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Landscape Ecology 1
Landscape Ecology Lecture Test One
| Question | Answer |
|---|---|
| Landscape Ecology | study of the causes and consequences of spatial heterogeneity across a range of scales |
| Carl Troll | German scientist to introduce concept of landscape ecology based upon studies geography, vegetation sciences and aerial photography |
| Landscape Ecology | study of landforms and the organisms which inhabit the area; considers the causes and consequences of habitats from a small scale to larger scales |
| Configuration | specific arrangement of spatial elements; also referred as spatial structure or patch structure |
| Connectivity | spatial continuity of a habitat or cover across a landscape |
| Corridor | relatively narrow strip of particular type that differs from the areas adjacent on both sides |
| Cover Type | category within a classification scheme defined by the user that distinguishes among the different habitats, ecosystems, or vegetation on a landscape |
| Edge | Portion of an ecosystem or cover type near its perimeter and within which environmental conditions may differ from the interior location in the ecosystem; also used as a measure of the length of adjacency between cover types in a landscape |
| Fragmentation | breaking up of a habitat or cover type into smaller, disconnected parcels |
| Heterogeneity | quality or state of consisting of dissimilar elements, as with mixed habitats or cover types occuring on a landscape |
| Landscape | area that is spatially heterogeneous in at least one factor of interest |
| Matrix | background cover type on a landscape, characterized by extensive cover and high connectivity; not all landscapes have a definite matrix |
| Patch | surface area that differs from its surroundings in nature or appearance |
| Scale | measured by 2 factors : grain or extent; spatial or temporal dimension of an object or process |
| Factors for Emergence Landscape Ecology | 1. Broad scale environmental issues and land management problems 2. Development of new-scale related concepts in ecology 3. Technological advances |
| Development of Landscape Ecology | Resource management needs led to development to manage native plants and animals as land use and climates changed |
| Government Agencies Involved in Environmental Agencies | Forest Service, Bureau of Land Management, National Park Services |
| Scale | scope of study changes depending on the type of ecological problems; insight at one scale does not translate directly to another scale |
| Whitaker | Gradient Analysis studied plant communities in Great Smokey Mountains and distinct vegetation patterns emerge with changes in elevation due to temperature and moisture(1952, 1956) |
| MacArthur & Wilson | Island Biogeography -1. probability of a species reaching an island is inversely proportional to the distance from mainland and is directly proportional to island size 2. Probability of extinction on an island is function of island size |
| MacArthur & Wilson | studied island biogeography which studied correlation between island size and distance from mainland to determine immigration and extinction of organisms |
| Equilibrium Theory of Island Biogeography | MacArthur & Wilson study shows islands that are large and close have a lower rate of extinction and higher rate of immigration while small islands far away from the mainland have a lower rate of immigration and higher rate of extinction |
| Simberloff | Island Biogeography study offers a good null model important for the design of nature reserves; study compares single, large habitats to several,small habitats [SLOSS}(1974) |
| Hanski | Metapopulation Theory(1998)collection of interconnected subpopulation with source surrounded by areas known as sink, areas |
| Source | area has higher fitness or capability to pass DNA to next generation |
| US Endangered Species Act | Established 1.Recovery Plan 2. Critical Habitat Designation |
| Huffaker | Experiments with frugivorous & predatory mites to study spatial manipulation of oranges shift dynamics between unstable(close together) and stable (Close together) |
| Huffaker | Study showing spatial pattern can effect both stability of populations and total population size. |
| Spatial Patterns | Result of complex interplay of abiotic factors, biotic factors and disturbances |
| Abiotic Factors | environmental factors such as weather,dissolved oxygen, silt, temperature or elevation ; most important landscapes variable are climate and landform |
| Biotic Factors | competition,predation,mutualism which effect populations which then effect communities |
| Disturbancces | Examples include : clear cuts, burns, glaciers, hurricanes: effect abiotic and biotic factors and directly effects populations and communities |
| Population | One species in certain area |
| Communities | collection of organisms in a defined area |
| Population Dynamics | Factors affecting include : diet, habitat use, population size, predator, reproduction including clutch size and clutch frequency. and sex ratio |
