Sheep Trampling Research Articles

Evaluation of Sheep Trampling at Different Grazing Periods on Soil Attributes

With the objective of evaluating the possible deterioration in some physical and chemical soil attributes, caused by sheep trampling in pasture areas compared to preserved areas. The study was conducted at the Instituto Federal de Educação, Ciência e Tecnologia da Paraíba - Campus Sousa, located in the Irrigated Perimeter of São Gonçalo, between the geographic coordinates 06o 50` 22 "S; 38o 17 ` 42" W; at 220 meters of altitude. The statistical design was in Randomized Blocks (DBC), with 3 treatments composed of: T1= no animals (preserved); T2= rainy period sheep grazing; T3= dry period sheep grazing, with six repetitions each. To determine the chemical attributes, soil samples were collected at a depth of 0 - 20 cm to determine (pH, phosphorus, potassium, sodium, calcium, magnesium, aluminum and organic matter) and physical attributes (sand, silt clay, soil density, total porosity, water dispersed clay) except for bulk density was taken from unformed samples at a depth of 0 - 10 cm from the soil. The sheep grazing in the different periods promoted soil compaction expressed by increased soil density, reduced total porosity and lower clay aggregate content. The permanence of grazing animals promoted a reduction in soil chemical quality, notably for phosphorus, calcium, magnesium and SOM contents in grazed sheep during the dry season and an increase in sodium and PST, compared to the area without grazing (preserved).

Effects of yak and Tibetan sheep trampling on soil properties in the northeastern Qinghai-Tibetan Plateau

Grassland soil is affected by trampling, ingestion and excretion by herbivores, of which the effects of trampling are most pronounced and intense. However, the mechanism of livestock trampling on grassland soil remains uncertain. The objective was to ascertain the differential effects of trampling by yaks and Tibetan sheep on grassland at different grazing intensity. Therefore, we simulated yak and sheep trampling during two consecutive years of 2015 and 2016 at different intensities and investigated their effects on soil properties in a Tianzhu alpine meadow in Gansu Province, China. Our results revealed that soil bulk density under heavy trampling at 0–10 cm depth was significantly higher than that of untrampled treatment (CK), while saturated hydraulic conductivity, respiration rate, and number of microbial colonies (bacteria, fungi, and actinobacteria) significantly decreased. With increase in trampling intensity, the soil available nitrogen (AN) and available potassium (AK) increased at 0–20 cm depth, while total nitrogen (TN) and total phosphorus (TP) at 0–20 cm and available phosphorus (AP) at 0–10 cm decreased. Total potassium (TK) and organic matter did not differ significantly with trampling intensity. Yak trampling increased bulk density, AN, and AK, and decreased the soil respiration rate, saturated hydraulic conductivity, number of microbial colonies, TN, TP, and AP. Soil consolidation was alleviated after freeze-thaw cycling and the off-season grazing in the cold season. Our results demonstrated that heavy trampling by livestock compacted surface soil, reduced soil permeability, and weakened the living environment for microorganisms. Therefore, yak trampling had more severe effects on soil consolidation than that by Tibetan sheep in the alpine meadow of the Qinghai-Tibetan Plateau.

Yak and Tibetan sheep trampling inhibit reproductive and photosynthetic traits of Medicago ruthenica var. inschanica.

Livestock grazing affects grassland stability, resilience, and productivity owing to trampling, foraging, and excretion. Over time, trampling influences a wide range of grassland components and can have lasting effects. Trampling helps maintain grassland health but may also cause its degradation. In a field experiment over two growing seasons, we simulated yak and sheep trampling at different intensities and investigated their effects on the reproductive and photosynthetic characteristics of Medicago ruthenica var. inschanica in a Tianzhu alpine meadow in Gansu Province, China. Our results show that simulated trampling inhibited the asexual and sexual reproduction and growth of M. ruthenica. The root surface area, root volume, root biomass, pod length, pod number per unit area, number of seeds per pod, thousand-seed weight, and seed yield were significantly reduced under simulated trampling in the upper 30cm of soil (P < 0.05) but were not reduced in the deeper soil layers (> 30cm). Light trampling by both yak and Tibetan sheep promoted photosynthesis, while heavy trampling by both species inhibited photosynthesis. Yak trampling inhibited photosynthesis more than Tibetan sheep trampling, and overall, the adverse effects of yak trampling on asexual and sexual reproduction and growth of M. ruthenica were greater than those of Tibetan sheep trampling. Thus, the effect of yak trampling is greater than the effect of trampling by Tibetan sheep, where the different trampling intensities of yak and Tibetan sheep can result in direct but varied influences on grasslands, potentially leading to grassland differentiation.

