Environmental Monitoring and [629553]

123
Environmental Monitoring and
Assessment
An International Journal Devoted to
Progress in the Use of Monitoring Data
in Assessing Environmental Risks to
Man and the Environment

ISSN 0167-6369
Volume 184
Number 12

Environ Monit Assess (2012)
184:7491-7515
DOI 10.1007/s10661-011-2515-7Status of the Southern Carpathian forests
in the long-term ecological research
network
Ovidiu Badea, Andrzej Bytnerowicz,
Diana Silaghi, Stefan Neagu, Ion Barbu,
Carmen Iacoban, Corneliu Iacob,
Gheorghe Guiman, et al.

123
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Status of the Southern Carpathian forests
in the long-term ecological research network
Ovidiu Badea &Andrzej Bytnerowicz &
Diana Silaghi &Stefan Neagu &Ion Barbu &
Carmen Iacoban &Corneliu Iacob &
Gheorghe Guiman &Elena Preda &
Ioan Seceleanu &Marian Oneata &Ion Dumitru &
Viorela Huber &Horia Iuncu &Lucian Dinca &
Stefan Leca &Ioan Taut
Received: 11 July 2011 /Accepted: 28 December 2011 /Published online: 11 January 2012
#Springer Science+Business Media B.V. 2012
Abstract Air pollution, bulk precipitation, throughfall,
soil condition, foliar nutrients, as well as forest healthand growth were studied in 2006 –2009 in a long-term
ecological research (LTER) network in the Bucegi
Mountains, Romania. Ozone (O
3) was high indicating
a potential for phytotoxicity. Ammonia (NH 3) concen-
trations rose to levels that could contribute to depositionof nutritional nitrogen (N) and could affect biodiversity
changes. Higher that 50% contribution of acidic rain
(pH<5.5) contributed to increased acidity of forest soils.Foliar N concentrations for Norway spruce ( Picea
abies ), Silver fir ( Abies alba ), Scots pine ( Pinussylvestris ), and European beech ( Fagus sylvatica )w e r e
normal, phosphorus (P) was high, while those of potas-sium (K), magnesium (Mg), and especially of manga-
nese (Mn) were significantly below the typical
European or Carpathian region levels. The observed
nutritional imbalance could have negative effects on
forest trees. Health of forests was moderately affected,with damaged trees (crown defoliation >25%) higher
than 30%. The observed crown damage was accompa-
nied by the annual volume losses for the entire researchforest area up to 25.4%. High diversity and evenness
specific to the stand type ’s structures and local climateEnviron Monit Assess (2012) 184:7491 –7515
DOI 10.1007/s10661-011-2515-7
O. Badea ( *):D. Silaghi :S. Neagu :I. Barbu :
C. Iacoban :C. Iacob :G. Guiman :M. Oneata :L. Dinca :
S. Leca :I. Taut
Forest Research and Management Institute (ICAS),
Eroilor Bld. 128,077190 Voluntari, Ilfov, Romaniae-mail: [anonimizat]
A. Bytnerowicz
USDA Forest Service, Pacific Southwest Research Station,4955 Canyon Crest Drive,
Riverside, CA 92507, USA
E. Preda
University of Bucharest,
M. Kog ălniceanu Bld. 36-46, Sector 5,
Bucharest 050107, RomaniaI. Seceleanu
:H. Iuncu
National Forest Administration —Romsilva,
Magheru Bld. 31, Sector 1,
Bucharest 010325, Romania
O. Badea :D. Silaghi :V. Huber :S. Leca
“Transilvania ”University Brasov,
Eroilor Bld. 29,
Brasov 500030, Romania
I. Dumitru
“Valahia ”University,
Carol I Bld. 2,
130024 Targoviste, Dambovita, Romania
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conditions were observed within the herbaceous layer,
indicating that biodiversity of the vascular plant com-munities was not compromised.
Keywords Air pollution .Climatic conditions .
Atmospheric deposition .Drought .Forest health .
Biodiversity .Tree growth
Introduction
Forest ecosystems provide socio-ecological and eco-
nomic benefits indispensable for life quality at global,
regional, and local levels. Forest ecosystem servicescan be maintained by ensuring its appropriate health
status, stability, and sustainability through proper for-
est management. However, climate change, air pollu-tion, and forest land-use changes are important
destabilizing factors of forest ecosystems composition,
structure, and functions (ICP-Forests 2010b ).
In Europe during 1970 –1980, most countries
reported the presence of numerous types of damage
in forests caused by unspecified factors. The rapiddevelopment of damage symptoms and their spatial
distribution and independent occurrence affecting var-
ious forest species has been described as the “un-
known decline of the forests syndrome ”(ICP-Forests
1997 ,2006a ), meaning that research results could not
explain all aspects of this phenomenon due to thecomplexity of multiple biotic and abiotic factors
(ICP-Forests 2010b ). However, in areas near industrial
air pollution sources, forest ecosystems decline hasbeen often attributed to the harmful effects of atmo-
spheric pollutants. In this context there has been a
need for better understanding of multiple interrelation-
ships between long-range trans-boundary air pollution
and the main ecosystem components and processes.
