Download Notes from Introduction - Forest Landscape Ecology Lab

Principles of Landscape Ecology
Forest Ecology & Mgmt. 565
D. Mladenoff
Spring 2007
Intro to LE Handout
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Lessons 1: Landscape ecology roots, applications, and definitions
Landscape Ecology Introduction
Historical roots and development
European antecedents
North American roots and development
Relation to U.S. ecology, environmental
management, landscape architecture, planning
Applications of landscape ecology
Research
Land use planning
Ecosystem management
Definition of landscape ecology
Basic concepts
Terminology
General Principles
Landscape ecology- Study of the interaction of landscape pattern and ecological processes at
different spatial and temporal scales (from Risser 1984, 1987).
Scale- defined by grain (resolution) and extent (size of LS of interest). Not fixed.
Landscape ecology is concerned with: 1) development and maintenance of spatial
heterogeneity, 2) interactions across heterogeneous landscapes, 3) the influence of heterogeneity
on processes, management of that heterogeneity (Risser).
Landscape heterogeneity- The variable spatial distribution of landscape elements (such as land
cover types).
Landscape defined by repeated patterns of : 1) clusters of ecosystems, 2) flows/interactions
among clusters, 3) geomorphology and climate, disturbance regimes, relative abundance of
ecosystems w/in cluster (Forman and Godron 1986) 4) typically greater extents.
Fundamental characteristics of LS: Structure- spatial relationships among ecosystems,
distribution of materials, species, energy, in relation to distribution of ecosystems (size, shape,
number, types). Function- processes and interactions among spatial elements; flows of matter,
energy, species, among ecosystems. Change- alteration in structure and function over time.
Key developments in 19th and early 20th C. for modern landscape ecology : 1) Vegetation as
recognizable entities beyond indiv. plant species. 2) Recognition of importance of broad-scale
landform and edaphic factors, within climatic constraints. 3) Notion of the ecosystem and
concepts of interacting species and physical properties. 4) Theories of spatial dynamics in forests
(disturbance and succession) illustrating change through time.
Patch- LS surface area different from majority surroundings (matrix).
Principles of LE (Risser et al. 1984): 1) Relationship of spatial pattern not restricted to one
scale, 2) Understanding processes at given scale may profit of study at scales above or below, 3)
Processes vary in their importance or effects at different scales, e.g., biogeographic processes not
imp. in determining local abundance or presence. 4) Different species or groups operate at
different scales, and study at only one scale may treat them with unequal resolution;
heterogeneity and homogeneity can both be perceived at different scales. 5) Scales defined by
size and objectives or questions. Focusing at one scale may perceive finer scale processes as
averaged, and miss large scale processes.
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Primary lecture references:
Burgess, R. L., and D. M. Sharpe. 1981. Forest island dynamics in man-dominated landscapes.
Springer-Verlag.
Forman, R. T. T., and M. Godron. 1986. Landscape ecology. Wiley.
Golley, F. B. 1993. Development of landscape ecology and its relation to environmental
management. In M. E. Jensen and P. S. Bourgeron, eds. Eastside forest ecosystem health
assessment. Vol. II. Ecosystem management: Principles and applications. USDA Forest
Service.
McIntosh, R. P. 1985. The background of ecology: concepts and theory. Cambridge.
Naveh, Z., and A. Lieberman. 1984. Landscape ecology: theory and application. Second edition
1994. Springer-Verlag.
Risser, P. G. 1987. Landscape ecology: state of the art. In M.G. Turner, ed. Landscape
heterogeneity and disturbance. Springer-Verlag.
Risser, P. G., Karr, J. R., and R. T. T. Forman. 1984. Landscape ecology: Directions and
approaches. Illinois Natural History Survey Publ. No. 2.
Zonneveld, I. S., and R. T. T. Forman. eds. 1990. Changing landscapes: an ecological
perspective. Springer-Verlag.
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INTRODUCTION
- Historically, traditional ecology, and most field science, assumed homogeneity
populations, communities, ecosystems. E.g., can sample a forest stand and
generalize characteristics.
 Often also assumed equilibrium conditions; little change through time, or
disturbance. More recently, past 25 yrs., ecologists recognize importance of
heterogeneity, disturbance, and change.
- Landscape ecology considers spatial variation or heterogeneity as an intrinsic
phenomenon of natural systems, and the role of disturbance (natural or humancaused).
- Considers the interaction of landscape pattern and ecological processes that
depend on them.
Where does this new focus in ecology come from?
