Abstract:
Two research questions are posed: (1) How have ecosystem conditions
changed through time in southwestern Oregon? (2) How have culture-driven and
climate-driven processes contributed to ecosystem change in southwestern
Oregon? A brief introduction to the Little River study area is followed by a
cultural and ecological history of the watershed. Historical, ecological and
archaeological data are used to describe shifts in landscape structure, stand
structure and fire behavior. Changes in corridor/patch/matrix relationships,
increases in stand densities, and changes in stand age and species structure are
documented, and changes in fire dynamics from frequent to infrequent, and small
to large are corroborated with descriptive statistics from the nearby 2002
Umpqua Fires. Hypotheses are then proposed to test the relative influence of
humans vs. climate on landscape change during Aboriginal (<1820) vs. Euroagrarian
(1850-1950) cultural phases. While precipitation shows no correlation
with fire frequency or tree recruitment before 1820, significant associations are
observed from 1850 to 1950. Moreover, a significant correlation exists between
fire frequency and subsequent tree recruitment after 1850, but is not observed
during aboriginal times. This suggests that indigenous management fires may
have obscured precipitation influences that become apparent only after 1850. In
order to test spatial hypotheses concerning the associations between indigenous
humans and the landscape, archaeological sites were digitized into a GIS, and
ergonomic pathways were modeled between them. These maps are then
compared to historically fire-maintained upland meadows interpreted from 1946
aerial photos. A significant spatial correlation was found between archaeological
sites and historic meadows, and a highly significant spatial correlation was found
between modeled travel networks and historic meadows. The close spatial
association between cultural features and fire-maintained habitats again
suggests active landscape management by local Indians. These associations
are corroborated with historical records. After summarizing the shifts in
ecological conditions and describing current conditions, I argue that while
restoring the landscape to aboriginal conditions is no longer possible, emulating
those conditions within the framework of the Little River Adaptive Management
Area Plan can improve the resilience and productivity of the Little River
watershed.