Most hypotheses on the causes of different types of
injury, such as physiological and mechanical, have
been interpreted as an expression of a lack of resil-ience of the entire ecosystem, with air pollution being
considered as a facilitating, accompanying, or even a
mitigating factor. However, there is still insufficientknowledge of the normal functioning of forest ecosys-
tems to understand the causes of forest decline and
deterioration of forest health (Lorenz et al. 2004 ).
Environmental pollution, climate changes, and var-
ious biotic and abiotic factors that cause the decline of
forest ecosystems have been evaluated in differentnational and international studies of individual trees,
stands, and forest ecosystems as undivided growthdynamics (Badea and Neagu 2011 ). However, all these
stress factors, mainly anthropogenic, are characterized
by a more intense dynamic than the natural adaptationprocesses of forests, because trees as living organisms
have a slow ability to adapt to changes in environmental
conditions. Increasing anthropogenic influences on theenvironment, especially pollution loads, have caused
negative changes in natural ecosystems, such as biodi-
versity decline or reduced productivity (Shparyk andParpan 2004 ).
There is clear evidence that during the past century
ambient ozone (O
3) concentrations in the northern hemi-
sphere have significantly increased due to increased
anthropogenic emissions of nitrogen oxides and volatile
organic compounds that are O 3precursors (V olz and
Kley 1988 ). The present background O 3concentrations
have already reached phytotoxic levels in many parts ofthe world, and it is predicted that by 2050 about 50% of
global forests will experience negative O
3effects
(Fowler et al. 1999 ). At present, ambient O 3is the
most important phytotoxic air pollutant for forest vege-
tation in Europe, including tracts of the Carpathian
Mountains, while nitrogen and sulfur oxides (NO xand
SOx) at concentrations harmful to forest vegetation rare-
ly occur (Bytnerowicz et al. 2005 ). However, combined
effects of O 3, sulfur dioxide (SO 2), and nitrogen dioxide
(NO 2) could have negative effects on some forest stands
in the western Carpathians (Muzika et al. 2004 ). In
addition, high levels of nitrogen (N) and sulfur (S)deposition occur widely across Europe, particularly in
its central part, including the Carpathians, and may
cause acidification and N enrichment of forest ecosys-tems (ICP-Forests 2010a ). Ammonia (NH
3) is one of the
main drivers of atmospheric N deposition to forests and
other ecosystems with its effects increasing over time(Erisman et al. 2008 ).
High levels of O
3and other phytotoxic pollutants,
as well as N and S deposition at the levels found in theCarpathian Mountains, may cause negative effects on
forest health status and biodiversity, including visible
leaf injury, losses in stand growth and productivity, aswell as higher sensitivity to biotic and abiotic stressors
(Bytnerowicz et al. 2005 ; Silaghi et al. 2011 ). Conse-
quently, secondary stresses such as the increasing rateof bark beetle attacks or changes in nutritional status
of forest soils caused by acidic precipitation may con-
tribute to the worsening condition of forest stands.7492 Environ Monit Assess (2012) 184:7491 –7515
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Spatial and temporal distribution of air pollutants
vary significantly due to physiographic differences,such as altitude, and environmental changes, including
climate change and human activities. Long-term mon-
itoring activities of O
3and other phytotoxic pollutant
concentrations, as well as dry and wet atmospheric
deposition (bulk deposition), are necessary in order
to understand the nature and future risks to forestecosystems. In the Romanian Carpathian Mountains,
the effects of air pollution on forest ecosystems were
studied on an international network of long-term eco-logical research (LTER) sites. The Bucegi Natural
Park in the Bucegi Mountains located in the southern
Carpathian Mountains was chosen as one of the sitesbecause it has important scientific value for the entire
Carpathian Mountains, as well as for the Romanian
Carpathians. This is intended as a long-term investi-
gation of the effects of air pollution on forest ecosys-
tems in Bucegi Natural Park. It was expected that theBucegi forests would have a "normal" environmental,
nutritional, forest health and growth status, as shown
in different other research conducted in RomanianCarpathians (Bytnerowicz et al. 2005 ).
The general objective of these research and monitor-
ing activities in the Romanian Carpathians Mountains isto determine the level of air pollution and its potential
effects on forest ecosystem s status and biodiversity, and
its connection with the effects of climate change inBucegi Natural Park. The specific objectives of this paper
are: (a) to assess the spatial and temporal distribution of
selected air pollutants (O
3and NH 3); (b) to determine
precipitation and throughfall acidity and chemical com-
position in selected forest sites; and (c) to evaluate forest
health status, biodiversity, growth of trees, and soil con-dition affected by the air pollution and other risk factors.
Materials and methods
Study areaThe Bucegi Mountains are located in the southern
Carpathians in Romania and have an area of32,498 ha with more than 60% forest cover. Natural
reserves cover 8,216 ha, of which 4,997 ha are in the
administrative territory of Prahova County, 1,575 ha inDambovita County, and 1,644 ha in Brasov County,
representing around 25% of Bucegi Natural Park
(RNP-Romsilva 2010 ). The vast richness and diversityof the Park ’s vegetation, many endemic species, and
unique plant associations provide high scientific value.This diversity was the main reason for assigning Natural
Park status to the Bucegi Mountains, aiming to preserve
natural landscapes and specific biocenoses of thesemountains.