HISTORICAL DEVELOPMENT OF LANDSCAPE ECOLOGY
* LE has its origins in northern Europe, a much longer history there, and a different
character.
- LE development embedded in the history of 18th and 19th century natural
history, field sciences, and ecology.
- Alexander von Humboldt (1807) placed natural history in a larger
context.
- Made observations of characteristic vegetation types, based on
physiognomy, that varied with altitudinal zonation,
aspect. E.,g. n vs. s sides of mountains, and moving up.
- Also observed similar patterns in different biogeographic
locations.
E. g., similar patterns of physiog., zonation on dif.
continents.
- Individual plant species geography began to develop into geography
of vegetation- attention to broad-scale patterns, not explained by
still larger scale biogeographic distributions, or very local
presence or absence of species.
- During 19th century, vegetation distribution was studied and mapped
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in relation to factors such as climate and soils, and these factors
were seen as responsible for long-term convergence and stability
of landscapes and biota.
- This view influenced the American ecologist Clements (early
1900s), developed concept of stable, regional climatic climax
vegetation.
- European plant ecology in the first half of this century also
developed in relation to its surroundings, and the strong natural
history, taxonomic tradition.
- European plant sociology was based on the notion of
detailed, discrete, characteristic associations of plants in a
clear overall classification.
- Influenced by the long-time human-dominated, discrete
vegetation characteristic of Europe.
- England- at the same time, Tansley (1935) developed the concept of
the ecosystem- "an organism complex, and phyisical factors"
and recognized the hierarchy of systems.
- Somewhat later Watt (1947), placed observed vegetation patterns in
a dynamic spatial context, describing the importance of small
scale disturbances or gaps and succession as important in
maintaining the overall heterogeneity of a forest.
- Ideas related to these were also put forth by the American
ecologists Cooper and Gleason.
* These antecedents provided and important foundation for the
development of landscape ecology:
1) vegetation as recognizable entities with properties beyond
individual plants,
2) recognition of the importance of broad scale landform and
edaphic factors, operating within climatic constraints, as
"landscape templates".
3) the notion of the ecosystem and concepts of interacting species and
physical properties providing the basis for process concepts,
4) an explicit formulation of theories of spatial dynamics in forests,
how, through time, changes occur on the landscape
providing a relationship between landscape pattern and
biotic interactions.
* Next step- development of landscape ecology, occurred also in Europe where
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most of the foundations were developed, where orderly, human-dominated
landscape made conceptualizing landscape structure and relationships more
feasible, as opposed to the relatively untamed N. American landscape.
- "Landscape Ecology" first used by Troll (1939), a geographer and
biologist. He was influenced by Tansley's ecosystem concepts, and
applied the ideas to patterns and landscape units he observed on aerial
photographs beginning to be used in planning.
- This holistic approach continued, and became well integrated as the
foundation of land planning in northern and central Europe.
NORTH AMERICAN DEVELOPMENT* Descriptions of the development and growth of landscape ecology in NA
typically start with the early 1980's, which surely is the period
when it burst upon the ecological scene. But I would like to back up a
little in this country before picking up that thread.
- North American seeds of LE derive from development of ecology in
general in the U.S.
- But especially from a few key programs and events.
1) The growth of ecosystems ecology- by definition integrative-deriving from: the U.S. funded Analysis of Ecosystems
Program of the IBP in the 1960s and 1970s (1967-1974).
- Structured as large ecosystem analysis and modeling research
programs focused on major biomes.
2) NSF funded Research Applied to National Needs (RANN)
program.
- Also large-scale ecosystem modeling program.
- Applying ecological modeling to large-scale environmental
problems in urban environments and developed
landscapes.
- Both of the programs had very mixed results, judged from meeting nearterm goals, but important for development of ecological science in
U.S.
- Same time- not unrelated- environmental movement, first Earth Day (1969).
- Environmental concern, Environmental management (also journal), first
efforts at national land use planning legislation, mid-1970s (failed).
- Planners, landscape architects became influenced by then current ecological
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research.
- Two important landscape architects/planners toured U.S.,
competition.
Ian McHarg (Penn), Phil Lewis (UW).
- Lewis developed the idea of regional environmental corridors
as important features in interpreting the nature, use and
areas for preservation of landscapes.
- Produced large visuals, wall-sized maps of important
features that were congregated in
environmental corridors.
-Landform driven- land cover, land use.
- McHarg developed process of mapping various "layers" of
information on mylar overlays, combined to examine
concentrations and juxtapositions of features in making design
and planning decisions.
- Before GIS, a visual revelation. Used weighting of layers in
qualitative models- still used in GIS
- Wrote the book- Design on the Land (1969). Lewis never
wrote the book until 1996.
