Turkey Lakes Watershed Study reference list: 2015

15-01 Lawrence, G.B., P.W. Hazlett, I.J. Fernandez, R. Ouimet, S.W. Bailey, W.C. Shortle, K.T. Smith and M.R. Antidormi. Declining acidic deposition begins reversal of forest-soil acidification in the northeastern U.S. and eastern Canada. Environmental Science and Technology 49 (22), 13103-13111, doi: 10.1021/acs.est.5b02904, 2015.

Summary: Documentation of the effects of acidic deposition on soils has been limited, and little is known regarding soil response to ongoing decreases of acidic deposition. Resampling of soils in eastern Canada and the northeastern U.S. was done at 27 sites, including the TLW, which were exposed to reductions in wet SO₄^2- deposition of 5.7-76% over intervals of 8-24 years. Decreases of exchangeable Al in the O horizon and increases in pH in the O and B horizons were seen at most sites. At all sites SO₄^2-reductions were positively correlated with ratios (final sampling/initial sampling) of base saturation and negatively correlated with exchangeable Al ratios in the O horizon. These results are unique as they show that the effects of acidic deposition in eastern Canada and the northeastern U.S. have begun to reverse.

15-02 Morse, J.L., J. Duran, F. Beall, E. Enanga, I.F.Creed, I. Fernandez and P.M. Groffman. Soil denitrification fluxes from three northeastern North American forests across a range of nitrogen deposition. Oecologia 177 (1), 17-27, DOI 10.1007/s00442-014-3117-1, 2015.

Summary: Large amounts of N are unaccounted for in N balances at scales ranging from small watersheds to large regional drainage basins in northern forests. The missing N may be related to N-gas production by soil microbes. Samples were taken from the TLW and two other research sites, each differing in N enrichment. Fluxes of N₂ and N₂O were quantified with intact-cores in the laboratory, and were tested for correlation with N availability, soil O2 status and forest type. Total N-gas flux ranged from <1 to >100 kg N ha^-1 year^-1. These findings demonstrate that denitrification is an important and potentially underestimated term in N budgets of upland forests in northeastern North America.

15-03 Ross, D.S., S.W, Bailey, R.D. Briggs, J. Curry, I.J. Fernandez, G. Fredriksen, C.L. Goodale, P.W. Hazlett, P.R. Heine, C.E. Johnson, J.T. Larson, G.B. Lawrence, R.K. Kolka, R. Ouimet, D. Paré, D.deB. Richter, C.D. Schimer and R.A. Warby. Inter-laboratory variation in the chemical analysis of acidic forest soil reference samples from eastern North America. Ecosphere 6 (5), 1-22, http://dx.doi.org/10.1890/ES14-00209.1, 2015.

Summary: To determine the uncertainty associated with specific analytical methods for forest soils, samples from two soil horizons  were collected and distributed to 15 laboratories in the eastern United States and Canada including the GLFC where TLW samples are analyzed. Soil properties measured included total organic carbon and nitrogen, pH and exchangeable cation. Overall, results were consistent despite some differences in methodology. Recommendations include a continuation of reference forest soil exchange programs to quantify the uncertainty associated with these analyses in conjunction with ongoing efforts to review and standardize laboratory methods.

15-04 Webster, K.L. and P.W. Hazlett. Long-term ecological research at the Turkey Lakes Watershed: 35th anniversary of interdisciplinary, cooperative research, program booklet and workshop summary.Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Information Report GLC-X-13, 25pp. 2015.

Summary: This information report provides background material and outputs from a TLW 35^th anniversary workshop held at the Great Lakes Forestry Centre in Sault Ste. Marie on November 19-20, 2014. The report includes a participant list, workshop program and abstracts from the workshop presentations. Workshop outcomes from a moderated discussion of the science and policy connections directing long-term science at TLW with federal and provincial government, industry and academia representative is also provided.

15-05 Creed, I.F., T. Hwang, B. Lutz and D. Way. 2015. Climate warming causes intensification of the hydrological cycle, resulting in changes to the vernal and autumnal windows in a northern temperate forest. Hydrological Processes 29: 3519-3534.

Summary: An investigation into whether rising temperatures altered timing of snowmelt and snowpack accumulation or extended forest growing season length in the TLW. Vernal (spring) and autumnal (fall) windows were defined using archived satellite imagery to track changes in timing of snowpack loss/gain and canopy leaf on/off in the Batchawana watershed and TLW. Archived time series (1983-2009) of temperature, precipitation and discharge data for a nested set of catchments were used to track changes in magnitude, timing and partitioning of precipitation into evapotranspiration and discharge. Results indicated forest growth is not responding significantly to temperature increases during the windows, but hydrological cycling intensified with higher dryness index (PET/P) during summer growing season and earlier spring snowmelt discharges, and later more concentrated autumn storm discharges during the shoulder seasons.