Trends and variability in weather and atmospheric deposition at UK Environmental Change Network sites (1993–2012)

We characterised temporal trends and variability in key indicators of climate and atmospheric deposition chemistry at the twelve terrestrial UK Environmental Change Network (ECN) sites over the first two decades of ECN monitoring (1993–2012) using various statistical approaches. Mean air temperatures for the monitoring period were approximately 0.7 °C higher than those modelled for 1961–1990, but there was little evidence for significant change in air temperature over either the full monthly records or within individual seasons. Some upland ECN sites, however, warmed significantly over the first decade before cooling in the second. Summers at most sites became progressively wetter, and extremes in daily rainfall increased in magnitude. Average wind speeds in winter and spring declined at the majority of sites. Directional trends in summer precipitation could be linked to an atypically prolonged negative deviation in the summer North Atlantic Oscillation (NAO) Index. Several aspects of air quality improved markedly. Concentrations and fluxes of sulphate in precipitation declined significantly and substantially across the network, particularly during the earlier years and at the most polluted sites in the south and east. Precipitation concentrations of nitrate and ammonium, and atmospheric concentrations of nitrogen dioxide also decreased at most sites. There was less evidence for reductions in the loads of wet deposited nitrogen species, while trends in atmospheric ammonia concentration varied in direction and strength between sites. Reductions in acid deposition are likely to account for widespread gradual increases in the pH of soil water at ECN sites, representing partial recovery from acidification. Overall, therefore, ECN sites have experienced marked changes in atmospheric chemistry and weather regimes over the last two decades that might be expected to have exerted detectable effects on ecosystem structure and function. While the downward trend in acid deposition is unlikely to be reversed, it is too early to conclude whether the trend towards wetter summers simply represents a phase in a multi-decadal cycle, or is indicative of a more directional shift in climate. Conversely, the first two decades of ECN now provide a relatively stable long-term baseline with respect to air temperature, against which effects of anticipated future warming on these ecosystems should be able to be assessed robustly.     

Short-Term Medieval Settlement Activities Irreversibly Changed Forest Soils and Vegetation in Central Europe

In Europe, many contemporary forests are not continuous, but were established on former agricultural land in territories of deserted villages. We aimed to explore whether medieval settlement activities of only 60 years irreversibly changed soil properties and whether these changes were reflected by contemporary forest vegetation. The research was performed in the deserted village of K?í, which existed from 1357 to ca 1420 AD in a current oak forest on sandy soils in the Czech Republic. We identified four former land-use types (building sites, courtyards, the village square, and gardens), where we analyzed soil properties and plant species composition of the forest understory. Higher concentrations of plant-available P, K, Ca, and Mg as well as the total concentrations of organic C and trace elements (As, Cd, Cu, and Zn) were recorded at former building sites with neutral soils, compared to the other former land-use types with acidic soils. The four-times higher species richness at former building sites compared to the former gardens indicate the strong effect of soil pH and nutrient availability on plant species composition, even on the spatial scale of several square metres. Understanding recent patterns in soil properties and biodiversity in Central European forests requires detailed knowledge of former land use over centuries. Analysis of contemporary soil properties together with analysis of vegetation can help to identify former land-use types in deserted villages.     

Patterns of plant species richness in pasture lands of the northeast United States

Pasture lands are an important facet of land use in the northeast United States, yet little is known about their recent diversity. To answer some fundamental questions about the diversity of these pasture lands, we designed a broad survey to document plant species richness using an intensive, multi scale sampling method. We also wanted to learn whether environmental (soils or climate) or land management variables could help explain patterns of species richness. A total of 17 farms, encompassing 37 pastures, were sampled in New York, Pennsylvania, Vermont, Maryland, Massachusetts and Connecticut during July and August 1998. We positively identified a total of 161 different plant species across the study region. Species richness averaged 31.7±1.1 on pastures. Infrequent, transient species that were mostly perennial and annual forbs accounted for 90% of the species richness. Except for a subjective rating of grazing intensity, land management methods were not good predictors of species richness. Over time, it appears that grazing neither reduces nor increases species richness in pastures. Of the environmental variables measured, only soil P explained a significant amount of the variation in species richness. Soil P was inversely related to species richness at the 1m² scale. Percent SOM was positively associated with species richness at this scale, although weakly. At larger spatial scales, we suggest that patterns of species richness are best explained by the species diversity of soil seed banks, or seed rain, and stochastic recruitment of these species into existing vegetation.     

