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Geog358LndEco > Lecture > Flashcards

Lecture Flashcards

1
Q

What is the most widespread and destructive defoliator of coniferous forests in western NA?

A
  • Western Spruce Budworm
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2
Q

What does WSB feed on?

A
  • Larvae emerge after overwintering at same time as new spruce buds emerge and feed on them
  • Coevolution to emerge at same time as buds develop on trees
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3
Q

What is the tree scale habitat of WSB?

A
  • Bud flush: timing and abundance

- Size of Crown and available foliage (puffy = lots of food)

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4
Q

What is the stand scale factors of WSB?

A
  • Species composition (homogeneous good for connectivity, hetero bad)
  • Stand structure (Vertical heterogeneity and multiple age classes good, spin down from top and reach more food sources of lower tree tops)
  • Site quality
  • Standscale alone cannot fully explain spatiotemporal patterns of insect outbreaks
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5
Q

What could control the expansion of distinct and randomly distributed infestation patches to more continuous landscape level outbreaks?
- Landscape-level factors:

A
  • Composition, configuration of host populations (connectivity, abundance)
  • Adult moth dispersal and pred-prey interactions (dense forest decreases bird predators and increases dispersal)
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6
Q

What could control the expansion of distinct and randomly distributed infestation patches to more continuous landscape level outbreaks?
- Regional Factors:

A
  • Physiography
  • Climate (moisture deficits, warm dry conditions to disperse and survive, autumn precipitation)
  • Drought year before outbreak causes outbreak initiation due to survivability and dispersal as well as increased nutrition in hosts from stress forcing more sugar into needles
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7
Q

What are the most important infestation predictors?

A
  • Proximity to infestations in the previous year
  • Landscape-scale host abundance
  • Dry autumn conditions
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8
Q

What scale is the most important to manage for WSB outbreaks?

A
  • Landscape because these are the factors that contribute most to the outbreaks
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9
Q

Pattern and fire

A

Species compostition and structure, including fuel amounts, size classes and arrangement
- Affects how a fire will burn

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10
Q

Low severity fire and where in BC does it occur

A
  • Ecological effects minimal, species are adapted
  • Fire consumes surface fuel, not into large tree canopy
  • Dry forest that experiences frequent fire (except for the modern suppression)
  • Interior BC, Douglas Fir, Ponderosa Pine
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11
Q

Severity

A
  • Ecological effects above and below ground of a disturbance
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12
Q

High severity fire and where in BC does this occur

A
  • Ecological effects profound
  • Big highly flammable trees not adapted to fire, tree crowns burn
  • Coastal and northern forests
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13
Q

Mixed severity fire and where does it occur

A
  • Some patches of high and of low severity
  • Dry and northern forests
  • More common/dominant in NA than previously thought
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14
Q

Patch size of low severity fires

A
  • Openings created by fire within which post-fire regeneration occurs
  • Low-severity fire regime generally has small patches in larger matrix of homogeneous forest cover
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15
Q

Ponderosa pine forests and fire

A
  • Open forest so fire moves quickly across landscape, consumes fuel on surface, doesn’t burn in one place for long, bark resistant to fire, not very flammable
  • Small patches with homogeneous matrix
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16
Q

Patch size of mixed severity fires

A
  • Results in both large and small patches from areas of low, moderate, and high severity fire
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17
Q

Patch size of high severity fires

A
  • Small patches of isolated extreme fire activity or very large patches that an remain treeless for up to a century after the fire
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18
Q

High elevations and fire

A
  • not well adapted to fires

- Regeneration time may be long

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19
Q

Landscape Metrics: Patch Edge

A
  • Calculate edge index by measuring whole perimeter of disturbance (fire), including the undisturbed islands within patch
  • Compute ratio between total perimeter and the perimeter of a circle of same size to get edge index
  • Can be adapted to measure/compare edges around areas affected by different severities (fire)
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20
Q

High vs. low edge index

A
  • High: very impactful for regeneration

- Low: less edge and less recolonization options and longer regeneration time

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21
Q

Which is easier to define, edges of high or low severity fire patches?

A
  • High severity is more prominent

- Low severity is diffuse and difficult to define

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22
Q

What shape does a patch of wind driven fire take?

