Diapositiva 1

1
CARBON DIOXIDE FLUXES OF A RECENT LARGE WIND
THROW IN THE HIGH TATRA FORESTS
S. Giorgi(1), P. Fleischer(2), B. Gioli(3), O.
Kolle(4), G. Manca(5), A. Matese(3), A.
Zaldei(3), W. Ziegler(4), A. Cescatti(6), F.
Miglietta(3), E-D. Schulze(4) and R. Valentini(1)
(1)Department of Science of Forest Environment
and Resources, Università della Tuscia, Viterbo,
Italy. (2)State Forest of Tatra National
Park-Research Station, Vysoke Tatry, Slovakia.
(3)CNR Institute of Biometeorology, Firenze,
Italy. (4)Max Plank Institute for
Biogeochemistry, Jena, Germany. (5) JRC Institute
for Environment and Sustainability, Ispra (VA),
Italy. (6) Center for Alpine Ecology, Trento,
Italy.
On November 2004 the area of High Tatra foothills
(Slovak Republic) was struck by a violent storm
where strongest gusts reached almost 200 km/h. By
the total area of the Tatra National Park (TANAP,
74,000 ha) about 12,000 ha of forest ecosystems
were affected by wind throw and about 2.5 million
m3 of timber were downed (fig.1). Slovak
institutions decided to remove about 90 of
fallen trees for processing, and to leave
untouched few patches of wind throw for
conservation purposes. This dramatic event
created the condition to study the impact of such
catastrophic wind throw, and its subsequent
management, on carbon cycle of coniferous
forests. Three experimental sites were chosen -
EX (extracted) wind throw where every log was
extracted for commercial purposes. Standing but
seriously damaged trees was cut and removed as
well. - NEX (non exctracted) wind throw where
all logs and still standing trees remained on the
site. - IF (intact forest) forest site not
affected by wind throw and used as a reference
for comparison between disturbed and undisturbed
ecosystems. All sites belong to Lariceto-Picetum
forest community consisting mainly in Norway
spruce with presence of Scotch pine and European
larch. At each site a tower for net ecosystem
exchange measurements by eddy covariance has been
set up starting from early Autumn 2005. Each
tower is equipped with an open-path CO2/H2O gas
analyser (Li-7500, Licor, USA) and an ultrasonic
anemometer (R3-50, Gill, UK in EX and IF. Metek,
USA1, Germany in NEX). Additional meteorological
and soil variables are also monitored at each
site. Measurements started in September 2005 in
EX-site and October 2005 in NEX and IF sites.
EX site
Fig. 1 (Waldemar Ziegler)
Fig. 2 - NEX-site
Fig. 3 - IF-site
Rain-EX
Air temp-EX
Air temp-NEX
The main evidence coming from the half-hour
fluxes (Fc) is obviously the dramatic falling of
photosynthesis and carbon uptake in the two wind
throw sites (EX, NEX) compared to the activity in
the IF. Anyway the trend of mean daily Fc on
monthly base shows a pattern of uptake of carbon
higher in the EX-site rather than in the
NEX-site. Also seasonality differs between the
two sites as in August the uptake is more
comparable. This is likely due to different
vegetation succession dynamics reflecting the
different disturbance regime occurred in the two
sites. A new vegetation community could establish
more rapidly in the EX-site rather than in
NEX-site thanks to the severe soil disturbance
caused by machinery. Cumulated monthly fluxes
were obtained from the progressive sum of the
daily integration of half-hour fluxes. Gaps in
the dataset were filled using the monthly day
average value corresponding to each missing
half-hour value. Also these graphs show different
annual trend between the two wind throw sites.
While NEX-site appears as a stable source of CO2
with a maximum in summer, the EX-site has a more
variable trend showing a net uptake of CO2 in
June. Considering only the period of
August-September 2006 the net emission of CO2
from the EX-site and NEX-site was of 49.2 t/ha
and 78,1 t/ha respectively.
Rain/Snow-IF
Air temp-IF
EX site
2005
2006
Half hour time series of Fc
IF EX NEX
Aknowledgment Luca Belelli Marchesini, Mauro
Cavagna, Daniel Gaspar, Karl Kuebler, Lubos
Slamen.