formation of O-O bonds, decoupled from proton transfer. This reaction mechanism is distinct from that under more acidic conditions (pH < 4), although the water molecule is the same reactant. Under acidic conditions, noticeable isotope effects were observable, which is consistent with the formation of O-O bonds being the rds on uncoordinated bare Ir sites as the most abundant surface species. This study provides a quantitative description of the reactant- and mechanistic-switching that points to concurrent optimization of both electrode materials and electrolyte for improved OER performance at near-neutral pH levels.

Excellent separation performance in a mesoporous MOF induced by 1D rhombic channels and bare nitrogen-donor sites

Metal-organic frameworks with open active sites and appropriate pore size show great application promises in gas storage and separation due to their structural characteristics and functionality can be adjusted and controlled. Based on a benzimidazole and carboxylate decorated new MOF, [Cd(PCA)2]n, (YAU-1, HPCA=(2-(pyrid-4′-yl)-benzimidazole-5- carboxylic acid) has been gained under solvent-thermal conditions. Each dinuclear [Cd2] unit are linked through PCA− ligands to obtain a 2D layer structure, and the 2D structure is further connected by PCA− ligands to form the 3D framework of YAU-1. Remarkably, the un-coordinated benzimidazole and pyridine groups of PCA− ligand not only provide the 1D channels with exposed N atoms to create a mesoporous environment but also stabilizes 3D framework by π⋯π stacking. Taking advantage of these structural characteristics, YAU-1 shows different adsorption capacity for CO2, C2H2, C2H4 and CH4, and remarkable separation effect of C2H2/CH4, C2H4/CH4 and CO2/CH4. The research on the configuration-effect relationship of YAU-1 provides a promising methods to design and construction materials with high gas uptake and separation performance.

The Ecotoxicological Effects of Microplastics on Primary Producers in the Marine Environment

Plastic debris is an emerging environmental threat all over the world. But its effect and distribution in the marine ecosystem is barely known. Microplastics abundance in the marine vegetated area is about 2 to 3 times higher than the bare site in the ocean. Although seagrass meadows trap huge amount of microplastics over the ocean floor, a considerable amount of microplastics are also sink incorporating with the marine aggregates from the epipelagic zone of the ocean. Scavenging of microplastics by diatom aggregation decreases the sinking rate of them rather than cryptophyte. As we know, marine snow is the leading carbon source for zoobenthos, but the ubiquitous presence of microplastics damages cell of different microalgae which may alter the food webs of marine ecosystems. Additionally, microplastics releases immense amount of dissolved organic carbons (DOC) in the surrounding seawater that stimulates the growth of heterotrophic microorganisms as well as their functional activity. Plastic debris result in outbreaks of disease in the marine environment and coral reefs are highly affected by it. When coral reef comes in contact with microplastics, the disease infestation rate of the reef increases massively. Three major disease viz., skeletal eroding band, white syndrome and black band of coral reef causes approximately 46% of reef mortality due to microplastics consumption. Due to complex structure and size, the corals accumulates huge amount of microplastics that increases growth of pathogens by hampering the coral immune system. Existing scientific evidence presents that exposure of microplastics in aquatic environments triggers a wide variety of toxic insult from feeding disruption to reproductive performance, disturbances in energy metabolism throughout the ocean. The present review focused on the ecotoxicological effect of microplastics on primary producers of ocean, its uptake, accumulation, and excretion, and its probable toxicity with risk assessment approaches.

Attribution of the land surface temperature response to land-use conversions from bare land

Abstract Since the early 1980s, large-scale revegetation has been implemented in Northwest China and has been found to be useful in desertification prevention. However, it remains unclear, how land cover changes affect local meteorological conditions, such as land surface temperature. In this study, the land surface temperature response to land-use changes was comparatively evaluated using micrometeorological observations from a cropland site, a mixed forest site, a shrubland site, and adjacent bare land sites in the Heihe River Basin, Northwest China. The surface temperature changes (ΔTs) are decomposed into contributions from changes in radiative forcing, heat resistance, evapotranspiration, soil heat flux and air temperature based on the intrinsic biophysical mechanism (IBM) and the two-resistance mechanism (TRM). The results indicate that 1) the IBM attribution method is more applicable than the TRM method in these arid ecosystems; 2) the influence of different types of vegetation cover on the surface temperature exhibits temporal variance on the diurnal and seasonal time scales; 3) the dominant biophysical components in the daytime of the growing season are evaporative cooling in the cropland paired sites and heat resistance change in the mixed forest paired sites, but these two components are both at a moderate level in the shrubland paired sites. This study provides a useful reference for local climate impact assessments when implementing environmental protection projects in similarly arid areas.