- Some ecologists in turn were influenced by these applications
of their science- Planners, landscape architects, incorporating ecology into their work.
- None of this yet being called Landscape Ecology. Very similar to what
was called LE in Europe. Here, maybe applied ecology, environmental
planning.
* Ecology in 1970s- not only development of ecosystem ecology, but other
areas of ecology were paying greater attention to landscapes, spatial
component of problems, temporal change, concept of non-equilibrium
and importance of disturbance.
- Vegetation/plant community ecology- gap dynamics (spatial), nonequilibrium dynamics (temporal).
- Population modeling
- MacArthur and Wilson book (1967), Island Biogeography continued to
influence many areas of ecology- concept of islands, variable
dispersal with different island size/area, area effect on processes,
diversity.
- Growing availability and functionality of computers, methods and
capability for more sophisticated mathematical modeling of
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populations, ecosystems, furthered interest in temporal scale.
- B. Burgess and D. Sharpe (1981)- Forest island dynamics in mandominated landscapes. Based on 1977 ESA symposium.
* Based on IBP landscape productivity work in SE Wis., other eastern
U.S. studies, many part of Eastern Deciduous Forest Biome
Proj.
* Burgess, a Wis. ecologist at Oak Ridge, Sharpe a geographer.
*Forest Stearns, UW ecologist, then at UW Milwaukee, directed
SE Wis. IBP work. xpecial US-Iale award in 1995.
- Stearns and Sharpe obtained what may have been first NSF grant for
LE in 1980- study affect of agricultural development over time
on Cadiz township, WI.
- J. Curtis studied, most famous fig. in ecology.
- At this point, also begins explicit development of LE in U.S.* 1981 LE symposium in Netherlands- important.
U.S. ecologists attended- F.Golley, R. Forman, D. Sharpe.
More american Ecologists attended European meetings for next
several years.
* 1981 paper- R. Forman, M. Godron, Patches and structural
components for a landscape ecology (Bioscience).
* 1982 first LE papers at ESA meeting (R. Forman, B. Milne)
* 1982- Iale formed at Czech meeting- Forman, Golley, two officers.
* 1983- NSF funded workshop in Illinois organized by P. Risser,
James Karr, R. Forman (1984 Report).
* 1984 first ESA paper session on LE.
Books: * Naveh and Lieberman, (1982) Landscape Ecology: theory and
application.
Israeli and American landscape architects- heavily influenced by systems
analyis, hierarchy ideas.
* T. Allen and Tom Starr (1982) Hierarchy: perspectives for ecologcial
complexity.
* R. Forman (1986) Landscape Ecology.
First U.S.-Iale meeting (1986), hosts, M. Turner, F. Golley.
* 1987 paper- D.Urban, R. O'Neill, H. Shugart, Landscape ecology: a
hierarchical perspective.
* 1987 Landscape Ecology journal, first volume.
DEFINITION OF LANDSCAPE ECOLOGY
Risser (1984, 1987): LE considers a mixture of processes at different spatial
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and temporal scales, linked in a system
LANDSCAPE IS HETEROGENEOUS- composed of diverse elements
(depends on scale); more later).
- LANDSCAPE ECOLOGY:
1) considers the development and maintenance of spatial heterogeneity,
2) interactions across heterogeneous landscapes,
3) the influence of heterogeneity on processes,
4) and management of that heterogeneity, on managed and natural
landscapes.
Terms in definition of LE (Risser):
- HETEROGENEITY- diverse constituents
- Forman and Godron (1986)- LANDSCAPE defined by 5 repeated
characteristics:
1) clusters of ecosystem types,
2) flows/interactions among clusters,
3) geomorphology and climate,
4) set of disturbance regimes,
5) relative abundance of ecosystems w/in cluster,
landscape composed of "a hetergeneous land area composed of a
cluster of interacting components..." that repeats this format or pattern
throughout.
- Disturbance- def. difficult: (Pickett and White 1985)- "any relatively
discrete event in time that disrupts ecosystem, community, or
population structure and changes resources, substrate availability, or
the physical environment."
"Primary focus of LE includes: spatially heterogeneous areas, fluxes and changes
of materials and energy among LS elements, human actions as responses, and
influences on, ecological processes" (Risser et al 1984).
- Fundamental characteristics of LS: Structure, Function, Change (Forman
and Godron 1986)- STRUCTURE: spatial relationships among ecosystems; distributions of
materials, energy, species in relation to configuration of
ecosystems (size, shape, number, types).
