Levels Of Trampling Research Articles

A field study of the surface disturbance effects of animals and motor vehicles on aeolian sediment emission from a silty playa surface

Dry playa surfaces can be extremely vulnerable to disturbance which breaks their surface crusts resulting in increased aeolian sand and dust emissions. Trampling by livestock and motor vehicles is an important source of this disturbance. The Hamoun Lakes in the Sistan region of Iran are a major source area of dust storms which are causing damage to infrastructure and communities. This study performed portable wind tunnel tests of controlled surface disturbance by animals (cow, sheep) and motor vehicles (automobile, motorcycle) on a silty playa surface of Hamoun Saberi lake. The aim of this study was to assess the effect of different levels of trampling and disturbed surfaces by both vehicles and livestock on dust emission at wind speeds of 6 and 12 m s−1. A significant increase of sediment emission was found with increased number of passes of vehicles and livestock and the degree of surface disturbance, more so at the high wind speed (12 m s−1). No significant differences were observed between a 10–20% disturbance level and an undisturbed surface, but statistically significant differences became apparent when disturbances reached 50–60% to 90–100% compared to undisturbed surfaces. Greater emission rates were reached by disturbances provided by automobile and cow compared to motorcycle and sheep, indicating greater trampling effects of automobile and cow likely related to greater weight and larger footprint. The automobile was the most surface-destructive of the four anthropogenic disturbances, providing emission in a lower number of passes compared to the motorcycle, cow and sheep. Better management of vehicle and livestock allocation on playas subject to disturbance, such as the Hamoun Lakes, will be a useful strategy to reduce disturbance and the frequency and intensity of dust storms.

A preliminary faunistic study of soil nematodes from different land uses in Tropical Deciduous Forest in the Costa Chica of Guerrero, Mexico

Tropical Deciduous Forest (TDF) is an important biome threatened globally by climate change and human encroachment. Changes in diversity and abundance of soil nematodes can serve as indicators of soil disturbance due to human activities. Our objective was to present a first inventory of the generic biodiversity of soil nematodes in seven TDF sites subjected to different current or decade-old land uses, located near Copala in the Costa Chica region of Guerrero, Mexico. TDF landscapes are especially heterogeneous in many soil and microclimate parameters, while subsistence agriculture systems in this biome are highly diverse and present great challenges for sampling design with replication. We therefore chose to focus on characterizing the soil nematode fauna, as a first step before undertaking detailed analyses of all potentially relevant biotic and abiotic factors. Genus-level diversity ranged from 12 to 18 taxa for the sampled land uses, or 27 total taxa for all samples combined. Statistical tests for data analysis without replication revealed significant differences in nematode diversity, trophic structure, and abundance between land uses. Four sites, left as fallows for ten years after prior human uses, were statistically different from each other as well as from a forest site undisturbed for at least twenty years. Despite the methodological limitations inherent in this initial study, we hypothesize that some effects on nematode communities may persist for more than a decade after the anthropogenic impacts of subsistence farming in TDF. Thus, future nematode surveys in the TDF biome should not only analyze the current properties of sampling sites, but also document data related to factors from past human use activities. Example factors, suggested by the pattern of nematode abundance from the seven sites in our study, include past levels of trampling by human traffic and grazing, as well as estimates of past amounts of plant debris deposition accumulated by harvesting or weeding.

Vegetation and Animal Performance Responses to Stocking Density Grazing Systems in Nebraska Sandhills Meadows

Management-intensive grazing, which is proposed to increase forage and animal productivity and maintain soil integrity and biodiversity, is seen as an alternative to meet 21st century agricultural and environmental challenges. The purpose of this study was to test the hypothesis that high levels of trampling of standing vegetation associated with mob grazing (a.k.a., ultrahigh stocking density) leads to increased plant diversity and productivity. A long-term experiment was established on a subirrigated meadow in the Nebraska Sandhills as a complete block design comparing three grazing treatments applied annually during the growing season for 8 consecutive yr (2010−2017): 120-pasture rotation with one grazing cycle (mob; 225 000 kg live weight ha−1), four-pasture rotation with one grazing cycle (4PR1; 7 000 kg live weight ha−1), and four-pasture rotation with two grazing cycles (4PR2; 5 000 kg live weight ha−1). All treatments were set at a moderate stocking rate (7.4 animal unit months ha−1) using yearling steers. Percentage trampling, plant production, species composition, and steer weight gain were estimated annually. We applied linear mixed-effect models to account for year and treatment effect on the response variables. Percentage trampling on mob pastures ranged from 40% to 55% over the 8 yr of the study, nearly double that of the 4PR1 and 4PR2 pastures. We observed that mob grazing had no overall effect on plant species composition, aboveground production, and root growth relative to low stocking densities. Average daily gain of steers in the mob pastures was less than gain of steers in 4PR2 pastures in all years, with intermediate weight gains for the 4PR1 steers. Overall, stocking density did not appear to be a driver of plant composition and productivity in rotationally grazed pastures on subirrigated meadows in the Nebraska Sandhills.