Molecular mechanisms of per- and polyfluoroalkyl substances on a modified clay: a combined experimental and molecular simulation study

Repeated application of aqueous film-forming foams (AFFF) in designated firefighting training areas has caused severe groundwater contamination by per- and polyfluoroalkyl substances (PFASs). Many research efforts are currently engaged for the effective removal of these chemicals from environmental waters. In this study, we demonstrate that modified clay produced by intercalating quaternary ammonium cations in the exchangeable interlayer sites of smectite clay can effectively remove PFAS pollutants in real groundwater via strong adsorption. The performance of the modified clay (with removal efficiencies 95~99%) is superior to those of granular activated carbon or hard-wood biochar and comparable to an ion exchange resin. Removal efficiency is not impacted by potential organic co-contaminants (e.g., diesel, BTEX, TCE, and 1,4 dioxane) or water chemistry (Ca2+ and Na+) at environmentally relevant concentrations. Furthermore, piecewise isotherms are identified to represent the uptake of PFASs by the modified clay. Based on molecular dynamics simulations, the anionic PFASs first occupy the highly polarized bare interlayer edge sites leading to a linear isotherm and then the interlayer surface sites resulting in a Langmuir isotherm. The ionic interactions between the cationic intercalant (N+) and the terminal oxygen atoms of carboxylate or sulfonate groups of PFASs play a dominant role in adsorption, and the lateral interaction in particular fluorophilic attraction among PFASs accelerate the adsorption. The strength of these interactions is quantified using Density Functional Theory calculations. Simulation results match reasonably well with the experimentally determined basal spacing and Fourier transform infrared spectroscopy of the modified clay loaded with PFASs. Overall, the combined experimental and molecular simulation studies elucidate the adsorption mechanism of PFASs on the modified clay and provide critical information to guide the use of modified clays for PFAS water treatment in the field.

Analysis of Successive Land-Use Changes in Old Residential Area of “Festival of Art &amp; Culture (FESTAC) Town” Lagos, Nigeria

In recent times, land use for commercial, residential, and transportation purposes among others is dislodging former units and bare sites as a result of structural alteration, mostly in the urban centers of Nigeria. The changes are due to various guises and structural shift, outright demolition and redevelopment and their impact is consequential. This paper assesses the current pattern which residential zones have assumed within the old Festival of Art and Culture (FESTAC) Town in Lagos, Nigeria. The methods used in the study included the delineation of the study area into six avenues which the researcher(s) adopted for the purpose of even coverage, as well as the use of structural questionnaires, base map and GPS in sourcing for necessary data on the field. Additionally, the data collected were assembled, coded and analyzed using simple descriptive statistics and conventional mapping techniques. The findings revealed the factors responsible for the alteration of land use to enhance financial gains, such as changing neighborhood characteristics and the evasion of permission from the town planning authorities. The findings also provided evidence that many structures still remain vulnerable to conversion, alteration, and/or demolition. The paper recommends that adequate permission should be granted by the legal authority before the conversion and rebuilding of any structure into a new land use.

Structure of microbial communities in amended and unamended acid-generating mine wastes along gradients of soil amelioration and revegetation

Understanding the structure of microbial communities in acidic, metal contaminated tailings and waste rock in cool, continental northern temperate climates is important for identifying their potential for use in phytostabilization and bioremediation programs. In this study, microbial community compositions across two large mine waste sites in the Sudbury basin, Ontario Canada were analyzed along gradients of barren-to-vegetated tailings and waste rock. Microbial communities were less diverse, more homogenous, and mainly chemolithoautotrophic in barren sites, transitioning to more diverse communities of organoheterotrophs, nitrogen-fixing/plant-growth promoting bacteria, and ectomycorrhizal fungi in the vegetated areas. Co-occurrence analyses of microbial communities demonstrated higher levels of association among microbial groups in the barren tailings, which were related to the extreme environmental and chemical conditions and restricted anabolic nutrient availability of the substrates. We also show that vegetation and plant-derived organic matter in the tailings are associated with the shifts observed in the structure of microbial communities towards more soil-like communities. These changes in microbial communities can improve soil fertility through increased rates of heterotrophic decomposition of plant-derived organic matter, and sequentially further aid in the establishment of vegetation. These findings will help develop phytostabilization approaches in mine tailings and waste rock in cool, continental northern temperate and boreal climates.

