spatial ecology ii: landscapes

Spatial ecology II: landscapes

Bio 415/615

Questions

1. Landscape ecology is the study of spatial patterns… and what else?

2. What are three main agents of landscape pattern?

3. What is GIS?4. What are two examples of a

landscape element?

Landscape Ecology

Space: grain and extent

“Heterogeneity is not an annoyance that complicates experimental designs, it is a critical ingredient in explaining the stability of ecological systems.” – Robert O’Neill (2001)

Landscapes are heterogeneous!

Landscape Ecologyvs. Island Biogeography and

Metapopulation biology

• Islands, populations, patches vary• The matrix is not neutral• The patch-matrix contrast is low or

high• There are edge effects• There are corridors, stepping stones,

and barriers

Landscape ecology

Landscape ecology is the study of the causes, consequences, and dynamics of spatial pattern in ecosystems

Like conservation biology, it is a relatively new subfield (1980s).

Landscape

Landscapes are blocks of land that contain this spatial pattern

Landscapes are defined either by natural boundaries (watersheds, divides) or by political or management boundaries

So, how BIG is a landscape?“The view from a small airplane”

So, how BIG is a landscape?

REALLY ANY SCALE, but most oftenused to refer to areas 10 to 100 km2

(2,500 to 25,000 acres) or larger

Depends on the process in question!

Wiens & Milne 1989 in Landscape Ecology

Landscapes can be of any resolution (grain) or extent.

Wiens & Milne 1989 in Landscape Ecology

5 m

Landscapes can be of any resolution (grain) or extent.

GIS: THE tool of landscape ecology

Geographic information systems (GIS) are tools for capturing (GPS units), managing & analyzing (software products) data that are referenced to spatial coordinates on Earth (‘georeferenced’).

GIS example: lat-longTreats the Earth as perfect sphere, divides each hemisphere into 90 degrees (plus divisions of 60 minutes and 60 seconds).

At equator, distance between longitude lines is about 69 miles.

Syracuse:

45° 2' 53" N, 76° 6' 54" W

Robinson projection: note any treatment of the Earth in 2D must be distorted!

GIS example: Universal Transverse-Mercator (UTM)

60 (distorted) world zones; tropics distorted the least

Syracuse: zone 18N

Easting: 412194 E

Northing: 4988893 N

Why UTMs? Values are in meters.

Pattern & ProcessThe Landscape Ecology

Mantra

Pattern & ProcessThe Landscape Ecology Mantra

Spatial pattern affects ecological processes

. . . and . . .Ecological processes affect spatial

pattern

This is why landscape ecology is not simply the study of pattern (more akin to traditional geography).

Patterns: discrete and continuous

• Landscape ecology can be similar to metapopulations, in that landscape positions are discretized (made into homogeneous patches)

• Landscapes can also be treated in more continuous fashion (such as elevation or contour maps, ie a surface)

• Both types are used in a GIS

Example of landscape modeling as a continuous

surface• Modeling ground-level temperature

in mountainous terrain

Example: How landscapes control near-ground temperature

A landscape modelA landscape model: how temperatures can : how temperatures can be predicted by factors derived from GISbe predicted by factors derived from GIS

Level 1: Minimum Temp = β0+ β1synoptic + β2radiation +

β3cos(ωvt) + β4sin(ωvt) + β5synoptic x radiation + ε

Level 2: β0 = π00 + π01elevation + π0ilog(strdist) + π03log(tci)β1 = π10 + π11log(strdist) + π11elevation + π13log(tci)β2 = π20 + π21elevation + π22log(strdist)β3 = π30 + π31elevation + π32log(strdist) + π33log(tci)β4 = π40 + π41elevation + π42log(strdist) + π43log(tci)β5 = π50

Mapping fine-scale GSMNP Mapping fine-scale GSMNP temperaturetemperature

Run model for each pixel (about 4 million at 30 m grain)Run model for each pixel (about 4 million at 30 m grain)

Scales of variationScales of variation

Mean annual tempMean annual temp

Patches & patch dynamics

Process of patch change– Disturbance– Recovery from disturbance

(succession)• Feedback to disturbance rate!

