16 Landscape Connections
Think for a moment about where you were over the past 24 h. Draw a map and on it place all the locations of those places where you spent more than 5 min in the past 24 h. Now draw a straight line from one place to the other in the order they were visited. Do these straight lines represent your path from one place to another? Probably not. Most likely you used roads, sidewalks, doors, and hallways to get to where you were going. These connections from place to place are similar in some respects to the connections used from patch to patch for some species of animals, but not all. Consider how you would use a compass or global positioning system (GPS) to find your way through an unfamiliar forest. You take a bearing, know a distance, and then walk through whatever is between you and your goal (within reason), more or less in a straight line. Some of the walking through closed canopy forests will be easy, and other places with dense shrubs will be very difficult. So rather than using a connection, you walk in a straight line with intervening patches representing various “risks” to your walking ability. These two types of movement are similar to the types of dispersal that other animal species experience. Some use corridors or connections across a landscape and others disperse across the matrix or the intervening conditions between patches of suitable habitat. And the matrix poses various risks to survival during dispersal depending on its habitat quality. This is analogous to a differentially permeable membrane in which some molecules can pass through the membrane easily and others cannot. For dispersing animals, matrix conditions represent differentially permeable conditions for moving organisms. Some intervening conditions allow the animal to move easily during dispersal, others present significant risks to survival (Martin and McComb 2003, Popescu and Hunter 2011).