Grazed Site Research Articles

Microbial responses to herbivory-induced vegetation changes in a high-Arctic peatland

Herbivory by barnacle geese (Branta leucopsis) alters the vegetation cover and reduces ecosystem productivity in high-Arctic peatlands, limiting the carbon sink strength of these ecosystems. Here we investigate how herbivory-induced vegetation changes affect the activities of peat soil microbiota using metagenomics, metatranscriptomics and targeted metabolomics in a comparison of fenced exclosures and nearby grazed sites. Our results show that a different vegetation with a high proportion of vascular plants developed due to reduced herbivory, resulting in a larger and more diverse input of polysaccharides to the soil at exclosed study sites. This coincided with higher sugar and amino acid concentrations in the soil at this site as well as the establishment of a more abundant and active microbiota, including saprotrophic fungi with broad substrate ranges, like Helotiales (Ascomycota) and Agaricales (Basidiomycota). A detailed description of fungal transcriptional profiles revealed higher gene expression for cellulose, hemicellulose, pectin, lignin and chitin degradation at herbivory-exclosed sites. Furthermore, we observed an increase in the number of genes and transcripts for predatory eukaryotes such as Entomobryomorpha (Arthropoda). We conclude that in the absence of herbivory, the development of a vascular vegetation alters the soil polysaccharide composition and supports larger and more active populations of fungi and predatory eukaryotes.

Effects of Grazing Enclosures on Species Diversity, Phenology, Biomass, and Carrying Capacity in Borana Rangeland, Southern Ethiopia

A grazing enclosure (GE) is one of the most effective techniques for restoring degraded rangelands by modifying the composition, abundance, and diversity of species. However, the effect of GEs on different grazing intensities and durations compared to open-grazing (OG) rangelands is not well known. We aimed to assess the effect of GE on the characteristics of plant species. We established five plots in a short-term enclosure, a long-term enclosure, and an OG treatment to examine the effect of GE on vegetation species’ height, abundance, diversity, phenology, biomass, heterogeneity, and the carrying capacity (CC) of rangeland under grazed and enclosed conditions. We found that GE significantly (P< 0.05) increased vegetation height, abundance, biomass, CC, phenological period, and species diversity. However, the increase in height, diversity, and phenological periods were not consistent with enclosure duration, and higher increments were recorded at the short-term enclosure site. The highest Shannon index value recorded at StGE (2.45) was 28.6 and 12.2% greater than the LtGE (1.75) and OG (2.15) sites, respectively. The advanced phenological periods were higher at the StGE site and showed 22.6 and 60.3% higher values than the LtGE and OG sites, respectively. The highest carrying capacities of 23.4 and 114.3% for livestock were observed at the LtGE compared to the StGE and OG grazing sites. In addition, the heterogeneity of the plants’ community was significantly higher in the long-term GE, due to the decrease in species’ diversity. In conclusion, this paper further contributes to the development of the theoretical basis on the effects of GEs and recommends strategies like rotational grazing and reseeding to be used in tandem with a GE for sustainable management of rangelands.

Effects of different livestock grazing intensities on plant cover, soil properties, and above and below ground C and N pools in arid ecosystems (Jiroft rangeland, Iran)

This study was conducted in Jiroft rangeland, Kerman, Iran to assess the effects of different livestock grazing intensities (low, moderate, heavy) on ecological factors, soil properties, and root and shoot carbon and nitrogen pools. In each plant sampling site, five points were selected and five quadrates (a total of 75 quadrats) were investigated. Soil surface samples were taken in quadrats (75 samples). Data analysis was carried out by analysis of variance (SPSS18.0). Findings indicated that canopy cover (46.23%) had the maximum level in the low grazing site. The diversity index was maximum in the overgrazed site (1.63), while the low grazing site had the minimum species diversity (1.27). In the three sites, the nitrogen and carbon pools were higher in the roots compared to the shoots. In the low grazing site, the plants' nitrogen and carbon pools were notably more than the heavy and moderate grazing sites. Potassium (612.87 mg kg-1), nitrogen (3.30 g kg-1), and organic carbon (39.20 mg kg-1) were considerably higher under heavy grazing conditions. However, the low grazing condition resulted in notable enrichment of phosphorus (11.44 mg kg-1). The soil nitrogen and carbon pool in the overgrazed site were higher. In spite of the fact that the soil nutrients in the heavy grazed site were higher because of livestock manure; we could not interpret it as greater soil fertility. Our results suggest that low grazing can be effective for managing plant community and soil quality in arid ecosystems.

