Characteristics of Coastal Dune Topography and Vegetation in Environments Recently Modified Using Beach Fill and Vegetation Plantings,Veneto, Italy

Human actions can contribute to degradation of coastal environments or they can increase the likelihood that these environments will be restored. Beach nourishment provides a basis for restoration, but ways must be found to add habitat improvement to projects designed for shore protection. This study examines how beach nourishment projects can help reinstate dune landscapes in locations where beaches and dunes had been replaced by static shore protection structures. Dune topography and vegetation on three nourished sites on the northern Adriatic Coast of Italy are compared to a reference site to evaluate changes after beach fill was emplaced. Results reveal how nourishment projects used for shore protection can restore the space available for dunes to form, increase the likelihood of sediment transfers inland and increase the diversity of topography and vegetation. Beach raking prevents formation and growth of hummocky, incipient backshore dunes that would otherwise evolve into a naturally functioning foredune. Sand-trapping fences can speed the process of foredune development but can be counterproductive if they interfere with transport to beach grass (Ammophila littoralis) planted landward of them. Shore protection structures can provide stability and more time for dune evolution on eroding shores, resulting in greater species richness and longer retention of ecological niches. These structures need not be required if re-nourishment occurs frequently enough to provide a beach wide enough to protect against storm wave uprush.     

Use of off-road vehicles and mitigation of effects in Alaska permafrost environments: A review

Use of off-road vehicles (ORVs) in permafrost-affected terrain of Alaska has increased sharply over the past two decades. Until the early 1960s, most ORV use was by industry or government, which employed heavy vehicles such as industrial tractors and tracked carriers. Smaller, commercial ORVs became available in the 1960s, with the variety and number in use rapidly increasing. Wheeled and tracked ORVs, many used exclusively for recreation or subsistence harvesting by individuals, are now ubiquitous in Alaska. This increased use has led to concern over the cumulative effects of such vehicles on vegetation, soils, and environmental variables including off-site values. Factors affecting impact and subsequent restoration include specific environmental setting; vegetation; presence and ice content of permafrost; microtopography; vehicle design, weight, and ground pressure; traffic frequency; season of traffic; and individual operator practices. Approaches for mitigating adverse effects of ORVs include regulation and zoning, terrain analysis and sensitivity mapping, route selection, surface protection, and operator training. We regret the untimely death of Gunars Abele on August 27, 1989; he was a valued colleague and good friend.     

Impacts of Off-Road Vehicles (ORVs) on Macrobenthic Assemblages on Sandy Beaches

Sandy beaches are the prime sites for human recreation and underpin many coastal economies and developments. In many coastal areas worldwide, beach recreation relies on the use of off-road vehicles (ORVs) driven on the shore. Yet, the use of ORVs is not universally embraced due to social conflicts with other beach user groups and putative environmental consequences of vehicle traffic on sandy shores. Such ecological impacts of ORVs are, however, poorly understood for endobenthic invertebrates of the intertidal zone seawards of the dunes. Consequently, this study quantified the degree to which assemblages of intertidal beach invertebrates are affected by traffic. The study design comprised a series of temporally replicated spatial contrasts between two reference sites (no ORVs) and two beaches with heavy ORV traffic (in excess of 250,000 vehicles per year) located in South-East Queensland, Australia. Macrobenthic assemblages on ORV-impacted beaches had significantly fewer species at substantially reduced densities, resulting in marked shifts in community composition and structure. These shifts were particularly strong on the middle and upper shore where vehicle traffic was concentrated. Strong effects of ORVs were detectable in all seasons, but increased towards the summer months as a result of heavier traffic volumes. This study provides clear evidence that ORVs can have substantial impacts on sandy beach invertebrates that are manifested throughout the whole community. Demonstrating such an ecological impact caused by a single type of human use poses a formidable challenge to management, which needs to develop multi-faceted approaches to balance environmental, social, cultural, and economic arguments in the use of sandy shores, including management of “beach traffic.”     

