Effect of different grazing management systems on the herbage mass and pasture height of a Nardus stricta grassland in western Scotland, United Kingdom

The aims of this study were to examine the effect of three grazing treatments (year‐round stocking rates of 0·8 ewes ha^?1, 0·5 ewes ha^?1 and 0·5 ewes ha^?1 plus grazing cattle in summer), imposed for 4 years, on the herbage mass and surface height of a Nardus stricta‐dominated grassland in western Scotland and to obtain estimates of annual productivity of this grassland. Nardus stricta‐dominated grassland comprised proportionately 0·20 of the grazing area. Stocking rate of sheep had no significant effect on the herbage mass of the grassland in the first 2 years of the experiment, although mean summer pasture heights were significantly higher under the lower stocking rate of sheep. The pasture on the treatment with cattle grazing in summer had a significantly lower herbage mass and lower surface height than the two sheep‐only grazing treatments. Year‐to‐year variation in the herbage mass and surface height of herbage in summer was greater than the effect of treatments. Despite changes in surface height, the structural diversity of the grasslands was not increased by the treatments. The annual production of vascular plant material ranged from 417 g DM m^?2 in 1994 to 628 g DM m^?2 in 1996.     

Trends and approaches in the analysis of ecosystem services provided by grazing systems: A review

The ecosystem services (ES) approach is a framework for describing the benefits of nature to human well‐being, and this has become a popular instrument for assessment and evaluation of ecosystems and their functions. Grazing lands can provide a wide array of ES that depend on their management practices and intensity. This article reviews the trends and approaches used in the analysis of some relevant ES provided by grazing systems, in line with the framework principles of the Millennium Ecosystem Assessment (MA). The scientific literature provides reports of many studies on ES in general, but the search here focused on grazing systems, which returned only sixty‐two papers. This review of published papers highlights that: (i) in some papers, the concept of ES as defined by the MA is misunderstood (e.g., lack of anthropocentric vision); (ii) 34% of the papers dealt only with one ES, which neglects the need for the multisectoral approach suggested by the MA; (iii) few papers included stakeholder involvement to improve local decision‐making processes; (iv) cultural ES have been poorly studied despite being considered the most relevant for local and general stakeholders; and (v) stakeholder awareness of well‐being as provided by ES in grazing systems can foster both agri‐environmental schemes and the willingness to pay for these services.     

Evaluation of the effects of ewe prolificacy potential and stocking rate on herbage production,utilization, quality and sward morphology in a temperate grazing system

This study investigated the effect of ewe prolificacy potential (PP; predicted number of lambs born ewe^?1 year^?1), stocking rate (SR; ewes/ha) and their interaction on herbage dry matter (DM) production, utilization, quality and sward morphology within a temperate grass‐based lamb production system. The study had a 2 × 3 factorial design, consisting of two ewe PP as dictated by sire breed (180 medium prolificacy potential (MP—Suffolk crossbred) and 180 high prolificacy potential ewes (HP—Belclare crossbred)) and three SR: low (LSR; 10 ewes/ha), medium (MSR; 12 ewes/ha) and high (HSR: 14 ewes/ha). Each treatment was managed in a rotational grazing system, with LSR, MSR and HSR treatments grazing to target post‐grazing sward heights (PGSH) of 4.55, 4.15 and 3.75 cm respectively. Herbage DM production (above target PGSH) and utilization were highest at the HSR, intermediate at the MSR and lowest at the LSR (p < .001). Ewe PP had no effect on herbage DM production, utilization, quality or sward morphology (p > .05). The proportion of leaf in the sward (above target PGSH) was 4% greater in MSR and HSR compared with LSR (p < .05). In conclusion, findings demonstrate the potential to support increased ewe PP through the selection of ewe genotypes of a genetically higher PP and lower mature live weight and increased SR within a temperate grass‐based lamb production system.     

Interaction of plant genotype and management in the persistence of a perennial grass exposed to grazing and soil fertility stresses

Increased stocking rates under typical pasture improvement practices in southern Australia have often been associated with low persistence by sown perennial grasses subjected to continuous stocking. Cultivars of the perennial grass phalaris (Phalaris aquatica L.), which is widely used in southern Australia, vary in their phenology and growth habit. Winter‐active cultivars have also been developed with improved stress tolerances, viz. heavy grazing pressure (Holdfast GT) and acid soils (Advanced AT). This study examined the persistence of phalaris genotypes over 4 years under five management treatments: high P‐high stocking rate (18 sheep per hectare) rotationally stocked (HPRS); high P‐high stocking rate continuously stocked (HPCS); high P‐intermediate stocking rate (13·5 sheep per hectare) continuously stocked (HPCS13.5); low P‐low stocking rate (9 sheep per hectare) rotationally stocked (LPRS); and low P‐low stocking rate continuously stocked (LPCS). Basal frequency of phalaris declined rapidly under HPCS and LPCS in the first year of treatments when periods of low herbage mass occurred under low rainfall. Basal frequency in high P treatments stabilized and partially recovered but continued to decline in low P treatments. Holdfast GT survived the early decline in the HPCS treatment better than other winter‐active cultivars and similar to a known grazing tolerant, semi‐winter‐dormant cultivar. Advanced AT and older winter‐active cultivars were sensitive to continuous stocking but persisted better under rotational stocking or under a reduced rate of continuous stocking (HPCS13.5). Rotational management clearly promoted persistence of winter‐active phalaris, but long‐term persistence will be better ensured by combining management with the use of genotypes with grazing tolerance traits.     

Persistence of tall fescue in a subtropical environment: tiller survival over summer in response to flowering control and nitrogen supply

Enhancing pasture persistence is crucial to achieve more sustainable grass‐based animal production systems. Although it is known that persistence of perennial ryegrass is based on a high turnover of tillers during late spring and summer, little is known about other forage species, particularly in subtropical climates. To address this question, this study evaluated survival of grazed tall fescue tillers growing in a subtropical climate. We hypothesized that hard tactical grazing during winter to remove reproductive stems (designated as ‘flowering control’), and nitrogen fertilization in spring, would both improve tiller survival over summer, and thus enhance tiller density. This was assessed in two experiments. In both experiments, few tillers appeared during late spring and summer and so tiller density depended on the dynamics of vegetative tillers present in the sward in spring. In Experiment 2, flowering control and nitrogen fertilization both enhanced the survival of that critical tiller cohort, but the effects were not additive. Responses were similar but not statistically significant in Experiment 1, which had a warmer, drier summer and lower overall survival rates. Unlike grasses in temperate environments, persistence of tall fescue in this subtropical site appeared to follow a ‘vegetative pathway’; i.e., new tillers were produced largely in autumn, from vegetative tillers that survived the summer.