The effects of land use and microsite availability on early seedling recruitment of Acacia tortilis (synonym: Vachelia tortilis) in a southern African savanna

Many tree recruitment studies in African savannas target individual factors that limit recruitment, yet recruitment of some species could be limited by an interplay of environmental filters. This study investigated the effects of land use and microsite availability on early seedling recruitment of Acacia tortilis in riverine woodlands in north-western Zimbabwe. The riverine woodlands were divided according to the level of human disturbance into protected and unprotected sites. Each site was further divided into riverine and off riverine microsites. In each microsite, we laid five main plots (100 × 50 m) and nine seedling subplots (5 × 5 m) nested in each main plot, making a total of 60 main plots and 180 subplots. We found higher seedling recruitment in unprotected than protected sites. Although seeder density was twice greater in protected than unprotected sites, seed bank density was lower in the former by a factor of 1.5. Tree cover and herbaceous biomass was 1.4 and 1.8 times greater in protected than unprotected sites, respectively but were negatively correlated with seedling density. Across all microsites, herbivory-related mortality was less than 40% while drought-related mortality was more than 60%. Put together, the results suggest that higher recruitment in unprotected sites was most likely facilitated by domestic ungulates through seed dispersal and grass suppression which enhanced the quality of regeneration sites. We conclude that encroachment of A. tortilis in communal grazing sites is not only important for its conservation but for a variety of goods and services derived from it.

Spontaneous poisoning by Dodonaea viscosa (Sapindaceae) in cattle in Southern Brazil

ABSTRACT: In this study, an outbreak of spontaneous poisoning by Dodonaea viscosa (D. viscosa) in a herd of dairy cattle in the municipality of Capão do Leão, Rio Grande do Sul, was investigated. Three deaths occurred in a batch of 16 Jersey cattle, aged between three and four years, kept in a native field. The clinical signs observed were apathy, decreased production, and anorexia, with death occurring within approximately 48 h after the onset of signs. The three cattle were necropsied, and tissue samples were sent for histopathological examination. Necropsy findings included serosanguineous fluid in the abdominal cavity, intestines with congested serosa, and marked mesenteric edema. The mucosa of the abomasum of two of the animals was hemorrhagic with bloody content, and among the ruminal content of a bovine, leaves with morphological characteristics compatible with D. viscosa were observed. The livers of the three animals were enlarged, with accentuation of the lobular pattern. Histologically, centrilobular coagulation necrosis with congestion and hemorrhage was observed in the liver. Vacuolization and degeneration of hepatocytes were observed in the mid-zonal and periportal regions. The diagnosis of poisoning by D. viscosa leaves was based on epidemiological data, necropsy findings, and histopathological alterations. The presence of the plant in the rumen and in the grazing site of the affected cattle was essential for the diagnosis.

Evaluation of Early Spring Grazing on Meadow in Erzurum, Turkey

This study was conducted in irrigated meadow with deep water table level in 2014 in Erzurum, Narman, Demirdag, and aimed to evaluate the effects of early spring grazing on meadows. Soil properties and dry matter yield and some quality parameters such as dry hay yield, crude protein, ADF, NDF and crude ash rates were assessed in meadow. Average dry matter yield was lover in spring grazed site than that of the ungrazed meadow site. Crude protein content was determined as 8.25%, 8.35% in grazed and ungrazed meadow sites, respectively. In spring grazed site ADF and NDF ratio were lower than that of the ungrazed one (36.95%, 36.72%; 55.98%, 56.82%). In grazed meadow site digestible dry matter ratio (60.29%) was lower than that of the ungrazed site (61.40%). Based on the results of the study, it is important to prevent of spring grazing in meadows for increasing of dry matter yield and forage quality.

