Holocene fire regimes and geomorphic response in conifer forests of central Idaho
- 出版日期：2004.
- 页数：1 v. :
- 第一责任说明：Jennifer L. Pierce.
- 分类号：a517 ; a222
- ISBN：0496176072(ebk.) :
MARC全文
02h0029365 20120611164506.0 cr un||||||||| 120611s2004 xx ||||f|||d||||||||eng | 3156695 0496176072(ebk.) : CNY371.35 NGL NGL NGL a517 ; a222 Pierce, Jennifer L. Holocene fire regimes and geomorphic response in conifer forests of central Idaho [electronic resource] : evidence of millennial scale climate change / Jennifer L. Pierce. 2004. 1 v. : digital, PDF file. Adviser: Meyer, Grant. Thesis (Ph.D.)--The University of New Mexico, 2004. Relations exist between fire, vegetation, and climate over different spatial and temporal scales. Severe fires change processes and rates of erosion, fuel loads and conditions vegetation) influence fire severity, and variations in climate change vegetation, fire regimes and geomorphic response. Interpretation and dating of fire-related alluvial-fan deposits in the South Fork Payette River SFP) drainage, Idaho reveals a &sim；8000-year record of sedimentation events following fire in ponderosa forests in central Idaho mountains. Alluvial fan records show maxima in the probability of frequent, small fire-related events in Idaho &sim；350--500, 1200--1300, and 2800--3000 cal yr BP. The most recent episode &sim；350--500 cal yr BP) coincides with the LIA, a time of hemispheric-to-global cooling； prior episodes correspond with paleoclimatic indicators of colder climates in the Northern Hemisphere. I infer that during cooler and effectively moister intervals, Idaho ponderosa pine forests maintained high canopy moisture content which inhibited stand-replacing fires, and increased understory grass growth provided fuel for frequent, low- to moderate-severity burns. These fires correspond with limited geomorphic response recorded in alluvial fan deposits. In contrast, severe stand-replacing fires occur infrequently during times of widespread and severe drought, such as during the Medieval Climatic Anomaly MCA, &sim；1050--650 cal yr BP). The MCA is characterized by fires in a range of ecosystems, and MCA fires promoted infrequent but large sedimentation events that contributed significantly to long-term sediment yields and landscape evolution. Results indicate climate is a key control over fire regimes on centennial to millennial timescales, and suggest that continued large, severe burns are likely with anticipated future warming. Dating and characterization of Holocene terraces of the SFP River indicate a general trend of downcutting during the Holocene. Episodes of stability and floodplain widening &sim；8000--6600, &sim；4000--1300, and &sim；1155--540 cal yr BP are punctuated with intervals of downcutting &sim；6600--5800, 1293--1155, and after 542 cal yr BP. Incision 1293--1155 cal yr BP corresponds with a peak in fire-related sedimentation events &sim；1300--1150 cal yr BP. The average incision rate of the upper South Fork Payette River was &sim；0.82--0.73 m/kyr from 7 ka to present, likely several times faster than incision averaged over the last glacial-interglacial cycle. Paleoclimatology ; Geomorphology ; Paleoclimatology Idaho ; Payette River Watershed. ; Idaho ; Payette River Watershed. Holocene. Electronic dissertations. aeBook. aCN bNGL http://pqdt.bjzhongke.com.cn/Detail.aspx?pid=CJbuFWhst%2bI%3d NGL Bs1465 rCNY371.35 ; h1 bs1204