Fog is an important environmental phenomenon affecting, among other things, geochemical cycles via atmospheric deposition pathways. It is generally accepted that fog contributes substantially to ...atmospheric deposition fluxes especially in mountain forests. Nevertheless, due to intrinsic constraints, fog pathway has thus far been neglected in the quantification of atmospheric deposition and fog pathway has not been accounted for in nation-wide spatial patterns of atmospheric deposition of air pollutants. In this review we explore the causes as to why it is so complex to create a spatial pattern of fog contribution to atmospheric ion deposition fluxes on a national scale. Physical and chemical principles of fog formation are presented and factors influencing the abrupt temporal and spatial changes in both fog occurrence and fog chemistry are elucidated. The focus is on both constituents essential for fog deposition flux quantification, i.e. (i) hydrological input on fog water and (ii) chemistry of fog water.
Display omitted
•Fog as a cross-cutting issue•Fog pathway desirable to include to atmospheric deposition•Complexity of including of fog contribution to deposition spatial patterns highlighted•Factors influencing fog deposition•Abrupt changes in fog deposition due both to fog water and fog chemistry
Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of ...resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low- and moderate-severity fires suggests that even the least fire-prone ecosystems may be affected by alteration of the surrounding landscape and, consequently, ecosystem functions. Vegetation spatial patterns in fire-excluded forested landscapes no longer reflect the heterogeneity maintained by interacting fires of active fire regimes. Live and dead vegetation (surface and canopy fuels) is generally more abundant and continuous than before European colonization. As a result, current conditions are more vulnerable to the direct and indirect effects of seasonal and episodic increases in drought and fire, especially under a rapidly warming climate. Long-term fire exclusion and contemporaneous social-ecological influences continue to extensively modify seasonally dry forested landscapes. Management that realigns or adapts fire-excluded conditions to seasonal and episodic increases in drought and fire can moderate ecosystem transitions as forests and human communities adapt to changing climatic and disturbance regimes. As adaptation strategies are developed, evaluated, and implemented, objective scientific evaluation of ongoing research and monitoring can aid differentiation of warranted and unwarranted uncertainties.
There are plenty of mesoscale meteorological discontinuities in the atmosphere, acting as atmospheric internal boundaries (AIBs). In conjunction with the atmospheric boundary layer in the vertical ...direction, they form confined three-dimensional structures that significantly affect air pollution. However, the role of AIBs in regional pollution has not been systematically elucidated. Based on surface observations, this study investigates PM2.5 pollution distributions under the forcing of various AIBs in the North China Plain. A total of 98 regional pollution episodes are identified during the autumn and winter of 2014–2020, and are further classified according to the impact of AIBs. In the pollution formation-maintenance stage, there are three categories. The frontal category (with a frequency of 41%), including the frontal trough type and frontal inverted trough type, displays the most polluted air masses along the mountains. The frontal AIB defines the lateral border of the pollution zone and forms a frontal inversion above, creating a closed and stable structure wherein the highest concentration of PM2.5 accumulates. The wind shear category (29%) is decided by the dynamic convergence AIB, which causes lighter PM2.5 pollution with diverse spatial patterns corresponding to west-southwest shear, southeast-east shear, and south-north shear. The topographic obstruction category (14%) presents as a narrow arc-shaped pollution belt at the foot of the windward mountains, resulting from the cold air damming AIB with dynamical obstruction and thermal stratification. Pollution diffuses in three ways: northwest, west, and northeast, respectively. The first one is the strongest and most frequent (42%), with both strong horizontal wind and vertical mixing. The second category is relatively rare (17%), characterized by foehn-induced active vertical ventilation. The last one is frequent (41%), but relatively weak, mainly relying on horizontal diffusion. Some evolution details of the AIB affecting PM2.5 pollution are also illustrated by a typical case.
Display omitted
•The effects of atmospheric internal boundaries on regional air pollution are elucidated.•A method to identify various atmospheric internal boundaries based on surface observations is proposed.•Three categories, six types of atmospheric internal boundaries are classified under polluted conditions in North China Plain.