Different levels of rainfall and trampling change the reproductive strategy of Kobresia humilis in the Qinghai-Tibet Plateau

The sedge Kobresia humilis (C.A. Mey. ex Trautv.) Serg. is the dominant plant in the alpine meadows of China’s Qinghai-Tibet Plateau, which has experienced substantial grassland degradation due to reduced rainfall and overgrazing. In this study we sought to determine the reproductive strategy of K. humilis under three levels of rainfall and seven levels of trampling by Tibetan sheep and yaks with a two year simulation trial on the Plateau. With a reduction in rainfall and an increase in trampling intensity, there was a decrease in sexual reproduction indices, plant height and single leaf number. The highest rainfall promoted sexual reproduction, whereas average rainfall was conducive to vegetative reproduction, and the lowest rainfall inhibited reproduction. The reproductive strategy of K. humilis could be judged according to the average rainfall from July to August. Notably, after two years of low rainfall and a heavy trampling treatment, K. humilis produced more seeds with smaller size. The rainfall presented a two-way regulation function in the trampling effect on K. humilis reproductive characteristics.

Trampling, defoliation and physiological integration affect growth, morphological and mechanical properties of a root-suckering clonal tree.

Grazing is a complex process involving the simultaneous occurrence of both trampling and defoliation. Clonal plants are a common feature of heavily grazed ecosystems where large herbivores inflict the simultaneous pressures of trampling and defoliation on the vegetation. We test the hypothesis that physiological integration (resource sharing between interconnected ramets) may help plants to deal with the interactive effects of trampling and defoliation. In a field study, small and large ramets of the root-suckering clonal tree Populus simonii were subjected to two levels of trampling and defoliation, while connected or disconnected to other ramets. Plant responses were quantified via survival, growth, morphological and stem mechanical traits. Disconnection and trampling increased mortality, especially in small ramets. Trampling increased stem length, basal diameter, fibrous root mass, stem stiffness and resistance to deflection in connected ramets, but decreased them in disconnected ones. Trampling decreased vertical height more in disconnected than in connected ramets, and reduced stem mass in disconnected ramets but not in connected ramets. Defoliation reduced basal diameter, leaf mass, stem mass and leaf area ratio, but did not interact with trampling or disconnection. Although clonal integration did not influence defoliation response, it did alleviate the effects of trampling. We suggest that by facilitating resource transport between ramets, clonal integration compensates for trampling-induced damage to fine roots.

Effects of fragmentation and trampling on carabid beetle assemblages in urban woodlands in Helsinki, Finland

We studied the effects of fragmentation (edge effects and patch size) and trampling (path cover) on carabid beetle assemblages in urban woodland patches in Helsinki, Finland. We expected that (1) open habitat and generalist species would benefit and forest species would suffer from increased woodland fragmentation, and (2) most carabid species would respond negatively to increased levels of trampling. A total of 2088 carabid individuals representing 37 species were collected. A cluster analysis distinguished sites in the interior of large woodland patches, with low or moderate path cover, from the other sites. The other sites did not cluster meaningfully, suggesting increased variation in the carabid fauna with increasing human impact. All species and ecological species-groups decreased with increasing distance from the edge toward the woodland interior and with increasing patch size. This pattern is in accordance with our expectation for open habitat and generalist species but opposite to what we expected for forest species. The reason for these surprising results may be that (1) the species we collected are not true forest interior species, (2) urban woodland edges are optimal habitats for many forest carabids, or (3) edges are actually sub-optimal, and high catches simply reflect increased activity of beetles moving away from the edge. Trampling did not have an overall negative effect on carabids as hypothesized. Species associated with moist forest habitat responded as predicted: they decreased in abundance with increasing path cover. Furthermore, open habitat species decreased with increasing path cover but more straightforward than we had predicted. Model elaboration, by dropping the highly trampled sites from the analyses, suggested that our data of high trampling may be too scarce: the results without these sites were more in accordance with our predictions than with the full dataset.