Sheep trampling on surface‐lying seeds improves seedling recruitment in open sand ecosystems

Low‐intensity grazing with domestic ungulates is an important tool in restoration to enhance habitat openness and foster light‐demanding plant species. Ungulates affect plant regeneration in different ways; one important factor is trampling. We hypothesized that in dry open sand ecosystems sheep trampling is beneficial for seedling recruitment. Therefore, we set up a standardized laboratory experiment, where we simulated trampling on surface‐lying seeds and measured the number of seedlings, mean germination time, synchrony of germination, and aboveground phytomass of seedlings. We studied seeds of 16 herbaceous species occurring in European open inland sand ecosystems, which depend on continuous disturbance dynamics. The species set comprised four plant families (Asteraceae, Caryophyllaceae, Fabaceae, and Poaceae) and two species groups (target and ruderal nontarget species). Across species, trampling had profound effects on seedling emergence, that is it induced a 3.5‐fold increase in the number of emerging seedlings. In addition, germination synchrony and aboveground phytomass increased after trampling, whereas mean germination time decreased. Interestingly, ruderal species seemed to be more susceptible toward trampling than target species. We conclude that sheep trampling strongly promotes seedling emergence in grazed open sand ecosystems by pressing seeds into the uppermost soil layer and improving microclimatic conditions.

Goat trampling affects plant establishment, runoff and sediment yields over crusted dunes

AbstractMainly attributed to goat and sheep trampling, the sand dunes at the Israeli and the Egyptian sides of the border present contrasting geomorphological conditions. In an attempt to assess the trampling effect upon vegetation, runoff and sediment yield, two pairs of plots and miniplots (each pair contains a trampled plot and a control) were constructed during 1991 and monitored during 1991–1995. In order to assess the impact on vegetation, three pairs of vegetation plots, subjected to light, medium and heavy trampling, were established during 1993 and monitored. In addition, the effect of the micro structures created by the goat hooves (mounds and depressions) were studied in three pairs of plots subjected to medium trampling during 1993 and monitored during 1993–1996. As far as trampling intensity is concerned, the findings indicate an increase in species diversity, density and biomass from the intact crusted surface to the plots subjected to light and medium trampling with a decrease thereafter at the plots subjected to heavy trampling. As for the micro scale, the findings indicate significantly higher plant biomass for the first 2 years at the hooves‐formed mini mounds and mini depressions in comparison to intact crusted surfaces, with no significant difference during the third year. Significantly lower runoff and sediment yields characterized the trampled plots implying a reduction in water redistribution. The data point to the differential effect that trampling has upon plants and soil. While increasing annual plant growth along the slope, it hinders runoff flow to the footslope, negatively affecting water availability for footslope vegetation. Recovery, as also supported by chlorophyll and microrelief measurements, was scale dependent (attributed to differential supply of aeolian sand) with estimated recovery for the plots and miniplots being 4–5 and 8–10 years, respectively. The data indicate that upon the cessation of grazing and under similar precipitation regime, recovery time of the biocrust in the Sinai sand dunes may be short, within 5–6 years. Copyright © 2016 John Wiley &amp; Sons, Ltd.

The impact of sheep grazing on burrows for pygmy bluetongue lizards and on burrow digging spiders

AbstractGrazing by domestic stock has altered and degraded natural grassland ecosystems worldwide, directly and indirectly impacting the endemic plant and animal species occupying those grasslands. The pygmy bluetongue lizard Tiliqua adelaidensis is an endangered species, restricted now to fragments of native grassland habitat in South Australia, which are predominantly grazed by sheep. These lizards exclusively occupy burrows dug by spiders, and use them as refuges, basking sites and ambush points. They do not dig their own burrows and rely on coexisting spiders for this essential resource. We asked how sheep grazing influences construction and persistence of spider burrows by comparing burrow dynamics in adjacent grazed and ungrazed grassland habitats. In ungrazed plots, spider burrows increased over one spring and summer period, particularly after a summer rain event that softened the soil. In grazed plots, more existing burrows were destroyed, presumably by sheep trampling, and fewer new burrows were constructed, leading to a net loss in burrow numbers over the same period. However, in this short study, grazing did not affect the number of pygmy bluetongue lizards or the number of lycosid spiders. Burrows that were lost tended to be shallower and to have smaller diameter entrances than those that were retained, suggesting that the best burrows for lizard refuges were more likely to persist despite sheep activity. However, heavy grazing may have negative impacts on both lizards and spiders, resulting from a reduction in available burrows and in spider digging behaviour.