Responses of plant, soil bacterial and fungal communities to grazing vary with pasture seasons and grassland types, northern Tibet

AbstractSynthetic responses of plant and soil microbial communities to grazing are indefinite in alpine grasslands on the Tibetan Plateau. Three paired, fenced and free grazing sites (alpine steppe meadow for winter pasture [ASMWP]; alpine steppe meadow for summer pasture [ASMSP]; alpine meadow for summer pasture [AMSP]) were used to compare how pasture season and grassland type affect responses of the α‐diversity and community composition of plant, soil bacteria and fungi to grazing. Cold‐season grazing reduced soil moisture by 12.10%, ammonium nitrogen (NH4+‐N) by 53.71%, the ratio of available nitrogen to phosphorus by 64.11%, species richness (SR) by 31.4% and the Shannon by 11.9% of plant community on the ASMWP. Warm‐season grazing reduced nitrate nitrogen by 30.45%, SR of soil bacterial community by 21.98% on the ASMSP, but increased soil NH4+‐N by 90.02% on the AMSP. Warm‐season grazing‐induced changes in plant community composition were mainly related to the composition of forbs on the AMSP. Grazing‐induced changes in the community composition of soil bacteria were mainly related to Proteobacteria, Acidobacteria, Bacteroidetes, Firmicutes and Verrucomicrobia on the ASMWP, and Proteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi and TM7 on the ASMSP. Grazing‐induced changes in the community composition of soil fungi were mainly related to Ascomycota and Basidiomycota on the ASMWP, Basidiomycota on the ASMSP and Ascomycota on the AMSP. Therefore, the effects of grazing on plant and soil microbial communities may vary with grassland types and pasture seasons, which may be related to grazing‐induced changes in available nitrogen, the ratio of available nitrogen to phosphorus and soil moisture.

Nutrient concentrations in two savannah grass species and their implications for grazers

The diversity of grazers on savannahs exerts pressure on the grass to provide nutrition. In this study the concentrations of major and trace animal nutrients in above ground grass tissue as influenced by grazing were examined. Two palatable grass species grazed by both livestock and wild grazers were sampled: Brachiaria nigropedata and Eragrostis lehmanniana. Samples of grass tissue were collected from widely spread sampling sites in both livestock and wildlife grazing sites, at the end of the growing season. Although B. nigropedata had higher nutrient concentrations, there was general covariance in nutrient levels in the two grasses. The covariance indicated that the respective sites generally had location context-dependent low or high nutrient concentrations in all grasses. The adequacy of the nutrient concentrations for grazer nutrition was assessed using literature-sourced minimum and maximum tolerable limit requirements of cattle and the high population gazelle-like species as illustration. The results showed that, in these nitrogen-limited savannahs, the grass generally met grazer requirements in terms of crude protein, potassium, molybdenum, nickel and zinc but that it had deficiencies in phosphorous, sodium, and boron, as well as grazing intensity-related localised toxic levels of potassium, phosphorous, magnesium, iron and manganese. The deficiencies and toxicities were inferred to result in abnormalities in grazer physical condition and reproduction. Given the importance of livestock in semiarid savannahs, these effects on livestock grazers were inferred as threatening human food security. The study shows that high grazing intensity can raise the concentrations of some animal nutrients in above ground grass tissue to levels above grazer tolerable limits. Grazing rotation to reduce grazing intensity is recommended as a proactive grazing management strategy to limit the effects.