Eigenvector-mapping methods such as Moran’s eigenvector maps (MEM) are derived from a spatial weighting matrix (SWM) that describes the relations among a set of sampled sites. The specification of ...the SWM is a crucial step, but the SWM is generally chosen arbitrarily, regardless of the sampling design characteristics. Here, we compare the statistical performances of different types of SWMs (distance-based or graph-based) in contrasted realistic simulation scenarios. Then, we present an optimization method and evaluate its performances compared to the arbitrary choice of the most-widely used distance-based SWM. Results showed that the distance-based SWMs generally had lower power and accuracy than other specifications, and strongly underestimated spatial signals. The optimization method, using a correction procedure for multiple tests, had a correct type I error rate, and had higher power and accuracy than an arbitrary choice of the SWM. Nevertheless, the power decreased when too many SWMs were compared, resulting in a trade-off between the gain of accuracy and the loss of power. We advocate that future studies should optimize the choice of the SWM using a small set of appropriate candidates. R functions to implement the optimization are available in the adespatial package and are detailed in a tutorial.
In near-natural basins, zooplankton are key hubs for maintaining aquatic food webs and organic matter cycles. However, the spatial patterns and drivers of zooplankton in streams are poorly ...understood. This study registered 165 species of zooplankton from 147 sampling sites (Protozoa, Rotifers, Cladocera and Copepods), integrating multiple dimensions (i.e., taxonomic, functional, and phylogenetic) and components (i.e., total, turnover, and nestedness) of α and β diversity. This study aims to reveal spatial patterns, mechanisms, correlations, and relative contribution of abiotic factors (i.e., local environment, geo-climatic, land use, and spatial factors) through spatial interpolation (ordinary kriging), mantel test, and variance partitioning analysis (VPA). The study found that α diversity is concentrated in the north, while β diversity is more in the west, which may be affected by typical habitat, hydrological dynamics and underlying mechanisms. Taxonomic and phylogenetic β diversity is dominated by turnover, and metacommunity heterogeneity is the result of substitution of species and phylogeny along environmental spatial gradients. Taxonomic and phylogenetic β diversity were strongly correlated (r from 0.91 to 0.95), mainly explained by historical/spatial isolation processes, community composition, generation time, and reproductive characteristics, and this correlation provides surrogate information for freshwater conservation priorities. In addition, spatial factors affect functional and phylogenetic α diversity (26%, 28%), and environmental filtering and spatial processes combine to drive taxonomic α diversity (10%) and phylogenetic β diversity (11%). Studies suggest that spatial factors are key to controlling the community structure of zooplankton assemblages in near-natural streams, and that the relative role of local environments may depend on the dispersal capacity of species. In terms of diversity conservation, sites with high variation in uniqueness should be protected (i) with a focus on the western part of the thousand islands lake catchment and (ii) increasing effective dispersal between communities to facilitate genetic and food chain transmission.
Display omitted
•Unravelling the relative roles of abiotic factors on zooplankton α and β diversity.•Phylogenetic and taxonomic β diversity are highly correlated.•Spatial factors strongly affect phylogenetic and functional α diversity.•Environmental filtering and spatial processes co-drive phylogenetic β diversity.•Zooplankton diversity protection should focus on the western TIL catchment.
•We quantify large scale afforestation projects impact on forest spatial patterns.•Remote sensing time series is used to analyze the effects of restoration projects.•Clear footprints were observed on ...the forest landscape of the Loess Plateau.•Core and fragmented forests greatly increased following afforestation projects.•Analysis of spatial pattern dynamics offers a new view on forest ecosystems.
The spatial pattern of forests impacts on biodiversity, stability and sustainability of forest ecosystems. Afforestation and reforestation projects have massively increased forested areas on the Chinese Loess Plateau, however, the spatial pattern of the new and old forests, as well as their interaction, remains unknown. Here we study the spatiotemporal dynamics of old and new forests for the period 2001–2016, and found that 84.21% of the old forests existed throughout the study period. Moreover, core forests (defined as a forest area which is surrounded by other forest areas) significantly increased (2585 km2 yr−1, in total 39, 597 km2). Two ecological restoration projects have left clear footprints on the forest landscape of the Loess Plateau: (1) The Natural Forest Conservation Project, aiming at expanding old forest, has resulted in the establishment of considerable areas of new forest surrounding old forest. Consequently, this has promoted new core forest areas to emerge. (2) The Grain for Green Project has mainly caused a fragmented landscape of forest islets which gradually connect to core forest areas. The general increase in core forest areas can be considered an ecological improvement, and the assessment method presented here may guide stakeholders in measuring the success of forest restoration activities that goes beyond a classical quantification of forest cover.