| Community Dynamics | Factors affecting include: number of species, biomass, biological indices concerning condition of community such as IBI(fish), B-IBI (benthic invertebrates) QHEI(habitat index) |
| Broad Spatial Scale Understanding Needed For: | Pattern and Processes Issues such as acid rain, global climate change, habitat fragmentation and conservation of biodiversity |
| Biotic Hierarchy | Levels of organization (larger to smaller) include continental,terrestrial/aquatic, biomes, ecoregions,habitat ecotypes, trees, organisms living in trees...most meaningful interactions occurring at the lowest level or smallest scale |
| Hunter | research studied avain community patterns which were dependent on spatial, temporal and taxonomic resolution. Songbirds require small spatial habitats while raptorial birds require continuous spatial habitats |
| Spatial Pattern | Pattern inherent at one scale may disappear when you scale up because data is not always transferable. |
| Absolute Scale | actual distance, direction, shape and geometry |
| Cartographic Scale | degree of spatial reduction indicating the length used to represent a larger unit of measurement; ratio of distance on the map to distance on the earth's surface represented by the map, usually 1:10,000 |
| Cartographic Scale | large scale -> fine resolution small scale -> coarse resolution |
| Critical Threshold | point at which there is an abrupt change in quality, property or phenomenon |
| Extent | size of the study area or the duration of time under consideration |
| Extrapolate | to infer from known values ; to estimate a value from conditions of the argument not used in the process of estimation |
| Extrapolate | to transform information 1. from one scale to another(either grain size or extent 2. from one system(or data set) to another system at the same scale |
| Grain | finest level of spatial resolution possible within a given data set |
| Hierarchy | system of interconnections or organization where in higher levels constrain and control the lower levels constrain and control the lower levels to various degrees depending on the time constraints of the behavior |
| Holon | representation of an entity as a two-way window through which the environment influences the parts and parts communicate as a unit to the rest of the universe (Koestler,1967) |
| Levels of Organization | place within a biotic hierarchy |
| Relative Scale | transformation of absolute scale to a scale that describes the relative distance, direction or geometry based on some functional relationship |
| Resolution | precision of measurement; grain size if spatial |
| Scale | spatial or temporal dimension of an object of process, characterized by grain and extent |
| Schoener | (1976) documented an increase in area yields an increase in species richness; quantitatively shown with species richness equlaed to fitted constant multiplied by the area squared |
| Schoener | species-area relationship is one of community ecology's few laws and tend to give asymptotic,with limit,curve |
| Preston | Small,isolated island have fewer species per unit of area and higher slope values; small island are small targets and have higher probabilities of extinction |
| Founder Effect | bredding within a population; loss of genetic variationdue topopulation started by a small number of individuals (special case of genetic drift) |
| Island Effects | Gigantism - Giant Tortoise due to no predator and herbivore Dwarfism -Komodo Dragons - resource limitation |
| Haggert | Scale Problems: 1. Scale Coverage Patterns 2. Scale Linkage Patterns 3. Scale Standardization Problem |
| Hierarchy Theory | interconnected systems have higher levels which constrain lower. Ex. of this theory includes the local fish assemblage in a field site contain organisms remaining from filtering of upper levels along with abiotic factors, biotic factors and disturbances |
| Sampling Methods | Transect - line count along a linear path Quadrat - count inside a square area |
| Scale Up | most measurements in ecology made at transect or quadrat scale - need to extrapolate |
| King | (1991) direct extrapolation uses data or model simulations froma number of samples in the landscape to estimate to larger areas |
| King | (1991) extapolation by expected value involves imulation modeling |
| Schneider | (1994) confidence intervals around a measurement made at one scale may not directly translate to another scale |
| Succession | predictable change in vegetation communities immediately following a disturbance 1.primary succession completely destroys soil layer 2. secondary succession keeps soil intact |
| Categories of Spatial Patterns | 1. Local Uniqueness ex: mountain 2. Phase Difference ex: succession 3. Dispersal ex: wind , water |
| Levin | (1976) studied unique features of landscape such as uniqueness of locality, succession phase difference, and dispersal of plant species |
| Climate & Landforms | Most important abiotic landscape variables which establish template for soils and biota |
| Biomes | form primarily because of temperature and precipiation |
| Climate | 1.warms earth's surface & energy used to fuel food webs 2. equator gets most sun 3. temperate latitudes have seasons 4. artic & antartic one day of total light and total darkness per year at solstice |
