Natural processes, corridors, and networks
intensively used by many wetland animals, which also tend to move
longer distances in the direction of other wetlands and suitable habitat.
(G) Wetland restoration and creation.Restoration is typically more successful
than wetland creation, and establishing the right hydrologic conditions
and flows is normally more important for the formation and stability
of wetlands than are soil conditions and vegetation, that will develop
naturally over time.
(H) Wetland aspollutant filter.Wetlands tend to be effective filters for water-
borne suspended sediment, phosphorus, and biological-oxygen-demand
(BOD), but less so for bacteria and nitrogen, unless the water flows a
long distance through a wetland.
(I) Rare species in wetlands.Because wetland removal by drainage and filling
has been so pervasive in urban regions, the wetlands remaining typically
have among the highest concentrations of rare species in the region.Natural processes, corridors, and networks
This second set of principles emphasizes function, the flows and move-
ments across space, that in effect describes how the land or region works.
Natural systems are the focus. The following references are especially useful for
these principles: Forman(1995,2004a), Dramstadet al.(1996), Harriset al.(1996),
Ludwiget al.(1997), Beier and Noss(1998), Burel and Baudry (1999), Bennett
(2003), Turneret al.(2001), Wiens(2002), Groomet al.(2006), Lindenmayer and
Burgman (2005), Hiltyet al.(2006), and Lindenmayer and Fischer (2006). Chapter 4
also contains insight on this subject.
Four groupings of principles are present: (1) natural processes and species
movement; (2) water flows; (3) natural corridors and the matrix; and (4) natural
networks.
Natural processes and species movement
(A) Form and function.Compact forms effectively conserve internal resources,
convoluted forms enhance interactions with the surroundings, and net-
work forms serve as an internal transport system, so that a natural veg-
etation patch with a rounded core, some curvilinear boundaries, and
afewlonglobes or attached corridors provides a range of ecological
benefits.
(B) Interactions between patches.Species interactions (movements) are greatest
between a small patch or site and its adjacent land uses, somewhat
lower with nearby patches of the same type, and lowest with distant
patches of a different type.