Archuleta Mesa - USACH024 Additional Site Information Peter M. Brown, Rosalind Wu Dating Method: Crossdated Sample Storage Location: Rocky Mountain Tree-Ring Research, Inc., Ft. Collins, CO Reference: P.M. Brown & R. Wu. 2005. Climate and disturbance forcing of episodic tree recruitment in a southwestern ponderosa pine landscape. Ecology 86:3030-3038. Abstract: Strong but relatively short (annual to decadal length) climate change can have broad-scale and long-lasting effects on forest communities. Climate impacts forests through direct effects on tree demography (mortality and overstory recruitment) and indirect effects on disturbance regimes. Here, we compare multicentury chronologies of tree recruitment from a 307-ha ponderosa pine forest in southwestern Colorado to reconstructions of fire years, hydroclimate, and the El Nino-Southern Oscillation (ENSO). Few trees predate a regional multiyear megadrought centered in the 1580s. A prolonged pluvial in the early 1600s resulted in a pulse of tree recruitment that corresponds to recruitment seen over much of the Southwest. Other cohorts in the early 1700s and mid-1800s established during multidecadal fire- quiescent periods. These periods correspond to shifts in ENSO that apparently resulted in dampening of interannual wet/dry oscillations responsible for fuel buildup and drying. Fires, mediated by stochastic climate variation, acted as a density independent regulation on tree populations since establishment was not limited by overstory tree density, but rather by fire-caused mortality of seedlings and saplings during periods of more frequent fires. Even-aged cohorts in ponderosa pine forests likely have little if anything to do with episodic mortality caused by more severe fires, but rather relate mainly to episodic recruitment opportunities. Fire cessation after Euro-American settlement in the late 1800s resulted in an increase in tree density and changes in forest composition, which are major factors that have contributed to recent severe wildfires in other Southwestern forests. Our results document clear linkages between synoptic climate forcing, fires, and recruitment episodes, and highlight the importance of regional historical processes on contemporary forest composition and structure. Comments: The "." and "|" symbols were not used in the standard manner as described in the FHX2 users manual, in that they do not indicate whether or not a year is considered a "recorder" year. Rather, the "|" symbol is used to indicate that a dated ring was present, while the "." symbol is used to indicate that no dated ring was present (typically before and after the age range of the tree as well as between an estimated pith date and the earliest ring that was present). Trees A247 and AA246 were added to this file after Figure 2 in the paper was completed so this file includes 52 trees rather than 50 as stated in the publication. Individual Tree Locations (Tree ID, UTM-E, UTM-N (NAD83 Zone 13)) A041,298517,4116560 A042,298517,4116561 A141,298838,4116407 A142,298857,4116578 A143,298875,4116592 A1541,299258,4116412 A241,299260,4116534 A242,299232,4116411 A244,299244,4116406 A247,UNKOWN,UNKOWN A342,300081,4116292 A344,299834,4116385 A345,299832,4116358 A346,299848,4116298 A347,299809,4116296 A348,299819,4116298 A349,299806,4116293 AA141,298785,4116124 AA142,299004,4116223 AA143,299022,4116237 AA1541,299198,4116238 AA1542,299198,4116246 AA241,299302,4116303 AA242,299289,4116303 AA246,UNKOWN,UNKOWN B3542,300046,4115921 C441,300449,4115411 D242,299416,4114903 ACH001,298790,4116331 ACH002,298769,4116390 ACH003,298723,4116454 ACH004,298683,4116539 ACH005,298646,4116472 ACH010,298485,4115856 ACH011,298442,4115946 ACH012,298744,4115655 ACH027,298714,4116368 ACH029,298727,4116434 ACH030,298686,4116539 ACH052,298904,4116438 ACH053,298931,4116407 ACH054,298841,4116220 ACH055,298880,4116150 ACH056,298945,4116154 ACH057,299278,4116359 ACH058,299245,4116331 ACH059,299382,4116367 ACH060,299455,4116308 ACH061,299502,4116420 ACH062,298567,4115800 ACH101,299689,4116181 ACH102,299781,4116008 Fire History Graphs: Fire History Graphs illustrate specific years when fires occurred and how many trees were scarred. They are available in both PDF and PNG formats. The graphs consist of 2 parts, both of which show the X axis (time line) at the bottom with the earliest year of information on the left and the latest on the right. The Fire Index Plot is the topmost plot, and shows two variables: sample depth (the number of recording trees in each year) as a blue line along the left Y axis, compared with the percent trees scarred shown as gray bars along the right Y axis. Below, the Fire Chronology Plot consists of horizontal lines representing injuries by year on individual sampled trees. Symbols are overlain that denote the years containing the dendrochronologically-dated fire scars or injuries. The sample ID of each tree is displayed to the right of each line. The Composite Axis below represents the composite information from all individual series. The symbols used to represent the fire scars or injuries, and the filters used to determine the composite information, are shown in the legend. These graphs were created using the Fire History Analysis and Exploration System (FHAES). See http://frames.nbii.gov/fhaes/ for more information.