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Explore environmental questions, ecological changes, and ecological systems in the context of human impact on nature. Learn key concepts and principles of ecology for sustainable practices.
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www.greenresistance.wordpress.com Know that site.
Homework due February 24 • Email me - as a MS Word Attachment - answers to the following question: • What are environmental and/or particular ecological questions that you want answered from this class? • Talk to elderly people in your communities (such as your grandparents) and tell me how the physical landscape of the environment in your village / neighborhood has changed during the past 50 years. • Be sure to use correct grammar - both in the paper and in the email itself. • My email: rania.masri@balamand.edu.lb
Chapter 1: Introduction Robert E. Ricklefs The Economy of Nature, SixthEdition
Cow burping? • Cadbury is to encourage its cows to burp less to reduce the carbon footprint of its milk chocolate. • The company is working with its 65 dairy farmers in Wiltshire to reduce the emissions of their animals. Production of the famous glass-and-a-half of milk in every bar is responsible for 60% of the chocolate's carbon emissions, according to experts at the Carbon Trust who audited the carbon emissions from the company's products. Experts at the Institute of Grassland and Environmental Research have also looked at how the diet of farmed animals can be changed to make them produce less methane, a much more potent global warming gas than CO2.
Gazelles on a mountain side of the West Bank city of Hebron/Al-Khalil
Background • Human perceptions of nature and mankind’s relation to nature: • there is a balance of nature • nature is pristine in the absence of humans • Ecological studies conclude otherwise: • there is historical variation in nature • the pervasive influence of human activities extends to the most remote regions of the earth
? “Where we humans fit in a less than perfect world is a judgment each of you must make, guided by your own sense of values and moral beliefs. Regardless of your own stand, it will be more useful to you and to human kind in general if your judgment is informed by a scientific understanding of how natural systems work and the ways in which humans are a part of the natural world.”
What is Ecology? …. Oikos = home “By ecology, we mean the body of knowledge concerning the economy of nature -- the investigation of the total relations of the animal both to its organic and to its inorganic environment; including above all, its friendly and inimical relation with those animals and plants with which it comes directly or indirectly into contact -- in a word, ecology is the study of all the complex interrelationships referred to by Darwin as the conditions of the struggle for existence.” Ernst Haeckel, 1870.
So, what is ecology? • Ecology is the science by which we study how organisms (animals, plants, and microbes) interactin and with the natural world. • Please note the important key words in the above definition!
Ecology - A Science for Today • We have a great need for ecological understanding: • what are the best policies for managing our environmental support systems -- our watersheds, agricultural lands, wetlands? • we must apply ecological principles to: • solve or prevent environmental problems • inform our economic, political, and social thought and practice Example?
Our Objectives... We are on the road to ecological thinking: • we’ll have many vantage points of varying complexity • we’ll understand ecological systems and the interdependence of their components • we’ll establish a core of principles regarding: • physical and chemical attributes • regulation of structure and function • evolutionary change
Ecological Systems Large and Small • Organism (“No smaller unit in biology ... has a separate life in the environment...”) • Population (many organisms of the same kind living together) • Guild (a group of populations that utilizes resources in essentially the same way) • Community (many populations of different kinds living in the same place) • Ecosystem (assemblages of organisms together with their physical environment) • Biosphere (the global ecosystem, all organisms and environments on earth)
Perspectives of Ecologists: Organism Approach • How do form, physiology, and behavior lead to survival? • Focus is on adaptations, modifications of structure and function, that suit the organism for life in its environment: • adaptations result from evolutionary change by natural selection, a natural link to population approach… ? - Why are trees the dominant plants in warm, moist environments – and shrubs the dominant plants in regions with cool, wet winters and hot, dry summers?
Perspectives of Ecologists: Population Approach • What determines the numbers of individuals and their variations in time and space? • Focus is on processes of birth and death, immigration and emigration, influenced by: • the physical environment • evolutionary processes • interactions with other populations, a natural link to community approach… ? – Why have mosquitoes increased in number and in extent?