Response of Three Plant Communities to Trampling in a Sand Dune System in Brittany (France)

Dunes that are protected because of their very rich and diverse plant communities are often exposed to excessive visitor pressure. The effects of trampling on the habitat must be known from a conservation viewpoint but also are important for management. To determine the response of plant assemblages to trampling by people, an experimental study was conducted on the state-owned dunes at Quiberon (Brittany, France). Indices of resistance and resilience were used to compare three typical plant communities belonging to the various landscape units: mobile dune, semifixed dune, and fixed dune. The strong contrasts between communities belonging to different successional stages reflect their ecological functioning. The mobile dune and semifixed dune with their low resistance contrasted with the fixed dune. Only the vegetation cover of the semifixed dune benefited from long-term trampling and had a very high resilience (134%). This response could be explained by a good balance of two opposite factors: soil compaction increasing soil stability and moisture content, and vegetation destruction. Because of their low resilience, trampling seems to be harmful for fixed dunes in the long term. The tourist pressure seems easier to integrate in to the mobile dunes and the semifixed dunes if periods of recovery are included in the management.     

Impact of Off-road Vehicles (ORVs) on Ghost Crabs of Sandy Beaches with Traffic Restrictions: A Case Study of Sodwana Bay,South Africa

Off-road vehicles (ORVs) are popular in coastal recreation, although they have negative impacts on sandy shores. In South Africa, ORVs are banned from most coastal areas, while some areas are designated for restricted ORV use, providing an opportunity to assess whether ORV traffic restrictions translate into biological returns. In Sodwana Bay, the impact of ORVs on ghost crab populations was investigated. During Easter 2012, ghost crab burrows were counted on beach sections open and closed to traffic. Burrow density in the Impact section was less than a third that of the Reference section, and by the end of the study burrow size in the Impact section was half that of the Reference section. ORV traffic caused a shift in burrow distribution to the Lower beach. However, differences in burrow densities between sections were 14 times smaller than differences obtained at a time when ORV use in Sodwana Bay was not controlled. While confirming the well-established detrimental effects of ORV use on sandy beach ecosystems, results demonstrated that traffic restrictions on beaches measurably minimize impacts to the fauna, thus translating into clear-cut biological returns.     

Human impact on beach and foredune vegetation of North Padre Island,Texas

Vehicular and pedestrian traffic decreased top and root production, percent cover, and diversity of vegetation, and modified species composition on beach and foredune areas of Padre Island National Seashore and Nueces County Park. Degradation of vegetal cover was directly related to the type and intensity of traffic; species in heavily trafficked areas represented earlier successional stages than those in comparable undisturbed areas.     

Use of Remote Sensing Techniques to Determine the Effects of Grazing on Vegetation Cover and Dune Elevation at Assateague Island National Seashore: Impact of Horses

The effects of grazing by feral horses on vegetation and dune topography at Assateague Island National Seashore were investigated using color-infrared imagery, lidar surveys, and field measurements. Five pairs of fenced and unfenced plots (300 m²) established in 1993 on sand flats and small dunes with similar elevation, topography, and vegetation cover were used for this study. Color-infrared imagery from 1998 and field measurements from 2001 indicated that there was a significant difference in vegetation cover between the fenced and unfenced plot-pairs over the study period. Fenced plots contained a higher percentage of vegetation cover that was dominated by American beachgrass (Ammophila breviligulata). Lidar surveys from 1997, 1999, and 2000 showed that there were significant differences in elevation and topography between fenced and unfenced plot-pairs. Fenced plots were, on average, 0.63 m higher than unfenced plots, whereas unfenced plots had generally decreased in elevation after establishment in 1993. Results demonstrate that feral horse grazing has had a significant impact on dune formation and has contributed to the erosion of dunes at Assateague Island. The findings suggest that unless the size of the feral horse population is reduced, grazing will continue to foster unnaturally high rates of dune erosion into the future. In order to maintain the natural processes that historically occurred on barrier islands, much larger fenced exclosures would be required to prevent horse grazing.     

Short-term changes in mobile dunes at Port Alfred,South Africa

Development along the western beachfront of Port Alfred, which is situated along a sandy shoreline, increased markedly in the 1960s as the coastal town became a popular holiday resort. This development included the removal of coastal vegetation, which resulted in the destabilization of dunes and migration of sand westerly onto the road, West Beach parking lot, and lawns of the cabanas. Sand traps were constructed to collect sand blowing across the dunes over set periods, and the net sand movement along the mobile dune belt was calculated using Hunter's equation. The dunes show an easterly movement of sand at a rate of 3.5 m/yr, which is comparable with figures recorded along other areas of this coastline. Considering the wind regime and amount of sand movement along this coast, it is inappropriate to clear vegetation and develop within the dune region.     