Wind erosion in the central Ebro Basin under changing land use management. Field experiments with a portable wind tunnel

The agricultural landscape in the semi-arid central Ebro Basin is changing from dry farming towards land abandonment. This study aims to describe quantitatively the influence of this land use change onto wind erosion susceptibility in this region. Additionally, the effects of tillage operations on wind erosion rates were evaluated. A portable wind tunnel was used to assess the relative sediment loss rates at three test sites near Zaragoza. Three different land use systems varying in crust disturbance level were investigated – (1) fallow land with undisturbed physical soil crusts, (2) simulated sheep trampling and (3) conventional tillage (dry farming). The results show that simulations on undisturbed crusted soils produce little soil loss. Consequently, wind erosion can be considered as negligible on these surfaces. Simulated sheep trampling during wind tunnel test runs produce 10 times higher sediment losses than simulations on undisturbed crusted soils. Highest sediment losses (50 times) were observed from rolled surfaces. Because of the ongoing extensification process, the distributions of physical soil crusts will most probably further increase. According to the results, this would lead to a reduction of wind erosion susceptibility in the central Ebro Basin depending on intensity and time of sheep pasturing and tillage.

Spatial variability of soil properties affected by grazing intensity in Inner Mongolia grassland

Analysis of the spatial variability of soil properties is important to interpret the site-specific ecosystems not only with respect to process investigations but also to model upscaling. This paper aims to study the effects of the grazing intensity on soil physical and mechanical properties and their interactions in a Leymus chinensis steppe of the Xilin River Basin, Inner Mongolia, China. The investigated sites were subjected to five grazing intensities (ungrazed since 1979, ungrazed since 1999, winter grazing, continuous grazing and heavy grazing). Soil water content (SWC), hydraulic conductivity ( K), water drop penetration time (WDPT), shear strength (SS), soil organic carbon (SOC) concentration, bulk density (BD), and soil texture were measured at a grid with 15 m sampling distance on the surface soil during the period of 2004–2005. The data were analyzed using descriptive statistics and geostatistics. The correlation and interaction between soil properties were analyzed by the methods of Pearson correlation, partial correlation and multiple regression analysis. The results showed that spatial distributions of soil properties could be well described by spherical or exponential models. The ranges of spatial dependence were the highest for WDPT and the lowest for SS. Grazing decreased SWC, SOC and WDPT but increased BD and SS. Multiple regression analysis showed significant correlations among SWC, K, WDPT, SOC and BD; as well as between SS and silt content. Soil compaction induced by sheep trampling, especially in the heavily grazed site, inclined to a homogenous spatial distribution of soil properties, which will possibly enhance soil vulnerability to water and nutrient loss, and consequently reduce the plant available water and thus grassland productivity.

Thick moss layers and high cover of grasses: Potential threats to herb diversity in hay meadows in Norway

In an old, species-rich hay meadow in Varaldsøy in Hardanger, the only known remaining managed site of its kind in West Norway, the moss layer is increasing in thickness in some places. Thick moss is associated with a high cover of monocotyledons, while a low cover of monocotyledons is associated with high numbers of herbs, including vulnerable species, which mainly occur in herb-rich areas. The increase in moss is probably caused by a reduction in both traditional means of moss removal and in sheep trampling and it may represent a potential threat to plant species diversity in traditionally managed hay meadows in the region. In order to increase the area of open, species-rich hay meadows, and thus the potential population sizes for indicator species of traditional management, increased grazing intensity (back to traditional levels) and removal of mosses during haymaking is recommended. The study demonstrates that, for conservation purposes, it is not easy to replicate past conditions unless the details of traditional management practices are known and understood, and these are now passing from general knowledge.

Epizoochorous and post-dispersal processes in a rare plant species: Jurinea cyanoides (L.) Rchb. (Asteraceae)

We used Jurinea cyanoides as a model plant species to ask the question whether sheep play a dual role in enabling the establishment of a rare species (1) by epizoochorous transport of diaspores and (2) by influencing post-dispersal processes. We carried out two field experiments in sand grassland (Jurineo–Koelerietum glaucae) in the northern upper Rhine valley, Germany. In the first one, we attached diaspores to the fleeces of sheep and assessed retention time, seed shadow, seedling emergence and establishment. In the second one, diaspore displacement by sheep trampling was investigated. It could be shown that establishment of J. cyanoides is possible after sheep-epizoochorous dispersal, but is severely limited by several factors. First, retention time is mostly short (only 18% of the diaspores remained in the fleeces >2 h). Thus, the seed shadow is concentrated around the place of attachment (mostly <5 m distance, maximum 17 m). Second, seedling emergence of dispersed achenes is severely limited by above-ground granivory (99%). Third, establishment is limited by seedling mortality (68%) due to summer drought. The seedlings germinated from achenes that had been incorporated into the soil (or into deeper parts of the bryophyte layer). The second experiment showed that sheep trampling significantly enhanced the incorporation of achenes into the soil compared with controls. Our study gives evidence that sheep can play a dual role: diaspore transport and facilitation of establishment by trampling.

