Physical limits on biota KGA172 Space, Place and Nature Presented by Associate Professor Elaine Stratford Semester 2

Limiting Conditions for Life (with apologies to Schultz)

LOOKING BACK, LOOKING FORWARD Part 1

Revising Lecture In what ways is glaciation related to processes of Earth’s orbit, wobble, and tilt? 2.Glaciers are classified, first, by two fundamental characteristics. What are these? 3.In terms of thermal character, there are two kinds of glacial feature. Again, what are they and what are their principal characteristics? 4.Describe the difference between an ice sheet and an ice cap. 5.Define the following term for a landscape feature in a glacial environment and explain how each arises or operates: a.Cirque b.Arête c.Truncated spur d.Horn e.Moraine f.Glacial trough g.Roche moutonee h.Hanging valley i.Glaciofluvial sediment j.Till k.Outwash fans l.Meltwater m.Ablation n.Solifluction Auguste Rodin, A man thinking

Learning Objectives Module 2 Lecture 9 be able to – explain why scale and context are essential elements of all biotic patterns and processes – describe key interactions of organisms with their environments – appreciate and convey the importance of the multidisciplinarity of environmental studies KGA172 Know and be able to (a) employ basic geographical terminology and concepts, (b) find, evaluate, analyse and reference appropriate literature, (c) contribute to debates about development and sustainability Comprehend and be able to explain spatial patterns, generate basic maps, field sketches and graphs, and communicate in written and graphical forms Apply key academic skills and (a) engage in critical thinking, discussion and listening, and in self-reflection and reflection upon the viewpoints of others and (b) research, plan and conduct fieldwork to collect data Analyse and interpret basic spatial, numerical and qualitative information Synthesize and integrate knowledge of social and Earth systems

Textbook Reading Bergman and Renwick (2008) Critical reading 1. What is the author’s purpose? 2. What key questions or problems does the author raise? 3. What information, data and evidence does the author present? 4. What key concepts does the author use to organize this information, this evidence? 5. What key conclusions is the author coming to? Are those conclusions justified? 6. What are the author’s primary assumptions? 7. What viewpoints is the author writing from? 8. What are the implications of the author’s reasoning? [from Foundation for Critical Thinking]Foundation for Critical Thinking A man in a library

PHYSICAL LIMITS ON BIOTA Part 2

ECOSYSTEM FUNCTION ProductivityEnergy Transfer DisturbanceChange DiversityScale - ECOLOGY Definition and historic development (G L Unwin)

Niche = a species’ function in an ecosystem = a species’ lifestyle Habitat = where a species lives = a species’ address Kerry Bridle

Kirkpatrick 1999 HOW BIOTA FIND PLACE – potential vs actual niche

Biodiversity = the variety of life, including genotypes, species, communities and ecological processes.

Ecosystem function …Ecosystem processes and population dynamics Reproduction Regeneration Growth Competition SenescenceMortality Disturbance, change and succession

Abiotic and biotic (including human) conditions, resources and Interactions: Physico-geo-chemical and biological conditions (that is, the “environment” for establishment, survival, growth and reproduction) Available resources (materials and energy) … all depend on conditions and resources which are limited and limiting for life

Conditions - physical or chemical attributes of the environment that influence the organism’s growth and reproduction Resources - substances that are consumed by an organism Unknown photographer

What are the major elemental constituents of life – that is, for nutrition and growth? Damien Catchpole Strahler and Strahler Geography and Man’s Environment

Liebig's law of the minimum (populations are limited in their growth and distribution by the resource in greatest scarcity) Shelford's law of tolerance (populations are limited in their growth and distribution by the resource closest to excess or deficiency) Adrian Pyrke

Processes and dynamics of biological interactions with the environment Biotic and abiotic interactions which determine the distribution and abundance of organisms Krebs 1985

Processes and dynamics of biological interactions with the environment Biotic and abiotic interactions which determine the distribution and abundance of organisms Krebs 1985

Influence of topography and soil characteristics on the limits of species, species’ distributions Via moisture, light and temperature regimes, nutrient availability, fuel and fire patterns Kirkpatrick and Marks

Growth and Productivity (G L Unwin)

SUNLIGHT Direct and diffuse radiation Shortwave (solar) and longwave (far red) radiation Light quality (wavelength) Light quantity (photon irradiance) Light duration, periodicity (diurnal / seasonal) and disturbance effects (red / far red and blue light effects)

Competition for light, light compensation point, shading Grant Dixon

Atwell, B., Kriedemann, P., and Turnbull, C. (1999) Plants in Action. ASPP / Macmillan, Melbourne, p Sun/shade light response in photosynthesis (including light- compensation point and quantum yield)

…or what about such response in a pond? (G L Unwin)

Conclusions Scale and context are implicit in biotic patterns and processes and intrinsic to any proper definition of the limits on biota Ecosystems contain and depend on interactions of organisms with their environment, hence ecosystem function requires a supply of resources and energy (nutrition) within a matrix of competitively limiting conditions for life (G L Unwin)

Conclusions Your environmental studies will need to be multidisciplinary in order to define and demonstrate important functional links between environmental physics and physiology at the smaller scale and the structural, evolutionary and demographic patterns and dynamics of whole ecosystems at the larger regional scale. (G L Unwin)