Spatial Distribution of Grazing Sites and Dung of Beef Cows in a Sloping Pasture

Spatial Distribution of Grazing Sites and Dung of Beef Cows in a Sloping Pasture

Grazing Effects on Soil Physical and Chemical Properties

Uncontrolled grazing can have deteriorative effects on soil properties. This paper studied the effect of different grazing intensities on soil physicochemical and hydraulic properties at Al-Khanasry Agricultural Station, Al-Mafraq, Jordan. In summer 2016. Treatments were (1) no-grazing (NG), (2) controlled grazing (CG), and (3) uncontrolled grazing (UnG) sites. Soil samples were collected from each site to determine bulk density (BD), aggregate stability (AS), soil organic matter (SOM), electrical conductivity (EC), soil acidity (pH), and cation exchange capacity (CEC). Infiltration (F (t)) and hydraulic conductivity (HC) were measured in the field. Results showed that UnG significantly increased BD, Controlled and un-controlled grazing sites showed similar BD (P=< 0.05), the highest was in controlled grazing (1.47 g cm-3). Aggregate stability also increased under grazing condition (P=< 0.05) only in the surface layer (AS), The lowest AS in surface layer was observed in no-grazed plot (17.4%), while no significant difference (P=< 0.05) were observed between controlled and un-controlled grazing plots (24.6 and 24.8%), respectively. In significant (P=< 0.05) Grazing increased soil OM in surface layers. Un-controlled grazing area had significantly (P=< 0.05) higher OM content (3.5%) compared to the no-grazed, but not significant (P=< 0.05) from the controlled grazing area (3%). Grazing significantly decreased F(t) and HC when compared to NG. Grazing significantly (P=< 0.05) reduced cumulative infiltration. The highest cumulative infiltration was observed in no-grazed area while the lowest was in un-controlled grazing area. Also, significant results showed that Grazing reduced (HC), however no significant (P=< 0.05) differences were observed between controlled and un-controlled grazing areas (P=< 0.05). The higher HC was in no-grazed site (0.172*103 cm s-1) while the lowest was in un-controlled grazing area (0.034*103 cm s-1). Therefore, controlling grazing intensity is recommended in these dry areas.

The effect of earthworms on plant diversity and soil properties under different landuses

Earthworms have significant effect on vegetation and soil physical and chemical properties. The relationship between earthworms and biodiversity is important in ecological researches. Therefore, the effects of earthworm on plant diversity and various indices of diversity and richness, as well as physical and chemical properties of soil in shrub, grass and bare vegetation types on exclosure and grazing sites of Miankaleh Mazandaran biosphere reserve is investigated in this work. Accordingly, sampling was carried out randomly-systematically in three different vegetative types (shrubs, grass and bare soil) at 0 to 20 cm depth. Each vegetative types was placed on three transects of 100 m, 10 plots at a distance of 30 m. Earthworm and soil were sampled from the center of each plot of 25 cm × 25 cm. The Simpson and Shannon-Wiener indexes and Margalef and Menhinick richness indices were used to evaluate diversity and richness of species at different grazing intensities. Stepwise regression was used to study the relationship between diversity and richness indices with different earthworm parameters. The results showed that there was significant difference of potassium and nitrogen in vegetation types of both exclosure and grazing sites at P ≤ .01. Furthermore, the organic carbon, organic matter and potassium in the exclosure site and nitrogen and soil moisture in the grazing site are increased by earthworm abundance.