The development of multidisciplinary studies for
the purpose of long-term research of forest ecosystemsunder the influence of air pollution and climate change
required an establishment of an LTER network repre-
sentative of the entire study area and its rich diversityof the forest ecosystems. Thus, forest ecosystems and
their accessibility, topography, altitude and exposition,
and air pollution by O
3and NH 3were investigated.
In 2006, a monitoring network of 10 uniformly
distributed LTER sites located in forest zones with
elevations ranging between 800 and 1,700 m was
established (Fig. 1). Each forest ecosystems category
(conifers, broadleaves, and mixed forests) was repre-sented at two to three LTER sites. Research activities
conducted within the network are presented in Table 1
(Gol Alpin location was selected only for air qualitymeasurements).
Methodology
After identifying and selecting representative forest eco-
systems category on maps and in the field, ten perma-
nent plots (LTER sites) with their subsequent subplotswere established and spatially positioned using a global
positioning system. At a distance of 30 m of the plot
center, four permanent subplots (PSPs) were arranged incardinal directions crosswise, as well as one in the center
of the LTER sites, in homogeneous stand conditions
(Lorenz et al. 2004 ).
The research area of each site was 0.7 ha. It contained
five circular PSPs of 500 m
2each in which annual
assessments of forest health, periodic measurements of
dendrometric characteristics (species, Diameter at Breast
Height, height, Kraft class, quality class; Dobbertin andNeumann 2010 ; Eichhorn et al. 2010 ), and seasonal
vegetation biodiversity assessments were conducted
(Fig. 2). In a buffer zone close to the permanent subplots,
destructive sampling (increment cores, foliar samples,
soil samples) and atmospheric deposition and soil solu-
tion sampling were carried out. Crown condition wasassessed annually in 2006 –2009 during July to August
(Badea et al. 2004 ; Bytnerowicz et al. 2005 ; Neagu and
Badea 2008 ). Each year, all the trees of the PSP areasEnviron Monit Assess (2012) 184:7491 –7515 7493
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Fig. 1 Long-term ecological research (LTER) network in Bucegi Natural Park7494 Environ Monit Assess (2012) 184:7491 –7515
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located in Kraft classes I, II, and III (predominant,
dominant, and codominant) were evaluated accordingto the ICP Forests methodology (ICP-Forests 2006b ).
Dendrometric measurements were taken during the veg-
etation season according to the methodological manualdeveloped under this research project (Badea et al.
2008 ). Phytosociological (plant community) data were
recorded for each permanent plot twice over the grow-ing season (spring and summer) using the Braun Blan-
quet’s method (Grodzinska et al. 2004 ; Badea 2008 ;
Vadineanu et al. 2008 ). Increment core samples were
taken from 20 –25 trees located in the buffer zone of
each site, both for main living tree species and for the 0 –
1( d e f o l i a t i o n ≤25%) and 2 –3 (defoliation >25%) defo-
liation group classes.
In mixed stands consisting mainly of Norway
spruce ( Picea abies ), European silver fir ( Abies alba ),
and European beech ( Fagus sylvatica ) the increment
cores were taken from 10 –15 trees of each main spe-
cies. Based on radial increment and a single periodicmeasurement of trees, the average annual volume
growth and yield (Giurgiu 1979 ; Leahu 1994 ; Giurgiu
et al. 2004 ) as well as losses due to the effects of
different stress factors (air pollution, climatic changes)
were determined. The average annual increment (theaverage tree ring width) was determined for all living
trees (defoliation classes 0 –3), for healthy trees (defo-
liation group classes 0 –1), and for damaged trees
(defoliation group classes 2 –3) of individuals of sim-
ilar age at each site and for the entire network for themain species ( P . abies ,A. alba , and F . sylvatica ). In
order to obtain statistically significant results, at each
site at least ten dominant or codominant trees werecore sampled at 1.3 m height for each species and
defoliation group classes. The data processing and
interpretation was performed according to Badea etal. (2008 ).
Calculation of the normal (theoretical) growth was
made assuming that all trees were healthy (defoliationclasses 0 –1), by inferring the growth of healthy trees
to the damaged ones (defoliation classes 2 –3), taking
into consideration the corresponding DBH.
The growth losses are computed based on the as-
sumption that the damaged trees (defoliation classes
2–3), in ‘normal ’conditions, would have been healthy
and would have had similar axiological behavior with
the healthy ones (Badea and Neagu 2011 ). This as-
sumption does not take into consideration the growth
losses that occurred before the study period (the last
10 years), which could have an accumulated effect. InTable 1 Research activities performed in the long-term ecological research (LTER) sites in the Bucegi Mountains, Romania, 2006 –
2009
LTER
locationsAltitude
a.s.l.
