Landscape Ecology Landscape elements (patches, corridors, boundaries) Terms/people

Patch corridor boundary hardness/softness

Ecotone 10% rule edge effect

Composition configuration homogeneous

Heterogeneous area, perimeter, shape (for patches)

Ecological trap Alexander von Humboldt matrix

Geometric module “rescue effect” landscape composition, configuration, & connectivity

“contagious catastrophes” “ecological fire escape” species-area relationship

Darlington’s rule
But first, some background:

landmarks

“positional awareness”

geometric module (Cheng and Spetch 1998)

“sense of place”
Most organisms can recognize "landmarks" (which may be visual, olfactory, auditory, chemosensory, magnetic, or tactile), indicating that they recognize that the world is heterogeneous and can identify landscape structure. In this way they become oriented and consequently know where they are (Healy 1998). But in addition to landmarks, most other organisms also have an instinctive “positional awareness.” Experiments on rats, for example, have shown that they utilize geometric space more than other cues like odors in orientation. This trait has also been found in domestic chicks and in human children and is called a geometric module (Cheng and Spetch 1998). This "sense of place" is a strong instinctive response in many animals, including humans. These facts indicate that animals recognize that they exist within a spatial context–in other words, they recognize that they exist within a landscape.

The features that are recognized/used as landmarks and to reinforce the geometric module are patches, corridors, and boundaries. These to be embedded in a matrix, the background land‑use type, characterized by extensive cover, high connectivity, and/or control over dynamics that occur within patches and corridors and along boundaries.

The matrix can have a PROFOUND effect on pattern-process relationships happening within patches (much more in future lectures); see recent review by Prevedello and Vieira 2010 for more info.

What is a landscape?

Consider these varied definitions:

"the total spatial entity of human living space" (Troll 1968)

"[the] physical, ecological and geographical entities [that integrate] all natural and human (‘caused’) patterns and processes" (Naveh 1987)

"heterogeneous land area composed of clusters of interacting ecosystems [that] is repeated in similar form throughout" (Forman and Godron 1986)

"a particular configuration of topography, vegetation cover, land use and settlement patterns which delimits some coherence of natural and cultural processes and activities" (Green et al. 1996)

A landscape, by the way, need not be terrestrial. It can also be aquatic.

Alexander von Humboldt -

From what are landscapes made?

Landscapes are (usually) heterogeneous in composition (vs. homogeneous, which would be rather boring). Landscapes are comprised of three main elements: patches, corridors, and boundaries (all embedded in a matrix). Different landscapes differ in the configuration of these elements. Recall that landscape ecology is the study of the effect of pattern on process. Therefore, it is important to describe landscape structure in terms of its pattern of patches, corridors, and boundaries:

Patches are defined as regions that are more or less internally homogeneous with respect to a measured variable (a set of spatially proximate homogeneous units). There are several approaches to defining specifically what a patch is:

There are three main components of landscape structure (O'Neill et al. 1988):

“narrow strips of land which differ from the matrix on either side” (Forman and Godron 1986, p. 123)

“a linear landscape element that provides for movement between habitat patches” (Rosenberg et al. 1997, p. 678)

“routes that facilitate movement of organisms between habitat fragments” (Hilty et al. 2006, p. 5)

“a landscape element that plays a key role in connectivity” (Anderson and Jenkins 2006, p. 3)

Corridors have been of especial concern in conservation with respect to reserve design to combat fragmentation-induced habitat isolation (“bandages for wounded landscapes” according to Laurance and Laurance 2003). They are presumed to decrease extinction risk by boosting connectivity (click here for a modeling example). Why would connectivity be important for this?

Click here for some properties of corridors.

There are:

But see a recent review by Haddad et al. 2014 - No evidence that corridors increase unwanted disturbances or invasives, and there were as many positive as negative edge effects…

(The paper cited in the article won the 2002 Best Paper in Landscape Ecology award.)

-bat species richness increased in patches linked by forested corridors in French Guiana (Brosset et al. 1996)

-small mammal species richness increased in patches of Atlantic forest in Brazil that were linked by corridors compared to isolated patches (Pardini et al. 2005)
Gilbert-Norton et al. (2010) conducted a meta-analysis of corridor use and effectiveness in 78 experiments from 35 studies; you should know what their key findings were (from assigned reading).

Keep in mind that something that is a corridor to one species may not be perceived or used as such by another species (i.e., corridors [and, thus, connectivity] are taxon-dependent). And corridors may have both positive and negative effects on the same species at different life stages (Orrock and Damschen 2005). And the landscape matrix surrounding a corridor may influence its use (Pearson 1993; see Turner et al. text pp. 236-238 for more details).