A
  • Oblong or oval
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23
Q

Which fire regime has higher edge index value?

A
  • Mixed

- Indicates greater landscape level heterogeneity in pattern

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24
Q

Describe fire characteristics of high vs. low severity or index

A
  • Low severity: small patches, low edge index, highly similar pre-post fire
  • High severity: large variable patches, depends on topography, moderate edge, high index, low pre-post fire similarity
  • Mixed severity: moderate patch size, high edge, moderate pre-post fire similarity
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25
Q

What factors could contribute to fires with greater edge indices?

A
  • Weather: Wind driven fires, larger fires w/ longer burn length and greater topographic variability
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26
Q

What are the effects of patch edge with fire?

A
  • Microclimates
  • Birds like edge environments (increase MBP and WSB predators)
  • Quantifiably measure landscape and apply to other features
  • Reduce connectivity and host abundance for pests?
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27
Q

Measures of landscape connectivity

A
  • Spatial graphs
  • Network analysis
  • Social network models
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28
Q

Metrics of landscape composition

A
  • Refers to cover types in an area and how much of each class is present
  • Not spatially explicit
  • Fraction occupied
  • Diversity and dominance
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29
Q

Measures of spatial configuration

A
  • Quantitative description of the spatial arrangement of cover types on the landscape
  • Edge length and edge density
  • Contagion
  • Patch-based metrics
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30
Q

Fraction occupied

A
  • Calc proportion of landscape that is occupied by each cover type
  • Estimate proportion by counting number of grid cells over landscape that are occupied by a cover type, then divide by total number of grid cells
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31
Q

Diversity and Dominance

A
  • Based on relative abundance of each cover type
  • Inversely related, usually only 1 reported because implies the other
  • Diversity refers to how evenly the proportion of cover types are distributed
  • Require at least 2 cover types
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32
Q

Normalized landscape diversity metric

A
  • H = diversity
  • pi = Proportion of landscape occupied by cover type i
  • s = number of cover types present
  • H = (negative sum of pi ln(pi))/ ln (s)
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33
Q

What is a limitation of H (diversity) and D (dominance) metric

A
  • Metrics tied to proportions, not qualitative aspects of landscape
  • Same H and D may occur for landscapes that have a different proportion of cover (i.e. 10% forest and 90% agriculture = same H and D as 10% agriculture and 90% forest)
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34
Q

Study or concept when diversity or dominance metric would be useful to make comparisons?

A
  • MaMu and logged landscapes and old growth
  • Sea otters and kelp forests
  • Urban environments of apartments vs. retail vs. park etc. (compare w/ pollution and calc with index of dominance leads to most pollution
  • Compare species invasion w/ native diversity and which areas more susceptible to invasion
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35
Q

What is often excluded in the calculation of edges?

A
  • The perimeter of the map

- Don’t know what is happening outside of map, can’t use

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36
Q

Edge density

A
  • Calculated by summing edge length and dividing by map area

- Can be tallied total or by cover type

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37
Q

Contagion Metric

A
  • Uses adjacency info and distinguishes btwn overall landscape patterns that are clumped or dissected
  • Probabilities of adjacency, how likely is it to occur
  • Sensitive to fine-scale spatial distribution of cover types
  • Adjacency of similar and different cover types
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38
Q

Contagion Metric pre-calculation

A
  • qi,j = ni,j/ni
  • qi,j = probability of adjacency
  • ni = number of grid cells of cover type i
  • ni,j = number of instances when cover type i is adjacent to cover type j
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39
Q

Contagion Metric calculation

A

C = 1 + sum of i * sum of j [(piqij)ln(pi*qij)]/2ln(s)

- s = area of inquiry

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40
Q

Patch-based metrics

A
  • Patch number, size, perimeter and shape
  • Report for individual cover types
  • Frequency distributions of numbers of patches and the mean, median and SD of patch size
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41
Q

Perimeter to area ratios

A
  • Index of shape complexity
  • High P/A = complex shape
  • Low P/A = compact and simple shape
  • Sensitive to patch size
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42
Q

Largest patch index

A
  • Relate to fragmentation of a given cover type
  • Calculates the size of the largest patch relative to the maximum size possible if the cover type occurred as a single patch
  • Straightforward way to characterize landscape and compare btwn study areas
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43
Q

Largest patch index calc

- When index = 1?

