SUBJECT
Grassland Ecology
lecture
Master
2
Semesters 1-4
Autumn/Spring semester
1.) Seminatural grasslands Global distribution of grasslands. Major grassland biomes of the Earth: steppe, prairie, pampa, campos, (grass)veld, tussock. Tropical grasslands: llanos, savanna. Grassy semideserts. Physiognomy, dominant grasss genera, characteristic vegetation dynamics. Main grassland types in Hungary (rock grasslands, dry shortgrass steppe, haymeadows, pastures, etc.).
2.) Poaceae – the dominant components of grasslands Main characteristics of grasses: evolution, diversity and taxonomy. What traits make these plants highly successful in open habitats? Further components of grasslands: legumes (Fabaceae), Apiaceae, Asteraceae, their ecological role. Plant functional groups in grasslands.
3.) Climate as a major determinant of grassland distribution The role of climate in the development of grasslands: temperature and precipitation. The importance of the amount, annual distribution and regularity of precipitation. The place of grassy biomes in Whittaker’s qualification of bioclimates. The role of marked seasonality.
4.) Edaphic determinants: effect of soil and bedrock Soil-grassland interactions, soil physical, chemical and biological characteristics in grasslands. Soil water relations as an important local modifier of regional climate.
5.) Grass – fungi interactions Mycorrhyzal symbioses between grassland plants and fungi. The importance of endomycorrhiza (VAM): generality (wide taxonomic and geographic distribution), functional significance (role in the plant’s mineral nutrition).The species specificity of VAM symbioses, plant efficiency with different VAM symbionts. Underground mycorrhyzal network connecting plants: resource sharing, epiparasitism. Grass endophytes: main properties of this symbiosis, role in the plant’s physiology and ecological success (e.g. influence on herbivore damage).
6.) Fire – an important factor in the maintenance of semiarod grasslands The role of fire in the grassland biome. Frequency, regularity, intensity and extent. Forest fire and grassland fire: similarities and differences. The role of marked seasonality of the climate in the availability of fire fuel in grasslands. Adaptedness of grasses to fire. The influence of large herbivores on the accumulation of grass fuel, and thus on fire regime. The role of fire in the expansion of the savanna biome in the Quaternary. Fire effects on species diversity, spatial structure, and heat, water and mineral nutrient relations of grasslands.
7.) Herbivores in grasslands General and specific effects of herbivores: grazing, selectivity, coevolution of grasses and large herbivores. Trampling, removal of grass fuel, creation of new microhabitats, alteration of biogiochemical cycles. Grazing pattern of large herbivores and grassland vegetation dynamics. Specific effects of invertebrate herbivores.
8.) Mineral nutrient turnover in grasslands Spatial and temporal distribution of mineral nutrients in grasslands. Special characteristics and modification of roots of grasses for nutrient uptake. The unique role of legumes: fixing aerial N2. Mineral nutrient rich islands under bushes and trees in grasslands. Relationship between nutrient supply and species richness in grasslands. The influence of disturbances on mineral nutrien supply in grasslands.
9.) Ecophysiological responses of grassland plants in variable environment Major environmental factors limiting plant growth in grasslands. Main ecophysiological traits of grassland constituents: different photosynthetic pathways (C3, C4 , and subtypes), adaptadnes and acclimatory mechanisms. Various ways of tolerating temporary drought among grassland plants. Secondary plant metabolites and their role in grasslands.
10.) Biomass and productivity in grasslands Specificity of biomass production in grasslands main limiting factors, temporal and spatial patterns. Global data on garssland productivity and figures for Hungary. Distribution of phytomass between above- and belowground parts in grasslands, its adaptive modification under different ecelogical scenarios (climate, disturbance regime, etc.).
11.) Grassland vegetation dynamics Vegetation dynamics and succession in grasslands. Influence of disturbances on species composition, spatial structure and functioning of grasslands. Degradation. Non-equilibrium grasslands maintained by repeated disturbances (fire, cutting, etc.), successional processes after the cessation of disturbance, forest regeneration. Effects of human grassland management practices (cutting, overseeding, fertilization, burning, grazing by large herbivores) on grassland structure and dynamics.
12.) Plant invasion in grasslands Adventive species spreading en masse in grasslands. Plant traits promoting invasiveness, and community susceptibility for invasion. The “enemy release” and the “fluctuation resources” hypotheses explaining plant invasions. The possible link between the two hypotheses. Influence of invasive plants on grassland dynamics, nutrient regime, and ecosystem processes: the specific effect of invasive legumes. Most important invasive grasss species in the world (e.g. Bromus tectorum, Cynodon dactylon).
13.) Possible outcomes of global climate change in grasslands Main characteristics of climate change: causes, mechanisms, global pattern. Potential responses of plants, what can be realized of this within spatial and temporal constraints? Favourable short-term effects of “CO2 fertilization”, diminishing return in the long-term: limitation of other resources („N-starvation”, impoverishment of phytomass in N, and subsequent low qaulity for herbivores). Specificity of grassland response to climate change: enhanced susceptibility to climate warming, irregularities end extremeties. Changes in the species and functional group composition of grasslands. Experimental approaches to assess the effects of climate change on grasslands.
14.) Nature conservation in grasslands Major problems threatening the persistence of grasslands: fragmentation, isolation, increasing disturbance, impoverishment of regional species pools. Active nature conservation: regular interventions for the maintenance of grasslands. Grassland rstoration. Ecosystem services provided by grasslands and the role of biodiversity in these. The most precious grasslands of Hungary.
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Chapman, G. P. 1996: The biology of grasses. CAB International.
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Knapp, A.K., Briggs, J.M., Hartnett, D.C. & Collins, S.L. 1998: Grassland dynamics. Long-term ecological research in tallgrass prairie. Oxford Univ. Press. Oxford.