SUBJECT

Physiological Plant Ecology

lecture

Master

Faculty of Science

Biology MSc

2

Semesters 1-4

Autumn/Spring semester

1.) The subject of plant ecophysiology Physiological and associated morphological/anatomical plant tolerance traits explaining ecological phenomena. Environment - plant tolerance realtionships: fundamental and realized niche, physiological and ecological optimum. Major determinants of plant distributions, the particular role of physiological characteristics. Short history of plant ecophysiological research.  

2.) Environmental stress, plant responses Abiotic environmental limitations (stress) and physiological and structural responses of plants to these: immediate stress response, acclimation, phenotypic plasticity, adaptation. General and specific stressresponse among terrestrial vascular plants: resistance, avoidance and tolerance of abiotic stress, avoidance and tolerance of reversible / irreversible strain (Levitt's conceptual framework). General traits of stress tolerant plants.  

3.) Fine-tuning plant physiological functioning to the environment  The evolutionary imprint of the performance / persistence trade-off in plant physiological functioning. The functional convergence hypothesis. Major physiological characteristics of plant ecological strategies (r and K life history strategies, Grime's C, S and R strategies).  

4.) Dessication tolerance among plants Poikilohydric organisms: tolerance of dessication. Poikilochlorophyllic and homoiochlorophyllic dessication tolerant plants: mechanism of functioning, anatomical and morphological traits, succes in particular habitats. Poikilohydric cryptogams and vascular plants.    

5.) Adaptation to temporary drought  Homoiohydric vascular plants: water spenders and water savers, stable or labile plant water relations. Morphological and anatomical adaptations to water shortage. Water relations of ephemeral plants, xeromorphic perennials and succulents.  

6.) Water transport in plants under variable water supply  The cohesion theory of water transport, root pressure, tension in the xylem, breaks in the water column: gas embolism, avoidance mechanisms, repair, ecological consequences. Variation among vascular plants in the tolerance of embolism. Redistribution of soil water through plant roots: the hydraulic lift.  

7.) Plant water content in terrestrial habitats Variables describing plant water status: water content, water potential and components (osmotic-, turgor- and matric potential), and their role in the regulation of plant water status. Osmotic adjustment and cell wall elasticity as tools for maintaining plant hydration and/or turgor during temporary water shortages. The water content - water potential relationship, pressure-volume analysis, ecological applications.  

8.) Regulation of plant water status  Environmental responses of stomata, feed-forward and feed- regulation mechanisms, the optimality theory of Cowan and Farquhar. Stomatal responses to air humidity, light quaility, mesophyll CO2 concentration, and leaf water relations. Direct signal from roots to stomata during soil drying: mechanism based on abscisic acid and/or xylem tension. Improvement of stomatal response to habitat environment during evolution of terrestrial vascular plants. Responses beyond immediate stomatal movements: stomatal density, leaf arrangements, leaf surface area, morphological adjustments to water availability. Photosynthetic-, growth and stand-level water use efficiency (WUE).  

9.) Plants on waterlogged and saline soils  Physiological effects of soil waterlogging and plant avoidance mechanisms: aerenchyma, fermentation ability, etc. Salt tolerance mechanims of halophytes: selective ion uptake, ion accumulation and secretion. Mangroves: under the combined influence of salinity and waterlogging.

10.) Photosynthetic pathway types among vascular plants: evolutionary responses to CO2 starvation during earth history Major types of photosnthetic CO2 fixation (C3, C4, CAM) among vascular plants; subtypes and variations of photosynthetic pathways (intermediate C3-C4, C3-CAM, C4-CAM, inductive CAM, C4 NAD-ME, C4 NADP-ME, C4 PEPCK, etc.): adative value, evolution, and taxonomical, geographical and ecological distributions. CO2 uptake among aquatic plants.  

11.) Differing ecophysiology of different photosynthetic pathway types Physiological base traits: light-, temperature- and CO2 concentration response of photosynthesis, water-, nutrient- and quantum use efficiency of photosynthesis, plant productivity, stress tolerance.  

12.) Fine tuning of photosynthesis to the quality and quantity of light  Adaptation and acclimation to high light environments and to shade. Photoinhibition of photosynthesis, canopy light use efficiency, infuence of plant water stress on photosynthesis. The phytochrome system and its role in perception of shade. Nitrogen availability and photosynthesis. Light gradient within plant canopies and stand-level photosynthetic responses.  

13.) Photosynthesis in variable environments The photosynthetic light induction, photosynthetic response to sunflecks, its importance for plants in deep shade at the bottom of canopy. Seasonal acclimation of photosynthesis. Ecophysiological changes associated with vegetation succession.  

14.) Plant ecophysiological and vegetaion responses to global climate change  The effects of global warming, increasing atmospheric CO2 concentration, changing quantity and distribution of precipitation, and increasing extremities and irregularities in climate on vegetation. Short term benefits of „CO2 fertilization” on plant growth usually diminishes on the long run, limitation by other resources. Different success of different photosynthetic pathway types under changing climate. Climate change and other global changes: interacting effects. Experimental approaches to studying plant responses to climate change.  

15.) Field methods for studying plant ecophysiological functioning Measuring plant water status (water content measurements, determination of water potential (psychrometry, hygrometry, pressure chamber). Measurement of water transport in plants (stem conductance, leaf transpiration, stomatal conductance), instantaneous photosynthetic rate (leaf CO2 gas exchange by infrared gas analysis), the efficiency of photosynthetic light reactions (chlorophyll-a fluorescence induction). Determination of photosynthetic pigments: wet laboratory techniques and remote sensing based methods. Ecological applications of plant growth analysis.  

• Lambers, H., Chapin III., F.S. & Pons, T.L. 1998: Plant Physiological Ecology. Springer, New York.

• Additional information available on the web: http://ramet.elte.hu/~ramet/oktatas/novfizol.html