Microbial Water Quality Conditions Associated with Livestock Grazing, Recreation, and Rural Residences in Mixed-Use Landscapes

Contamination of surface waters with microbial pollutants from fecal sources is a significant human health issue. Identification of relative fecal inputs from the mosaic of potential sources common in rural watersheds is essential to effectively develop and deploy mitigation strategies. We conducted a cross-sectional longitudinal survey of fecal indicator bacteria (FIB) concentrations associated with extensive livestock grazing, recreation, and rural residences in three rural, mountainous watersheds in California, USA during critical summer flow conditions. Overall, we found that 86% to 87% of 77 stream sample sites across the study area were below contemporary Escherichia coli-based microbial water quality standards. FIB concentrations were lowest at recreation sites, followed closely by extensive livestock grazing sites. Elevated concentrations and exceedance of water quality standards were highest at sites associated with rural residences, and at intermittently flowing stream sites. Compared to national and state recommended E. coli-based water quality standards, antiquated rural regional policies based on fecal coliform concentrations overestimated potential fecal contamination by as much as four orders of magnitude in this landscape, hindering the identification of the most likely fecal sources and thus the efficient targeting of mitigation practices to address them.

Effects of grazing exclusion on soil respiration components in an alpine meadow on the north-eastern Qinghai-Tibet Plateau

Grazing exclusion has been widely used to restore degraded grasslands worldwide. Total soil respiration (Rs) (consisting of heterotrophic respiration (Rh, microbes and soil fauna respiration) and autotrophic respiration (Ra, plant root and their symbionts respiration)) play a critical role in the global carbon (C) balance. Quantifying Rs, Rh and Ra in relation to different grazing exclusion durations is vital to better understanding the impact of grassland management on global C cycling. However, how Rs and its components respond to different grazing exclusion durations remain unclear. Therefore, in this study, a trenching method was used to separate the Ra and Rh in an alpine meadow with different grazing exclusion durations (0, 4, 7, 10 and 12 years) on the north-eastern Qinghai-Tibet Plateau. Our results demonstrated that the growing season Rs, Rh and Ra showed nonlinear (hump-shaped) response patterns with the length of grazing exclusion, with a peak point at the 7-year grazing exclusion. Meanwhile, grazing exclusion treatments significantly increased the Rs, Rh and Ra compared to the grazed site. Grazing exclusion substantially increased the soil respiration temperature sensitivity (Q10) values of Rs, Rh and Ra. Moreover, the Q10 values of Ra and Rh showed hump-shaped response patterns with the length of grazing exclusion, with a threshold of 7 years grazing exclusion. The annual Ra/Rs ratio ranged from 53% to 69% during the growing season, indicating that changes in soil respiration were mainly determined by changes in autotrophic respiration. In addition, soil temperature could better explain Rh (R2 = 0.89–0.94) than Ra (R2 = 0.84–0.9). Our research highlights the nonlinear response of Rs, Rh and Ra to the length of grazing exclusion, and suggests that different grazing exclusion durations should be considered for better evaluating the impact of grassland management on global C cycling on the north-eastern Qinghai-Tibet Plateau.

When savannas recover from overgrazing, ecohydrological connectivity collapses

Grasslands and savannas across the globe have undergone a dramatic transition over the past century. Historical overgrazing has set in motion a cascade of events ranging from desertification in arid climates to woody plant encroachment (WPE) in semiarid and subhumid climates. In recent decades, grazing pressure on many of these landscapes has declined significantly, and where rainfall is sufficient (as in most semiarid and subhumid settings), herbaceous vegetation in intercanopy areas will recover. An important question is, how has this transition altered ecohydrological connectivity (overland flow and runoff–runon dynamics)? A woody-plant-encroached, subhumid savanna site in South Texas with a history of heavy grazing (but ungrazed since 1981) was used as a model landscape to address this question. Overland flow, soil moisture, and field saturated hydraulic conductivity (Kfs) were measured along a catena extending from the upland savanna-parkland areas to the downslope, more densely wooded areas. For comparison, Kfs and infiltrability were also measured at a moderately grazed upland site 14 km east of our study site, selected as a surrogate for past conditions at our site. In contrast to the prevailing hypothesis that the downslope areas (‘drainage-woodlands’) at our study site have continued to be supported by runoff generated from the upland areas, our measurements yielded no evidence for the redistribution of water from the uplands to the drainage areas under the current ungrazed conditions. Further, Kfs at the ungrazed study site was two orders of magnitude higher than that at the grazed site and infiltrability was twice as high at the ungrazed site than the grazed site. These findings, coupled with historical information from the site, strongly suggest that historical overgrazing amplified the runoff–runon process, resulting in significant subsidies of water from the uplands to the drainage areas. Then, with the relaxation of grazing pressure and subsequent landscape recovery, redistribution of water via surface runoff was relatively rare. We believe that our results are generalizable for savannas that have recovered from overgrazing. When these savannas are heavily grazed, ecohydrological connectivity is greatly increased; but if grazing pressure relaxes, ecohydrological connectivity will collapse. These changes in ecohydrological connectivity have important, but not always well understood, ecological consequences.