Human impact on beach and foredune microclimate on North Padre Island,Texas

The microclimate of beach and foredune areas of North Padre Island along the mid-Texas coast was found to be greatly modified by vehicular and pedestrian traffic during investigations made from late fall to early summer 1973–74. The primary effect of human activity on microclimate was expressed as reduced cover and species diversity of the vegetation. As the intensity of human activity increased, elevation, especially of areas near the beach, was decreased, whereas average wind velocities near the ground surface, evaporation, atmospheric salinity near the ground surface, wind-carried sand particles near the ground surface, soil salinity, soil pH, average soil temperature and range in temperature, soil bulk density, and soil-water contents were increased.     

Effects of Trampling Limitation on Coastal Dune Plant Communities

Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1–2 years) and effective method for improving and safeguarding the diversity of dune plant communities.     

Mediterranean Coastal Sand Dune Vegetation: Influence of Natural and Anthropogenic Factors

The aim of the present work was to assess the conservation status of coastal dune systems in Tuscany (Italy). Emphasis was given to the presence and abundance of plant communities identified as habitat in accordance with the Directive 92/43/EEC. Twenty transects perpendicular to the shoreline were randomly positioned on the whole coastal area (30 km in length) in order to sample the full spectrum of plant communities. Vegetation zonation and relationships with the most frequent disturbance factors in the study area—beach cleaning, coastline erosion, presence of paths and roads, bathing settlements and trampling—were investigated through principal coordinate analysis and canonical correspondence analysis. Natural factors, such as distance from the sea and total length, were also considered. Differences in the conservation status of the sites were found, ranging from the total disappearance of the foredune habitats to the presence of the complete psammophilous (sand-loving) plant communities. Erosion, trampling, and paths were found to be closely correlated with degradation and habitat loss. Furthermore, the overall plant species diversity of dunes was measured with NH_Dune, a modified version of the Shannon index; while the incidence of invasive taxa was calculated using N, a naturalness index. However, these diversity indices proved to be a weaker bioindicator of ecosystem integrity than habitat composition along transects. A possible strategy for the conservation and management of these coastal areas could be to protect the foredunes from erosion and limit trampling through the installation of footbridges or the use of appropriate fences.     

Recovery in Naturally Dynamic Environments: A Case Study from the Sperrgebiet,Southern African Arid Succulent Karoo

Little is known about the process of vegetation recovery and associated time frames in the Succulent Karoo Biome of southern Africa. This study investigated the recovery of vegetation on sites impacted by mining (different types of dumps and mined areas) in the arid succulent karoo. The main aim of this study was to determine the state of recovery, time frames, successional stages, and the influence of environmental factors on recovery of coastal dune and sand plain plant communities. For this purpose, vegetation was recorded on some 121 sites throughout a coastal strip of approximately 100 × 3 km in Namibia’s restricted diamond area (Sperrgebiet). Using the species pool concept to derive vegetation reference sites and dominance-diversity curves, recovery of vegetation (measured in terms of species richness and cover) in these altered landscapes reached about 46% on the oldest, 51-year-old mine dumps. However, based on species richness, richness levels similar to the undisturbed reference sites were recorded after 30 years, following a logarithmic trend. Successional stages of natural recovery were indicated in this dynamic coastal environment and Cladoraphis cyperoides and Galenia fruticosa appear to be early successional species. Scaling up of studies to landscape level and developing a target community using the species pool concept are discussed as means to measure recovery in dynamic biological communities. On these altered, man-made landforms, the availability of seed may be the bottleneck to achieve vegetation cover comparable to undisturbed vegetation in the surrounding. Hence, restoration efforts should focus on this aspect.     

