Spontaneous Vegetation Succession in Gravel–Sand Pits: A Potential for Restoration

Vegetation variability, the participation of target and undesirable species, and the role of local species pool were studied in the course of spontaneous succession in disused gravel–sand pits. The study was conducted in various regions of the Czech Republic, Central Europe. The regions represented either agrarian lowlands with a relatively warm and dry climate or mostly woodland uplands with a relatively cold and wet climate. The gravel–sand pits (36) comprised stages of different age from 1 to 75 years since abandonment. Altogether, 224 vegetation samples were recorded with species cover (%) visually estimated. Species affinity to different vegetation types was assessed in each sample based on the species cover. Local site factors, such as water table and soil characteristics, and landscape characteristics, namely climatic parameters, presence of nearby (semi)natural plant communities and main land cover categories in the broader surroundings, were evaluated as well as the participation of target (grassland, woodland, and wetland) and undesirable (ruderal, alien) species. Ordination analyses showed that vegetation succession led to target grassland, wetland, or woodland vegetation depending on local site factors, especially moisture and the presence of (semi)natural vegetation in the surroundings (local species pool). Restoration of target vegetation in disused gravel–sand pits by processes of spontaneous succession can be possible and successful in about 25 years, especially if (semi)natural vegetation exists in the surroundings. The invasion of the alien tree Robinia pseudacacia must be taken into consideration within the dry sites in lowlands.     

The importance of environment vs. disturbance in the vegetation mosaic of Central Arizona

Abstract. The vegetation of central Arizona is a mosaic of four vegetation types: chaparral, chaparral grassland, woodland, and woodland grassland. We analysed ten environmental variables, three disturbance variables, and five disturbance indicators to answer the question: What is the relative importance of environment and disturbance in explaining the vegetation pattern of our study area? We found that chaparral, chaparral grassland, and woodland are differentiated primarily by environmental factors and have high stability in the landscape. In contrast, woodland grassland is differentiated primarily by disturbance and is likely an early‐successional stage of woodlands. Although other researchers have indicated that semi‐arid vegetation is generally unstable, the vegetation of central Arizona is composed of two systems: those with a more stable landscape position determined primarily by environmental factors and those with a less stable landscape position determined primarily by disturbance factors.     

Scale‐dependent occupancy patterns in reptiles across topographically different landscapes

Understanding what factors influence species occupancy in human‐modified landscapes is a central theme in ecology. We examined scale‐dependent habitat relationships and site occupancy in reptiles across three topographically different study areas in south‐eastern Australia. We collected presence–absence data on reptiles from 443 sites associated with three long‐term biodiversity monitoring programs, on four to seven occasions, between 2001 and 2013. We characterised sites by the following four variable domains: 1) field design, 2) topography, 3) local‐scale vegetation attributes and 4) landscape‐scale vegetation cover. We constructed occupancy models for 14 species and used an information‐theoretic approach to compare multiple alternative hypotheses to explain occupancy within and between study areas. We modelled detection probability and used the model with the lowest AIC in subsequent analyses. We then modelled occupancy probability against all subsets of the variable groups (field design, topography, local‐ and landscape‐scale vegetation), as well as a model that held occupancy constant (null model). We found that local‐scale vegetation attributes were important for explaining site occupancy in 12/19 possible models, although, in several cases model fit was improved by the addition of topographic variables or native vegetation cover in the surrounding landscape. Occupancy models for widespread species were broadly congruent across study areas. We demonstrate that topographic variables are important for explaining reptile occupancy in hilly landscapes, and local‐ and landscape‐scale variables are important for explaining reptile occupancy in flat or gently undulating landscapes. Management actions that improve habitat complexity at a site‐level, and encompass entire topographic gradients, will have greater benefit to woodland reptiles than simply increasing vegetation cover in the surrounding landscape.     

