TY - JOUR
T1 - Fire catalyzed rapid ecological change in lowland coniferous forests of the Pacific Northwest over the past 14,000 years
AU - Crausbay, Shelley D.
AU - Higuera, Philip E.
AU - Sprugel, Douglas G.
AU - Brubaker, Linda B.
N1 - Publisher Copyright:
© 2017 by the Ecological Society of America
PY - 2017/9
Y1 - 2017/9
N2 - Disturbance can catalyze rapid ecological change by causing widespread mortality and initiating successional pathways, and during times of climate change, disturbance may contribute to ecosystem state changes by initiating a new successional pathway. In the Pacific Northwest of North America (PNW), disturbance by wildfires strongly shapes the composition and structure of lowland forests, but understanding the role of fire over periods of climate change is challenging, because fire-return intervals are long (e.g., millennia) and the coniferous trees dominating these forests can live for many centuries. We developed stand-scale paleorecords of vegetation and fire that span nearly the past 14,000 yr to study how fire was associated with state changes and rapid dynamics in forest vegetation at the stand scale (1–3 ha). We studied forest history with sediment cores from small hollow sites in the Marckworth State Forest, located ~1 km apart in the Tsuga heterophylla Zone in the Puget Lowland ecoregion of western Washington, USA. The median rate of change in pollen/spore assemblages was similar between sites (0.12 and 0.14% per year), but at both sites, rates of change increased significantly following fire events (ranging up to 1% per year, with a median of 0.28 and 0.38%, P < 0.003). During times of low climate velocity, forest composition was resilient to fires, which initiated successional pathways leading back to the dominant vegetation type. In contrast, during times of high climate variability and velocity (e.g., the early Holocene) forests were not resilient to fires, which triggered large-scale state changes. These records provide clear evidence that disturbance, in the form of an individual fire event, can be an important catalyst for rapid state changes, accelerating vegetation shifts in response to large-scale climate change.
AB - Disturbance can catalyze rapid ecological change by causing widespread mortality and initiating successional pathways, and during times of climate change, disturbance may contribute to ecosystem state changes by initiating a new successional pathway. In the Pacific Northwest of North America (PNW), disturbance by wildfires strongly shapes the composition and structure of lowland forests, but understanding the role of fire over periods of climate change is challenging, because fire-return intervals are long (e.g., millennia) and the coniferous trees dominating these forests can live for many centuries. We developed stand-scale paleorecords of vegetation and fire that span nearly the past 14,000 yr to study how fire was associated with state changes and rapid dynamics in forest vegetation at the stand scale (1–3 ha). We studied forest history with sediment cores from small hollow sites in the Marckworth State Forest, located ~1 km apart in the Tsuga heterophylla Zone in the Puget Lowland ecoregion of western Washington, USA. The median rate of change in pollen/spore assemblages was similar between sites (0.12 and 0.14% per year), but at both sites, rates of change increased significantly following fire events (ranging up to 1% per year, with a median of 0.28 and 0.38%, P < 0.003). During times of low climate velocity, forest composition was resilient to fires, which initiated successional pathways leading back to the dominant vegetation type. In contrast, during times of high climate variability and velocity (e.g., the early Holocene) forests were not resilient to fires, which triggered large-scale state changes. These records provide clear evidence that disturbance, in the form of an individual fire event, can be an important catalyst for rapid state changes, accelerating vegetation shifts in response to large-scale climate change.
KW - Pacific Northwest
KW - Tsuga heterophylla Zone
KW - charcoal
KW - fire history
KW - fire regime
KW - paleoecology
KW - pollen analysis
KW - rapid ecological change
KW - state change
UR - http://www.scopus.com/inward/record.url?scp=85027849877&partnerID=8YFLogxK
U2 - 10.1002/ecy.1897
DO - 10.1002/ecy.1897
M3 - Article
C2 - 28500791
AN - SCOPUS:85027849877
SN - 0012-9658
VL - 98
SP - 2356
EP - 2369
JO - Ecology
JF - Ecology
IS - 9
ER -