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Cutting Regime (cutting + regime)

Distribution by Scientific Domains

Earth and Environmental Science	77%

Selected Abstracts

Model predicting dynamics of biomass, structure and digestibility of herbage in managed permanent pastures.

GRASS & FORAGE SCIENCE, Issue 2 2006

Abstract A mechanistic model, simulating the dynamics of production, structure and digestibility of managed permanent pastures, was developed. Its evaluation consisted of (i) studying model response to a range of grassland communities, cutting frequencies and site characteristics, and (ii) testing the model against experimental data, focusing on biomass accumulation and digestibility during three different cutting cycles, herbage production under a frequent cutting regime, and sward dynamics during the winter. The model realistically predicted the dynamics of biomass, structure and digestibility of herbage for various communities of permanent pastures, in different sites and under different management conditions for upland areas of the Auvergne region in France. The predicted responses to environmental conditions and cutting regimes were close to field observations and experimental results. Although the model successfully predicted the dynamics of average herbage production, it lacked precision in predicting the low biomass production observed in relation to the weather conditions found in a few specific years. The model was able to predict the dynamics of the sward during winter and is, therefore, fit for producing multiple-year simulations. To improve the prediction of variability of biomass production and to predict the medium- to long-term dynamics of permanent pastures, the model could be refined by adding seasonal and multiple-year variation in nitrogen availability and in the proportion of grass functional groups in the grassland community. [source]

Floristic composition of a Swedish semi-natural grassland during six years of elevated atmospheric CO2

JOURNAL OF VEGETATION SCIENCE, Issue 5 2002
Mark Marissink
Krok & Almquist (2001) Abstract. A semi-natural grassland in Sweden was exposed to an elevated CO2 concentration during a six-year open-top chamber experiment. Vegetation composition was assessed twice a year using the point-intercept method. The field had been grazed previously, but when the experiment started this was replaced with a cutting regime with one cut (down to ground level) each year in early August. From the third to the sixth year of the study the harvested material was divided into legumes, non-leguminous forbs and grasses, dried and weighed. Elevated CO2 had an effect on species composition (as analysed by Principal Component Analysis) that increased over time. It also tended to increase diversity (Shannon index) in summer, but reduce it in spring. However, the effects of the weather and/or time on species composition and diversity were much more prominent than CO2 effects. Since the weather was largely directional over time (from dry to wet), with the exception of the fifth year, it was difficult to distinguish between weather effects and changes caused by a changed management regime. In all treatments, grasses increased over time in both mass and point-intercept measurements, whereas non-leguminous forbs decreased in mass, but not in point-intercept measurements. Legumes increased in the point-intercept measurements, but not in biomass, at elevated CO2, but not in the other treatments. Overall, we found that elevated CO2 affected species composition; however, it was only one of many factors and a rather weak one. [source]

Using distributed optimal control in economics: A numerical approach based on the finite element method

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 5-6 2001
Elena Calvo Calzada
Abstract The finite element method is employed to transform a distributed optimal control problem into a discrete optimization problem which can be solved with standard mathematical techniques. We use distributed optimal control in order to determine the optimal selective logging regime of a privately owned non-homogeneous forest. This regime has become nowadays a standard approach for the management of public forest. However, resource economists still have not come forward yet with an economic model for this widely applied management technique and base their economic analysis of the optimal management of a homogeneous forest on a clear cutting regime utilizing the Faustmann,Pressler,Ohlin Theorem. Copyright © 2001 John Wiley & Sons, Ltd. [source]

The influence of seed addition and cutting regime on the success of grassland restoration on former arable land