Historical land‐use and landscape change in southern Sweden and implications for present and future biodiversity

The two major aims of this study are (1) To test the performance of the Landscape Reconstruction Algorithm (LRA) to quantify past landscape changes using historical maps and related written sources, and (2) to use the LRA and map reconstructions for a better understanding of the origin of landscape diversity and the recent loss of species diversity. Southern Sweden, hemiboreal vegetation zone. The LRA was applied on pollen records from three small bogs for four time windows between AD 1700 and 2010. The LRA estimates of % cover for woodland/forest, grassland, wetland, and cultivated land were compared with those extracted from historical maps within 3‐km radius around each bog. Map‐extracted land‐use categories and pollen‐based LRA estimates (in % cover) of the same land‐use categories show a reasonable agreement in several cases; when they do not agree, the assumptions used in the data (maps)‐model (LRA) comparison are a better explanation of the discrepancies between the two than possible biases of the LRA modeling approach. Both the LRA reconstructions and the historical maps reveal between‐site differences in landscape characteristics through time, but they demonstrate comparable, profound transformations of the regional and local landscapes over time and space due to the agrarian reforms in southern Sweden during the 18th and 19th centuries. The LRA was found to be the most reasonable approach so far to reconstruct quantitatively past landscape changes from fossil pollen data. The existing landscape diversity in the region at the beginning of the 18th century had its origin in the long‐term regional and local vegetation and land‐use history over millennia. Agrarian reforms since the 18th century resulted in a dramatic loss of landscape diversity and evenness in both time and space over the last two centuries leading to a similarly dramatic loss of species (e.g., beetles).     

Weather effects on birds of different size are mediated by long‐term climate and vegetation type in endangered temperate woodlands

Species occurrence is influenced by a range of factors including habitat attributes, climate, weather, and human landscape modification. These drivers are likely to interact, but their effects are frequently quantified independently. Here, we report the results of a 13‐year study of temperate woodland birds in south‐eastern Australia to quantify how different‐sized birds respond to the interacting effects of: (a) short‐term weather (rainfall and temperature in the 12 months preceding our surveys), (b) long‐term climate (average rainfall and maximum and minimum temperatures over the period 1970–2014), and (c) broad structural forms of vegetation (old‐growth woodland, regrowth woodland, and restoration plantings). We uncovered significant interactions between bird body size, vegetation type, climate, and weather. High short‐term rainfall was associated with decreased occurrence of large birds in old‐growth and regrowth woodland, but not in restoration plantings. Conversely, small bird occurrence peaked in wet years, but this effect was most pronounced in locations with a history of high rainfall, and was actually reversed (peak occurrence in dry years) in restoration plantings in dry climates. The occurrence of small birds was depressed—and large birds elevated—in hot years, except in restoration plantings which supported few large birds under these circumstances. Our investigation suggests that different mechanisms may underpin contrasting responses of small and large birds to the interacting effects of climate, weather, and vegetation type. A diversity of vegetation cover is needed across a landscape to promote the occurrence of different‐sized bird species in agriculture‐dominated landscapes, particularly under variable weather conditions. Climate change is predicted to lead to widespread drying of our study region, and restoration plantings—especially currently climatically wet areas—may become critically important for conserving bird species, particularly small‐bodied taxa.     

Landscape structure influences tree density patterns in fragmented woodlands in semi‐arid eastern Australia

Landscape and local‐scale influences are important drivers of plant community structure. However, their relative contribution and the degree to which they interact remain unclear. We quantified the extent to which landscape structure, within‐patch habitat and their confounding effects determine post‐clearing tree densities and composition in agricultural landscapes in eastern subtropical Australia. Landscape structure (incorporating habitat fragmentation and loss) and within‐patch (site) features were quantified for 60 remnant patches of Eucalyptus populnea (Myrtaceae) woodland. Tree density and species for three ecological maturity classes (regeneration, early maturity, late maturity) and local site features were assessed in one 100 × 10 m plot per patch. All but one landscape characteristic was determined within a 1.3‐km radius of plots; Euclidean nearest neighbour distance was measured inside a 5‐km radius. Variation in tree density and composition for each maturity class was partitioned into independent landscape, independent site and joint effects of landscape and site features using redundancy analysis. Independent site effects explained more variation in regeneration density and composition than pure landscape effects; significant predictors were the proportion of early and late maturity trees at a site, rainfall and the associated interaction. Conversely, landscape structure explained greater variation in early and late maturity tree density and composition than site predictors. Area of remnant native vegetation within a landscape and patch characteristics (area, shape, edge contrast) were significant predictors of early maturity tree density. However, 31% of the explained variation in early mature tree differences represented confounding influences of landscape and local variables. We suggest that within‐patch characteristics are important in influencing semi‐arid woodland tree regeneration. However, independent and confounding effects of landscape structure resulting from previous vegetation clearing may have exerted a greater historical influence on older cohorts and should be accounted for when examining woodland dynamics across a broader range of environments.     

