Dec 3, 2013
Ecology at a landscape level has been made possible by new tools that can view the
environment in multiple dimensions and at many scales.
Aerial photography gave ecologists the first means to look at “the big picture.”
More recently, our access to space has vastly expanded our ability to acquire images of
Earth through remote sensing. Remote sensing satellites provide images of Earth that
expand our view of large-scale ecological patterns.
Geographic information systems (GIS) are used in landscape planning for conservation and
Geographic Information Systems (GIS)
Computer-based systems that allow the storage, analysis, and display of spatial data (data
pertaining to specific geographic areas).
The data used in GIS are derived from multiple
sources, including aerial photography, satellite
imagery, and ground based field studies (GPS
and radio telemetry to document precise
locations and track animal
movements/migration patterns). Collected
data includes rainfall, elevation, vegetation
cover at specific locations, and land use. This
data is referenced by spatial coordinates to
geographic locations and displayed as multi
Layers of mapped GIS data can be put
together to show patterns and answer specific questions.
Multilayered maps can be used to address questions posed by the Gap Analysis Program
(GAP) in the USGS. The goal of GAP is to identify species of concern that are not
adequately represented on existing conservation lands (prevent biodiversity decline).
Identifying species of concern that reside in unprotected areas will enable ecologists to
make decisions about which lands should be protected in order to prevent future losses
GAP analysis is a two step process. First, you must input information about vegetative
cover, and other environmental conditions required/preferred by the species of
interest. This information will be used to predict its geographic distribution. Next, the predicted distribution is compared with another GIS layer that shows the locations of
We can do a GAP analysis for lark bunting. The lark bunting depends on Prairie
habitats for breeding,
but much of this
habitat has been
humans. As a result,
populations of lark
bunting are declining.
by lark buntings are
mapped to predict its
distribution. Locations of conservation lands are mapped in another layer. By
comparing the two layers, it is clear that only a small portion of the bird’s
potential range is in protected areas.
Data analysis and GIS continually improve with better computers and statistical methods.
Landscape ecology examines spatial patterns and their relationship to ecological processes and
Landscape ecology emphasizes the causes and consequences of spatial variation across a range
Landscape ecologists look at the spatial arrangement of landscape elements across Earth’s
surface. Landscape elements include forest patches, soil types, lakes, etc.
Spatial patterns of landscape elements can influence what species live in an area, and the
dynamics of ecological processes (disturbance/dispersal).
Landscape: An area in which at least one element is spatially heterogeneous (varies from one
place to another) Landscapes often include multiple ecosystems.
Landscapes may be heterogeneous with regards to composition (what different types of
landscape elements are present?) or in the way their elements are arranged (small patches
occurring regularly or large clusters?)
Ecologists refer to the pattern of heterogeneous elements that make up a landscape as a
mosaic. The images below indicate landscape heterogeneity. Landscapes can be heterogeneous in many
different kinds of elements, which may be arranged independently of one another. The image to
the left shows a map of 6 different soil types within the same area. The map to the right shows 7
different landscape elements within the same area.
Multiple ecosystems make up a landscape. The ecosystems that make up a landscape are
dynamic and interacting. Interactions include the flow of water, energy, nutrients, or pollutants
between ecosystems. There is also biotic flow as animals, seeds, pollen, etc., move between
For biotic flow to occur, patches of the same habitat must be connected to one another,
or the surrounding habitat (matrix) must be a type through which dispersal is possible.
The image below indicates movements across a landscape. Movements
between landscapes may occur frequently (thick arrow) or rarely (thin arrow).
Exchange between similar habitats is frequent if a corridor connects them (A).
Exchange between a habitat and the surrounding environment (matrix) is rare
The heterogeneity we see in landscapes can be described in terms of composition and structure.
Landscape composition: The kinds of elements or patches and how much of each kind is
Landscape structure: Physical configuration of the landscape elements (habitat fragmentation). Landscape structure is characterized by: Size of patches, whether patches are aggregated or
dispersed, complexity of patch shape (simple/complex), and degree of fragmentation.
