Module 2Biocomplexity of the North

Dactylica arctica

Algae under Arctic sea ice

Xanthoria elegens

Poripidia flavocaerulescens

Objectives

• Learning about feedback mechanisms

• Using feedbacks to meet management goals

• Properties of ecological systems

• Material and energy cycles

• Human-induced ecological changes

• Notion of ecological health

Terms and Concepts

• Homeostasis– Maintenance by an organism of a constant

internal environment, such as regulation of blood sugar level

• Equilibrium– Steady state for a population, community, or

environmental parameter

Terms and Concepts

• Chemical cycles– Temporal and spatial changes in the

distribution of a chemical compound in the environment due to physical or biological processes

• Energy flow– Transfer of energy from sun radiation, through

food chains, and dissipation to the environment (subject to the 2 laws of thermodynamics)

Terms and Concepts

• Resiliency– The ability of a natural system to return to a

state of equilibrium after a disturbance (similar to “environmental robustness”)

• Carrying capacity– The level of a population that can be

sustained in an ecological environment assuming no human exploitation: dynamic in nature

Principles

Life on earth depends on:

A. Natural cycling of chemical elements

B. Energy flow

Principles

No ecosystem can function without a source of energy, generally through

photosynthesis

Chemical Cycles

Carbon Cycle

Water Cycle

Nutrient Cycle

N-S Cycles

• Box 11: The role of fungi

Required Reading

Feedback Systems

Positive feedback:

An interaction that increases or amplifies the response of the system in which it is incorporated

• Positive feedback increases change– E.g. Increased CO2 warmer temperatures

more methane production in peat lands higher greenhouse effect higher temperatures

Positive Feedback

Positive Feedback

Feedback Systems

Negative feedback

• An interaction that reduces or dampens the response of the system in which it is incorporate

• Stabilizing; tends to oppose change– E.g. Population regulation; increased CO2

increased cloud cover;

Negative Feedback

Negative Feedback

Potential feedback mechanisms in climate change

Using feedback systems to meet management goals

• Increased harvest of caribou leads to lower caribou numbers, less competition for food, less predation, and higher caribou reproduction

Properties of Ecological Systems

Biological Organization

• Individual– One whole organism – Individuals have size, shape, health, or

condition– They grow, reproduce, and die over time

Biological Organization

• Population– A group of individuals of the same species

occupying the same area at a given time– Populations have abundance, biomass, size,

and age and sex class structures– They compete, exploit prey, and produce

biomass

Biological Organization

• Community– The collection of all organisms that live in a

specific region at a given time– Communities have biomass, diversity

(evenness, richness), and trophic structure– Produce biomass, process materials, and

change through succession over time

Biological Organization

• Ecosystem– All of the organisms in an area, together with

the physical environment with which they interact

– Ecosystems have biological as well as physical and chemical structure

– They move energy, materials, and nutrients

Energy Flow

• Energy is a requirement for any ecosystems

• The North receives less sun energy due to the earth’s orientation towards the sun (changes with season)

• Ambient temperatures are lower in the Arctic, which means less primary productivity

Energy Flow within Trophic Chains

Plants

Detritus

Herbivores Predators

Detritus Detritus

RespirationRespiration Respiration

Energy

Arctic Monitoring and Assessment Program. 1997. Arctic Pollution Issues: A State of the Arctic Environment Report. [online] http://amap.no/. Oslo: AMAP.

Ecological health in the Arctic

• Functions: productivity, food chain integrity, biodiversity

• Toxicology (contaminants)

Stresses of Arctic Ecosystems

• Global changes (e.g. climate)

• Industrial developments

• Human exploitation (new technologies)

Box 31: North Slope of Alaska

Box 28: Harvest of Murres

Case Study: Snow Geese

• Rapid expansion (26 million in N. Canada• Habitat Degradation (over grazing)

Conclusions:

•South-North landscapes are connected

•Humans’ influences at macro scales

Toxicants: Large Scale Inputs

Toxicants: Biomagnification

Required Reading

• Implementing the Precautionary Principle by P.L deFur and M. Kaszuba– Sections 1, 2, 3, 4.1, 5