Trampling resistance of tropical rainforest soils and vegetation in the wet tropics of north east Australia

Controlled trampling was conducted to investigate the trampling resistance of contrasting high fertility basaltic and low fertility rhyolitic soils and their associated highland tropical rainforest vegetation in north east Australia's Wet Tropics. Although this approach has been taken in numerous studies of trampling in a variety of ecosystem types (temperate and subtropical forest, alpine shrubland, coral reef and seagrass beds), the experimental method does not appear to have been previously applied in a tropical rainforest context. Ground vegetation cover and soil penetration resistance demonstrated variable responses to trampling. Trampling, most noticeably after 200 and 500 passes reduced organic litter cover. Bulk density increased with trampling intensity, particularly on basalt soils as rhyolite soils appeared somewhat resistant to the impacts of trampling. The permeability of the basalt and rhyolite soils decreased markedly with increased trampling intensity, even after only 75 passes. These findings suggest physical and hydrological changes may occur rapidly in tropical rainforest soils following low levels of trampling, particularly on basalt soils.

The ecological response of forest ground flora and soils to experimental trampling in British urban woodlands

The ecological impact of recreation in woodlands and forests is now a subject of considerable world-wide interest. However, there are few studies examining the effects of recreation on woodland vegetation and soils in Britain. This paper quantifies the impact of controlled experimental trampling on three different woodland ground flora stands in lowland urban fringe W10 Quercus robur—Pteridium aquilinum—Rubus fruticosus woodlands (Rodwell, J.S. (1991) British Plant Communities I: Woodland and Scrub. Cambridge University Press) near Coventry, West Midlands. Relationships of plant cover, plant height and soil compaction with trampling in homogeneous stands of Hyacinthoides non-scripta (bluebell), Pteridium aquilinum (bracken) and Rubus fruticosus agg. (bramble) were curvi-linear, suggesting that rates of damage were most rapid at the initial stages of trampling. By virtue of its rosette growth form, the most resistant stand type was the Hyacinthoides stand. Least resistant was the Pteridium stand, but both the Pteridium and the Rubus stands were able to recover well from heavy levels of trampling by the following year. The ability of ground flora to tolerate impacts was more a function of an ability to recover from trampling, rather than to resist. Trampling had the most profound impact on the ability of Hyacinthoides non-scripta to produce seeds, and even two years after the cessation of impact, samples that had received one season of 500 passes had still not produced any seed bearing scapes. The carrying capacity of woodlands in terms of visitor numbers was lower than previously thought, with only 35 people permitted in stands dominated by Hyacinthoides, rising to 450 and 500 people in woodlands dominated by Rubus and Pteridium stands respectively. Models summarising these ecological changes are provided, along with applied recommendations to help manage urban sites with recreation and conservation in mind.

Effects of trampling by humans on animals inhabiting coralline algal turf in the rocky intertidal

This paper investigates the effects of trampling by humans on the fauna associated with articulated coralline algal turf. Patches of intertidal turf in a low-use area of the Cape Rodney to Okakari Point Marine Reserve (in north-eastern New Zealand) were experimentally trampled over 5 days at three levels that fell within those measured in a part of the reserve subject to heavy visitor use. Two days after trampling ended there were ∼2·10 5 individual macrofauna (>500 μm) per m 2 in control plots, but densities declined with increasing trampling intensity in the treatment plots, and were reduced to 50% of control values at the highest trampling intensity. Densities of five of the eight commonest taxa were negatively correlated with trampling intensity, with polychaetes being particularly susceptible to low levels of trampling. Three months after trampling ended densities of all taxa had returned to control values, with the exception of polychaetes. Reductions in animal densities are tentatively attributed to the loss of turf and associated sand caused by trampling, rather than direct destruction of the organisms. Given the likely importance of these abundant and productive animals in the rocky reef ecosystem, and their vulnerability to low levels of trampling by humans, we conclude that the effective management of marine protected areas may necessitate total exclusion of humans in some cases.

