Grassland Ecology

 

bb2n1e23 Grassland Ecology L.
also BIO/01/02E , KÖR/28E, KÖR-2/1/28E  PhD courses
Tibor Kalapos (kalapos@caesar.elte.hu
 
Aims of the subject
Give an introduction to the ecological properties (main determining factors, physiognomy, composition, structure, dynamics) of grassland ecosystems. 
 
Topics covered
1.) Natural and seminatural grasslands
Major grassland biomes of the Earth. Tropical grasslands (savanna, llanos) and temperate grasslands (prairie, steppe, pampa, campos, veld). Physiognomy, dominant grass genera, typical vegetation dynamics and human land use in the major grassland formations. Most important grassland types in Hungary (loess, sand and salt steppe grasslands, hay meadows, pastures). 
2.) Graminoids: the dominant constituents of grasslands
Graminoids (Poaceae and related families (e.g. Cyperaceae, Juncaceae, Restionaceae)): evolutions, diversity and taxonomy. What properties made graminoids the dominant components of grasslands? Further abundant elements in grasslands (e.g. legumes (Fabaceae), umbellifers (Apiaceae) and composites (Asteraceae)), special ecological roles, plant functional groups.
3.) Climate as an important determinant of grasslands
The role of climate in the development and existence of grasslands: the roles of temperature and the amount, temporal distribution and predictability of precipitation. Grass-dominated ecosystems in Whittaker's graphical scheme for climatically zonal vegetation. The importance of marked seasonality.
4.) Edaphic factors: the effects of bedrock and soil
Soil-grassland interrelationships. Physical, chemical and biological properties of grassland soils.  Soil water regime as a local factor modifying the macroclimate. 
5.) Grass – fungi interrelationships
Arbuscular mycorrhizal fungal (AMF) symbioses in grasslands: universality (taxonomical and ecological distribution), functional significance (contribution to the uptake of mineral nutrients (particularly phosphorus). Species specificity of AMF symbioses, the efficiency of the symbiosis in different grass-fungus connections. AMF network connecting multiple individuals/species: redistribution of mineral nutrients and opportunity for epiparasitism. Grass endophytes: characteristics of the symbiosis, role in plant functioning and ecological success (e.g. modification of herbivore pressure on plants).
6.) Fire: typical disturbance maintaining semiarid grasslands 
The role of marked seasonality of climate in the accumulation of fuel in grasslands. Adaptive traits of grasses in habitats subject to recurrent fires. The fire regime: extent, intensity, frequency and predictability of fire. The role of fire regimes in the organization of grasslands. Influence of herbivores on the fire regime. The role of fires in the expansion of savanna ecosystems at the expense of tropical seasonal forests during the Quaternary and today. Differences between forest and grassland fires. The influence of fires on the composition, heat-, water and mineral nutrient regime of the grassland.  
7.) The role of herbivores in grasslands
General and specific effects of large-bodied herbivores (megaherbivores) on grasslands: removal of aboveground phytomass, selective grazing, trampling, removal of fuel, creation of novel microhabitats, modification of availability and dynamics of soil mineral nutrients, acceleration of nutrient cycling. Coevolution of grassland plants and megaherbivores. Mutual relationship between grassland vegetation pattern and spatial pattern of herbivore activities. Specific influences of microherbivores (phytophagous insects) on grasslands.
8.) Mineral nutrients in grasslands
Spatial distribution and availability of mineral nutrients in grassland soils. Specific properties of grass root systems in the service of uptake of mineral nutrients. The unique role of legumes: fixation of atmospheric nitrogen. Mineral-nutrient-rich patches ("islands") in grasslands in the vicinity of trees or shrubs. Relationships between mineral nutrient availability and plant species richness in grasslands. Effect of disturbances on mineral nutrient availability in grasslands.  
9.) Nature conservation of grasslands
Fragmentation and isolation: the main problem of surviving natural grasslands.Invasive plants, influence on grassland composition, dynamics and ecosystem functioning. Anticipated impacts of climate change on grasslands. Managinhóg of grasslands for nature conservation. Grassland restoration.