(m)Main species Growth
and
yieldCrown
conditionSoil
conditionAnalysis of
needles and
leavesDeposition
(bulk and
throughfall)Soil
solutionBiodiversity Air
quality
1. Salvamont
Bran1250 Picea abies ✓ ✓✓✓ ✓ ✓ ✓ ✓
2. Observator Urs 930 Picea abies,
Fagussylvatica,Abies alba✓ ✓✓✓ ✓ ✓
3. Timen-Grofi 1000 Picea abies ✓ ✓✓✓ ✓ ✓
4. Poiana Stanii 1300 Fagus
sylvatica✓ ✓✓✓ ✓ ✓ ✓ ✓
5. Valea cu Brazi 1450 Picea abies ✓ ✓✓✓ ✓ ✓
6. Dichiu 1250 Fagus
sylvatica✓ ✓✓✓ ✓ ✓
7. Brandu și 1750 Picea abies ✓ ✓✓✓ ✓ ✓
8. Cariera-
Lespezi1480 Fagus
sylvatica✓ ✓✓✓ ✓ ✓
9. Podu cu Flori 1750 Picea abies ✓ ✓✓✓ ✓ ✓ ✓ ✓
10. B ătrana 1700 Picea abies ✓ ✓✓✓ ✓ ✓
11. Gol Alpin 1950 – ✓
All the research activities started in 2006Environ Monit Assess (2012) 184:7491 –7515 7495
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2007, to assess forest soil condition, several soil profiles
were excavated for mineral and organic layers sampling
at all LTER sites (Geambasu and Danescu 2008 ). The
morphological, physical, mechanical, and chemical
properties of forest soils were analyzed at the Chemistry
Laboratory of Forest Research and Management InstituteICAS Bucharest.
Foliar samples for analysis of the nutritional status of
trees were harvested by main species ( P. ab ies ,A. alba ,
Pinus sylvestris ,a n d F. sy lva ti ca) from eight trees of each
species in each site ’s buffer zone. For conifers (spruce,
fir, pine), foliar samples were collected in April 2007 andfor beech in August 2007 (Blujdea and Ionescu 2008 ).
TheP. s y l ve s tr i s andA. alba foliage samples for chem-
ical analysis were collected only from single locations.
The population of Scots pine ( P . sylvestris )a tt h eT i m e n –
Grofi site was unique in the specific composition of thatstand and poorly represented. For A. alba ,s a m p l e sw e r e
collected at the Observator Urs site, where this species
was well represented in the stand composition. FoliageofF . sylvatica was collected in two locations, Poiana
Stanii and Cariera-Lespezi. The chemical analyses of
foliar samples were performed according to the method-ology described by Mankovská et al. ( 2004 ).
Close to the LTER plots in locations of optimal
exposure to incoming air masses, concentrations ofO
3and NH 3were monitored during the growing sea-
sons (15 May to 15 October) of the 2006 –2009 study.
Passive samplers for O 3,N H 3, and NO 2(Ogawa and
Co., USA, Pompano Beach, Florida) were placed in
protective caps and hung on wooden stands at ∼2m
aboveground. Each O 3sampler (Koutrakis et al. 1993 )
contained two replicate cellulose filters coated with
nitrite, which is oxidized by O 3to nitrate. Nitrate
was extracted from passive samplers with ultrapure
water, and its concentrations were determined with
ion chromatography (Dionex, Model DX 600, DionexCo., USA, Sunnyvale, CA). Based on comparisons
with collocated UV absorption active O
3instruments,
the nitrite formation rates and O 3concentrations were
Fig. 2 Design of study site and spatial distribution of circular permanent subplots (PSP) for forest vegetation assessment7496 Environ Monit Assess (2012) 184:7491 –7515
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calculated (Bytnerowicz et al. 2008a ). Each NH 3sam-
pler (Roadman et al. 2003 ) contained two replicate
filters coated with citric acid that in the presence of
NH 3is converted to ammonium citrate. Ammonium
from filters was extracted in ultrapure water and itsconcentrations were determined colorimetrically with
TRAACS 2000 Autoanalyzer (Bran Luebbe, 611 Sugar
Creek Road, Delavan, WI 53115), and ambient concen-trations were calculated based on comparison with col-
located annular denuder systems (Bytnerowicz et al.
2010 ). Each NO
2sampler contained two replicate cel-
lulose filters coated with triethylamine that captures
NO 2as nitrite that is extracted in water and determined
with ion chromatography (Dionex, Model DX 600).Concentrations of NO
2were calculated based on collo-
cated NO 2real-time monitors (Monitor Labs) chemilu-
minescence analyzers. Passive samplers were collected
monthly, sealed in plastic containers and ziplock bags,
and immediately shipped for chemical analyses. Con-centrations of NO
2were also determined and were
presented with the preliminary O 3and NH 3results for
t h e2 0 0 9s e a s o nb yB a d e ae ta l .( 2011 ).
Bulk deposition (open field and throughfall) was
collected at three plots (Salvamont Bran, Poiana Stanii,
and Podu cu Flori). Precipitation samples were collectedboth during the growing season (15 May to 15 October)
and during the dormant period (15 October to 15 May).
