Transcript Ecosystems
Ecology An introduction to the study of the relationships between living things and their environments Introducing Ecology….. •The term ‘ecology’ is derived from the Greek words oikos for ‘home’, and logos for ‘study’ and was first used in the mid 1800s. In those days, ecologists spent most of their time describing nature and less time developing models and theories as they do these days. •The ECOSYSTEM provides a framework in which to study the relationship between living things and their environments. An ecosystem is a self sustaining unit made up of living things (the community) interacting with and within a particular habitat. Why study ecosystems? What kind of ecological information would a fire fighter use to help him/her perform their job better? How has the habitat of these kangaroos changed? What will help them survive? How would the lives of these horses be affected by the bush fires? How does a bush fire like this affect the daily lives of humans? Will this environment completely return to how it was before the fire? What effects would the smoke have on an urban ecosystem like Melbourne? Is the city in danger from the fire? Where do we find ecosystems? •We find ecosystems where ever there is life, for example in the hydrosphere (where water and ice are found), in the lithosphere (on the land) or in the atmosphere (in the air). •Hydrosphere + lithosphere + atmosphere = biosphere. •The biosphere is about 20km thick and reaches from the bottom of the oceans to the peaks of the highest mountains. Components of an ecosystem 3. Community 2. Environment sum of all the living things in a particular habitat at a particular time sum total of all the factors that effect or influence a living thing 1. Boundary arbitrary line drawn around ecosystems 5. Population total number of a particular species in a particular habitat at a particular time 4. Dominant Species most common species in a community Components of an ecosystem Boundary •An ecosystem can be any size and varies from hundreds of kilometers wide, such as in a biogeographical area or bioregion (an area with similar patterns of ecological characteristics), to just a few meters such a pond. •Whatever the size, an ecosystem must have a boundary to be defined. •Sometimes the boundaries of ecosystems are difficult to define and can actually overlap. Components of an ecosystem Abiotic Factors Physical and Chemical factors: •temperature •salinity •pH •light intensity •rainfall •air quality •space •shelter •resources Environment Biotic Factors The Effect one Living thing has on another Living thing: •competitors •predators •parasites •pathogens Components of an ecosystem Community •Made up of all the living things in a habitat at a particular time •Consists of a variety of intraspecies (same species or within species) relations and interspecies (different species) relations. This will be looked at in more depth in a future lessons. Components of an ecosystem Dominant Species •Some ecosystems can have one type of plant or animal that dominates over others. •Usually an ecosystem can be named according to its dominant species - examples include; coral reefs, river red gum woodland, pine forests, mangrove swamps, alpine forest. •Other ecosystems are named after the physical environment - examples include: rock pools, caves. Components of an ecosystem Population •Populations in ecosystems are dynamic, that is they are constantly changing. •They can change in size from one season to another or from one generation to another through migration, birth, death, immigration and emigration. •Studying populations is important when monitoring ecosystems as it helps to manage endangered species, assists in agriculture when wanting to know if enough food is available and helps restore damaged or degraded ecosystems. Measuring populations Distribution Random Cluster Uniform Can you think of some examples or situations where the different types of distribution would occur? Measuring populations Distribution Low lying bush Small burrowing animal Predator What are the different types of distribution for these three species? Can you identify the factors (biotic and abiotic) that would determine these distribution patterns? Measuring populations Abundance •Abundance is simply the measure of the number of individuals in a particular population •The more individuals there are, the greater their abundance •Ecologists cannot always know the absolute numbers in a population and must apply techniques to make estimate sample sizes •The distribution and/or abundance of a population can be measured by three main methods…………with transects, quadrats or using a capture-mark-recapture method Transects 1. A line is set out to measure the position and distance of the transect 2. Vegetation types along the transect line are recorded 3. Slope gradient recorded along the profile line 4. Soil samples can also be recorded Transects Peppermint eucalypt Large grasses i.e. tussock grass Manna gums Kangaroo Grass Drier rockier conditions 0M 36M River bankmoister soil After taking the measurement, a profile can be drawn out to scale to indicate the distribution of various species. Transect The vegetation types can also be drawn out (this one is not to scale as it is more an ‘artists impression’ by 10yr old Charlotte!) Quadrats •Small sections of the community are randomly sampled and the species type are recorded. This way, a general picture of the overall community is gained. Is this method of sampling populations as useful for fauna as it is for flora? Capture-Mark-Recapture •Used to sample animal populations •A certain number are captured, marked, and then released !st capture and marking 2nd capture •At a later date the N = # marked 1st time x total 2nd time animals are captured again from the same site # of marked recaptures and the ratio of marked to unmarked animals N = 9 x 12 = 13.5 helps to estimate the 8 overall population Further Studies •Energy flows in ecosystem •Food chains and food webs •Human influence in ecosystems The End!