TY - CHAP

T1 - Avoiding irreversible change

T2 - Considerations for vegetation cover, vegetation structure, and species composition

AU - Fischer, Jörn

AU - Lindenmayer, David

N1 - Chapter 20

PY - 2008/4/15

Y1 - 2008/4/15

N2 - An important goal in landscape design is to avoid potentially irreversible ecosystem changes. Such changes have been discussed in the context of thresholds, regime shifts and extinction cascades. Thresholds occur where small changes in one variable result in a large change in another variable. Regime shifts occur when a system 'flips' from one state to another. Extinction cascades occur where the extinction of one species triggers the loss of one or more other species, which in turn leads to further extinctions. Potentially irreversible changes may occur as a result of changes in many variables. Three variables are discussed here: (i) the amount of native vegetation cover; (ii) the structure of native vegetation; and (iii) species composition. Species extinctions may occur more rapidly at particularly low levels of native vegetation cover. However, negative effects may be partly mitigated in heterogeneous landscapes and where the matrix resembles natural vegetation structure. The structure of native vegetation is often related to disturbance regimes. Extinction cascades are more likely to occur following the loss of structural attributes that many species depend upon, such as features typical of old-growth forest or other ecosystem-specific keystone structures. Changes to species composition per se also may result in extinction cascades. This risk is particularly high when entire functional groups or keystone species are lost. Landscape design should attempt to maintain: (i) high levels of natural vegetation cover embedded within a heterogeneous matrix; (ii) structurally characteristic native vegetation, including keystone structures; and (iii) a diversity of species within and across functional groups, including keystone species.

AB - An important goal in landscape design is to avoid potentially irreversible ecosystem changes. Such changes have been discussed in the context of thresholds, regime shifts and extinction cascades. Thresholds occur where small changes in one variable result in a large change in another variable. Regime shifts occur when a system 'flips' from one state to another. Extinction cascades occur where the extinction of one species triggers the loss of one or more other species, which in turn leads to further extinctions. Potentially irreversible changes may occur as a result of changes in many variables. Three variables are discussed here: (i) the amount of native vegetation cover; (ii) the structure of native vegetation; and (iii) species composition. Species extinctions may occur more rapidly at particularly low levels of native vegetation cover. However, negative effects may be partly mitigated in heterogeneous landscapes and where the matrix resembles natural vegetation structure. The structure of native vegetation is often related to disturbance regimes. Extinction cascades are more likely to occur following the loss of structural attributes that many species depend upon, such as features typical of old-growth forest or other ecosystem-specific keystone structures. Changes to species composition per se also may result in extinction cascades. This risk is particularly high when entire functional groups or keystone species are lost. Landscape design should attempt to maintain: (i) high levels of natural vegetation cover embedded within a heterogeneous matrix; (ii) structurally characteristic native vegetation, including keystone structures; and (iii) a diversity of species within and across functional groups, including keystone species.

KW - Biology

KW - irreversible change

KW - vegetation cover

KW - vegetation structure

KW - species composition

KW - landscape design

KW - irreversible change

KW - vegetation cover

KW - vegetation structure

KW - Species composition

KW - lanscape design

KW - Environmental planning

UR - http://www.scopus.com/inward/record.url?scp=84889390872&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/79a82774-474c-360d-b821-3fca42564956/

U2 - 10.1002/9780470692400.ch20

DO - 10.1002/9780470692400.ch20

M3 - Chapter

SN - 978-1-405-15914-2

SP - 229

EP - 244

BT - Managing and Designing Landscapes for Conservation

A2 - Lindenmayer, David

A2 - Hobbs, Richard

PB - Wiley-Blackwell Publishing, Inc.

CY - Oxford

ER -