Physical limits on biota

KGA172 Space, Place and NaturePresented by Associate Professor Elaine StratfordSemester 2

Limiting Conditions for Life

(with apologies to Schultz)

LOOKING BACK, LOOKING FORWARD

Part 1

Revising Lecture 2.81. 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. Cirqueb. Arête c. Truncated spurd. Horne. Morainef. Glacial troughg. Roche moutoneeh. Hanging valleyi. Glaciofluvial sedimentj. Till k. Outwash fansl. Meltwater m. Ablation n. Solifluction

Auguste Rodin, A man thinking

Learning ObjectivesModule 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 reading1.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]

A man in a library

PHYSICAL LIMITS ON BIOTAPart 2

ECOSYSTEM FUNCTION Productivity Energy Transfer

Disturbance Change

Diversity Scale

-

ECOLOGYDefinition 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

Senescence Mortality

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’ distributionsVia moisture, light and temperature regimes,

nutrient availability, fuel and fire patterns

Kirkpatrick and Marks

Growth and Productivity

(G L Unwin)

(G L Unwin)

(G L Unwin)

SUNLIGHTDirect and diffuse radiationShortwave (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, shadingGrant Dixon

Atwell, B., Kriedemann, P., and Turnbull, C. (1999) Plants in Action. ASPP / Macmillan, Melbourne, p. 385.

Sun/shade light response in

photosynthesis (including light-

compensation point and quantum yield)

…or what about such response in a pond?

(G L Unwin)

(G L Unwin)

(G L Unwin)

ConclusionsScale 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)

ConclusionsYour 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)