Environmental pollution caused by electrical waste (E-waste) dismantling has attracted much attention from environmental researchers in China and worldwide. A total of 90 topsoil samples, 10 soil ...profile samples and 14 groundwater samples, were collected from a typical E-waste dismantling area in southeastern China. The spatial and vertical variations of potentially hazardous metals (PHM) in paddy soils and their potentially ecological risks were studied. The results showed that the mean total concentrations of five PHM (Cd, Cu, Pb, Zn and Ni) in paddy soils were 0.38, 35.13, 35.40, 121.38 and 28.13 mg kg−1, respectively. The total Cd, and Pb concentrations in paddy soils had strong variability coefficients of 121.05% and 109.38%, respectively. Compared with the background values in Zhejiang province, the PHM were enriched in paddy soils. Part of the study area was seriously contaminated by these metals. The soil was contaminated with Cd, with high Pi Ave value (>1). The shallow groundwater was also contaminated by Cd in the E-waste dismantling area. Results of vertical variations of PHM in soils revealed significant accumulation of PHM in the topsoil (0–20 cm, 20–40 cm). Soil pH and organic matter (SOM) was significantly correlated with most of the total PHM in soils. Kriging interpolation and Moran's I were used to identify the contaminated hotspots of these PHM. It was found that high soil Cd, Cu, Ni, Zn were located in Da Xi and Zhe Guo towns, which was attributed to E-waste dismantling and other anthropogenic activities. Soil Ni was mainly influenced by the parent material. The PHM in soils may pose a potential threat to local ecosystem and human health.
•Horizontal and vertical variation of soil PHM in E-waste dismantling area was investigated.•The shallow groundwater was contaminated by Cd.•Moran's I and geostatistics were applied to reveal spatial patterns of PHM in soils•The PHM mainly accumulated at the topsoils (0–40 cm).
Evidence is mounting that the immense diversity of microorganisms and animals that live belowground contributes significantly to shaping aboveground biodiversity and the functioning of terrestrial ...ecosystems. Our understanding of how this belowground biodiversity is distributed, and how it regulates the structure and functioning of terrestrial ecosystems, is rapidly growing. Evidence also points to soil biodiversity as having a key role in determining the ecological and evolutionary responses of terrestrial ecosystems to current and future environmental change. Here we review recent progress and propose avenues for further research in this field.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Land ecological security (LES) refers to the environmental health and sustainability of the land resources and ecosystems, which are substantially affected by biophysical and socio-economic factors. ...We assess the spatiotemporal patterns of LES in Ningbo city on the southeast coast of China from 1975 to 2015 and explore the effects of driving factors. Expert evaluation is used to estimate the LES score for each 2×2km grid and map the patterns by Kriging. Five levels of LES are used: very secure, secure, neutral, insecure and very insecure. A generalized additive model (GAM) captures the relationships between LES and driving factors, and identifies the dominant factors. Our results show that the Ningbo LES has been deteriorating since 1975, and it is now very insecure in Ningbo city center and the central area of the satellite city Cixi. The dominant factors affecting LES are distances to city center (Dcity), district center (Ddistrict) and road networks (Droads), and the moving window built-up area (Dndbi). Among these, Dndbi is most important as inferred by the highest explained deviance of the GAM. This study improves our understanding of the spatiotemporal patterns of LES in Ningbo and how LES changes. As a result, it provides insight to help local governments optimize land-use configuration, potentially improving the environment and ecosystems and creating a more environmentally friendly city.
Display omitted
•We assess the spatiotemporal patterns of LES in Ningbo, China during the past four decades.•Five levels of LES are applied including very secure, secure, neutral, insecure and very insecure.•The Ningbo LES has been deteriorating since 1975, and it is now very insecure in the city center.•GAM captures the relationships between LES and driving factors, and identifies the dominant factors.•The dominant factors are proximity to urban infrastructures and the moving window built-up area.
PDF