| Elevation | effects temperature, density, pressure and moisture. Air density & pressure decrease as elevation increases. |
| Coriolis Effect | deflects winds; winds blowing to equator deflect to west and known as trade winds and winds blowing to poles deflect east as westerlies |
| Landforms Influence Climate | Examples: 1. coastal California lower temperature , inland Californai higher temperature 2. Death Valley, Nevada green,lush on west side mountain while east side of has desert conditiond |
| Milankovich Cycles | climate cycles caused by the earth's wobbling on it axis; Glacial/Interglacial Cycles 90,000 years of gradual cooling followed by 10,000 years of rapid warming |
| Croin & Schneider | (1990) Organisms response to climate change 1. Evolve & Speciate 2. Migrate Long Distances 3. Become Extinct |
| Mass Extinction Events | ~6 events, largest being formation of Pangea because 1/2 shoreline which decreased habitat |
| Organism Response to Climate Change | 1. Glacial-Interglacial cycles trigger disassembly of communities,followedby reassembly that can be unpredictable |
| Organism Response to Climate Change | 2. past communities @ many sites feature mixtures of species that are absent or rare on modern landscape |
| Organism Response to Climate Change | 3. displacement of entire vegetation zones or communities can occur |
| Swanson | (1988) Effects of landform on ecosystem patterns & proceses: 1. Elevation,aspect,parent materials & slope of landforms affect air & ground temperature and quantities of moisture, nutrients, & other materials available |
| Swanson | 2. Landforms affect the flow of organisms (wind) 3. Landforms affect frequency & spatial pattern of natural disturbance (fire, wind, grazing) |
| Swanson | 4. Landforms constrain spatial pattern and rate or frequency of geomorphic processess (landslides or shifts to river channels) |
| Gause | (1934) determined no two species can occupy the same niche by studying two different types of parmecium |
| niche | everything an individual species needs to survive and reproduce ; Hutchinson defined as (n)dimensional hypervolume |
| Sutherland | (1974) multiple states can occur when several species can potentially occupy and dominate site; can results in small stochastic(random) changes in initial conditions |
| Paine | (1974) studied interactions in rocky intertidal zone which determined sea stars were keystone species that kept mussels in check; removal of sea stars caused increase in mussels which led decline in sea otters over competition for food source |
| Keystone Species | keeps dominant species in check; doesn't allow an organism to overpopulate ; aka predator-mediated coexistence |
| Dominant Organisms | 1. Define spatial patterns on landscape 2. Alter abiotic conditions & provide resource base & substrate for other populations in ecosystem 3. Rest of ecosystem is constrained to operate in spatial pattern (plants/terrestrial, coral/marine) |
| Dominant Organisms | Examples: Redwood trees, American Bison |
| Human Land Use | dramatically altered biodiversity of organisms 1. pollen & fossil record show shifts in patterns 2. Advent of agri. crops such as corn, wheat,and rice shifted land use patterns 3. Weeding & Nutrient Addition for permanent fields |
| Human Land Use | 4. Loss of native diversity in Middle East and Eutope from long-term use 5. Native Americans in North America influenced landscape by settlements, agriculture, hunting & fire use 6. Agri,livestock,forest harvest,& construction have greatest threat |
| Dsts Used in Landscape Analysis | 1. aerial photography 2. digital remote sensing 3. published data and censuses 4.field mapped data |
| Methods of Representing Spatial Data in GIS | 1. Raster (celled) based 2. Vector based |
| Anderson | (1976) Developed heirarchical land classification system used for landscape analysis; divided into 2 levels |
| Sources of Potential Error in GIS Data | 1. Obvious Sources - age of data,aerial coverage,map scale,political boundaries 2. Natural Variation in Original Measurements- positional accuracy,content accuracy,variation in data sources |
| Sources of Potential Error in GIS Data | 3. Processing Errors - numerical computation,topological analysis,classification |
| Problems for Landscape Pattern Analysis | 1.Identification of Classification Scheme 2.Definition of Scale 3.Identification of Patch 4.Correlation of Metrics 5.Idenitification of Significant Change |
| Considerations to Decrease Error | 1. Dificulty to specify biases for map of different extent 2.no single map extent optimal for all snalyses 3.Sample maps with greatest extent unless optimal sample size is known |
| O'Neill | (1996) Proposed general rule to avoid bias in calculating landscape metrics; 1. Grain 2X-5X smaller than spatial feature 2. Extent 2X-5X larger than largest patches |
| Ritters | Identified 5 independent landscape metrics 1.# of classes of cover types 2.texture, fine or coarse 3.patches,compact or dissected 4.patches,linear or planar 5.patch perimeter,complicated or simple |
| Landscape Metric Categories | 1. Landscape Composition 2. Spatial Configuration 3. Fractals |