Perspectives of Ecologists: Community Approach • How are communities structured from their component populations? • Focus is on the diversity and relative abundance of different kinds of organisms living together, affected by: • population interactions, promoting and limiting coexistence • feeding relationships, responsible for fluxes of energy and materials, a natural link to ecosystem approach... ? – what is the relationship between birds, crops, and insects?
Perspectives of Ecologists: Ecosystem Approach • How can we account for the activities of populations in the common “currencies” of energy and materials? • Focus is on movements of energy and materials and influences of: • organisms large and small • climate and other physical factors, including those acting on a global scale, a natural link to biosphere approach... ? – movement of Nitrogen… ?
Perspectives of Ecologists: Biosphere Approach • How can we understand the global movements of air and water, and the energy and chemical elements they contain? • Focus is on the global circulation of matter and energy, affecting: • distributions of organisms • changes in populations • composition of communities • productivity of ecosystems ? – climate change ?!
Kinds of Organisms and Their Ecological Roles • Characteristics of ecosystems depend on varied forms of life: • plants and animals are conspicuous and important, • but no more so than more primitive forms, like the bacteria, • which dominated much of earth’s early history, • making it possible for their more complex descendents to survive!
Plants use energy in sunlight to produce organic matter. • Plants capture the energy of sunlight and transform it into chemical form. • Plants must use external surfaces for absorbing light and exchanging gases, water, and nutrients. • Plants stay closely attached to their sources of water, from soil, atmosphere, or bodies of water.
Animals feed on other organisms or their remains. • Animals depend on organic foods ultimately produced by plants. • Animals can use internal surfaces for exchange of gases, nutrients, and water. • Animals can assume streamlined shapes, with other systems permitting motility. • Animals can be less directly tied to sources of water than plants.
Fungi are highly effective decomposers. • Fungi assume unique roles in ecosystems because of their distinctive form. • Fungi penetrate dead materials effectively, making nutrients available to others. • Fungi digest externally, and capture inorganic nutrients and water from soils.
Protists are single-celled ancestors of more complex life forms. • Protists are highly diverse single-celled forms, including algae, slime molds, and protozoa. • Protists lack specialized tissues and organs, yet fill almost every ecological role: • photosynthetic organisms • grazers and predators • decomposers
Bacteria have a wide variety of biochemical mechanisms for energy transformations. • Bacteria consist of simple, single cells lacking nuclei and chromosomes. • Bacteria are biochemical specialists, accomplishing unique transformations: • nitrogen fixation • chemoautotrophic production • metabolism under anaerobic conditions
Organisms cooperate in nature. • Many types of organisms live together in close association, forming symbioses: • each partner provides something the other lacks • examples of symbiotic relationships include: • lichens (fungus and alga) • bacteria fermenting plant material in a cow’s gut • beneficial fungi associated with the roots of plants • photosynthetic algae in corals and clams • nitrogen-fixing bacteria in root nodules of legumes
Habitat and Niche • The habitat is a place or physical setting in which an organism lives. Examples include: • forests • deserts • coral reefs • The habitat is characterized by: • conspicuous physical features • dominant plant (or animal) life
Classifying habitats is useful but difficult! • The habitat concept is useful; it emphasizes conditions experienced by organisms. • Classification systems are varied and typically hierarchical: • aquatic habitats (vs. terrestrial) • marine habitats (vs. freshwater) • oceanic habitats (vs. estuarine) • benthic habitats (vs. pelagic) • Finer subdivisions overlap rather broadly!
Niche • The niche of an organism encompasses: • ranges of conditions tolerated • role in ecological systems • No two species have the same niche: • each has distinctive form and function • No organism can live under all conditions: • each has unique habitat requirements • each has a unique niche
These Aphids: suck juices from stems and leaves of milkweed plants