Interaction effects between local flower richness and distance to natural woodland on pest and beneficial insects in apple orchards

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Role of substrate and landscape context in early succession: An experimental approach

Both local site conditions and landscape context influence the course of succession, but there is a lack of experimental studies on the relative importance of these two factors. It is hypothesised that convergence vs. divergence in succession is determined by the interplay of site factors, such as type of substrate and the nature of the surrounding landscape. In order to evaluate the role of substrate and surrounding landscape in the initial development of vegetation, experimental plots with tertiary clay, sand, peat, sterilised local soil and undisturbed local soil as a control were established in two contrasting regions, and the cover of all the species present was recorded annually for 10 years. In early succession, vegetation was affected by both the substrate and surrounding landscape, but their effects resulted in different trends. The importance of the substrate gradually decreased, while that of the landscape context increased. In the course of succession the vegetation between the two regions diverged and converged within each region. We concluded with regard to the divergence vs. convergence dichotomy in succession: if contrasting habitats occur in the same or similar landscapes, convergence is expected, whereas if similar or the same habitats are located in contrasting landscapes, divergence is expected. For the remaining combinations, i.e. contrasting habitats in contrasting landscapes or the same habitats in the same or a similar landscape, successions may exhibit no or only slight divergence or convergence.     

Rate of succession in restored wetlands and the role of site context

Question: Are changes in plant species composition, functional group composition and rates of species turnover consistent among early successional wetlands, and what is the role of landscape context in determining the rate of succession? Location: Twenty‐four restored wetlands in Illinois, USA. Methods: We use 4 years of vegetation sampling data from each site to describe successional trends and rates of species turnover in wetlands. We quantify: (1) the rate at which composition changes from early‐successional to late‐successional species and functional groups, as indicated by site movement in ordination space over time, and (2) the rate of change in the colonization and local extinction of individual species. We correlate the pace of succession to site area, isolation and surrounding land cover. Results: Some commonalities in successional trends were evident among sites. Annual species were replaced by clonal perennials, and colonization rates declined over time. However, differences among sites outweighed site age in determining species composition, and the pace of succession was influenced by a site's landscape setting. Rates of species turnover were higher in smaller wetlands. In addition, wetlands in agricultural landscapes underwent succession more rapidly, as indicated by a rapid increase in dominance by late‐successional plants. Conclusions: Although the outcome of plant community succession in restored wetlands was somewhat predictable, species composition and the pace of succession varied among sites. The ability of restoration practitioners to accelerate succession through active manipulation may be contingent upon landscape context.     

Impact of rewetting on the vegetation of a cut‐away peatland

Abstract. We tested whether rewetting improved environmental conditions during peatland restoration and promoted colonization and development of mire vegetation. Vegetation change was monitored in a cut‐away peatland one year before, and four years after, rewetting. Colonizers before rewetting were perennials, mostly typical of hummocks or bare peat surfaces. The main variation in vegetation was related to variation in the amounts of major nutrients and water table level. The wettest site with the highest nutrient level had the highest total vegetation cover and diversity, as well as some species typical of wet minerotrophic mires. Raising the water table level above, or close to, the soil surface promoted development of wet minerotrophic vegetation. Diversity initially decreased because of the disappearance of hummock vegetation but started to recover in the third year. Eriophorum vaginatum and Carex rostrata were both favoured, and bryophytes typical of wet habitats colonized the site. Moderate rewetting promoted the development of Eriophorum vaginatum seedlings and an increase in the cover of tussocks. Bryophytes typical of disturbed peat surfaces spread. In the control site development continued slowly towards closed hummock vegetation. The study showed that raising the water level to, or above, soil surface promotes conditions wet enough for a rapid succession towards closed mire vegetation.     