The Dynamics of Livelihood Assets on Moving Duck Farmers

Moving duck farming is a livelihood system that does not occupy a settled location but moves. Therefore, the relationship between livelihood assets, livelihood strategies, and livelihood outcome is influenced by the characteristics of the moving. This study aims to explain the dynamics of livestock capital of duck farmers moving at various distances in their moving cycle. Data collection techniques were participatory observation, in-depth interviews, and documentation. Comparative analysis was applied to see the dynamics of livelihood assets composition based on sequences and moving distances. The result showed that there was a dynamic utilization of livelihood assets based on the moving cycle between the travel process and the settling process at the grazing location. It was concluded that there were differences in the composition of the use of human capital, financial capital, physical capital, natural capital, and social capital between short-distance, medium-distance, and long-distance movements. This study found that the livelihood assets usage on moving duck farming was attributed to the moving traveled distance. At nearby movements, livelihood assets tend forgone for moving duck farming since they are also used for paddy fields. Livelihood assets, such as human, natural, and physical capital, are more dominant than the financial and social capital. The capital carries out to retrieve the fields after harvesting as a grazing site while sustaining that access. It can be concluded that the livelihood assets utilization in moving duck-based livelihood systems are dynamics based on the cycle and the distance of moving covered.

Spontaneous Poisoning by Sprouts of Xanthium spp. in Cattle in Southern Rio Grande do Sul

Background: Xanthium spp., the cockleburs, are invasive plants found on riverbanks, lakeshores, and floodplains. Ingestion of Xanthium sprouts or fruit causes cocklebur toxicosis, which is characterized clinically and pathologically by acute liver failure. The main lesion observed is an accentuation of the lobular pattern of the liver (nutmeg appearance), which is microscopically characterized by coagulation necrosis in the centrilobular region, hepatocyte degeneration in other regions of the hepatic parenchyma, and sinusoidal congestion. The objective of this study was to describe an outbreak of spontaneous cattle poisoning by ingestion of Xanthium spp. sprouts in the southern region of Rio Grande do Sul, Brazil.Case: In September 2018, a beef cattle farm located in Rio Grande county, Rio Grande do Sul, Brazil, reported significant mortality of cattle in a short period of time. There were 700 cattle on the property, divided by class into three different herds, all kept under extensive conditions in native wetlands. All fields were heavily infested by cocklebur, with most plants in the budding stage. Twenty animals developed muscle tremors, salivation, aggression, and recumbency. The clinical course lasted 24 to 48 hours, with a lethal outcome in all cases. An 18-month-old male crossbreed bovine was sent to the Regional Diagnostic Laboratory of the Universidade Federal de Pelotas (UFPel) School of Veterinary Medicine for necropsy. Gross examination revealed ascites and accentuation of the lobular pattern of the liver. Organ fragments were harvested and fixed in 10% buffered formalin. Microscopically, the liver exhibited marked coagulation necrosis in the centrilobular region and vacuolization of the hepatocyte cytoplasm in the midzonal and periportal regions. In the brain, there was perineuronal edema, cytoplasmic shrinkage and basophilia, gliosis, and satellitosis.Discussion: In the present case, the diagnosis of cocklebur toxicosis was based on clinical and epidemiological data as well as macroscopic and microscopic histopathology findings, and was confirmed by the presence of Xanthium spp. in the grazing sites of the affected animals. The detection and identification of Xanthium spp. are essential for correct etiologic diagnosis, since the pathological lesions observed in cocklebur toxicosis are similar to those described in poisoning by other hepatotoxic plants (Cestrum parqui, Cestrum corymbosum, Cestrum intermedium, Dodonea viscosa, Trema micranta) and by Perreya flavipes larvae. Central nervous system (CNS) symptoms were the main clinical manifestation observed in this outbreak, and the CNS lesions observed on necropsy were similar to those described in previous cases of cocklebur toxicosis. The predominance of nervous signs in this condition often misdirects the clinical diagnosis toward diseases such as rabies and cerebral babesiosis, which are endemic in southern Rio Grande do Sul and important causes of mortality in cattle herds. In these cases, careful attention to epidemiology, necropsy findings, and histopathology are fundamental for establishing the definitive diagnosis of cocklebur toxicosis and thus preventing further cases from being missed. The description of this outbreak emphasizes the importance of cocklebur toxicosis as an underreported cause of acute mortality in cattle in southern Brazil.