Prescribed burn frequency, vegetation cover, and management legacies influence soil fertility: Implications for restoration of imperiled pine barrens habitat

In fire-dependent ecosystems, the absence of fire can contribute to a positive feedback in which increased vegetation cover leads to increased accumulation of soil organic matter and nutrient stocks. These changes in turn can influence competitive shifts among plant communities, resulting in increased woody plant establishment, canopy closure, and ultimately leading toward mesophication. Poor soil conditions may be especially important for maintaining the open structure characteristic of pine barrens ecosystems, which are imperiled due to loss of key ecosystem processes such as fire and land conversion to cropland or pine plantations. Our objectives were to determine how soil characteristics are related to recent prescribed fire management, and how soils vary along gradients of current and historic vegetation cover in a barrens-forest mosaic in northern Wisconsin, USA. We sought to understand whether management with prescribed fire shifts soils toward barrens-type soil conditions, and whether soil conditions typify barrens habitat relative to shrub and forest habitat We analyzed organic (i.e. forest floor) and mineral soil horizons collected along gradients of recent prescribed burn history and current (barrens, pine woodlands, brush, and closed-canopy forest) and historic vegetation cover types (barrens, pine plantations, deciduous forests) to investigate the influence of each on specific components of soil fertility. Using a model selection approach, we found forest floor soil properties were most frequently associated with differences in current vegetation cover; for instance, pine woodland sites had greater organic matter stocks than barrens sites, and cation stocks were generally greater at brush sites than barrens and pine woodland sites. Some soil properties, including pH, however, appeared to be driven by prescribed burn frequency. Using ordination techniques to characterize multidimensional characterizations of soils, we identified a soil legacy effect related to historic vegetation cover and land management; native barrens sites had soil characteristics intermediate to restored barrens of pine woodland and deciduous forest origin. Our findings suggest restoration of pine plantations to barrens could benefit from fire activities that enhance consumption of the forest floor, while restoration of deciduous forest and brush habitats will likely be more related to the effective control of hardwood regeneration, after which soil conditions may return to a more archetypical barrens state.

Peroxidase activity along soil depth of a metal contaminated brownfield in New Jersey

The peroxidase enzyme is a member of the oxidoreductase family of enzymes. It has been referred to as a remediation enzyme, as more peroxidase activity is observed when soils are experiencing oxidative stress. At Liberty State Park, a New Jersey brownfield, there is a section of the park that is closed to the public because of high levels of metal contamination. Despite the presence of metals in the soil, much of the area supports plant life. The goal of this study is to determine how the peroxidase activity and metals are distributed along soil depth and to compare results from a forested and barren area of the site. To do this, we collected three 10 cm deep soil cores from each of the two sites. Using the cores, we examine the peroxidase activity and metal concentrations of each 2 cm cross section. We found a similar trend in distribution along depth for metal concentration and peroxidase activity in the forested site. The barren site had a measurable peroxidase activity with a high metal concentration found in the top 2 cm cross section. These studies can serve as tools to understand the relationship between peroxidase activity, metal load, and soil depth and determine how these factors effect plant growth.Support or Funding InformationNSF Grant CBET #1603741

Mapping natural forest cover using satellite imagery of Nkandla forest reserve, KwaZulu-Natal, South Africa

Natural forest ecosystems are vital environmental resources that provide multiple benefits to society, making it imperative for them to be monitored and mapped for practical management purposes. Satellite remote sensing technology is a new source of data and information for forest management and conservation. This study, therefore, applied Support Vector Machine (SVM) and Random Forest (RF) algorithms to Landsat 8 image for mapping a natural forest in South Africa. The objectives were to classify the forest into specific thematic cover classes that indicate its condition, compare the classification performance of the two algorithms based on their default parameters, and determine the most important variables that contributed to the mapping accuracy. The closed canopy forest was determined as the dominant thematic class, followed in descending order by the open canopy forest, grassland, and bare sites. Both algorithms obtained high classification accuracies of above 95%, though the SVM was slightly superior to the RF. The McNemer test indicated that the difference in performance between the two algorithms was statistically insignificant. The most important variables that contributed to the accuracy were the red, blue, green, Near Infrared and Short-Wave Infrared bands, which is attributed to their sensitivity to vegetation. The information provided through the study can be utilized for the planning, management and prioritization initiatives aimed at the protection and conservation of the forest reserve and similar forest ecosystems. The mapping approach could be used for other natural forest ecosystems to ascertain the spatial coverage of the specific thematic cover for conservation purposes. The SVM is recommended for forest ecosystem mapping as it optimally utilized the capabilities of the spectral bands that reflect their actual importance in the mapping of each cover class. The bands identified as important variables can be incorporated as part of input variables when using Landsat 8 satellite imagery for natural forest mapping.