Fine-scale temporal characterization of trends in soil water dissolved organic carbon and potential drivers

Long-term monitoring of surface water quality has shown increasing concentrations of dissolved organic carbon (DOC) across a large part of the Northern Hemisphere. Several drivers have been implicated including climate change, land management change, nitrogen and sulphur deposition and CO₂ enrichment. Analysis of stream water data, supported by evidence from laboratory studies, indicates that an effect of declining sulphur deposition on catchment soil chemistry is likely to be the primary mechanism, but there are relatively few long term soil water chemistry records in the UK with which to investigate this, and other, hypotheses directly. In this paper, we assess temporal relationships between soil solution chemistry and parameters that have been argued to regulate DOC production and, using a unique set of co-located measurements of weather and bulk deposition and soil solution chemistry provided by the UK Environmental Change Network and the Intensive Forest Monitoring Level II Network. We used statistical non-linear trend analysis to investigate these relationships at 5 forested and 4 non-forested sites from 1993 to 2011. Most trends in soil solution DOC concentration were found to be non-linear. Significant increases in DOC occurred mostly prior to 2005. The magnitude and sign of the trends was associated qualitatively with changes in acid deposition, the presence/absence of a forest canopy, soil depth and soil properties. The strongest increases in DOC were seen in acidic forest soils and were most clearly linked to declining anthropogenic acid deposition, while DOC trends at some sites with westerly locations appeared to have been influenced by shorter-term hydrological variation. The results indicate that widespread DOC increases in surface waters observed elsewhere, are most likely dominated by enhanced mobilization of DOC in surficial organic horizons, rather than changes in the soil water chemistry of deeper horizons. While trends in DOC concentrations in surface horizons have flattened out in recent years, further increases may be expected as soil chemistry continues to adjust to declining inputs of acidity.     

The UK Environmental Change Network after twenty years of integrated ecosystem assessment: Key findings and future perspectives

The UK Environmental Change Network (ECN), the UK's Long-Term Ecosystem Research (LTER) network, has now been operating for over twenty years. It was established in 1992 as a set of terrestrial sites at which sustained observations relevant to a range of ecological indicators and environmental parameters could be made. An additional ECN freshwater network was launched in 1994. In this paper we provide a brief history of the network, and describe its current structure and role within a complementary wider range of UK environmental monitoring and observation programmes that are either more focussed on specific parameters or habitats, or operate at different temporal and spatial scales. We then provide a review of the other papers within this Special Issue, which exemplifies the broad range of environmental concerns that ECN data and sites are helping to address. These include network-wide summaries of environmental and biological trends over the first two decades of monitoring, more site-specific assessment of the ecological impacts of local pressures resulting from changes in management, biological and ecosystem service indicator development, and the testing of new monitoring technologies. We go on to consider: (i) future directions of network development and adaptation in light of recently emerging environmental concerns, dwindling financial resources and the consequent need for greater efficiency; (ii) the desire for tighter integration with other monitoring and observation programmes both nationally internationally; (iii) opportunities raised by recent technological developments; and (iv) the need to process and make available data more rapidly to increase the capacity of ECN sites as early warning systems. In its first two decades of operation the ECN has accumulated a robust set of baseline data that describe environmental and biological variability across a range of habitats in unprecedented detail. With appropriate, informed development, these should prove invaluable in discerning the causes and consequences of environmental change for decades to come.     