EFFECTS OF PERIODIC DISTURBANCES FROM TRAMPLING ONROCKY INTERTIDAL ALGAL BEDS

We investigated the ability of an assemblage of animals and plants on rocky shores in southeastern Australia to resist and/or recover from repeated pulse disturbances in the form of trampling. Disturbances of four different intensities were applied experimentally over six summers, with no human access at other times of the year. The dominant intertidal plant, the brown alga Hormosira banksii, was affected by trampling, but the effects were heterogeneous between sites. At two sites, a series of pulse disturbances produced a series of pulse responses, although the effect of a given pulse varied among years, possibly related to the severity of summer desiccating conditions each year. At the third site, pulse disturbances produced a press response; at high levels of trampling, Hormosira was almost eliminated within 2 yr, and at two intermediate levels of trampling, cover was reduced from >90 to 60–70%, where it remained for 4 yr. Effects of trampling showed little small-scale spatial variation. Untrampled areas did fluctuate through time, often as a result of summer burnoff of algae. Natural disturbances occurred irregularly through the study, and their effects varied on very small spatial scales (among plots <30 m apart). Trampling enhanced the densities of a range of herbivorous mollusks, especially limpets, and reduced the abundance of articulated coralline algae, which were abundant in the understory of Hormosira mats. These effects varied among sites but showed much less variation on smaller spatial scales. The reductions in coralline algae may be a direct effect of trampling, but increases in mollusk abundance occurred some time after changes to Hormosira cover, and those changes may be an indirect effect of trampling. We compared the effects of trampling on areas of the shore that had been trampled for two and four summers, to test whether a past history of disturbance influenced the effect of a new disturbance. No significant effects were found on algae or mobile animals, although a mild summer may have made our test of history relatively weak. Hormosira banksii fits the definition of a keystone species or engineer and, as such, is an appropriate focus for management and as an indicator. Spatially heterogeneous effects of a constant physical perturbation, however, mean that management of these rocky shores requires more complex models and indicate that caution should be used in adopting this species as a uniform indicator of environmental change.

Trampling Effects on Bryophytes: Trail Surveys and Experiments

A survey was made of bryophytes associated with trails near Moun- tain Lake, Virginia, totaling 35 species, all common in the adjacent forest. The species having highest importance values on the trails were, in order of decreasing importance values: Hypnum imponens, Dicranella heteromalla, Thuidium delica- tulum, Atrichum angustatum, Polytrichum ohioense, Leucobryum glaucum, and Callicladium haldanianum. To assess trampling resistance in bryophytes, experi- mental plots of Polytrichum commune, Ditrichum pallidum, and Sphagnum recur- vum were subjected to known levels of trampling by humans. Sphagnum recurvitm was the most vulnerable species, fragmenting after 130 passages. After 4200 pas- sages Polytrichum commune showed considerable internal damage to portions of the stem and fragmentation of its leaves while Ditrichum pallidum showed little damage-the small shoots evidently cushioned by each other and by burial in the soil. After 19 days, regeneration of new shoots from the rhizome-like stems of Polytrichum commune was readily apparent in the field, and microscopic exami- nation showed the production of secondary protonemata and shootbuds from leaf fragments in the muck. Secondary protonemata and shootbuds were produced from stems and leaves of intact plants and of shoot fragments of Ditrichum pal- lidum. Trample-resistant structural features and high regenerative abilities ap- parently contribute to the importance of bryophytes on trails as potential inhibitors of soil erosion.

Effects of repeated use of an area of heather Calluna vulgaris (L.) hull moor at Kindrogan, Scotland, for teaching purposes

A triangular plot of heather moor at Kindrogan was used for teaching botanical analysis for eight years, using the same set of random coordinates to locate sample points. Because of the method of point location, there was a gradient of trampling pressure across the plot, and there were also parts of the plot that were never analysed. At the end of the eight-year period heather cover and mean height were found to have declined with increasing levels of trampling. Mean numbers of species/m 2 did not however decline, and were actually minimal on untrampled ground. With moderate levels of trampling, quadrats that had been analysed for eight years contained more heather litter than those that had not been analysed before. No decline in species frequencies was found in previously analysed quadrats. The value of the plot for teaching purposes does not seem to have declined, and may have actually increased over the period of use.

Effect of Trampling by Cattle on Bluegrass Yield and Soil Compaction of a Meadowville Loam1

AbstractThe objective of this research was to evaluate both the tolerance of a Meadowville loam soil (Typic Hapludult; fine‐loamy, mixed mesic) and bluegrass (Poa pratensis L.) grown in this soil to three levels of trampling by cattle. The protective effect of 2.5 cm, 7.6 cm, and 20.3 cm of bluegrass at tune of trampling, as measured by the resistance of the soil to penetration, was studied. The trampling pressures, repeated four times during the year, were 0, 60, and 120 trips/cow. The pressure, kg/cm2, required for the point of the penetrometer to penetrate the soil was significantly different among trampling pressures for 1, 3, and 4 trampling dates. As trampling intensity increased, maximum resistance to the penetrometer was encountered closer to the soil surface. The height of forage at trampling had no significant affect on either the force required to penetrate the soil or depth of soil at which maximum resistance to penetration was encountered.Yields of herbage from plots clipped from 20.3 cm to 7.6 cm prior to trampling and after trampling to 2.5 cm were compared with yields from plots clipped prior to and after trampling from 20.3 cm to 2.5 cm, respectively. Yields from plots clipped at 2.5 cm prior to trampling compared to plots not clipped prior to trampling were slightly lower. Increasing trampling pressure had a significantly adverse affect on forage yield for tramplings in June and September.