Probing Interactions of γ-Alumina with Water via Multinuclear Solid-State NMR Spectroscopy.

Interaction of γ-alumina with water are important in controlling its structure and catalytic properties. We apply solid-state multinuclear NMR spectroscopy to investigate this interaction by monitoring 1H and 17O spectra in real-time. Surface-selective detection is made possible by adsorbing 17O-enriched water on γ-alumina nanorods. Structural evolution on the surface was selectively probed by 1H/17O double resonance NMR and 27Al NMR at ultrahigh 35.2 T magnetic field. Formation of hydroxyl species on the surface of nanorods is rapid upon the exposure of water, which involves low coordinated aluminum ions with doubly bridging and isolated hydroxyl species being generated first. Fast exchange occurs between oxygen atoms in the water molecules and bare surface sites, indicating high reactivity of these oxygen species. These results provide new insights into the structure and dynamics on the surface of γ-alumina and the methods applied here can be extended to study the interaction of other oxides with water.

Incorporating a model for ground lichens into multi-functional forest planning for boreal forests in Finland

The quantitative assessment of forest management impacts on ecosystem services calls for ecological models to be linked to forest planning systems. In these systems, such models are expected to produce valid and accurate predictions to quantify the effects of alternative forest management strategies on ecosystem services. As an example, we present an evaluation of the model for the percent cover of ground lichens in forests on mineral soils in Finland. First, the performance of the lichen cover model fitted to the data of forest vegetation surveyed in 1985–1986 was comprehensively validated with the data resurveyed on the same plots in 1995. The differences between the observed and predicted values in lichen cover were calculated and analysed. Second, stand-level analyses were conducted to validate the predicted development of lichen cover in accordance with the rotation length development and management of forest stands. Third, the impacts of forest management scenarios on the average lichen cover at regional level were calculated to validate the results over larger areas. Lichen cover was predicted by site fertility, growing stock, forest harvests, soil preparation and geographic location. Our evaluation suggested that the model logically predicted the 10-year change in lichen cover at the stand level. A negative bias was found in predictions especially on xeric sites in northern Finland, although this was not related to stand management, but probably to global greening and reindeer grazing. The model based on the cross-sectional vegetation survey data showed its ability to describe the long-term changes in lichen cover along with the development and management of stands in different site fertility classes. On xeric and barren sites, the analyses showed decreasing trends in the average lichen cover at the regional level during the 30-year simulation period. However, the development of the average lichen cover varied only slightly among the alternative forest management scenarios. This study provides a modelling approach to evaluate the impacts of forest management on ecosystem services, here the cover of ground lichens, as an indicator of forest biodiversity and quality of reindeer pastures.

Interactive effects of vegetation and water table depth on belowground C and N mobilization and greenhouse gas emissions in a restored peatland

This study assesses the relative effects of hydrology and colonization by vascular plants on belowground C and N mobilization, and emission of CO2 and CH4 in an extracted bog under restoration in Alberta (Canada). A wet (high water table) and dry (low water table) area were identified at the site and plots with cottongrass (Eriophorum vaginatum) or bare peat were established in each area. Plant growth, peat and porewater dissolved C (DOC) and N (TDN), microbial biomass and the emissions of CO2 and CH4 were monitored at the plots throughout the growing season. The largest concentrations of DOC were measured in dry and bare sites. Lower E2:E3 ratios suggested a higher aromaticity of the DOC at these sites that were net sources of CO2 and CH4. The concentration of TDN was greater in plots with cottongrass and high water table, supporting a more abundant microbial biomass. Cottongrass dominated plots also had larger gas emissions as compared to bare plots even though they were net C sinks due to their high photosynthetic rates. Maintaining a high water table is key to reducing peatland C losses. While vascular plant presence seems to prime the release of N and greenhouse gases, the inputs of C exceeded the losses and recovered the C sink function of the peatland ecosystem in the short term. Carbon inputs are maximized under high water table and plant presence.