Site vegetation characteristics are more important than landscape context in determining bird assemblages in revegetation

The effectiveness of revegetation in providing habitat for fauna is expected to be determined both by within‐site factors and attributes of the landscape in which a revegetation site occurs. Most studies of fauna in revegetation have been conducted in landscapes that have been extensively cleared, modified or fragmented, and in Australia, predominantly in the southern temperate zone. We investigated how within‐site vegetation attributes and landscape context attributes were related to bird species richness and composition in a chronosequence of post‐mining rehabilitation sites within an otherwise intact landscape in tropical northern Australia. Our working hypothesis was that bird species richness in rehabilitating sites would be positively related to site vegetation structure and landscape context including (1) proximity to woodland and (2) the proportion of woodland within a 500‐m buffer of rehabilitation sites. Within each of 67 sites, we sampled vegetation once and surveyed for birds eight times over 16 months. Landscape context variables were calculated using GIS. There were large differences between bird assemblages of woodland and rehabilitation sites and between age classes of rehabilitation. Bird assemblages were strongly related to site vegetation attributes across all rehabilitation sites. Proximity to woodland was only related to bird assemblages in rehabilitation sites older than 4 years old. We conclude that the relative importance of landscape context and site variables at any point in time will be a function of how closely vegetation within the revegetation site matches the habitat resource requirements of individual species.     

Half a century of succession in a temperate oakwood: from species‐rich community to mesic forest

Aim Lowland woodlands in Europe went through dramatic changes in management in the past century. This article investigates the influence of two key factors, abandonment of coppicing and increased pressure of ungulates, in thermophilous oakwoods. We focused on three interconnected topics: (1) Has the assumed successional trend lead to impoverishment of the vegetation assemblages? (2) Has it resulted in vegetation homogenization? (3) Are the thermophilous oakwoods loosing their original character? Location Czech Republic, Central Europe. Methods The vegetation in 46 semi‐permanent plots was recorded three times: firstly, shortly after the abandonment of coppicing (1953) and then, after four to six decades of secondary succession and strong game impact (1992 and 2006). Overall trends and changes in species spectra were analysed. Results There is a marked successional shift towards species‐poorer communities growing in cooler, moister and nutrient‐richer conditions. The change was significantly different in parts affected and unaffected by high numbers of ungulates yet only for herbs, not the woody species. However, observed change in species composition was not accompanied by significant homogenization process that is the general process reported from elsewhere. A sharp decline in plant species typical for thermophilous woodland communities and in endangered species indicates that the original character of the woodland has been gradually lost. Main conclusions Thermophilous oakwoods have been largely replaced by mesic forests. Lowland oakwoods in continental parts of Europe historically depended on active management, which kept the understorey conditions light and warm. Successional processes in the 20th century caused a critical loss of species diversity at various spatial levels. However, artificially high numbers of ungulates, which otherwise have a negative impact, probably held up succession, so that the changes may still be reversible.     

Effects of landslides on the mountain vegetation of Flores Island,Azores

Question: What are the consequences of frequently occurring landslides on vegetation dynamics, floristic and structural diversity? Location: 39°27′N; 31°13′W – Morro Alto, Flores Island, Azores, Portugal. Methods: Six comparable landslides were selected. Plots were placed at the top, slope and toe of landslides. Data on floristic composition and biovolume, demography and size structure of the dominant tree species (Juniperus brevifolia) were collected. Hierarchical agglomerative clustering and Principal Component Analysis were used in order to identify succession stages and compare succession pathways and vegetation recovery in different parts of the landslides. Results: Four stages of primary succession on substrates formed by landslides were identified: pioneer (Festuca‐Sphagnum grassland), assembly (Juniperus‐Festuca‐Sphagnum open scrub), building (Juniperus‐Sphagnum scrub) and mature (Juniperus‐Sphagnum woodland). Concerning J. brevifolia populations, the succession pathways are independent of location on the landslide. However, at the floristic level, there are some differences, mainly in the pioneer stage at the toes of landslides. Better abiotic conditions, resulting in a higher succession rate, are probably responsible for a faster vegetation recovery on landslide toes. Conclusion: Landslides trigger succession processes that enable a massive regeneration of the dominant tree species and existence of species not present in mature forests. They are also responsible for the simultaneous occurrence of vegetation of different structures. Overall, landslides increase the floristic and structural diversity of the vegetation, consequently increasing landscape heterogeneity.     

