14. Patch Dynamics for Forested Ecosystems in the Pacific Northwest
303
to larger-scale phenomena (e.g ., physiological response to global climate
change), there is greater probability that the original successional trajectory will be altered. This phenomenon is illustrated with the topography-gap decoupling which may occur in the case of hemlock seedling
regeneration and also in the case of understory vegetation response
(Bradshaw, 1991; Bradshaw and Spies, 1992).
Landscape and regional model development should identify and
evaluate critical components of pattern and their potential interactions
over time. Depending on the particular landscape and ecological process,
certain elements are more likely to exert influence than others (e.g. ,
patch size versus patch-patch connectivity). Once again, while seeking
for general principles , accomodation for the idiosyncracies of each ecosystem is necessary to fully capture system dynamics. It remains to determine to what extent local interactions and patterns influence variability
observed within the region. Within the context of global change, several
questions emerge. For example, as one moves latitudinally in the Northwest, the dominance of given landscape processes and patterns change
accordingly. Will the effects of fine-scale change (e.g. , stand-level land
conversion) be uniform throughout the region? Will a change in regional
climate multiply the effects of disturbance or will a threshold be reached
and result in negative feedback shifting to a different dynamic regime?
Will rates of change be constant throughout the region? Clearly, the
construction of simple spatially and temporally explicit models in conjunction with large-scale field studies will contribute to our understanding.
Acknowledgments. The authors would like to thank Barbara Marks for
programming assistance, William J. Ripple (ERSAL) for provision of
satellite imagery, and Mark Harmon , and Mark Easter for helpful comments and discussion. Research has been conducted in part under the
auspices of LTER site studies , H.J. Andrews Experimental Forest (NSF
BSR 90 11663).
References
Agee, J.K., and Huff, M.H. 1987. Fuel succession in a western hemlock/Douglasfir forest. Can J For Res, 17,697-704.
Alaback, P.B., and McClellan, M.H. 1993. Effects of global warming on managed
coastal ecosystem of western North America. In H .A . Moonpy , E .R. Fuentes,
and B.I. Kronberg (eds.) , Earth System Responses to Global Change: Contrasts
Between North and South America (pp . 299-303). New York: Academic Press.
Bedard, W.D . 1950."The Douglas-fir beetle. U .S.D.A. Circular No. 918.
Borchers, J.G. 1994. A hierarchical context for sustaining ecosystem health. In
R.G. Jaindl and T.M . Quigley (eds.), Search for a Solution: Sustaining the
Land, People, and the Economy of the Blue Mountains. American Forests
Publications.
Bradshaw, G.A. 1991. Hierarchical Analysis of Patterns and Processes of DouglasFir Forests. Unpublished doctoral dissertation, Oregon State University.
303
to larger-scale phenomena (e.g ., physiological response to global climate
change), there is greater probability that the original successional trajectory will be altered. This phenomenon is illustrated with the topography-gap decoupling which may occur in the case of hemlock seedling
regeneration and also in the case of understory vegetation response
(Bradshaw, 1991; Bradshaw and Spies, 1992).
Landscape and regional model development should identify and
evaluate critical components of pattern and their potential interactions
over time. Depending on the particular landscape and ecological process,
certain elements are more likely to exert influence than others (e.g. ,
patch size versus patch-patch connectivity). Once again, while seeking
for general principles , accomodation for the idiosyncracies of each ecosystem is necessary to fully capture system dynamics. It remains to determine to what extent local interactions and patterns influence variability
observed within the region. Within the context of global change, several
questions emerge. For example, as one moves latitudinally in the Northwest, the dominance of given landscape processes and patterns change
accordingly. Will the effects of fine-scale change (e.g. , stand-level land
conversion) be uniform throughout the region? Will a change in regional
climate multiply the effects of disturbance or will a threshold be reached
and result in negative feedback shifting to a different dynamic regime?
Will rates of change be constant throughout the region? Clearly, the
construction of simple spatially and temporally explicit models in conjunction with large-scale field studies will contribute to our understanding.
Acknowledgments. The authors would like to thank Barbara Marks for
programming assistance, William J. Ripple (ERSAL) for provision of
satellite imagery, and Mark Harmon , and Mark Easter for helpful comments and discussion. Research has been conducted in part under the
auspices of LTER site studies , H.J. Andrews Experimental Forest (NSF
BSR 90 11663).
References
Agee, J.K., and Huff, M.H. 1987. Fuel succession in a western hemlock/Douglasfir forest. Can J For Res, 17,697-704.
Alaback, P.B., and McClellan, M.H. 1993. Effects of global warming on managed
coastal ecosystem of western North America. In H .A . Moonpy , E .R. Fuentes,
and B.I. Kronberg (eds.) , Earth System Responses to Global Change: Contrasts
Between North and South America (pp . 299-303). New York: Academic Press.
Bedard, W.D . 1950."The Douglas-fir beetle. U .S.D.A. Circular No. 918.
Borchers, J.G. 1994. A hierarchical context for sustaining ecosystem health. In
R.G. Jaindl and T.M . Quigley (eds.), Search for a Solution: Sustaining the
Land, People, and the Economy of the Blue Mountains. American Forests
Publications.
Bradshaw, G.A. 1991. Hierarchical Analysis of Patterns and Processes of DouglasFir Forests. Unpublished doctoral dissertation, Oregon State University.