To minimize chemical contamination of the samples,special precautions were taken, especially rinsing all
equipment after each collection. Using different analyt-
ical methods (ion chromatography, colorimetry, conduc-tometry), a set of parameters like pH, conductivity,
alkalinity, and potassium (K), calcium (Ca), magnesium
(Mg), sodium (Na), ammonium N (N-NH
3), chlorine
(Cl), nitrate N (N-NO 3), sulfate S (S-SO 4)w e r ed e t e r –
mined Barbu and Iacoban ( 2008 ).
A meteorological station was installed in a repre-
sentative location (Laptici) near the B ătrana site
(Fig. 1) in order to measure air temperature, air hu-
midity, precipitation, and wind parameters. Additionalair temperature and humidity data loggers were set up
inside representative forest stands.
Forest health status was assessed annually, during the
15 July to 31 August period, which corresponds to the
maximum physiological activity of the trees. Crown
condition and mechanical damages of trees wereassessed according to the methodological manual
(Badea 2008 ). Statistical analysis of data was made with
the SPSS software, using correlation, linear regression(simple and multiple) and ANOV A analysis (mean com-
parison method used in Tukey ’st e s t ) .
Results and discussion
Air chemistry
In the Bucegi Mountains during the 2006 –2009 grow-
ing seasons, both spatial and temporal trends of ambi-
ent O
3distribution showed high variability (Table 2,
Fig.3). Ranges of the monthly average O 3concentra-
tions for individual locations were similar for 2006,
2007, and 2009 (20.7 –61.6 ppb, 23.0 –66.8 ppb, and
19.2–67.0 ppb, respectively), but were more variable
in 2008 (13.5 –80.0 ppb). Seasonal averages for vari-
ous sites varied between 22.5 ppb (Observator Urs in2009) and 57.4 ppb (Podu cu Flori in 2007), and large
differences between the sites (Table 2) and times of the
season (Fig. 3) were determined. Highest O
3concen-
trations typically occurred in the middle of summer
(mid-June to mid-August), with the lowest values after
the photochemical smog season in mid-September tomid-October (Fig. 3). Considering that O
3is a second-
ary photochemical pollutant, its higher concentrations
in the middle of summer can be explained by hightemperature and solar radiation (Finlayson-Pitts and
Pitts 2000 ) The determined seasonal means of 42.5 –
47.2 ppb in 2006 –2008 were higher than those deter-
mined in the Romanian Carpathians in the 1997 –1999
period (39 –42 ppb), while the 2009 mean of 40.0 ppb
was in the range of those values (Bytnerowicz et al.2004 ).
The O
3levels determined in the Bucegi Mountains
were slightly higher than those at the Retezat National
Park in the southern Carpathians (Bytnerowicz et al.
2005 ). During the study period, ambient O 3concen-
trations increased in the Bucegi Mountains with alti-
tude up to ∼1,500 m, and then decreased as the altitude
increased to ∼1,750 m (Badea et al. 2011 ). Results of
the multiple linear regression analysis for each expo-
sure period of the 2006 –2009 growing seasons
showed that altitude accounted for 49% of the varia-tion of ozone concentrations, and mean temperatures
corresponding to each exposure period during the
2006 –2009 growing seasons explained another
18.5% of ozone variation. Therefore, the altitude in-
crease and temperature together accounted for 67.5%
of the observed O
3changes.Environ Monit Assess (2012) 184:7491 –7515 7497
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The average monthly or seasonal O 3concentrations
found in the Bucegi Mountains should not be consid-ered toxic to the investigated tree species (Skärby and
Karlsson 1996 ; Bytnerowicz et al. 2005 ), although
effects on sensitive understory plant species (althoughno visible injury were observed) cannot be ruled out
(Manning and Godzik 2004 ). In order to be more
specific about potential O
3phytotoxic effects, real-
time information on O 3concentration (hourly values)
is needed. This is because the toxicity of the pollutantTable 2 Summary statistics for ozone concentrations (ppb) measured as integrated monthly values (15 May –15 October), presented as
seasonal means with standard deviation (in parentheses), and ranges of concentrations
Location 2006 2007 2008 2009
1. Salvamont Bran 38.7 (6.3), cd, 31.3 –48.6 42.6 (7.6), abc, 32.5 –51.1 39.5 (9.3), 24.0 –48.9 36.2 (4.3), bcd, 31.1 –40.7
