نتایج جستجو برای: grazing severity
تعداد نتایج: 167942 فیلتر نتایج به سال:
Resilience-based frameworks, founded upon the existence of multiple attractors and regime shifts, have long been applied to complex dynamics of semiarid systems. Utilizing seed addition tests in experimental plantings along grazing gradients, we applied an increase-when-rare criterion to identify bidirectional (states can invade each other) and directional (only one state can invade) transition...
Predation by bacterivorous protists in aquatic habitats can influence the morphological structure, taxonomic composition and physiological status of bacterial communities. The protistan grazing can result in bacterial responses at the community and the species level. At the community level, grazing-induced morphological shifts have been observed, which were directed towards either larger or sma...
Grassland desertification by grazing and the resulting micrometeorological changes in Inner Mongolia
Overgrazing is one of the most primary causes of desertification in semi-arid zones of China. From 1992 to 1994 we conducted a grazing experiment in Naiman (lat. 42◦58′N, long. 120◦43′E, 345 m asl), Inner Mongolia, China to elucidate desertification mechanisms. Our experimental field, which was covered with some short grasses, legumes and forbs, included four plots where grazing sheep numbers d...
This trial provided information about effects of defoliation frequency, defoliation intensity and winter management (grazing or rest) on the productivity, morphology and plant population of a 3-year-old plantain (Plantago lanceolata) stand. Plant population density declined drastically over time independently of grazing management, with the greatest decrease in summer. Winter grazing had a crit...
Experts were interviewed on the grazing preferences of sheep in upland vegetation types and on the responses of plants to grazing. A qualitative model of direction of change in species abundance given different seasonal sheep grazing management regimes was constructed with the expert information. The model was tested against empirical data of sward responses to summer-only grazing. The approach...
Grazing ; modifies the structure and function of ecosystems, affecting soil organic carbon (SOC) storage. Although grazing effects on some ecosystem < attributes have been thoroughly reviewed, current literature on grazing effects on SOC needs to be synthesized. Our objective was to synthesize the effects of grazing on SOC stocks in grasslands, establishing the major mechanistic pathways involv...
Wetlands are ecologically and economically important ecosystems with high conservation value. Although wetland vegetation is strongly determined by abiotic factors, grazing disturbance may also be an important influence on this community. We evaluated the effects of livestock grazing on wetland vegetation in marsh and wet meadow zones in intermountain depressional wetlands in the southern inter...
Effects of grazing low-endophyte (Acremonium coenophialum Morgan-Jones and Gams, less than 1% infection) Johnstone (J) or high-endophyte (60% infection) Kentucky-31 (K) tall fescue (Festuca arundinacea Schreb.) on grazing behavior and voluntary intake were studied. Six Angus steers (average initial BW = 326 kg) grazed 1.21-ha plots of each forage cultivar (three steers per cultivar) in four 28-...
to clarify fermentative alterations in the large intestine (hindgut) during grazing, fecal alcohol and volatile fatty acids (vfas) concentrations were evaluated in 30 dairy heifers. the heifers were kept in pasture growing mixed grass herbage from spring (mid may) until october, and their rectal feces were collected periodically. concentrations of ethanol, methanol and isopropanol were increase...
In grazed habitats is a tradeoff between competition (decreases with the grazing intensity) and disturbance (increases). This may give tradeoffs between plant life stages. The seed production can be assumed to decrease at high disturbance intensities because of herbivory of reproductive organs, but also at high levels of competition (low grazing intensity) because of resource limitation. The es...
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