Weed vegetation of arable land in Central Europe: Gradients of diversity and species composition

Question: What are the main broad‐scale spatial and temporal gradients in species composition of arable weed communities and what are their underlying environmental variables? Location: Czech Republic and Slovakia. Methods: A selection of 2653 geographically stratified relevés sampled between 1954–2003 was analysed with direct and indirect ordination, regression analysis and analysis of beta diversity. Results: Major changes in weed species composition were associated with a complex gradient of increasing altitude and precipitation and decreasing temperature and base status of the soils. The proportion of hemicryptophytes increased, therophytes and alien species decreased, species richness increased and beta diversity decreased with increasing altitude. The second most important gradient of weed species composition was associated with seasonal changes, resulting in striking differences between weed communities developed in spring and summer. In summer, weed communities tended to have more neophytes, higher species richness and higher beta diversity. The third gradient reflected long‐term changes in weed vegetation over past decades. The proportion of hemicryptophytes and neophytes increased, while therophytes and archaeophytes decreased, as did species richness over time. The fourth gradient was due to crop plants. Cultures whose management involves less disturbances, such as cereals, harboured less geophytes and neophytes, and had higher species richness but lower beta diversity than frequently disturbed cultures, such as root crops. Conclusions: Species composition of Central European weed vegetation is mainly influenced by broad‐scale climatic and edaphic factors, but its variations due to seasonal dynamics and long‐term changes in agricultural management are also striking. Crop plants and crop‐specific management affect it to a lesser, but still significant extent.     

Composition and seasonal flux of the soil seed bank of species-rich Themeda triandra grasslands in relation to burning history

Abstract. Most species-rich grasslands dominated by Themeda triandra in southeastern Australia have been ungrazed and frequently burnt for decades. The seedling emergence technique was used to determine the size and taxonomic composition of the soil seed bank of five grasslands that had different fire histories (i.e. burnt at 1 yr, 3 yr and > 10 yr intervals) and this was compared to the standing vegetation at each site. A nested sampling design (subplot, plot, site) was used to determine the effect of spatial scale on the patterns observed in both the vegetation and the seed bank. Temporal variation in the seed bank was assessed by repeated soil sampling over a two year period. 61 native and 30 exotic species were recorded in the vegetation. Richness varied more between sites than within sites. Sites were therefore internally homogeneous for species richness. However, no correlation between burning frequency and richness was found. DCA ordination separated the sites into distinct groups, but sites with similar fire history did not necessarily group closely. 60 taxa germinated from the soil seed bank, comprising 32 native and 28 exotic species; 11 species, mostly therophytes, were restricted to the seed bank. The richness of the seed bank was significantly lower than the vegetation at all spatial scales. No correlation between seed bank richness and fire history was found. The seed bank of species-rich grasslands is dominated by a limited number of widespread, highly clumped, annual, native and exotic monocots. Most native hemicryptophytes, and perennials in general, were represented in the soil by a transient seed bank. Only 12 % of study species, all therophytes, were considered to form large, persistent seed banks, the size of which was greater in unburnt grasslands at all times of the year. The distinct floristic patterns observed in the vegetation are less clearly represented in the seed bank. The seed bank represents a floristically distinct (and less variable) component of the vegetation when compared to the standing flora. The size of the long-term soil seed bank suggests that it has little functional importance for many native species and probably contributes little to seedling regeneration processes following disturbance. Altering established fire regimes is likely to only change the composition and small-scale richness of the existing site vegetation and will not re-integrate species previously lost from the vegetation due to past management. It is suggested that the maintenance of vegetation remnants and processes that encompass a range of long-term burning histories will be necessary if the flora is to be conserved in situ. Restoration of degraded grasslands cannot rely on the soil seed bank but rather, will be dependent on the reintroduction of propagules.     

Plant species richness in continental southern Siberia: effects of pH and climate in the context of the species pool hypothesis

Aim Many high‐latitude floras contain more calcicole than calcifuge vascular plant species. The species pool hypothesis explains this pattern through an historical abundance of high‐pH soils in the Pleistocene and an associated opportunity for the evolutionary accumulation of calcicoles. To obtain insights into the history of calcicole/calcifuge patterns, we studied species richness–pH–climate relationships across a climatic gradient, which included cool and dry landscapes resembling the Pleistocene environments of northern Eurasia. Location Western Sayan Mountains, southern Siberia. Methods Vegetation and environmental variables were sampled at steppe, forest and tundra sites varying in climate and soil pH, which ranged from 3.7 to 8.6. Species richness was related to pH and other variables using linear models and regression trees. Results Species richness is higher in areas with warmer winters and at medium altitudes that are warmer than the mountains and wetter than the lowlands. In treeless vegetation, the species richness–pH relationship is unimodal. In tundra vegetation, which occurs on low‐pH soils, richness increases with pH, but it decreases in steppes, which have high‐pH soils. In forests, where soils are more acidic than in the open landscape, the species richness–pH relationship is monotonic positive. Most species occur on soils with a pH of 6–7. Main conclusions Soil pH in continental southern Siberia is strongly negatively correlated with precipitation, and species richness is determined by the opposite effects of these two variables. Species richness increases with pH until the soil is very dry. In dry soils, pH is high but species richness decreases due to drought stress. Thus, the species richness–pH relationship is unimodal in treeless vegetation. Trees do not grow on the driest soils, which results in a positive species richness–pH relationship in forests. If modern species richness resulted mainly from the species pool effects, it would suggest that historically common habitats had moderate precipitation and slightly acidic to neutral soils.     