APPLIED VEGETATION SCIENCE, Issue 2 2004
Clare S. Lawson
Abstract Questions: Can seed addition enhance the success of establishing species-rich grassland on former arable land? Are sowing date and cutting regime important in determining success? Location: Aberdeen and Elgin, northeast Scotland, United Kingdom. Methods: A field experiment was conducted at two sites to assess the effect of seed addition, sowing date and cutting regime on the vegetation developing on former arable land, the aim being to compare the success of different treatments at producing a species-rich grassland. Results: Sowing a seed mix resulted in the establishment of vegetation very distinct from the species-poor vegetation dominated by perennial grasses which otherwise developed, though establishment success of the sown grassland species was highly variable between sites. Where establishment of the sown species was poor, sowing date had no significant effect on species composition, whereas the cutting regime was very important. Cutting the vegetation significantly increased both the number and abundance of sown species compared with the uncut control. Conversely, where establishment had been good, the cutting regime in the first year had little effect on species composition. Cutting the vegetation at least twice a year appeared to be the most effective management over the length of the experiment. Conclusions: Sowing a seed mixture significantly reduced the abundance and number of naturally colonising species, effectively controlling problem weed species such as Senecio jacobaea and Cirsium vulgare, highlighting the agronomic value of sowing seed mixtures on fallow farmland. The sowing of a seed mix on former arable land has demonstrated that it is feasible to create vegetation similar in character to that of species-rich grasslands. [source]

Model predicting dynamics of biomass, structure and digestibility of herbage in managed permanent pastures.

Cutting frequency and stubble height of reed canary grass (Phalaris arundinacea L.): influence on quality and quantity of biomass for biogas production

GRASS & FORAGE SCIENCE, Issue 4 2002
U. Geber
Abstract Reed canary grass (RCG) used for land treatment of waste water can serve as a substrate for biogas production. The aim of this experiment was to study the effects of two, three or four cuts per year to stubble heights of 5, 12·5 or 20 cm on the digestibility and yield of digestible organic matter (DOM) of RCG. Both dry-matter yield and the yield of DOM decreased with more than two cuts per year. Height of cutting had no effect on the digestibility of the regrowth harvested from the different cutting regimes. Increased height of cutting resulted in increased dry-matter production and therefore also of increased DOM yield in the regrowth harvested from the four-cut regime. The total DOM yield from the four-cut regime was, however, only 0·84 of the DOM yield from the two-cut regime. [source]

Prediction of cutting effects on a population of Chaerophyllum aureum, a demographic approach

JOURNAL OF VEGETATION SCIENCE, Issue 4 2000
D. Magda
Abstract. A demographic study of the undesirable perennial weed Chaerophyllum aureum in extensified French Pyrenean hay meadows was carried out. For two successive years the effect of date and intensity of cutting on the population demography of this colonizer. Population density is sensitive to cutting practices essentially through fecundity, seedling survival rate and seed dispersal between fields. Cutting reduces fecundity by preventing seed formation (early cutting) or by exportation of some mature seeds with hay (late cutting). Nevertheless, the number of seeds transported between field populations by hay harvest, organic manuring and associated cutting practices compensates for the lack of seed production in early-cut populations, maintaining them at relative high densities. For each of three cutting regimes, the number of immigrant and emigrant seeds has been indirectly estimated from a prediction of population density at equilibrium from demographic parameters measured in field populations and compared with observed population densities. [source]

Evaluation of the effects of resistance to stem nematode (Ditylenchus dipsaci) in white clover (Trifolium repens L.) under sheep grazing and cutting

PLANT BREEDING, Issue 4 2007
T. A. Williams
Abstract Two field experiments were carried out to analyze the performance of white clover varieties differing in their resistance to stem nematode. Varieties were compared under grazing and cutting regimes in mixed swards with or without the addition of nematode and dry matter yields of white clover and perennial ryegrass recorded over a 3-year period. The resistant variety did not show a yield advantage in the absence of nematode but did so in the presence of nematode in the first year and for several of the sampling dates in the second year. White clover yields under grazing were significantly less than under cutting in both experiments. The hypothesis that the additional stress of grazing would increase the benefits of resistance relative to a cutting management was not supported. [source]