Patch dynamics: Processes of change (a) within a patch, and (b) interactions among patches on the landscape

Patch: A relatively homogeneous area defined by some criterion

Patch dynamics

The importance of computer modeling to simulate patch dynamics

Landscape Metrics• Composition: Kinds of patches,

matrix, connections, barriers• Size & Shape

– Perimeter/area ratio, Edge length– Shape or boundary complexity

• Arrangement:– Connectedness, dispersion,

isolation– Adjacency, contrast

Example of Example of discretizing a discretizing a landscape:landscape:

Mt LeConteMt LeConte

Great Smoky Great Smoky Mts National Mts National ParkPark

S

W

Let’s take a Let’s take a look at a look at a landscape:landscape:

Mt LeConteMt LeConte

Great Smoky Great Smoky Mts National Mts National ParkPark

S

W

Let’s take a Let’s take a look at a look at a landscape:landscape:

Mt LeConteMt LeConte

Great Smoky Great Smoky Mts National Mts National ParkPark

PP

PP

PP

PP

PP

PP

SW

Patches

Patches

Beetle kills

Patches

Patches

Matrix

Patches

Barrier Matrix

Matrix

Patches

Barrier

Landscape ecology

Matrix

Patches

Barrier

Landscape ecology

Connectedness

Landscape Elements:

Patch Matrix Corridor

Chardon et al. 2003

Landscape Elements:

Patch Matrix Corridor

Chardon et al. 2003

Landscape Elements:

Patch Matrix Corridor

Chardon et al. 2003

Size, quality

Chardon et al. 2003

Connectedness,Distance

Chardon et al. 2003

CorridorStepping stoneBarrier

Chardon et al. 2003

CorridorStepping stoneBarrier

Chardon et al. 2003

CorridorStepping stoneBarrier

Chardon et al. 2003

Matrix, Ecological Contrast

Chardon et al. 2003

Landscape Metrics• Composition: Kinds of patches,

matrix, connections, barriers• Size & Shape

– Perimeter/area ratio, Edge length– Shape or boundary complexity

• Arrangement:– Connectedness, dispersion,

isolation– Adjacency, contrast

Edge Area• Size effects edge• Large areas have relatively shorter edge

lengths than small areas

6ha

3ha

3ha

2ha 2ha2haEdge = 980m Total Edge =

1697m

Total Edge = 1386m

The shape of a patch influences amount of edge

All edge

Core & edge

Turner et al. 1997: How fire size influences vegetation response in Yellowstone NP

Small burned patches

recovered faster than

large burned patches

Size of burned patches

Landscape Metrics• Composition: Kinds of patches,

matrix, connections, barriers• Size & Shape

– Perimeter/area ratio, Edge length– Shape or boundary complexity

• Arrangement:– Connectedness, dispersion,

isolation– Adjacency, contrast

Patches

Barrier Matrix

Central Smokies: low connectivity

Western Smokies: high connectivity?

BIOTABIOTA

TOPOGRAPHYTOPOGRAPHYSUBSTRATESUBSTRATE

AGENTS OF LANDSCAPE AGENTS OF LANDSCAPE PATTERNPATTERN

CLIMATECLIMATE

Landscape Flows

• What processes connect patches or different landscape positions?

Landscape Flows

• Animal Dispersal• Wind movement• Hydrologic flows• Nutrient cycling• Insect outbreaks• Fire

Dynamic landscape models describe flows between landscape positions over time, including how the environment (eg, soil moisture) influences biota (eg plant growth) and vice-versa.

Process creates pattern+ Fire often

increases heterogeneity*

* (But not always!)

Post-fire mosaic, 1994 Rattlesnake Fire, Chiricahua Mts., AZ

Process creates pattern

+ Fire often increases heterogeneity*

- Succession sometimes decreases heterogeneity** (But not always!)

Blue Mts, California, at two periods

Pattern also affects process

+/- Fire spread regulated by fuel mass, moisture, distribution (“flammability”)

+/- Wind, humidity influenced by vegetation type and structure