Soil Characteristics Under Different Land Use Practices in Mangochar, Kalat District, Balochistan, Pakistan

Land use influence soil quality of rangelands. Taking arid rangeland of Mangochar, Balochistan, Pakistan into consideration, this study investigated soil quality such as concentration of soil organic matter (SOM), soil aggregation, concentration of mineral nitrogen (N) and concentration of soluble inorganic phosphorus (P) of sites with various land use history. The sampling sites were as follows; site under unmanaged grazing, site inaccessible for grazing due to remoteness from pastoralists, field under monocropping of tomato since last 30 years and under application of organic fertilizer as cow manure, grapes field of approximately 27 years of age and under application of organic fertilizer as cow manure, apple orchards of approximately 15 and 30 years of age and under conventional farming system. Although number of native plant species and their abundance m-2 was greater in ungrazed site as compared to grazed site, there was no significant difference in soil quality. Soils of these sites collected from sieves of 2 mm and 1 mm mesh sizes had pebbles and sand with no obvious clay or silt particles. The concentration of SOM was greater in soils of agricultural fields than ungrazed site while the higher concentration was observed for the soil from tomato field. The soils of agricultural fields also showed aggregates (rather than pebbles and sand particles) of > 2 mm, 1- 2 mm and 0.5 mm sizes. The soil of tomato field also had significantly higher pH and soluble mineral P than soils from grazed and ungrazed sites.

Effects of grazing management on leaf litter decomposition and soil microbial activities in northern Iranian rangeland

The effects of rangeland management on biogeochemical processes that control the exchange of C and nutrients between the soil and plant are not well understood. For this purpose, aboveground litter properties and decomposition of three dominant species (Artemisia aucheri, Astragalus podolobus, and Eurotia lanata) were studied in four rangeland management systems of northern Iran including continuous grazing, intermittent grazing, and two non-grazing sites (i.e. woody and non-woody rangelands). We tested the following hypotheses: (i) woody rangeland improves litter quality, with a higher rate of decomposition, soil fertility and biochemical functions compared to non-woody rangeland and grazed sites, and (ii) continuous grazing reduces microbial C and N turnover. Plant residues from all rangeland species in the grazing and non-grazing areas were collected and soil samples were taken and analyzed for chemical properties and microbial activities. Based on the obtained data, litter decomposition was faster under woody rangeland ecosystem (Artemisia aucheri > Astragalus podolobus > Eurotia lanata) compared with the other study sites. The results revealed improved litter quality and increased soil available nutrients, as well as C and N mineralization for the woody rangeland, whereas under intermittent grazing the soil C/N ratio, microbial basal respiration (BR), substrate induced respiration (SIR) and microbial biomass C (MBC) increased. Soil pH, EC, qCO2 (BR: MBC) were significantly higher under continuous grazing, but with lower contents of soil organic C, total N, and available Mg. Furthermore, C and N stocks, microbial entropy (MBC: organic C), C availability index (BR: SIR), particulate organic matter C, dissolved organic C, mineral N (i.e., NH4 and NO3), microbial biomass N, particulate organic matter N and dissolved organic N were decreased in the continuous grazing site. Thus, we concluded that continuous grazing might depress soil C and N microbial activity, but woody rangeland could improve soil quality.