- FUNCTION: interactions among spatial elements; flows among
ecosystems.
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- CHANGE: alteration in structure and function over time.
-STRUCTURE-- (Forman and Godron 1981, 1986) Largely described by
definition of PATCHES on landscapes.
PATCH- surface areas different in appearance from their surroundings or
MATRIX.
- Patch distribution can be due to landform or edaphic factors, or to
natural or human causes.
- Understanding patch cause or origin gives predictive insight.
- PATCH TYPES- (F&G), besides edaphic/landform discontinuities:
- DISTURBANCE PATCHES- F&G say these typically small, effect on
resident biota.
- e.g., tree fall gaps, to large fire patches. Species immigrate, colonize;
over time patch disappears.
- Chronic Disturbance Patch- repeated stress such as pollution,
grazing.
- Remnant Patch- Disturbance surrounding becomes the matrix, such
as clearcutting forest, and leaving isolated "islands".
- REGENERATION PATCH- regeneration patch- later stage of
disturbance patch.
- These basic definitions of patches can be extended, but looking at different
possible configurations on the LS- CONNECTIVITY between patches on a landscape may be important for
aspects of landscape stability- maintaining species or processes over
time.
- Linear patches can serve as CORRIDORS when connecting other
patches, or barriers to species or processes that depend on a
second patch type.
- Patches of a same type that are increasingly isolated from each other
can have consequences for habitat value, affect species
movement- cause extinction.
- Can natural or artificial connections serve as corridors? What
dimensions are critical?
- HEDGEROWS are very heavily studied line corridors in Europe;
important habitats in human-dominated landscapes, assist species
movement and colonization between woodland patches.
- FOREST PATHS may be little barrier to movement, but powerline ROW
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can be significant or constitute significant habitat themselves, e.g., for
grassland birds.
- STREAM CORRIDORS or riparian are complex, controlling water and
nutrient flows.
- These patch concepts assume human-perceived differences matter- other ways of
defining patches. Also assume clear contrast between patch and
matrix elements, boundary definition. Thresholds and boundary gradients
may vary for different species and processes.
* Individual patch characteristics- EDGE CONTRAST- definition between patch and matrix. New clearcut
patch vs. 5, 10, 40 year regrowth? When is it no longer a patch? No
single answer; depends on process of interest.
- Wildlife concept of "edge" as type of habitat- open, early
successional habitat, presumably conducive to high game productivity
vs. landscape feature- confusion and error. Not always the same, or
same consequences.
- Patch EDGE VS. INTERIOR can have important habitat consequences,
differentially affecting species and processes. Dependent on
combination of patch area and shape. For a given area, a patch with
complex shape will have more edge length, and less interior.
# Figure 1- structure (size and configuration of patches (Forman and Godron
1981).
# Figure 2- patch/matrix configurations (Forman and Godron 1986). Patch
origins, Others.
* Descriptive morphology, common terminology for structural attributes. Describe
and compare landscape characteristics.
* FUNCTIONAL ASPECTS more difficult to encapsulate in simple description.
Functions operate at different spatial scales, and temporal rates, can be
disrupted by a disturbance event, or respond differently (positive or negative
feedbacks). Functional aspects deal with process, and * Change.
* Three menchanisms or causal processes for development of LS heterogeneity
(Forman and Godron 1986): operate at different scales, both temporal and
spatial.
1) specific geomorphological processes,
2) colonization patterns of organisms over time,
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3) local disturbance events.
* Disturbance- is it enhanced by a homogeneous or heterogeneous landscape?
whichever occurs, how are mutiple disturbances over time then affected by
previous events? Interaction of heterogeneity and disturbance complex,
different scales important, and interactions through time.
Principles of LE (Risser et al. 1984): (Mention only, do not list; save for
discussion)
1) Relationship of spatial pattern not restricted to one spatial or temporal
scale,
2) Understanding processes at a given scale may profit form experiments or
study at scales above or below.
3) Processes vary in their importance or effects at different scales. eg,
biogeographic processes not imp. in determining local
abundance or presence.
4) Different species and groups operate at different scales, and study at only
one scale may treat them with unequal resolution; heterogeneity and
homogeneity can both be perceived at different scales.
5) Scales defined by size and objectives or questions. Focusing at one scale
may perceive finer scale processes as averaged, and miss large scale
processes.
- We can evaluate the effectiveness, usefulness, and validity of these terminologies
and "principles" in the readings for this week, and throughout the course as
we review a broader range of work that has taken place over the past decade.
The next lecture will provide further detail on scale will expand on the
material covered here.
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