A

LPIi = LCi/(pixmxn)

  • LCi = size of largest patch of habitat i
  • pi = proportion of landscape occupied by habitat i
  • m x n = gives size of landscape of m row and n column
  • if all cover i occurs as single patch, value of index = 1 (complete connectivity)
  • When dispersed, index approaches 0
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44
Q

Patch Isolation

A
  • Degree to which patches are isolated from other same cover patches
  • Connectivity and fragmentation (habitat-use pattern studies)
  • Mean inter patch distance
  • Could be applied for one cover type or for more (animal that requires 2 habitats in close proximity
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45
Q

Mean inter patch distance

A
  • Distance from centre of one patch to the centre of the next nearest patch
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46
Q

Proximity index

A
  • Relative isolation of patches

- Low = isolation, high = well connected patches

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47
Q

Proximity index calculation

A

PXi = sum of (Sk/nk)

  • PXi = proximity index for local patch i
  • Specific search area
  • Sk = area of patch k w/in search area
  • nk = nearest neighbour distance btwn the grid cell of the focal patch and the nearest grid cell of patch k
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48
Q

Issue of scale with patch-based metrics?

A
  • perimeter and area will change by scale, zoom in and scale changes (fine-scale = more detail discernible and more perimeter/area/complexity than at broad scale)
  • Only real fix is to report scale of research when writing about
49
Q

Fractals

A
  • Self-replicating data
  • Small shapes seen at larger scale in replication
  • Never ending
  • Shape made of parts of the whole
  • Mathematics of fractals thought to be able to fix scale issue of landscape ecology (shape of fine applies to large)
50
Q

Importance of measures of landscape connectivity

A
  • Some landscapes, cell-based approaches not good models, alternatives (dendritic, road density) could be used
  • Fragmented habitats, degree that organisms can move among patches becomes more important
  • Connectivity in conservation and reserve design has fostered a proliferation of connectivity metrics
51
Q

Connectivity

A
  • Structurally, based on habitat patterns and assumptions about organism dispersal, or functionally, based on where organisms actually move
  • Property of entire landscape or of a particular habitat patch
  • Degree to which landscape facilitates or impedes movement of organisms
  • Difference between patch connectivity and landscape connectivity
52
Q

Connectivity and MPB, what affects MPB functional connectivity?

A
  • Important b/c poor dispersers
  • Wind, pheromones to help guide beetles to good habitat, predators, birds, populations drive MPB movement through landscape
53
Q

Example of climate change effect on connectivity

A
  • Polar bears use ice to connect landscape

- More energy use to travel on landscape w/o ice

54
Q

Graph theory

A
  • Pattern across landscape as series of nodes (represent habitat patches) and links (connections among points/nodes)
  • Used to examine connectivity, id pathways for dispersal/movement, and prioritize patches for conservation
55
Q

Gamma index, spatial graphs

A
  • gamma = L/Lmax = L/3(V-2)
  • L = number of links
  • V = number of nodes
  • Values close to 0 = little connectivity, close to 1 = high connectivity
56
Q

Which patch(es) should be prioritized?

A
  • Focal b/c important for whole landscape, maybe prioritize other close patches but should also layer other habitat info such as water, predators, range etc.
  • Must understand organisms and other landscape features (are close patches important or further important for range)
57
Q

Network Analysis

A
  • More complex than graph theory
  • number of nodes, links, degree to which nodes are connected directly or indirectly
  • Nodes can be weighted by area or habitat quality to better represent importance for connectivity
  • What happens when a node or link is removed or added?
58
Q

Social network models

A
  • Incorporate movement into network analysis
  • Theoretical dispersal vs. actually measuring movement
  • Complex models
  • Research frontier
59
Q

Fragstats

A
  • Software program designed to compute variety of landscape metrics for categorical map patterns
  • Developed in 1995
  • Patch-based, cell-based, surface metrics, structural and functional metrics, batch processing, sampling strategies,
60
Q

Continuous vs. discrete data

A
  • Categorical = discrete
  • Landcape metrics effective with discrete datasets
  • Spatial stats incorporates continuous data series
61
Q