Vegetation establishment, succession and microsite frost disturbance on glacier forelands within patterned ground chronosequences

Aim The impact of microscale frost disturbance on vegetation colonization and successionary trends was examined within patterned ground features of Little Ice Age chronosequences. The goal was to investigate and compare vegetation response to micro‐site frost disturbance with that of previous studies done at a coarser landscape scale. Location The study sites occur on Little Ice Age glacier forelands within Jotunheimen, Norway (61°–62° N). The forelands of the glaciers Slettmarkbreen, Styggedalsbreen and Vestre Memurubreen have been well studied providing chronological controls for landscape studies. Sorted patterned ground features are found within the chronosequences, typically declining with frost intensity and disturbance with increasing terrain age. Methods Micro‐plots (8.3 × 8.3 cm) were placed at the inner borders and centres of patterned ground features. Species were identified and per cent species cover and per cent cover of life‐form category were noted. Nonparametric Kruskal–Wallis and Mann–Whitney U‐tests were used to test for differences between percent cover of life‐form categories within patterned ground features as well as to identify thresholds of successional change across the chronosequences. Results Significant relationships between life‐from groups and patterned ground positions of varying ages were deduced using nonparametric statistics. Findings were then used to discuss trends of succession within patterned ground features and across the chronosequences. Vegetation establishment occurs at the border positions of young (< 30 years) patterned ground features. With time and distance from the ice margin, vegetation encroaches inwards toward the disturbed centres. Succession within patterned ground exhibits several stages: (1) bryophytes/crusts and lichens, (2) grasses/sedges and (3) woody shrubs. The occurrence of forbs was sporadic and generally non‐significant. Main conclusions Frost disturbance in patterned ground appears to delay successional trends of vegetation communities when compared with previous studies on ‘stable’ terrain, producing micro‐site lag effects. These small patches of disturbed ground are therefore important regarding vegetation assemblages across the landscape and are unlikely to be detected at the landscape scale.     

Climate and pH as determinants of vegetation succession in Central European man‐made habitats

Questions: (1) What are the most important abiotic environmental variables influencing succession in central European man‐made habitats? (2) How do these variables interact with one another and with variation in community properties? Location: Central, western and southern parts of the Czech Republic. Habitats included old fields, urban sites, spoil heaps after coal mining, sites at water reservoirs, extracted sand pit and peatland and reclaimed sites in areas deforested by air pollution. Methods: We investigated vegetation patterns on 15 succes‐sional seres, sampled by the same methods. Time of succession over which the data were available ranged from 12 to 76 years. The cover of vascular plant species (in %) was estimated in 5 m × 5 m plots. The relationships between vegetation characteristics (species composition, total cover, cover of woody species, species number and rate of dominant species turnover) and 13 abiotic site factors, including climatic and soil variables, were tested using CCA ordination and regression models. Results: Substratum pH, the only substratum characteristic, and climate were the environmental variables significantly affecting the vegetation patterns in the course of succession. The rate of succession, measured as the turnover of dominant species, was significantly more rapid in lowland than in mountain climates. On alkaline soils, species numbers in succession increased towards warmer climates. However, acid soils prevented any increase in species numbers, regardless of the climate. Surprisingly, forms of nitrogen and contents of C, P and cations did not exhibit any significant effect on the vegetation characteristics studied. Conclusions: Our approach, to compare a number of seres, can contribute not only to our understanding of succession, but also to help restoration projects to predict vegetation change because the crucial environmental variables, as identified by this study, are easy to measure.     