2. Observator Urs 25.1 (3.9), e, 20.7 –31.1 29.2 (6.2), c, 23.0 –36.2 26.3 (7.8), 13.5 –33.9 22.5 (3.0), d, 19.2 –25.7
3. Timen-Grofi 33.0 (5.1), de, 28.0 –41.1 35.9 (6.9), bc, 27.7 –43.0 32.8 (8.4), 18.5 –39.7 29.3 (3.9), cd, 24.2 –32.8
4. Poiana Stanii 43.7 (4.5), bc, 38.2 –50.7 48.1 (6.6), ab, 36.2 –51.7 42.6 (10.6), 24.5 –51.4 40.1 (3.7), abc, 34.6, 42.9
5. Valea cu Brazi 48.7 (4.3), abc, 43.4 –54.9 50.6 (8.3), ab, 38.7 –57.8 47.2 (11.0), 28.0, 55.1 44.3 (4.9), abc, 37.5 –48.9
6. Dichiu 45.4 (4.3), abc, 40.8 –52.2 47.8 (8.3), ab, 35.0 –54.6 43.7 (9.6), 27.7 –52.9 38.4 (5.2), bc, 30.8 –42.5
7. Brandu și 50.5 (5.7), ab, 42.9 –58.8 53.7 (7.4), a, 41.7 –61.2 48.8 (23.0), 24.0 –71.7 48.7 (6.8), ab, 40.4 –57.0
8. Cariera-Lespezi 45.7 (3.6), abc, 40.3 –49.8 48.2 (10.0), ab, 38.1 –61.4 42.6 (18.8), 21.6 –67.2 42.0 (7.7), abc, 32.6 –51.4
9. Podu cu Flori 54.6 (5.2), a, 47.2 –61.6 57.4 (9.0), a, 42.7 –66.8 50.7 (23.9), 22.3 –80.0 54.6 (10.2), a, 42.1 –67.0
10. B ătrana 54.0 (4.5), ab, 47.4 –59.5 57.5 (8.0), a, 43.9 –64.5 49.0 (20.9), 24.3 –74.3 41.2 (9.7), ab, 29.4 –53.1
11. Gol Alpin 48.7 (5.6), abc, 42.7 –54.4 48.3 (7.3), ab, 37.8 –55.1 44.4 (8.0), 30.4 –50.3 42.2 (5.5), abc, 34.5 –47.3
Pvalue for “between
sites”comparison<0.05 <0.05 0.322 <0.05
All sites 44.4 (9.0), 25.1 –54.6 47.2 (8.6), 29.2 –57.5 42.5 (7.4), 26.3 –
50.740.0 (8.7), 22.5 –54.6
Pvalue for “all sites ”
comparison0.336 0.336 0.336 0.336
Different letters following mean and S.D. indicate significant differences between monthly mean ozone concentrations measured at
different monitoring sites at a specified Pvalue
Fig. 3 Comparisons of
mean O 3concentrations
(ppb) for each exposure pe-riod during each year from2006 –2009 period. Different
letters set as labels to each
column indicate significantdifferences between expo-sure periods at P<0.057498 Environ Monit Assess (2012) 184:7491 –7515
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increases with the occurrence (absolute values and fre-
quency) of its peak values (Musselman et al. 2006 ).
Although the highest O 3seasonal means were recorded
in 2007, that does not mean that the phytotoxic O 3
effects were also the highest. That potential could have
been lower due to the fact that in 2007 ambient temper-
atures were very high (often over 35°C). This in turn
promotes closure of stomata to reduce water transpira-tion and consequently O
3intake when its ambient con-
centrations are the highest (noon, early afternoon)
(Matyssek et al. 2007 ).
Ambient NH 3concentrations showed high spatial and
temporal variability (Table 3;F i g . 4). Ranges of monthly
average NH 3concentrations were similar for 4 years of
the study: 0.40 –3.80, 0.02 –3.31, 0.20 –4.60, and 0.10 –
2.64μg/m3, respectively, for 2006, 2007, 2008, and
2009. In 2006 and 2007, the highest seasonal averages
occurred in B ătrana (2.46 and 1.78 μg/m3, respectively),
while in 2008 and 2009 no significant differences be-tween the sites were determined (Table 3). Seasonal
averages for various sites varied between 0.63 μg/m
3at
Gol Alpin in 2007 to 2.46 μg/m3at B ătrana in 2006, and
except for rare peaks >4.0 μg/m3in 2008, most seasonal
values were <2.0 μg/m3(Table 3). For the entire area, in
2006, 2007, and 2009 there were no significantdifferences in NH 3between monitoring periods and
concentrations generally stayed <1.5 μg/m3.H o w e v e r ,
from 15 May to 15 June 2008 the entire area experienced
ah i g hN H 3episode with an average of 3.1 μg/m3
(Fig. 4). The spikes in NH 3concentrations were proba-
bly caused by intensive tourist activities, grazing, forest
operations (cuttings), or increased biological activity
(peat lands, insect outbreaks ’control activities).
In general, seasonal means of NH 3concentrations
monitored in the Bucegi Mountains were lower than the
levels found in the Retezat Mountains (Bytnerowicz et al.2005 ) or in other Carpathians regions. These levels are
similar to those found in the Canadian Rocky Mountains
(Legge and Krupa 1989 ) and in the Eastern Sierra
Nevada, California (Bytnerowicz and Fenn 1996 ). The
measured concentrations were below phytotoxic NH
3
levels (Bytnerowicz et al. 1998 ) and are not expected to
provide substantial amounts of dry-deposited nitrogen to
forest (Gessler and Rennenberg 1998 ).
Nitrogen dioxide (NO 2) concentrations were mea-
sured only in 2006 and 2007. In general, the monthly
averages were low (below 4 μg/m3) in most locations.