Tobler’s 1st law of Geography

A
  • Everything is related to everything else, but near things are more related than distant things
62
Q

2 approaches for spatial statistics

A
  • Point pattern analysis, analyzes observed ‘events’ (nest locations, fire starts)
  • Spatial autocorrelation and variography
63
Q

Point Pattern Analysis

A
  • Data is records of event-based spatial phenomena

- Ripley’s k-function

64
Q

Ripley’s k-function

A
  • K = 1/N2 * ASum of jSum of idIdij/wij
  • N = number of points
  • A is size of study area that contains points
  • dij subset of distances less than id
  • id range from min to max possible w/in A
  • wij = edge correction required to avoid boundary effects
65
Q

Interpreting ripleys-k

A
  • Where the data departs from random theoretical line is where data is significant
  • Above = clustered, below= dispersed
66
Q

What are the landscape-level processes affecting conifer encroachment into grasslands?

A
  • Climate, fire, grazing, biotic interactions

- Biotic interactions of facilitation among shade tolerant and intolerant tree species

67
Q

Spatial autocorrelation and variography

A
  • 2 widely used methods for characterizing spatial dependence or spatial structure in a variable as a function of its position in a landscape
68
Q

Spatial autocorrelation

A
  • Correlation of spatially, and temporally, distributed variables
  • Near things are more related
  • Association between features and determine distances at which relation is high and where it drops off
  • Breaks assumption that things are random in statistics
69
Q

Models

A
  • Abstract representation of a system or a process
  • Used in landscape ecology to represent at least one landscape pattern-process relationships of interest
  • All models are wrong, but some are useful
70
Q

Modelling tree-ring width to climate

A
  • If significant strong correlation exists, build simple linear model where variability in tree ring is explained by climate
  • Use model and time series of tree-ring to hindcast past climate
  • Not perfect, but useful
71
Q

Random maps

A
  • Simple standard for landscape pattern
  • Observed landscapes vs. replicate random maps reveal magnitude and significance of differences due to the structure of actual landscapes
72
Q

Neutral landscape models, 2 categories of models

A
  • Determine extent to which structural properties of landscapes (patch size, shape, edge connectivity autocorrelation) deviate from theoretical spatial distribution
  • Predict how ecological processes such as animal movement, seed dispersal, gene flow, or fire spread are affected by landscape pattern
73
Q

Landscape modelling: Conceptualization

A
  • How does system work
  • What are the entities that define the structure of the system
  • What are key processes
74
Q

Landscape modelling:

Formalization

A
  • What are the state variables
  • Mechanisms/constraints included/excluded
  • Assumptions about system
  • Spatial and temporal scale of model
75
Q

Landscape modelling:

Implementation

A
  • Form of model equations

- How will model be solved (language and platform)

76
Q

Landscape modelling:

Parameterization

A
  • Data needed to estimate all parameters and set the initial conditions of the model
77
Q

Landscape modelling:

Verification

A
  • Does model do what it was built to do?

- How accurate at representing true values?

78
Q

Markov chains

A
  • Change detection
  • Observations of the state of a landscape at 2 time periods
  • Transitional matrix
  • Ex. Mamu and id habitat change over last 20 yrs
  • Describe landcover change (remote sensing is useful)
79
Q

What are the main things that models allow us to do?

A
  • Handle complex multivariate relationships too complicated for human mind
  • Project into future
  • Id most influential driving factors, focus attention on the few things that matter most
  • Id critical empirical information needs, focus on future research where it will do most good
  • Id thresholds/system behaviour, inform management of where, when and how to avoid major impacts on system
  • Explore ‘what if’ scenarios, cannot be done in real world
80
Q

Natural range of variability

A
  • Stems from ‘dynamic view’
  • Ecological conditions, spatial and temporal variation in these conditions, that are relatively unaffected by people, w/in a period of time and geographical area appropriate to an expressed goal
81
Q

4 steps for natural variability

A
  • Obtain site based information
  • Compile landcape history for sites
  • Interpret landscape-scale disturbance regime from site specific data
  • Develop landscape management plan using these findings
82
Q

Management applications of natural variability

A
  • Understanding and evaluating change

- Reference for setting general management goals

83
Q

Target stand

A
  • conditions from historical evidence
  • Recreated historical stand structures
  • selected an appropriate stand structure
  • designed a silvicultural burn treatment
  • implement treatment
84
Q

