Dynamics of hardwood patches in a conifer matrix: 54 years of change in a forested landscape in Coastal Oregon, USA
2005
Kennedy, Rebecca S.H. | Spies, Thomas A.
Changes to minor patch types in forested landscapes may have large consequences for forest biodiversity. The effects of forest management and environment on these secondary patch types are often poorly understood. For example, do early-to-mid successional minor patch types become more expansive as late successional forest types are fragmented or do they also become more fragmented in managed landscapes? We evaluated the dynamics of early-to-mid successional hardwood patches in a conifer-dominated landscape in relation to environment and land ownership in the central Coast Range of Oregon, USA, from the time of early logging to the present-day using scanned and georeferenced aerial photographs and a GIS. Hardwood patches declined in size, number, total area, and within-patch cover-type heterogeneity, and became more irregular in shape. Patch turnover and fragmentation was high, with most patches present at the historical date disappearing by the present-day. Land ownership was important to hardwood patch dynamics: hardwoods declined on lands owned by the USDA Forest Service, increased on non-industrial private lands, and were at similar levels at both dates on private forest industry lands. Patch locations became more restricted to near-stream, lower elevation areas where hardwoods are competitive. The relatively extensive distribution of hardwood patches at the historical date probably resulted from earlier fire, selective logging, and grazing. In recent decades, forest management that includes fire suppression and intensive management, and ecological constraints have resulted in a landscape in which early-to-mid successional hardwood patches have been reduced in size, fragmented, and restricted to particular locales.
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