Red spruce foliar nutritional and metabolic responses to N, Ca, and N+Ca additions in a plot level study from Hubbard Brook Experimental Forest NH, Adirondack State Park, NY and Groton State Forest, VT from 1997-2000.

Plot Level Ca, N, Ca+N Study Background: Three mature red spruce ( Picea rubens Sarg.) – balsam fir ( Abies balsamea (L.) Mill.)
stands with closed canopies from across the northeastern United States
were selected to assess the effects of N and Ca additions on forest
growth. These sites included Groton, VT (Groton State Forest), Big
Moose Lake, NY (Adirondack State Park) and Watershed 9 in the Hubbard
Brook Experimental Forest, NH. Site descriptions can be found in the pdf file included in this
dataset. Full site descriptions have been published in Kulmatiski et
al, 2007, Nitrogen and calcium additions increase forest growth in
northeastern USA spruce–fir forests, Canadian Journal of Forest
Research 37: 1574-1585. This publication also provides more in-depth
site and soil descriptions. In 1992, three replicate 30 m by 30 m plots were randomly assigned to
each of four treatment levels: control (control), Ca addition (Ca), N
addition (N), or Ca + N addition (Ca + N) in NY and NH (for a total of
12 plots at each site). In VT, only control and Ca treatments were
established due to limited space and research goals (for a total of 6
plots). Beginning in July 1992 through July 2000, N amendments (100
kilograms of NH 4 NO 3 -N
per hectare per year), Ca amendments (80 kilograms of
CaSO 4 -Ca plus 80 kilograms of
CaCl 2 -Ca per hectare per year), and Ca + N
(same dosage as separate applications) amendments were hand broadcast
as commercial grade salts. Applications were made in June, July, and
August to each plot in each year. SUMMARY: The main objectives of this study were to evaluate changes
over time (1997-2000) in foliar metabolism of mature red spruce
( Picea rubens Sarg.) trees
in response to additions of nitrogen, Ca, or N +Ca supplementation. N
was applied as NH 4 NO 3 and Ca was applied as gypsum
[CaSO 4 . 2H 2 O
(2X) +
CaCl 2 . 2H 2 O
(1X)] and Ca + N treatment was a combination of both at the same
concentrations Three sites received these treatments; Groton, VT
(Groton State Forest), Big Moose Lake, NY (Adirondack State Park) and
Watershed 9 in the Hubbard Brook Experimental Forest, NH. In NH and NY
there were 3 plots for each of the 4 treatments, and in VT there were
3 plots for each of the 2 treatments (control and Ca only). Ten trees
were sampled per plot in 1997, 1999, and 2000. Samples were analyzed
for perchloric acid (5%) extractable ions, polyamines and amino acids.
N-treated spruce foliage had a reduction in Ca and Mg. It was
accompanied by significantly higher concentrations of putrescine,
proline and γ-aminobutyric acid, all of which are known indicators of
a variety of physiological stress factors including ammonia exposure.
Ca treatment did not have an effect on inorganic ions and amino acid
concentrations, but when added with N it positively modulated the
effects of N on tree physiology and ion uptake. We concluded that even
in the absence of knowledge about red spruce tolerance limits for
nutrients and critical N loads for these sites, metabolic monitoring
using a suite of biochemical parameters can be a very useful tool in
assessing current forest health. (Unpublished data)