An environmental perspective of the post-tsunami scenario along the coast of Tamil Nadu, India: role of sand dunes and forests

An endeavor to feel the pulse of a coast devastated by a powerful oceanographic event is made. Results of field investigations along Tamil Nadu seaside revealed that the tsunami of December 2004 demolished dwellings within strips ranging from 6 to 132m (average width, 41m) from the dune, and flooded up to 862m (average, 247m) from the shore. The event damaged sand dunes, ripped dune vegetation, created new water bodies and shattered high value assets. Comparatively, casuarina forests performed remarkably. Uprooting of trees was exclusively restricted to a frontal strip ranging from 5 to 25m (average width, 14m) nearest to the shore where the maximum wave run-up was 6.5m above sea level. Sand dunes in general, and casuarina forests in particular, posses an innate capacity to dissipate powerful waves. This inference is supported by (a) negligible over wash along belts characterized by high dune complexes, (b) intact villages shielded by dense forests as well as sand dunes, and (c) maximum destruction of open beach front influenced by intense human activity. In this context, the coastal regulation zone (CRZ) Notification of 1991 offers sufficient scientific validity to be endorsed. However, post-tsunami ecosystem management initiatives lack a scientific basis. Therefore, a coastal hazards policy, that considers adaptation, dune restoration and forested buffer zones, is a sustainable long-term option for Indian coasts.     

Soil Fertility, Salinity and Nematode Diversity Influenced by Tamarix ramosissima in Different Habitats in an Arid Desert Oasis

The aim of this paper was to assess the influence of tamarisk shrubs on soil fertility, salinity and nematode communities in various habitats located in an arid desert-oasis region in northwest China. Three habitats were studied: sand dune, riparian zone and saline meadow, where tamarisk shrubs have been established in recent decades in order to vegetation restoration used as desertification control and saline land rehabilitation projects and become the dominant plant community. The parameters measured include soil organic carbon (SOC), total nitrogen, available phosphorus (P) and potassium (K), pH, salt component, and nematode community characteristics. Enrichment ratios (a comparison of the soil measurements between soils under canopy and in the open interspaces) for soil nutrients and salinity were used to evaluate fertility and salinity islands underneath the tamarisk shrubs. The soil nematode community was used as a biological indicator of soil condition. SOC and available P and K were higher beneath the plant canopy than in the open interspaces outside that canopy. The enrichment ratios for SOC and nutrients were highest for the sand dune habitat and tamarisk shrubs clearly created islands of greater salinity under the canopies. Nematode abundance per 100 g dry soil varied considerably between the locations and habitats, with the highest abundance found in sand dune and the lowest in saline meadow. A significantly higher nematode abundance and a lower trophic diversity were found in soils under the canopy compared to the soils in the open interspaces. With the exception of saline meadow, the abundance of bacterivores increased and fungivores decreased under the canopy relative to the open interspaces, and bacterivores dominated under the canopies in the sand dune and riparian habitats. The enrichment ratios for salinity were higher than for fertility, suggesting that improved soil fertility can not limit the impact of salinization beneath tamarisk shrubs. The adverse effect of salt accumulation on the soil environment should be taken into account when using tamarisk as restoration plant species, especially in saline meadow and controlling of tamarisk density should be considered when undertaking re-vegetation projects in the arid desert oasis regions.     

THE EFFECTS OF VEGETATION AND SOIL TYPE ON STREAMBANK EROSION,SOUTHWESTERN VIRGINIA,USA1

The goal of this research was to evaluate the relative effects of root density, freeze/thaw cycling, and soil properties on the erodibility and critical shear stress of streambanks. The erodibility and critical shear stress of rooted bank soils were measured in situ at 25 field sites using a submerged jet test device; several soil, vegetation, and stream chemistry characteristics shown to influence soil erosion were also assessed. Multiple linear regression analysis was conducted to determine those factors that most influenced streambank erodibility and the relative impact of riparian vegetation. Study results indicated that soil erosion is a complex phenomenon that depends primarily on soil bulk density. Freeze/thaw cycling, soil antecedent moisture content, the density of roots with diameters of 2 to 20 mm, soil texture, and the interaction of soil pore water and stream water had a significant impact on soil erodibility and critical shear stress, depending on soil type. Riparian vegetation had multiple significant effects on soil erodibility. In addition to reducing soil erodibility through root reinforcement, the streamside vegetation affected soil moisture and altered the local microclimate, which in turn affected freeze/thaw cycling (FTC). This study represents the first in situ testing of the erodibility of vegetated streambanks and provides a quantitative analysis on the effects of vegetation on streambank erosion, relative to other soil physical and chemical parameters.     