Associations between vegetation patterns and soil texture in the shortgrass steppe

A recent conceptual model of controls on vegetation structure in semiarid regions includes the hypothesis that the balance between the dominance of woody and herbaceous species is partly controlled by soil texture. The model predicts that the dominance of woody plants is associated with coarse textured soils, and that ecotones between woody and herbaceous plant functional types are associated with soil textural changes. We analyzed vegetation and soil data (from US Soil Conservation Service maps) for an area of shortgrass steppe in Northern Weld County, Colorado, in a canonical correlation procedure to test the hypothesis at a regional scale. In support of the model, we found significant correlations between (a) a canonical vegetation variable correlated with C₃ grass biomass and shrub biomass, and a canonical soil variable correlated with sandy topsoils, and (b) a canonical vegetation variable correlated with succulent biomass, and a canonical soil variable correlated with clay soils. Relatively sharp transitions between shrub- and grass-dominated vegetation types occur in a number of areas in the shortgrass steppe of northeastern Colorado and southeastern Wyoming, and we selected four sites to test the above hypothesis at a local scale. We gathered data on vegetation cover and soil texture from transects (50 m long) positioned across the transition zones from grassland to shrubland. We conducted a further canonical correlation analysis of the vegetation and soil data to test for the relationships between vegetation structure and soil texture, and a performed regression analyses on individual site data to describe site-specific relationships between vegetation and soil texture variables. Vegetation structure along the transects, at the level of plant functional types, was similar at all four sites. The transition from grassland to shrubland encompassed a change from a C₄ grass/half-shrub complex to a shrub/C₃ grass/succulent complex. At two of the sites these transitions were associated with a change to coarser-textured soils in the shrubland zone. Within the context of the shortgrass steppe, our overall findings support the predictions of the conceptual at a regional scale, but indicate that soil texture is only one factor that can influence vegetation structure at the local scale.     

Small seed bank in grasslands and tree plantations in former grassland sites in the South Brazilian highlands

The soil seed bank can be an important source for vegetation regeneration, and data on the similarity between aboveground vegetation and the seed bank can provide information about successional pathways after disturbances or land-use change. We conducted this study in natural grasslands in the subtropical highland region in southern Brazil. We evaluated the effect of silviculture on richness, density, and composition of the seed bank at former grassland sites converted to pine plantations 25 years ago. We worked at six grassland sites and three pine plantation sites and used the seedling emergence method. Seed bank density and richness in grasslands were lower than those reported in similar environments in other regions. Species richness and density varied considerably within each vegetation type; therefore, richness and density were not statistically significant, while composition varied among vegetation types. In terms of species, the pine plantation seed bank was a small subset of the grassland seed bank. Seeds of typical grassland species were missing in the pine plantation, but also had only low abundances in the grassland, and similarity of seed bank and vegetation were low (less than 20%). The low seed density found in this study, including in grasslands areas, indicates that regeneration of species from the soil seed bank likely is of a limited role for the maintenance of plant populations after disturbances in this system. Our data further suggest that natural regeneration after tree planting in grasslands is reduced due to seed limitation.     

Vegetation change in acidic dry grasslands in Moravia (Czech Republic) over three decades: Slow decrease in habitat quality after grazing cessation

Aims

Shallow soils on acidic bedrock in dry areas of Central Europe support dry grasslands and heathlands that were formerly used as extensive pastures. These habitats are of high conservation value, but their abandonment in the 20th century triggered slow natural succession that poses a threat to specialized plant species. We asked how this vegetation and its plant diversity have changed over the past three decades and whether protected areas have positively affected habitat quality.