Ranges of NO 2concentrations were between 0.8 and
1.70μg/m3in 2006 and between 1.90 and 3.80 μg/m3
in 2007. Such values are low and typical for remote
Table 3 Summary statistics for ammonia concentrations ( μg/m3) measured as integrated monthly values (15 May –15 October),
presented as seasonal means with standard deviation (in parentheses), and ranges of concentrations
Location 2006 2007 2008 2009
1. Salvamont Bran 0.82 (0.46), b, 0.40 –1.60 0.99 (0.27), ab, 0.59 –1.26 1.60 (0.95), 0.90 –2.94 1.73 (0.38), 1.38 –2.12
2. Observator Urs 0.80 (0.12), b, 0.60 –0.90 0.84 (0.56), ab, 0.02 –1.55 1.40 (0.91), 0.56 –2.91 1.14 (0.70), 0.10 –1.50
3. Timen-Grofi 0.80 (0.17), b, 0.50 –0.90 1.03 (0.26), ab, 0.59 –1.25 1.68 (1.65), 0.60, 4.60 1.80 (0.48), 1.13 –2.26
4. Poiana Stanii 0.66 (0.11), b, 0.50 –0.80 0.78 (0.27), ab, 0.47 –1.19 1.86 (1.33), 0.88 –4.14 1.73 (0.62), 1.26 –2.64
5. Valea cu Brazi 0.74 (0.15), b, 0.50 –0.90 0.60 (0.12), b, 0.48 –0.77 1.40 (1.35), 0.19 –3.68 1.98 (0.32), 1.79 –2.45
6. Dichiu 0.86 (0.29), b, 0.50 –1.30 1.01 (0.37), ab, 0.68 –1.59 1.73 (0.59), 1.06 –2.44 1.65 (0.31), 1.28 –2.00
7. Brandu și 1.48 (0.68), ab, 0.50 –2.20 1.02 (0.29), ab, 0.77 –1.51 1.69 (1.35), 0.78 –4.03 0.82 (0.50), 0.18 –1.21
8. Cariera-Lespezi 1.36 (0.63), ab, 0.602.30 0.72 (0.60), ab, 0.22 –1.69 1.18 (0.35), 0.80 –1.73 0.98 (0.72), 0.44 –2.00
9. Podu cu Flori 0.73 (0.55), b, 0.11 –0.60 1.57 (1.10), ab, 0.50 –3.31 0.92 (0.80), 0.16 –1.98 0.86 (0.38), 0.51 –1.37
10. B ătrana 2.46 (1.28), a, 0.60 –3.80 1.78 (0.76), a, 0.81 –2.76 1.43 (0.95), 0.20 –2.30 1.19 (0.46), 0.49 –1.43
11. Gol Alpin 0.86 (0.47), b, 0.4 –1.50 0.63 (0.41), b, 0.23 –1.13 1.84 (1.12), 0.70 –3.66 1.08 (0.74), 0.21 –1.92
Pvalue for “between
sites”comparison<0.05 <0.05 0.954 0.112
All sites 1.05 (.54), .66 –2.46 1.00 (.37), .60 –1.78 1.52 (.29), .92 –1.86 1.36 (.42), .82 –1.98
Pvalue for “all sites ”
comparison0.175 0.175 0.175 0.175
Different letters following mean and S.D. indicate significant differences between monthly mean ammonia concentrations measured at
different monitoring sites at a specified PvalueEnviron Monit Assess (2012) 184:7491 –7515 7499
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European mountain locations with no potential for any
phytotoxic effects and minimal effect on N dry depo-sition given the low deposition velocity of this pollut-
ant (Hanson and Lindberg 1991 ).
Additional consideration should be given to the
interactive effects of various air pollutants (Muzika
et al. 2004 ). However, considering that NO
2and
NH 3levels were very low, and the SO 2levels, al-
though not measured, were probably similar to low
concentrations determined in the nearby Retezat
Mountains (Bytnerowicz et al. 2005 ), at present no
serious interactive effects on trees are expected.
Precipitation chemistry
Average precipitation quantities collected between 15
May and 15 October in 2006 –2009 in the LTER sites
are presented in Table 4. Precipitation deposition to
canopy depends mainly on the density of the stand,intensity and duration of an event, and wind speed
(Kimmius 1973 ; Matzner 1986 ). The highest precipi-
tation interception (9.08%) was recorded in the beechstand in Poiana Stanii plot and the lowest (-0.77% to –
5.25%) in the coniferous stands at Salvamont Bran
and Podu cu Flori. The main cause of high amountsof throughfall is frequent occurrence of fog and
clouds, which very effectively deposit water droplets
within the canopy (Villegas et al. 2007 ; Hildebrandtand Eltahir 2008 ). High variability of precipitation
interception during the growing period between thestudy years was recorded. In 2008, in all plots, the
open field (272.9 mm) precipitations were higher than
in throughfall (249.6 mm). In 2006 and 2009, theprecipitation interception rates were higher (8% and
14%, respectively) than in 2007 and 2008 (1% and
5%, respectively).
