The Influence of Long-term Grassland Management on Sward Parameters in a Semi-natural Grassland

Ing. Teowdroes Kassahun Teka

Disertační práce

Abstract:

Summary Semi-natural grassland especially those that are located in upland areas and less accessible is an important part of the European landscape. They have significant natural as well as cultural-historical significance, due to the influence of humans. But following the 1990s post-communism, several Central European countries (e.g. Czech Republic and Slovakia) with large areas of grassland in the upland areas were lost or converted to forest lands. These problems were further exacerbated with the declining livestock population that traditionally grazed on these lands. These lands are generally managed by grazing or mowing depending upon the site condition. And to keep these habitats open, maintain biodiversity in them, and avoid abandonment management is needed. Therefore, the overall aim of this thesis was to use long-term experiment data and investigate the effects of the different management on various sward parameters (biomass production, forage quality, nutrient in the soil, etc.). More specifically, effects of different grazing intensities and cutting management were investigated using data from existing long-term grazing experiments in the Czech Republic (Oldrichov Grazing Experiment) and Slovakia (experiment located at National Park of Nízké Tatry) with the aim of using the results to solve existing grassland challenges and providing potential management and methodological recommendations. Chapter 1 gives insight to temperate grasslands with a focus on semi-natural grasslands. It provides a literature review on the different management strategies, challenges as well as the effect of management on sward parameters. Chapter 2 investigated the effect of grazing and cutting management on plant functional groups at two different vertical layers. Analyses of the 15-year data revealed intensity of management to be the key driver affecting the vertical distribution of functional groups, while the type of defoliation (grazing or cutting) had less effect. Furthermore, a high proportion of living biomass was found in contrast to a lower layer which is filled will dead and ungrazed biomass. This suggests for adjustment of our methodological approach, especially when sampling for forage quality or productivity analysis. Chapters 3 and 4 studied the effects of different management methods on the herbage and soil nutrient concentrations and other sward parameters. Chapter 3 analyzed the effects of dung presence on the nutrient concentration of soil and herbage under sward height patches exposed to different grazing intensities. The analyses revealed intensity of grazing as the key driver for nutrient concentration (N, P, K) in the herbage while dung presence had no significant effect on soil nutrient concentrations. In contrast, Chapter 4 analyzed the restoration measures of upland meadows infested with expansive weedy species. The result indicates cutting management and herbicide application coupled with cutting management had affected both the soil and herbage nutrient concentrations. But the excessive presence of nutrients in the soil meant more management that can remove the excess nutrient from the soil while also removing the weedy species is necessary. Chapters 5 and 6 deal with the forage quality, biomass production and performance of heifers using a long-term experiment data from Oldrichov Grazing Experiment, Czech Republic. Chapter 5 focused on finding optimum period for introducing management (first cut or early grazing) in order to meet cattle nutritional as well as mineral concentrations need. This analysis is especially essential for grasslands that are protected under agri-environment schemes. The 13-year data analysis revealed that up to the first seven weeks of the vegetation season the forage quality is suitable for cattle even as the only source of feed, but after that the forage quality is very low and it is only suitable for low productive cows and beef cattle. This suggests the need to maintain the

Abstract:

agri-environment schemes to compensate for loss in forage quality while meeting the nature conservations aims. Similarly, Chapter 6 revealed that extensive management applied for almost two decades can meet the cattle requirements without compromising heifer performance and at the same time contribute to landscape management of upland grasslands. The published papers included in this thesis suggest different defoliation management (cutting/grazing) methods have different effect on the sward parameters of semi-natural grassland. One of the most important factors that influenced the sward parameters is grazing and its intensity. Compared to the traditional cutting management, grazing management seems to offer a higher biomass production, influences the nutrient cycle of the grassland via dung and urine return to the system as well as influencing the species composition of the grassland in the long run. In contrast the cutting management, played important role especially in upland areas that are typically neglected of management and under threat of encroachment by shrubs or dominance of weedy species. It especially helped to remove excess amount of nutrients from the soil as well as decrease the dominance of weedy species that are prevailing due to lack of any management. Therefore, choosing the appropriate method for specific sites, must consider the previous management history of the site, the existing condition, the future plan or objective and the cost implication for management.

Keywords

Sward structure, Grazing intensities, Forage quality, Grassland management

Jazyk práce: angličtina

Datum vytvoření / odevzdání či podání práce: 16. 11. 2021

Obhajoba závěrečné práce

• Vedoucí: prof. Dr. Ing. Vilém Pavlů

Česká zemědělská univerzita v Praze

Fakulta životního prostředí

Doktorský studijní program / obor:
Ecology / Ecology