Vertical seed distribution in the soil constrains regeneration of Bromus pictus in a Patagonian steppe

Abstract:Question: What is the effect of vertical seed distribution (i.e. seeds on soil surface or buried) and the relative importance of vertical and horizontal seed distribution (i.e. seeds near established vegetation or near bare soil) for seedling emergence?Location: Patagonian arid steppe.Methods: To evaluate the effect of vertical seed distribution on seedling emergence, four sowing treatments were used in field and greenhouse experiments. Vertical vs. horizontal seed distribution and the occurrence of seedlings were analysed in the field. Effects of trampling and mechanical drilling on seedling emergence were investigated experimentally in the field.Results: In field and glasshouse experiments buried seeds showed a higher emergence and larger seedling size than seeds lying on the soil surface. The observational field study indicated that natural emergence was not associated with particular microsites or plant cover (horizontal distribution), but that most seedlings emerged from buried positions (vertical distribution). Buried seeds represented less than 10% of the sampled seed cohort but account for almost 60% of the seedlings. The trampling/drilling experiment showed that sheep trampling and mechanical drilling increased seedling emergence compared to non‐treated controls.Conclusions: The population dynamics of Bromus pictus is strongly constrained by the vertical position of seeds, which largely affects emergence, and seed horizontal distribution, which largely affects seedling survival. Our results showed that sheep trampling after seed dispersal may be a low‐input technique for increasing grass recruitment.

Vertical seed distribution in the soil constrains regeneration of Bromus pictus in a Patagonian steppe

Question: What is the effect of vertical seed distribution (i.e. seeds on soil surface or buried) and the relative importance of vertical and horizontal seed distribution (i.e. seeds near established vegetation or near bare soil) for seedling emergence? Location: Patagonian arid steppe. Methods: To evaluate the effect of vertical seed distribution on seedling emergence, four sowing treatments were used in field and greenhouse experiments. Vertical vs. horizontal seed distribution and the occurrence of seedlings were analysed in the field. Effects of trampling and mechanical drilling on seedling emergence were investigated experimentally in the field. Results: In field and glasshouse experiments buried seeds showed a higher emergence and larger seedling size than seeds lying on the soil surface. The observational field study indicated that natural emergence was not associated with particular microsites or plant cover (horizontal distribution), but that most seedlings emerged from buried positions (vertical distribution). Buried seeds represented less than 10% of the sampled seed cohort but account for almost 60% of the seedlings. The trampling/drilling experiment showed that sheep trampling and mechanical drilling increased seedling emergence compared to non-treated controls. Conclusions: The population dynamics of Bromus pictus is strongly constrained by the vertical position of seeds, which largely affects emergence, and seed horizontal distribution, which largely affects seedling survival. Our results showed that sheep trampling after seed dispersal may be a low-input technique for increasing grass recruitment.

Trampling of microphytic crusts on calcareous soils, and its impact on erosion under rain-impacted flow

Twenty five intact soil monoliths dominated by microphytic crusts were tested for their susceptibility to erosion by raindrop-impacted flow transport after subjecting them to simulated sheep trampling. Using a sheep's hoof, five levels of trampling representing stocking rates ranging from nil to 1.6 sheep ha −1, were imposed on the monoliths. An erosive stress was applied to each surface using a simulated rainfall intensity of 65 mm h −1 (2.7 mm raindrops), surface flow depths of 4 mm and 8 mm with a flow velocity of 25 mm s −1. There was a significant effect of trampling on erodibility ( P=0.003), and trampling explained 33% of the variability in erodibility. Only the severe trampling treatment had significantly higher erodibility compared with the other treatments. Compared to the control, severe trampling resulted in a significant decline in the area of the surface covered by micro-depressions and attached microphytic crust, and concomitant increases in loose, detached microphytic crusts, coarse lag gravel and bare soil. The results were supported by micromorphological examination which revealed that trampling and subsequent rainfall simulation resulted in considerable surface sealing and sorting of sediments, loss of fine material and deposition of coarse material in micro-depressions.