How wide does a corridor need to be? Too narrow and it may expose organisms to adverse weather conditions, predation risk, etc. Too wide and it may cause animals to wander around in it, spending energy without finding a suitable territory. A “10% rule” has been proposed (see Laurance and Laurance 2003): the corridor’s width should be 10% of the area of the patches it is connecting.

Boundaries -

The transition zone between two distinct landscape elements (e.g. patch and matrix) is variously called:

This transition area possesses some characteristics of both landscape elements but is neither completely one nor the other. Therefore, some people refer to an ecotone as a landscape element (habitat type) unto itself. Edges are often drier and hotter, with more weedy species, than the patches of which it is an edge. Others recognize that although it may have some emergent properties, an edge/ ecotone/boundary’s primary function is as a barrier (permeable or impermeable) to ecological flows (movement of matter [including organisms] and energy). The transition may be subtle (a "soft" boundary, e.g. edge between mixed oak-beech stand to pure oak stand) or quite sharp ("hard," e.g. edge between forest and clear-cut), with implications for movement of matter and energy across the landscape. Soft boundaries may be traversed with relative ease, whereas a hard boundary may hinder, slow, or even deflect ecological flows. Edge effects create a "patch within a patch" situation (i.e., interior patch within patch as a whole). For example, Wilcove (1985) showed that nesting birds suffer greater predation the closer to forest edges they nested.

Similar deleterious edge effects have been found for plant growth and seed dispersal. Although certain taxa may be favored by ecotonal conditions (such as nest predators), boundaries can act as ecological traps: because they often have more sunlight, edges favor growth of weeds, which have lots of seeds and insects that songbirds feed upon; songbirds may be fooled by apparent high habitat quality and nest there, unwittingly exposing themselves (literally) to increased nest predation. See Battin (2004) for a nice review of the topic of ecological traps.

Determining boundary "hardness" (or "softness") is extremely difficult because it is more a posteriori than a priori: difficult to predict whether, when, and how a particle (especially an animal) will actually flow from one element to the other. Closed boundaries create a patch.

See Johnston et al. (1992) for quantitative methods for studying boundaries. One often-used technique is "sliding windows" (e.g. along a transect or within a quadrat), which is used to detect areas where variance changes suddenly (i.e., a boundary). Compare variances between one window position and the next using squared Euclidian distance (SED). Click here for an example of how changing the window size changes the results.

An alternative to detecting boundaries involves variance. Click here for an example.

We will discuss movement in greater depth later in the course, for movement is a key ecological process with implications for conservation biology, wildlife management, pest management, and many other areas.

How do these landscape elements affect ecological processes?

The composition, configuration, and connectivity of these landscape elements, singly and interactively, determine the abundance and distribution of organisms, where dispersal and flows occur, and the rates of biogeochemical reactions (Dunning et al. 1992, Taylor et al. 1993). These 3 descriptors should always be at the back (if not the front!) of your mind throughout this course.

Anderson, A., and C.N. Jenkins. 2006. Applying Nature’s Design: Corridors as a Strategy for Biodiversity Conservation. Columbia University Press, New York, NY.

Battin, J. 2004. When good animals love bad habitat: Ecological traps and the conservation of animal populations. Conservation Biology 18:1482-1491.

Brosset, A., P. Charles-Dominique, A. Cockie, J.C. Cosson, and D. Masson. 1996. Bat communities and deforestation in French Guiana. Canadian Journal of Zoology 74:1974-1982.

Cheng, K., and M.L. Spetch. 1998. Mechanisms of landmark use in mammals and birds. Pp. 1- 17 in: Spatial Representation in Animals (S. Healy, ed.). Oxford University Press, New York, NY.

Coffman, C.J., J.D. Nichols, and K.H. Pollock. 2001. Population dynamics of Microtus pennsylvanicus in corridor-linked patches. Oikos 93:3-21.

Dunning, J.B., B.J. Danielson, and H.R. Pulliam. 1992. Ecological processes that affect populations in complex landscapes. Oikos 75:169-175.

Forman, R.T.T., and M. Godron. 1986. Landscape Ecology. Wiley and Sons, New York, NY.

Gilbert-Norton, L., R. Wilson, J.R. Stevens, and K.H. Beard. 2010. A meta-analytic review of corridor effectiveness. Conservation Biology 24:660-668.

