## 2 Experimental Methods
### Gross and net primary production initiation and cessation  
We used the methods of [PERSON] _et al_. [18] to estimate the timing of NPP initiation and cessation from ecological inventories of daily net primary production of live wood, leaves, fruit, and branches, and fine roots for the entire forest from 2001-2003 and 2005-2006 (Figure 1). We did not calculate NPP in 2004 because high temporal resolution live wood dry mass production data were not available. Daily above- and belowground wood NPP was estimated from incremental changes in weekly to biweekly bole diameter (\(D\)) recorded for 190 trees with \(D\geq 10\) cm using band dendrometers, and from allometric equations relating \(D\) to wood dry mass [36]. Daily leaf, fruit, and branch NPP was calculated by multiplying annual leaf, fruit, and fine branch dry mass production estimated from frequently sampled litter traps placed on the forest floor (area = 0.264 m\({}^{2}\), n = 20) by the interpolated daily fraction of annual vegetation area production calculated from twice weekly (during leaf expansion) to monthly measurements of vegetation area index. Daily fine root structural C production was the product of daily fine root turnover estimated from daily mean soil temperature (\(T_{\text{S}}\), 7.5 cm) and standing fine root dry mass [36]. A site-specific C fraction of 0.49 (wood, leaves, fruit, fine branches) or 0.47 (fine roots) was used to convert dry mass to C mass [36]. Daily NPP was the sum of daily wood, leaf, fruit, fine branch, and fine root primary production. The times of initiation and cessation of NPP were defined as dates when 10% and 90% of total annual NPP, respectively, were achieved. Limitations and assumptions associated with this approach are detailed in [18].  
We estimated the initiation and cessation of GPP from meteorological estimates of daily net ecosystem CO2 exchange (NEE) between forest and atmosphere following [PERSON] _et al_. [37]. Detailed meteorological tower instrumentation, specifications, and data gap-filling procedures are described by [PERSON] _et al_. [38]. A 46 m tower equipped with eddy-covariance systems provided continuous measurements of 3-D turbulent velocity fluctuations and eddy-covariance fluxes of momentum (sonic anemometers; CSAT-3, Campbell Scientific, Inc.) and CO2 fluxes as hourly averages (infrared gas analyzer; LI-6262 or LI-7000 from 2005; LI-COR Inc.; Lincoln, NE). CO2 fluxes are subject to quality control, including outlier rejection, and a friction velocity u* \(\leq\) 0.35 m s-1 criterion to discard valuesobtained under low turbulence conditions where the change of CO\({}_{2}\) storage in the canopy air space could be important. Daily GPP is the 24-h sum of daytime hourly NEE and ecosystem respiration, inferred from models relating nighttime net ecosystem CO\({}_{2}\) exchange to soil temperature (7.5 cm depth). Times of GPP initiation and cessation were the dates when 10% and 90% of total annual GPP, respectively, were attained.  
We tracked leaf phenology with a LAI-2000 Plant Canopy Analyzer (LI-COR Inc.). Readings were taken every \(\sim\)3 m along seven 60 m transects for an average of 120 samples on each of 12 sampling dates from May (leaf expansion) to November (leaf abscission) during 2005 and 2006.