Static and dynamic approaches to landscape heterogeneity in the Hungarian forest‐steppe zone

Abstract. This paper describes the successional status of the vegetation in a clear‐felled dry oak woodland at the edge of the Hungarian forest‐steppe zone on the basis of a vegetation map. Due to a varied geomorphology of the colline landscape several so‐called landscape units can be distinguished. The patchwork on the vegetation map is evaluated using several, morphology‐based attributes (static morphological indices) traditionally applied in landscape ecology. In the ca. 100 years that elapsed since forest clear‐cut, xeric grassland species and steppe elements became more abundant and the former xeromesophilous vegetation – containing even some woodland components – is slowly turning into xeric grassland communities. The vegetation units mapped can be arranged into a hypothetical succession scheme in which successional distances (the number of steps between two stages) are determined. Based on the distances thus obtained, a new dynamic morphological index is introduced. This is applied to each landscape unit for the dynamic evaluation of successional vegetation, its results being compared with those obtained by static morphological indices.     

Mass‐flowering crops dilute pollinator abundance in agricultural landscapes across Europe

Mass‐flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi‐natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape‐scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator‐dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator‐supporting practices in agricultural landscapes.     

The role of landscape configuration in plant composition of floodplain forests across different physiographic areas

Questions: What is the relative importance of landscape variables compared to habitat quality variables in determining species composition in floodplain forests across different physiographic areas? How do species composition and species traits relate to effects of particular landscape variables? Do lowland and mountain areas differ in effects of landscape variables on species composition? Location: Southern Czech Republic. Methods: A total of 240 vegetation relevés of floodplain forests with measured site conditions were recorded across six physiographic areas. I tested how physiographic area, habitat quality variables and landscape variables such as current land‐cover categories, forest continuity, forest size and urbanization influenced plant species composition. I also compared how mountain and lowland areas differ in terms of the relative importance of these variables. To determine how landscape configuration affects the distribution of species traits, relationships of traits and species affinity with landscape variables were tested. Results: Among landscape variables, forest continuity, landscape forest cover and distance to nearest settlement altered the vegetation. These variables also influenced the distributions of species traits, i.e. life forms, life strategies, affinity to forest, dispersal modes, seed characteristics, flooding tolerance and Ellenberg indicator values for nitrogen, light, moisture and soil reaction. Nevertheless, physiographic area and habitat quality variables explained more variation in species composition. Landscape variables were more important in lowland areas. Forest continuity affected species composition only in lowlands. Conclusions: Although habitat quality and physiographic area explained more vegetation variability, landscape configuration was also a key factor influencing species composition and distribution of species traits. However, the results are dependent on forest geographical location, with lowland forests being more influenced by landscape variables compared to mountain forests.     

To what are woodland birds responding? Inference on relative importance of in‐site habitat variables using several ensemble habitat modelling techniques

We sought to identify those in‐site habitat characteristics that best predict distributions of woodland birds in the box–ironbark region of central Victoria, Australia. Our focus was on comparing and melding outcomes from several forms of ensemble modelling methods, which account for uncertainty in model structure and allow assessments of variable importance. We used boosted regression trees (BRT), Bayesian additive regression trees (BART) and random forests (RF) to model bird occurrences for 47 species using 43 predictor variables measured at 184 2‐ha sites. The majority of predictor variables were in‐site habitat variables, but vegetation cover in the surrounding landscape (500 m radius) and geographic coordinates were included to account for known effects of habitat fragmentation and of geographic clines. A consensus model also was developed, built from averaged predictions from the three techniques. We subdivided the avifauna into guilds and other categories (e.g. conservation status) to examine whether there were differences among such subdivisions. Based on cross validation, the consensus model and RF performed best, followed by BART and then BRT. Of the in‐site habitat variables, the basal area of red‐ironbark trees and groundstorey characteristics such as fine‐ and coarse‐litter cover and litter depth had greatest influence on bird occurrences. These results can inform on‐site restoration actions (what to restore) and, therefore, complement strategic landscape planning (where and when to restore).