Location

Southwestern and central Moravia, Czech Republic.

Methods

In 2018–2019, we resurveyed 94 vegetation plots first sampled in 1986–1991 at 47 acidic dry grassland and heathland sites. We compared the number of all vascular plant species, Red List species and alien species per plot using parametric and non-parametric tests, life-form spectra using the chi-square test, species composition using detrended correspondence analysis, and indicator values using a permutation test. We also compared these changes between sites within and outside protected areas.

Results

Vegetation changes over the past three decades have been relatively small. However, we detected a decrease in total species richness, the number of Red List species and the number of characteristic species of dry grasslands. Neophytes were infrequent, while archaeophytes increased slightly. The competitive tall grass Arrhenatherum elatius, annual species and young woody plants increased in abundance or newly established at many sites. Indicator values did not change except for a slight increase in nutrient values. These negative trends occurred both within and outside protected areas but were more pronounced outside.

Conclusions

Formerly grazed acidic dry grasslands and heathlands in Moravia are slowly losing habitat specialists, including threatened plant species, and are increasingly dominated by Arrhenatherum elatius. Conservation management, especially cutting in protected areas, slows down the negative trends of decline in plant diversity and habitat quality but is insufficient to halt these processes completely.     

Effects of fen management and habitat parameters on staphylinid beetle (Coleoptera: Staphylinidae) assemblages in north-eastern Germany

Because fens have undergone dramatic declines in recent decades, an important question is which management regimes and habitat parameters are most effective in preserving fen biodiversity. The aim of the present study was to assess the effects of five different management regimes (intensive grassland, moist meadows, summer harvested sites, winter harvested sites, fallows) on staphylinid beetle assemblages. During the study period 5,989 individuals from 92 staphylinid beetle species were recorded. Species richness and abundance were highest on intensive grassland and fallows, and water level and vegetation height had significant impacts on the abundance of staphylinids. On winter-harvested sites species richness and abundance were lowest. In general, staphylinid beetles did not show pronounced variation among management regimes, while the environmental factors water level, vegetation height and top soil mineralisation seemed to have a larger structuring impact. The number of threatened species and the conservation index were highest on summer-harvested sites and fallows, representing fairly well-preserved fens. We conclude that summer harvest of reed beds or no management at all appears to be most beneficial for the conservation of staphylinid beetles.     

Relationships Between Plant Spatial Patterns, Water Infiltration Capacity, and Plant Community Composition in Semi-arid Mediterranean Ecosystems Along Stress Gradients

Water redistribution from bare soil to vegetation patches is a key feature of semi-arid ecosystems, and is responsible for their patchy vegetation patterns. The magnitude of water redistribution depends on the properties of the bare soil (which determine the amount of water run-off) and the capacity of vegetation patches to trap water run-on. We examined the relationships between plant spatial patterns, water infiltration into bare soil, and plant community composition in semi-arid sites with different hydro-physical properties (silty and gypseous soils) in NE Spain. We also studied the effect of two stressors, aridity and grazing, on water infiltration and plant spatial patterns. Our results indicate a negative correlation of bare soil sorptivity (the capacity to absorb water by capillarity) and vegetation aggregation. There was a strong positive correlation between perennial grass cover and the spatial aggregation of vegetation, but aggregation was not associated with positive associations of different plant types. The aggregation of vegetation was positively correlated with species richness and the overall extent of vegetation cover. Grazing reduced water infiltration into silty soils, which are prone to compaction. In contrast, soil crust affected the hydrology of gypseous soils, especially in the most arid sites, where grazing increased infiltration, reducing surface sealing due to breaking of the soil crust. Together, our results suggest that biotic and abiotic factors affect the hydro-physical properties of soils in the semi-arid ecosystems of NE Spain, which is linked to the plant communities through the spatial distribution of plants.     