Grazing on Upland Pastures Part-Time Instead of Full-Time Affects the Feeding Behavior of Dairy Cows and Has Consequences on Milk Fatty Acid Profiles.

Simple SummaryTranshumance of dairy cows to upland pastures during summer is a tradition in mountain farming systems. Different management systems are practiced in the upland depending on topography and available infrastructures. This study aimed to assess the effects of two traditionally practiced upland pasture management systems (full-time grazing and part-time grazing) on feeding behavior and milk yield and quality. Cows with access to pasture for only 6 h per day had different feeding behaviors than cows on pasture 24 h per day; their milk yields, however, were similar. Although protein and casein contents were higher in the milk of cows with full-time access to pasture, milk coagulation properties did not differ between the two systems. The differences found in milk fatty acid profiles suggest that cows with part-time access to pasture mobilized more body fat reserves to counterbalance the energy expenditures required during fasting periods and for walking back and forth between the barn and the pastures.Different grazing management systems are practiced on upland dairy farms during summer, depending on topography, local traditions, and infrastructure. The present experiment compared two distinct management systems with respect to feeding behavior and milk-related properties. Two similar groups of eight Valdostana Red Pied cows originating from two farms were followed during three grazing events in summer on three upland grazing sites. Cows in the full-time grazing group were kept exclusively on pasture and milked twice daily in a mobile milking parlor. Cows in the part-time grazing group had access to pasture for 4 h and 2 h after their morning and evening milkings, respectively. The part-time grazing cows differed markedly in their feeding behavior; they exhibited shorter daily ingestion times and longer durations of ingestion and idling bouts than full-time grazing cows. Part-time grazing cows had lower milk protein and casein contents, but milk yield and milk coagulation properties did not differ from the full-time grazing cows. As a result of the fasting periods in the barn, part-time grazing cows synthesized less fatty acids de novo and mobilized body fat reserves, as evidenced by the higher proportion of oleic acid in their milk fat.

Carbon dioxide and methane fluxes in grazed and undisturbed mountain peatlands in the Ecuadorian Andes

Peatlands are widespread throughout the tropical Andean paramo. Despite the large carbon stocks in these ecosystems, carbon dioxide (CO2) and methane (CH4) flux data are lacking. In addition, cattle grazing is widespread in the paramo and could alter gas fluxes. Therefore, our objectives were to measure CO2 and CH4 fluxes with the static chamber technique in an undisturbed and in an intensively cattle grazed peatland in the mountains of Ecuador. We found that hummocks in the undisturbed site had higher net ecosystem exchange (NEE), gross primary production (GPP), ecosystem respiration (ER), and CH4 fluxes, compared to lawns. In contrast, microtopography at the grazed site did not predict CO2 fluxes, whereas vegetation cover was correlated for all three metrics (NEE, ER, and GPP). At low vegetation cover, NEE was positive (losing carbon). CH4 emissions in the undisturbed site were low (8.1 mg CH4 m-2 d-1). In contrast, CH4 emissions at the grazed site were much greater (132.3 mg CH4 m-2 d-1). This is probably attributable to trampling and nutrient inputs from cattle. In summary, the two peatlands differed greatly in CO2 and CH4 exchange rates, which could be due to the variation in climate and hydrology, or alternatively to intensive grazing by cattle.