Controlled grazing studies on Molinia grassland : effects of different seasonal patterns and levels of defoliation on Molinia growth and responses of swards to controlled grazing by cattle

摘要: Experiments were carried out at three sites in southern Scotland to determine the suitability of Molina grassland for sustained use providing summer grazing cattle, and investigate control as a tool manipulate species composition hill pastures Britain. Cutting experiments showed that frequency severity defoliation more important than timing their effects on Molinia. Weights clippings declined successive years only response treatments involved repeated within-season cutting. Three light (33% lamina length removed each June, July August), compared with uncut controls, reduced leaf production fourth uninterrupted growing season by 40%, while heavy (66% removal) it 78%. Reductions both numbers size tillers contributed this result. Single annual cuts 66% removal when they took place late season. Plots grazed cattle two 6 where rather 33% herbage was grazing. The rates extension Molinia higher level use. In comparison areas protected from during final year treatment only, biomass other grasses open taller utilized much greater extent grasses. After grazing, utilization 46-65% ungrazed exclosures, 86%. Basal internode greatly plots tiller base being variation concentrations determining amounts starch, total water soluble carbohydrates, N, P K per basis. Site x management interactions could be interpreted terms variations stage maturity, potential growth plant/animal nutrient cycling pathways. Floristic diversity increased areas. cover decreased broad-leaved At utilization, appeared levelling off (at around 60-65% after 3-5 years) continued downward trend evident. Species trends also influenced site factors, exclusion leading Festuca ovina conditions favourable high yields responses are discussed relation its pattern low rate turnover soil climatic factors. sward canopy structure, influencing competitive relationships species, considered wider issues relevant protocols outlined.