Vegetation coverage,species richness,and dune stability in the southern part of Gurbantünggüt Desert

This study investigated the relationship between vegetation coverage, species richness, and environmental factors, and also analyzed the relationship between vegetation coverage, species richness, and dune stability in different terrains, in the southern part of Gurbantünggüt Desert in China. The results showed that the order of vegetation coverage and species richness was greatest in middle areas, followed by the eastern areas, with the western areas being sparse. On a large scale, precipitation from April to June determined the amount of vegetation coverage. On a small scale, vegetation coverage was influenced by the type of terrain and the water and salt content in soils. Species richness of vegetation was determined by soil water and salt content on both the large and small scales. There were also remarkable differences in relative wind erosion among the different terrains and their order was: crest, slope, and inter-dune in descending order. The correlations between wind erosion and vegetation coverage and species richness were influenced by the type of terrain. Furthermore, there were significant correlations between wind erosion and vegetation coverage and species richness in dune slopes and crests. There was, however, no significant correlation between wind erosion and vegetation coverage and species richness in inter-dune sites. Vegetation coverage was the dominant factor influencing wind erosion in both slopes and crests. Species richness may have an impact on wind erosion through vegetation coverage in both slopes and crests. These results suggest that the effect of terrain type should be fully considered during the establishment of vegetation cover in the desert.     

Trends in structural compositional attributes of dune-interdune vegetation and their edaphic relations in the Indian desert

Vegetation of 127 sites on different aspects of dune-interdunes in the Indian Thar Desert was classified using TWINSPAN. TWINSPAN groupings of sites separated better vegetated dunes of the northeast form the poorly vegetated dunes of the northwest and the southwest. Of the different ordinations using noncentred, centred and centred and standardized principal component analysis, reciprocal averaging and detrended correspondence analysis (DCA), the site and species classes in DCA correlated well with ten edaphic and ten vegetational attributes of each site. Strong correlation of vegetation groupings with soil texture, moisture holding capacity and low correlation with pH and electrical conductivity revealed the possible importance of soil physical properties in affecting vegetation composition.The 11 species classes in TWINSPAN were regrouped into 18 species classes in DCA, which separated highly frequent species from those of less and least frequent species. Based on dominance-diversity attributes, Calligonum polygonoides-Lasiurus sindicus was brought out as bioedaphic climax stage. Correlation of ordination scores in different site groupings with vegetational attributes showed specific trends: From the zero of x, y and z axes to their maximum, the ordination scores of grasses and browse species declined while score of spinous species increased. The sites near the origin of the x, y and z axes were therefore least degraded and those at or near the maximum of x, y & z axes were most disturbed as was confirmed by the dominance diversity trends. Thus trends of compositional and functional attributes of vegetation of sites in different groupings helped in inferring a site's degradation status.Abbreviations RIV Relative importance value - TWINSPAN Two Way Indicator Species Analysis - PCA Principal Component Analysis - RA Reciprocal Averaging - DCA Detrended Correspondence Analysis - EC Electrical Conductivity - WHC Water Holding Capacity - BD Beta Diversity - DC Dominance Concentration - WWS Windward slope of the dune - LWS Leeward slope of the dune - ID Interdune Nomenclature: Bhandari, (1990)     

Long‐term trends in restoration and associated land treatments in the southwestern United States

Restoration treatments, such as revegetation with seeding or invasive species removal, have been applied on U.S. public lands for decades. Temporal trends in these management actions have not been extensively summarized previously, particularly in the southwestern United States where invasive plant species, drought, and fire have altered dryland ecosystems. We assessed long‐term (1940–2010) trends in restoration using approximately 4,000 vegetation treatments conducted on Bureau of Land Management lands across the southwestern United States. We found that since 1940, the proportions of seeding and vegetation/soil manipulation (e.g. vegetation removal or plowing) treatments have declined, while the proportions of prescribed burn and invasive species treatments have increased. Treatments in pinyon‐juniper and big sagebrush communities declined in comparison to treatments in desert scrub, creosote bush, and riparian woodland communities. Restoration‐focused treatment objectives increased relative to resource extraction objectives. Species richness and proportion of native species used in seeding treatments also increased. Inflation‐adjusted costs per area rose 750% for vegetation/soil manipulation, 600% for seeding, and 400% for prescribed burn treatments in the decades from 1981 to 2010. Seeding treatments were implemented in warmer and drier years when compared to the climate conditions of the entire study period and warmer and wetter years relative to several years before and after the treatment. These results suggest that treatments over a 70‐year period on public lands in the southwestern United States are shifting toward restoration practices that are increasingly large, expensive, and related to fire and invasive species control.     