A comparison between continuous and controlled grazing on a red duplex soil. I. Effects on soil physical characteristics

The effect of sheep trampling and grazing management practice on soil physical characteristics was examined over one pasture season. The soil studied was a fragile sandy clay loam (red duplex soil) located in a dryland agricultural area (307 mm average annual rainfall) of Western Australia. The pasture was predominantly Serena medic ( Medicago polymorpha). The three grazing management practices investigated were: (i) traditional set-stocking (where sheep were grazed continuously for 17 weeks, beginning soon after the start of the early winter rains); (ii) controlled grazing (where sheep were temporarily removed from the enclosure when the topsoil was close to its plastic limit); (iii) no grazing (where the pasture was mown to simulate grazing without trampling). Topsoil structure was assessed in several ways: dry bulk density, infiltration rate and tensile strength measurements, and image analysis of resin-impregnated soil blocks. At the end of the grazing period, all soil structure attributes measured showed that topsoil structure under the controlled grazing practice was not only superior to that found under the traditional set-stocking practice, but similar to that found in the ungrazed treatment. Soil remoulding appeared to be a significant process contributing to the deterioration in topsoil structure. The plastic limit was used diagnostically and found to be an important soil property which should be routinely determined in order to aid management decisions. Continuous (or set-stocking) grazing practices in the pasture phase of wheat ( Triticum aestivum): pasture rotations can exacerbate the susceptibility of red duplex soils to structure deterioration and hardsetting. However, the degree of structure deterioration inflicted by stock can be minimised by removing stock for brief periods when the soil is close to its plastic limit.

The impact of sheep trampling and stocking rate on the physical properties of a red duplex soil with two initially different structures

The effect of sheep trampling and stocking rate on the physical properties of a red duplex soil with two initially different structures was examined over an 8 week period when the soil was wet following winter rains. The experimental site was located at Merredin in Western Australia where the average annual rainfall is 307 mm. A previous long-term tillage and gypsum trial at the experimental site had resulted in the development of contrasting topsoil structures. Three grazing treatments were imposed at the trial site: grazing at the normal high stocking rate (8 DSE ha-1), grazing at half the normal stocking rate (4 DSE ha-1), and no grazing (where pasture was mown to simulate grazing without trampling). Topsoil structure was assesed by measuring water-stable aggregation (&gt; 2 mm diameter aggregates), the relative contribution of dispersion and slaking to structural instability (measured as soil strength on &lt; 2 mm fine earth soil fractions), steady-state infiltration rates (at 10 mm tension), and in situ soil strength characteristics (measured as penetration resistance). At the end of the grazing period, all structure attributes measured showed that topsoil structure had been damaged as a result of sheep trampling. The magnitude of such structure damage was affected by the initial physical condition of the soil and stocking rate. When compared with ungrazed pasture, there was a greater decline in structural condition as a consequence of grazing on less well-structured soil than on better-structured soil. Halving the normal stocking rate reduced the degree of structure damage on both soils. Within-season variability in soil hydraulic properties was large. The temporal changes in infiltration rates were attributed to changes in drainage pore volume brought about by the growth and decay of pasture roots, the formation and disruption of a surface crust, and the processes of soil compaction and remoulding resulting from animal trampling (no direct measurements were made). The variability in hydraulic behaviour found in this study emphasizes the need to maintain consistent sampling dates and soil water contents at sampling in long-term studies on soil structure changes.

The effect of sheep trampling and grazing on soil physical properties and pasture growth for a red-brown earth

The experiment reported examined the effect of sheep trampling and grazing during wet conditions on soil physical properties and pasture growth over three winter seasons. The soil type studied was a structurally unstable sandy clay loam (a calcic red-brown earth) located in a dryland agricultural area (307 mm average annual rainfall) of Western Australia. Deferred grazing was investigated as a management option to reduce structural deterioration at the soil surface. Changes in soil physical properties as a result of trampling were related to soil water storage and pasture productivity. Infiltration rates were reduced as a result of sheep trampling, but there were no measurable changes in soil bulk density. Differences in pasture production between continuously grazed and ungrazed treatments were related to the amount of stored soil water, which in turn was related to infiltration rates. Pasture root growth during the season was also reduced as a result of trampling. Deferred grazing yielded the same quantity of biomass for feed over the reduced period available for grazing and proved to be a beneficial management practice since reasonably high infiltration rates were maintained. Results from the study also indicated that pasture must be adequately grazed to reduce leaf area later in the season when evaporative demand increases. A high leaf area over this time period may result in early pasture senescence.