| Metrics of Landscape Composition | 1.Fraction or Proportion 2.Relative Richness 3.Diversity & Dominance 4.Connectivity |
| Metrics of Spatial Configuration | 1.Probabilities of Adjacency 2.Contagion 3.Patch Area & Perimeter 4.Connectivity 5.Proximity Index 6.Area-Weighted Average Patch Size |
| Fractals | 1.Fractal Dimension 2.Fractal as Measure of Patch Shape |
| Selection of Multiple Metrics | Subset should 1.explain pattern variability without redundancy 2.capture relevent aspects of pattern to answer to study question 3.use multivariate statistics |
| Ritters | Recommendation of Multivariate Measures for Landscape Analysis to Avoid Redundancy 1.total # of land cover types 2.contagion 3.fractal dimension 4.average patch perimeter-area ratio 5.relative patch area |
| McGarigal & Marks | (1995) Recommendation of Multivariate Measures for Landscape Analysis to Avoid Redundancy 1.patch shape & edge contrast 2.patch density 3.patch size |
| Li & Reynolds | (1994,1995) Theoretical considerations to compute aspects of spatial heterogeneity 1.#of land-cover types 2.proportion of each type on the landscape 3.spatial arrangement of patches 4.patch shape 5.contrast between neighboring patches |
| Purpose of Spatial Statistics | 1.identify the spatial scales over which patterns or processes remain constant 2.to interpolate or extrapolate point data to infer the spatial distributions of variables of interest |
| Important Question Addressed by Spatial Statistics | 1. What is the appropriate scale to conduct an anlysis? 2.What is the nature of spatial structure of a particular variable? |
| Correlograms | in analysis of time series,commonly-used tool for checking randomness in a data set |
| Semivariograms | defines spatial scales over which patterns are dependent ; are calculated by rearranging the data into N data pairs separated by distance ; flat variograms indicates patterns that lacks spatial structure |
| Criteria for Metrics to Quantify Landscape Patterns | 1. Selected to paticular question or objective 2. Distributed over full range of potential values & behavior of metrics known 3.indexes ahould be relativey independent of each other |
| Spatial Statistics | quantify aspects of landscape patterns and used to detect the spatial scales of autocorrelation for landscape elements or to interpolate point data to infer spatial distributions of a variable of interest |
| Potential Areas of Research Development for Landscape Pattern Analysis | 1. Statistical Properities & Behavior of Metrics 2. Relative Sensitivities of Different Metrics to Detect Changes in Landscape 3.Documentation of Empirical Relationship between Landscape Patterns and Ecological Processes of Interest |
| Proportion | metric of landscape composition used to calculate the amount of landscape that is occupied by each cover type |
| Relative Richness | metrics of landscape composition which calculates the number of cover types present, without regard to spatial arrangement,as a percent of total number of possible cover types |
| Diversity | measure of landscape composition which measures how evenly the proportions of cover types are distributed; relative evenness; high value = high evenness low value = low evenness |
| Dominance | metric of landscape composition which is the deviation from the maximum possible diversity high value=one or few cover types low value=cover types in close proportion |
| Connectivity | metric of landscape composition which is a pattern across a landscape represented by a series of nodes and linkages;known as gamma index low gamma index=low connectivity high gamma index=high connectivity |
| Probability of Adjacency | measure of spatial configuration which measures the probability that a grid cell of one type is adjacent to grid cell of another type; can be computed directionally |
| Contagion | measure of spatial configuation distinguishes between overall landscape patterns that are clumped or dissected; high value=high clump pattern of cover low value=dsipersed cover |
| Patch Area & Perimeter | measure of spatial configuration used to show frequency distribution of numbers of patches by patch size,cumulative frequency distribution of patch sizes,simple mean, standard deviation of patch size or area-weighted mean patch size |
| Patch Area & Perimeter | high value=complex boundary low value=simple boundary |
| Connectivity | measure of spatial configuration which measures the relative size of the largest patch of habitat or the inverse,fragmentation, to calculate the average distance between patche |
| Proximity Index | measure of spatial configuration which measures the degree to which patches in the landscape are isolated fromother patches; high value=connected patches low values=isolated patches |
| Area-Weighted Average Patch Size | measure of spatial configuration used to reflect the expected patch size that would be encountered by simple random placement of points on the map |
| Fractal Dimension | measure which shows the level of variation present at all scales |
| Mandelbrot | (1985) defined fractal as a shape made of parts similar to the whole in some way |
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