Example: In Yellowstone National Park, researchers designated 5 different age classes of
lodgepole pine forest (5 landscape elements), thus indicating landscape composition.
The five elements were mapped to show structural complexity. Looking at the below
map, we can see that some parts of the landscape contain continuous blocks of old
forest, while other parts are highly fragmented (small patches with a variety of different
The image below shows that only remnants of older forest remain in areas that have
been fragmented by recent fires. However, large stands of old forest remain in the
unburned regions. This information can be used to compare fire caused fragmentation
within the park to fragmentation caused by clear cutting in areas outside of the park.
Consideration of scale is very important in landscape ecology.
A landscape may be heterogeneous at a scale important to a tiger beetle, but homogeneous to a
warbler or a moose. The scale chosen for a study determines the outcomes.
Scale: the spatial or temporal dimension of an object or process, characterized by grain and
Grain: size of the
of study (e.g., a
pixel in a digital
which we view the
pixels=higher resolution, but more data to store and analyze). The selection of grain will affect the
quantity of data that must be manipulated and analyzed. A large-grained approach may
be appropriate for regional to continental scales (resolution drops but there are fewer
pixels to store and analyze than if you were to use a small grained approach for a large
Extent: boundary of the area or time period encompassed by the study. How the extent
is defined can change the composition of the landscape being described. There may be
natural or human created boundaries that determine the extent of a study, or they may
be defined by the researcher.
Panel 4 shows little late successional whitebark pine (dark blue), while panel 6
contains a considerable area of it.
Landscape ecologists must also consider how processes scale up or down.
Example: A researcher studying carbon exchange at the landscape level needs to know
how leaf-based measurements of CO exch2nge scale up to the whole plant, the
ecosystem, and to the mosaic of ecosystems that make up the landscape.
Landscape Patterns Affect Ecological Processes
Landscape structure plays an important role in ecological dynamics. It can affect whether and
how animals move, therefore influencing rates of pollination, dispersal, or consumption.
Henry et al. (2007) studied the movements of a fruit eating bat in a tropical forest that
had been fragmented by the construction of a reservoir. They found that more isolated
forest fragments were less likely to be visited by bats, even if they contained abundant
food resources. In other words, patch connectivity determined bat density. Thus, they
determined that landscape structure affected bat foraging behavior. Furthermore,
because frugivorous bats disperse plant seeds, it is also likely that landscape structure
also affected dispersal of the plants the bats fed on.
Landscape structure influences biogeochemical cycling. Ecologists have identified
biogeochemical "hotspots" where chemical reaction rates are higher than in the surrounding
landscape. Many of these hotspots are found at interfaces between terrestrial and aquatic
ecosystems. However, it was noted that other factors must play a role. Example: Inputs of sulfur, calcium, and nitrogen from atmospheric deposition were
higher at forest edges than in forest interiors. Denser canopies and greater physical
complexity at forest edges resulted in greater interception of airborne particles.
Fragmented forests surrounding urban areas may be strongly influenced by atmospheric
inputs of pollutants and nutrients.
Landscape patches vary in terms of habitat quality and resource availability. This variation can
affect the population densities of species inhabiting each patch, the time animals spend foraging
in a patch, and the movement of organisms between patches.
Patch boundaries, connections between patches, and the matrix between patches can also
affect population dynamics.
Example: Bog fritillary butterflies would cross readily from patch to patch when suitable
patches were close together.Where there was a wider distance of matrix to cross, the
butterflies were more hesitant to leave a patch (Schtickzelle and Baguette 2003).
The shape and orientation of landscape patches can be important in physically intercepting
Gutzwiller and Anderson (1992) found that northward-migrating, cavity-nesting birds
were more likely to nest in forest patches in Wyoming grasslands that were oriented
along an east–west axis (oriented perpendicular to dispersal path of migratory
organisms). The habitat patches serve as a net, intercepting birds as they migrate north.
Habitat loss and fragmentation has con