长庆气田——呼和浩特输气管道工程生态环境保护及恢复对策

针对管道工程的特点,尤其是管道工程穿越脆弱沙地生态系统的特点,在分析管道沿线生态环境现状及特点的基础上,重点从沙地生态系统的演替规律出发,分析了管道工程沙地段的主要环境问题,借鉴当地已有的生态恢复的成功经验,进一步提出了穿越脆弱沙地生态系统管道工程项目的生态保护和恢复对策。     

Revegetation of an abandoned uranium millsite on the Colorado Plateau, Arizona

We attempted to restore native plants on disturbed sites at a former uranium mill on the Colorado Plateau near Tuba City, AZ. Four-wing saltbush [Atriplex canescens (Pursh) Nutt.] was successfully established in compacted caliche soil and in unconsolidated dune soil when transplants were irrigated through the first summer with 20 L/plant/wk. The caliche soil was ripped before planting to improve water-holding capacity. The diploid saltbush variety, angustifolia, had higher survival and growth than the common tetraploid variety, occidentalis, especially on dune soil. The angustifolia variety grew to 0.3 to 0.4 m3 per plant over 3 yr even though irrigation was provided only during the establishment year. By contrast, direct seeding of a variety of native forbs, grasses, and shrubs yielded poor results, despite supplemental irrigation throughout the first summer. In this arid environment (precipitation = 100 to 200 mm/yr), the most effective revegetation strategy is to establish keystone native shrubs, such as four-wing saltbush, using transplants and irrigation during the establishment year, rather than attempting to establish a diverse plant community all at once.     

Enforcement Authority and Vegetation Change at Kumbhalgarh Wildlife Sanctuary,Rajasthan, India

Land cover change in protected areas is often associated with human use, especially illicit extraction, but the direction and spatial distribution of such effects and their drivers are poorly understood. We analyze and explain the spatial distribution of vegetation change at the Kumbhalgarh Wildlife Sanctuary in the Aravalli range of Rajasthan, India using remotely sensed data and observation of conservation institutions. Two satellite images are examined in time series over the 13 years following the founding of the sanctuary through a cross-tabulation technique of dominant classes of vegetation density. The resulting change trajectories are compared for their relative distance to high-traffic forest entrance points for local users. The results show 28% of the study area undergoing change, though in multiple trajectories, with both increasing and decreasing density of vegetation in discrete patches. Areas of change are shown to be closer to entrance points than areas experiencing no change. The patchiness of change results from complex issues in local enforcement authority for middle and lower-level officials in Forest Department bureaucracy, leading to further questions about the efficacy and impact of use restrictions in Protected Areas.     

Sand Fences in the Coastal Zone: Intended and Unintended Effects

Sand-trapping fences modify the character of the coastal landscape and change its spatial structure, image, and meaning. This paper examines the relationship between these changes and fence usage at the municipal level, where most decisions about fence deployment are made. Use of fences in 29 municipalities on the developed coast of New Jersey is examined over a 6-year period. Interviews with municipal officers indicate that wooden slat sand-trapping fences are used primarily to build dunes to provide protection against wave uprush and flooding, but they are also used to control pedestrian traffic and demarcate territory. These uses result in changes in landforms and habitats. An aerial video inventory of fences taken in 2002 indicates that 82% of the shoreline had fences and 72% had dunes. Single and double straight fence rows are the most commonly used. Fences are often built to accomplish a specific primary purpose, but they can cause many different and often unanticipated changes to the landscape. The effects of a sand fence change through time as the initial structure traps sand, creates a dune that is colonized by vegetation, and becomes integrated into the environment by increasing topographic variability and aesthetic and habitat value. Sand fences can be made more compatible with natural processes by not placing them in locations where sources of wind blown sand are restricted or in unnatural shore perpendicular orientations. Symbolic fences are less expensive, are easy to replace when damaged, are less visually intrusive, and can be used for controlling pedestrian access.