Does Eucalyptus grandis invasion and removal affect soils and vegetation in the Eastern Cape Province,South Africa?

Many invasive alien plants drive changes in native community composition, structure and diversity. They alter soil nutrient regimes of native communities and affect native plant recovery outcomes following their removal. We assessed whether Eucalyptus grandis invasion and removal alters the soil physico‐chemical properties and native vegetation recovery in the Eastern Cape Province, South Africa. We collected samples from topsoil in E. grandis invaded sites (canopy cover > 75%), cleared sites (eight years ago) and native sites (canopy cover > 80%) and quantified soil moisture, concentrations of soil macro elements (N, C and P), pH and exchangeable cations (K, Ca, Mg, Na) as well as measured soil water repellency using the Water Droplet Penetration Time and infiltration. We conducted vegetation surveys in plots measuring 10 × 10 m. Invasion by E. grandis had varying effects on soil physico‐chemical properties, causing increase in soil pH and P, while decreasing total N and C. The removal of E. grandis also showed varying effects on soil physico‐chemical properties, but seems to have further triggered the loss of some soil nutrients (especially soil P). Soil water repellency (a measure of soil compaction) has improved in cleared sites to non‐repellent soils compared to repellent soils in invaded site. Eucalyptus grandis reduced species richness of the invaded sites. The presence of native species on cleared sites indicates a positive trajectory towards vegetation recovery. We conclude that E. grandis invasion and removal trigger varying effects on soil properties (both increases and decreases). For soil and vegetation restoration of cleared sites to be effective, active restoration techniques such as soil transfer, nutrient manipulation and native plant seeding should be considered.     

Wetlands in flux: looking for the drivers in a central European case

Planet Earth is undergoing significant changes which are driven by natural and anthropogenic factors. However, it is difficult to identify the drivers and their effect on the environment and ecosystems because there are many interdependencies. In this study we present a multi-parameter approach to assess the effect of changes in human-induced and natural drivers on a wetland ecosystem. The study area is one of the most prominent European wetlands: the Biebrza Basin, located in north-eastern Poland. We analysed long-term (ca. 1960–2000) changes in meteorology, hydrology, soil and vegetation, and also conservation history. This approach enabled us to identify interactions between environmental change and management. We found significant trends (1960–2012) indicating climate change: increases in temperature, evapotranspiration and earlier start of spring floods. We identified (1970–2000) a shift towards drier vegetation types after drainage. However, we also found that restoration measures that were implemented have mitigated climate change effects and have led to increases in soil moisture and wetter vegetation types. We conclude that, if carried out sufficiently frequently, the management measures implemented in the Biebrza Basin, which are a combination of different restoration measures (blocking drainage, not clearing aquatic vegetation, bush removal, mowing), can to some extent mitigate the effects of climate change.     

Permafrost thaw induces short-term increase in vegetation productivity in northwestern Canada

Over the past several decades, various trends in vegetation productivity, from increases to decreases, have been observed throughout Arctic–Boreal ecosystems. While some of this variation can be explained by recent climate warming and increased disturbance, very little is known about the impacts of permafrost thaw on productivity across diverse vegetation communities. Active layer thickness data from 135 permafrost monitoring sites along a 10° latitudinal transect of the Northwest Territories, Canada, paired with a Landsat time series of normalized difference vegetation index from 1984 to 2019, were used to quantify the impacts of changing permafrost conditions on vegetation productivity. We found that active layer thickness contributed to the observed variation in vegetation productivity in recent decades in the northwestern Arctic–Boreal, with the highest rates of greening occurring at sites where the near-surface permafrost recently had thawed. However, the greening associated with permafrost thaw was not sustained after prolonged periods of thaw and appeared to diminish after the thaw front extended outside the plants' rooting zone. Highest rates of greening were found at the mid-transect sites, between 62.4° N and 65.2° N, suggesting that more southernly sites may have already surpassed the period of beneficial permafrost thaw, while more northern sites may have yet to reach a level of thaw that supports enhanced vegetation productivity. These results indicate that the response of vegetation productivity to permafrost thaw is highly dependent on the extent of active layer thickening and that increases in productivity may not continue in the coming decades.