Problems with natural range of variability approach

A
  • Wrong scale for effective management
  • Selected condition mostly arbitrary
  • Difficult/inappropriate to treat entire landscape w/ one treatment
  • Does not recognize inherent variability
  • Past conditions may no longer exist (due to climate change for ex.)
  • How do we know for sure what species assemblages existed before and have the species actually adapted to the new conditions
85
Q

Examples of applications of natural range of variability

A
  • Salmon forests and natural variability form tree rings of salmon and use of creek
  • Caribou and use of snow fields to escape bugs by carbon dating feces trapped in ice to get inferences on population and snow use
86
Q

What must be incorporated into any concept of landscape equilibrium?

A
  • Disturbance needs to be incorporated in order for an valid definition of an equilibrium state
87
Q

Landscape dynamics

A
  • Considers spatial and temporal scales of disturbance and the resultant landscape dynamics
  • Can be applied across range of scales
88
Q

4 Factors of landscape dynamics

A
  • Disturbance freq and return interval
  • Rate of recovery from disturbance
  • Size/spatial extent of landscape
  • Reduce this to just temporal and spatial pattern
89
Q

Temporal pattern (Landscape dynamics)

A
  • Ratio of the disturbance interval to the recovery time (to mature stage)
  • Disturbance interval longer than recovery time, system can recover before being disturbed again
  • Disturbance interval and recovery time being equal (stable but variable)
  • Disturbance interval shorter than recovery
90
Q

Spatial pattern (landscape dynamics)

A
  • Ratio of the size of disturbance relative to the size of landscape of interest
  • Disturbances are large or small relative to landscape
91
Q

What does the use of ratios in both temporal and spatial parameters permit in landscape dynamics?

A
  • Permits comparisons of landscape across range of temporal and spatial scales
92
Q

State-space diagram

A
  • Temporal ratio vs. spatial ratio

- When close to 1 on spatial scale, the disturbance is more than landscape and therefore unstable

93
Q

Landscape heterogeneity

A
  • Animal behaviour
  • Habitat selection
  • Movement rates and trajectories
  • Species interactions (pred-prey)
  • Patterns and rate of spread of invasive species
94
Q

Source

A

Habitat areas where local reproductive success is greater than mortality

95
Q

Sink

A
  • Poor habitats where local mortality exceeds reproductive success
96
Q

Examples of important factors for wolf habitat?

A
  • Vegetation type
  • Deer populations
  • Land ownership
  • Road density
  • Human population density
97
Q

Study that analyzed wolf habitat and organisms and landscape pattern?

A
  • Regional landscape analysis and prediction of favourable gray wolf habitat in northern great lakes region
  • Mladenoff, Sickley et al.
98
Q

Habitat selection

A
  • Act of choosing combination of available abiotic and biotic elements that best fulfills the life-history needs of the organism
  • Gather by trail cameras, hair snags, tracks (issues w/ when laid and how many individuals), radio collars
99
Q

What is habitat?

A
  • Continuos variable

- Can be mapped with lidar over landscape (and in 3D!)

100
Q

Resource selection functions

- Describe what it is and how used in model of habitat for particular animal

A

Model that yields values proportional to the probability of use of a resource unit

  • Often fit using linear models (continuous dataset)
  • Elk in Yellowstone use more habitat in summer, less in winter where they cluster more (driven by predator prey interactions with wolves and resource availability)
  • Elk moved frequently among preferred locations, not extend periods w/in preferred
  • Elk move about landscape to avoid detection by wolves
101
Q

How do organisms create landscape pattern? Example?