Green, B.H., E.A. Simmons, and I. Woltjer. 1996. Landscape Conservation: Some Steps Towards Developing a New Conservation Dimension. A draft report of the IUCN-CESP Landscape Conservation Working Group. Dept. Agriculture, Horticulture and Environment, Wye College, Ashford, Kent, UK.

Haddad, N.M., L.A. Brudvig, E.I. Damschen, D.M. Evans, B.L. Johnson, D.J. Levey, J.L. Orrock, J. Resasco, L.L. Sullivan, J.J. Tewksbury, S.A. Wagner, and A.J. Weldon. 2014. Potential negative ecological effects of corridors. Conservation Biology 28:1178-1187.

Healy, S., ed. 1998. Spatial Representation in Animals. Oxford University Press, New York, NY.

Hilty, J.A., W.Z. Lidicker Jr., and A.M. Merenlender. 2006. Corridor Ecology: The Science and Practice of Linking Landscapes for Biodiversity Conservation. Island Press, Washington, D.C.

Hobbs, R.J. 1992. The role of corridors in conservation: solution or bandwagon? Trends Ecol. Evol. 7:389-392.

Johnston, C.A., J. Pastor, and G. Pinay. 1992. Quantitative methods for studying landscape boundaries. Pp. 107-125 in: Landscape Boundaries: Consequences for Biotic Diversity and Ecological Flows (A.J. Hansen and F. di Castri, eds.). Springer-Verlag, New York, NY.

Laurance, S.G.W., and W.F. Laurance. 2003. Bandages for wounded landscapes: faunal corridors and their role in wildlife conservation in the America. Pp. 313-325 in: How Landscapes Change: Human Disturbance and Ecosystem Fragmentation in the Americas (G.A. Bradshaw and P.A. Marquet, eds.). Springer, New York, NY.

Legendre, P., and M.J. Fortin. 1989. Spatial pattern and ecological analysis. Vegetatio 80:107- 138.

Li, H., and J. F. Reynolds. 1995. On definition and quantification of heterogeneity. Oikos 73:280-284.

Mech, S.G., and J.G. Hallett. 2001. Evaluating the effectiveness of corridors: a genetic approach. Conserv. Biol. 15:467-474.

Naveh, Z. 1987. Biocybernetic and thermodynamic perspectives of landscape functions and land use patterns. Landscape Ecol. 1:75-83.

Noss, R.F. 1987. Corridors in real landscapes: a reply to Simberloff and Cox. Conserv. Biol. 1:159-164.

O'Neill, R.V., J.R. Krummel, R.H. Gardner, G. Sugihara, B. Jackson, D.L. DeAngelis, B.T. Milne, M.G. Turner, B. Zygmunt, S.W. Christensen, V.H. Dale, and R.L. Graham. 1988. Indices of landscape pattern. Landscape Ecol. 1:153-162.

Pardini, R., S.M. Souza, R. Braga-Neto, and J.P. Metzger. 2005. The role of forest structure, fragment size and corridors in maintaining small mammal abundance and diversity in an Atlantic forest landscape. Biol. Conserv. 124:253-266.

Pielou, E.C. 1984. The Interpretation of Ecological Data. Wiley, New York, NY.

Prevedello, J.A., and M.V. Vieira. 2010. Does the type of matrix matter? A quantitative review of the evidence. Biodiversity Conservation 19:1205-1223.

Rosenberg, D.K., B.R. Noon, and E.C. Meslow. 1997. Biological corridors: form, function, and efficacy. BioScience 47:677-687.

Simberloff, D., and J. Cox. 1987. Consequences and costs of conservation corridors. Conserv. Biol. 1:63-71.

Simberloff, D., J.A. Farr, J. Cox, and D.W. Mehlman. 1992. Movement corridors: conservation bargains or poor investments? Conserv. Biol. 6:493-504.

Taylor, P.D., L. Fahrig, K. Henein, and G. Merriam. 1993. Connectivity is a vital element of landscape structure. Oikos 68:571-572.

Troll, C. 1968. Landschaftsokologie. Pp. 1-21 in: Pflanzensoziologie und Landschaftsokologie (R. Tuxen, ed.). Berichte das Internalen Symposiums der Internationalen Vereinigung fur Vegetationskunde. Stolzenau/Weser, The Hague, The Netherlands.

Wiens, J.A. 1992. Ecological flows across landscape boundaries: a conceptual overview. Pp. 217-235 in: Landscape Boundaries: Consequences for Biotic Diversity and Ecological Flows (A.J. Hansen and F. di Castri, eds.). Springer-Verlag, New York, NY.

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