A
  • Ecosystem engineers like beavers and hippopotamuses
  • Hippos feed on aquatic veg, river and riparian habitat respond to the disturbance by creating more corridors and heterogeneity in landscape system as hippo use increases
102
Q

Response of organism to landscape heterogeneity (5 points)

A
  • Larger, more heterogeneous patches contain more species and more organisms
  • Relative abundance of edge and interior habitat affects species diversity w/in a patch
  • Characteristics of surrounding landscape can influence local populations in patch
  • Effect of landscape composition on organisms is often stronger than effect of landscape configuration
  • Corridor creation can both add habitat and promote movement (butterfly genetics, shape can have sig. effect on even fine-scale)
103
Q

Edges and landscape heterogeneity

A
  • Edges may be barriers (allow big mammals but not small) or filters to movement (filter male from female deer)
  • Agents that alter mortality rates (less protection)
  • Areas providing energetic subsidies or refuge (more insects for birds on edges)
  • Regions where novel species interactions occur
104
Q

Predator-Prey interactions

- How does heterogeneity mediate interactions between pred and prey

A
  • Landscape pattern influences probability of prey encounters
  • Each uses areas that give them advantages, reflective of each others usage
  • Odds of elk encountering wolves was 1.3x greater in pine forest and 4.1x less in grasslands
  • Cougars use large denser patches while deer use open areas away from edges
105
Q

Stages of invasion

A
  • Introduction (intentional or accidental)
  • Colonization
  • Establishment
  • Dispersal
  • Spatially distributed populations
  • Invasive spread
106
Q

Landscape effects of Introduction of invasive species

A
  • Topographic effects on human land-use patterns may indirectly increase frequency of introductions
107
Q

Landscape effects of Colonization of invasive species

A
  • Spatial distribution of disturbed areas, safe sites, or resources required for colonization
  • tend to be associated with disturbed ecosystems
108
Q

Landscape effects of Establishment of invasive species

A
  • Spatial configuration of habitat that promotes survival and reproduction (landscape effects on demography)
  • tend to be associated with disturbed ecosystems
  • Spatial distribution of disturbed areas, network, connectivity, to find vulnerable areas
109
Q

Landscape effects of Dispersal of invasive species

A
  • Spatial configuration of habitat that promotes movement of exotic species or their dispersal vectors across the landscape and thus affects the potential for invasive spread
  • Propagules, long vs. short range, different mechanisms/abilities
  • Invasives tend to be generalists and good at dispersing
110
Q

Landscape effects of Spatially distributed populations of invasive species

A

Interaction of previous stages w/ landscape structure may give rise to spatially distributed populations that set the stage for invasive spread (nascent foci)

111
Q

Landscape effects of Invasive Spread of invasive species

A
  • Landscape ecological perspective may be required to predict and manage invasive spread if spatial distributions of habitat or resources affect any of the stages of the invasion process
112
Q

Characteristics of invaders

A
  • Generalists
  • Tough competitors
  • Allelopathy (broom)
  • High reproduction rates (rats)
  • Persistance of reproductive resources (seed bank)
113
Q

Landscape effects of invaders

A
  • on dispersal vectors by enhancing the spread above some critical threshold
  • on promoting or altering species interactions in ways that enhance invisibility of communities
  • Comprising of enhancing the adaptive potential of native species to resist invasion
  • Interacting with disturbances in ways that cause resources to fluctuate, which can enhance invasibility
114
Q

Why should ecologists care about the effects of landscape heterogeneity on plant species diversity?

A
  • Disperse, establish, survive, reproduce
  • Dispersal of plant portables across landscape could be affected by the spatial arrangement of patches
  • Edge and dispersal, both facilitate and inhibit dispersal
  • Many invasive plants like edges and small patches
115
Q

Landscape effects on biodiversity of native species and non-native species (kumar et al., 2006)

A
  • At landscape level, best models explained 43% of variation in native plant species richness, and 70% of variation in non-native plant species richness
  • Variation explained was always higher for non-native richness, and inclusion of landscape metrics (heterogeneity, edge) always improved the models
116
Q

Non-native species management at the landscape level

A
  • Offense: Contain invaders at their source patch

- Defence: protect uninvaded destinations from invasion

117
Q

Which is better to reduce overall spread rates of invasives? Offence or defence? When?

A
  • Offense better for early invasions

- Defence better after increased invasion, and when goal is to protect high conservation value areas

118
Q

What factors may affect choice of offence or defence for invasion?

A
  • Spread mechanisms (do birds carry seeds long distances, streams are good at dispersing)
  • Connectivity and disturbance by humans
119
Q

Ecosystem services

A
  • Nutrient cycling
  • Pollination
  • Habitat

Geog358LndEco (11 decks)

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