Over the period 2006 –2009 the average frequencies
of rainfall with pH<5.5 were higher in open field
(59.4% in Poiana Stanii and 50.0% by Podu cu Flori)than those registered under the canopy (52.9% by
Poiana Stanii and 47.0% by Podu cu Flori). In contrast
to the other sites, in Salvamont Bran the occurrence ofacid rain events was lower in open field compared to
under canopy (Fig. 5).
Compared with acid rain frequencies in other
Romanian intensive forest monitoring plots (ICP Forests
Level II; Barbu et al. 2000 ;2001 )o rt h o s em e a s u r e di n
the Retezat National Park (Bytnerowicz et al. 2005 ),
those in the Bucegi Mountains were about two to three
times and one to three times higher, respectively.
Acidity of bulk precipitation was generally higher
than that of throughfall (Table 4). Comparing concen-
trations of acid (N, S) and alkaline (Ca, Mg) elements,
as well as high values of water conductivity (saltaccumulation, alkaline effects), it can be concluded
that bulk precipitation in the Bucegi Mountains was
Fig. 4 Comparisons of
mean NH 3concentrations
(in micrograms cubic
meters) for each exposure
period during each yearfrom 2006 –2009 period.
Different letters set as labels
to each column indicate sig-
nificant differences betweenexposure periods at P<0.057500 Environ Monit Assess (2012) 184:7491 –7515
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generally acidic. Therefore, rain precipitation could
contribute to the forest soil acidification process witha possible negative effect on forest health.
In open field (bulk deposition) in the 2009 growing
season, the inputs range of S-SO
4in three studied sites
was wider and varied from 2 to 8 kg ha−1(Badea et al.
2011 ). Throughfall inputs of S-SO 4recorded values
around 6 kg ha−1. Compared with 2009, in 2006 –2008
the inputs of S-SO 4in the open field were variable, from
1.1 kg ha−1(Podu cu Flori) to 3.7 kg ha−1(Salvamont
Bran) and 3.1 kg ha−1(Poiana Stanii). This level of
S-SO 4shows low interaction with stand canopies, a
low enrichment factor/ratio between fluxes under the
canopy and in the open field, and a low pollution levelof the studied area. Nitrogen inputs were very low
(0.2 kg ha
−1to 3.5 kg ha−1) and the range of N-NH 4
was higher than N-NO 3deposition, in relation to the soil
depth (Badea et al. 2011 ).
Throughfall had high concentrations of N-NH 4,m a i n –
ly at high altitude, and bulk precipitation of N-NH 4contributed to 0.5 kg N ha−1t o2 – 4k gNh a−1.I ns o m e
research sites (Poiana Stanii), concentration of NH 4in
throughfall was lower than in bulk deposition, due to
direct uptake of NO 3or NH 4by the canopy. Also, loca-
tions with low concentrations of NO 3-and NH 4+in bulk
precipitation recorded insignificant amounts of these ions
in throughfall, with an exception noted on Podu cu Flori,
most likely due to intensive human activities (e.g., graz-ing of animals, tourism; Badea et al. 2011).
The S-SO
4inputs under forest canopy (throughfall
deposition) was significantly correlated with N-NO3and N-NH
4(Pearson correlation coefficient r100.610
and r200.223, respectively, for α<0.01), relation
which points toward co-emissions from SO x(mainly
industry), NO x(mainly traffic), and NH x(mainly agri-
culture) in nearby industrialized areas (de Vries et al.
2003 ), and with S-SO 4from bulk deposition ( r00.638,
α<0.01), which is a normal relationship, although
imputes in throughfall are four times higher than the
ones in bulk precipitations in Podu cu Flori (Table 4).
In addition, N-NO 3and N-NH 4from throughfall were
negatively ( r0−0.285, α<0.01) and positively
(r00.221, α<0.01) significantly correlated with ambient
O3concentration. The negative correlation between N-
NO 3and O 3may lead to the conclusion that ozone
precursors (VOC ’s) do not have the same source as N-
NO 3ions in depositions (nearby traffic), and are the
result of long-range tran s-boundary air pollution
(UNECE 2004 ).
Nutritional status of trees
Defining nutritional status of trees in the LTER plots
was done by comparing concentrations of the mineralTable 4 Average concentrations of ions in bulk and throughfall precipitation samples collected during 2006 –2009
Location Pp (mm) pH Cond.
(μS/cm)S-SO 4
(mg/L)Cl (mg/L) N-NO 3
(mg/L)N-NH 4
(mg/L)Na (mg/L) K (mg/L) Mg (mg/L) Ca (mg/L)
Bulk precipitations
Salvamont Bran 279.9 5.02 27.12 0.83 1.77 0.28 0.61 0.23 0.31 0.09 2.55Poiana Stanii 245.4 5.28 27.70 0.91 1.11 0.42 1.00 0.19 1.06 0.13 1.87Podu cu Flori 151.8 5.21 29.43 0.81 0.60 0.13 0.24 0.19 0.65 0.12 2.75Throughfall precipitations
Salvamont Bran 294.6 5.26 38.46 1.56 0.96 0.48 1.37 0.23 2.42 0.24 2.06
Poiana Stanii 223.1 5.22 48.50 1.40 0.95 0.49 1.84 0.19 5.19 0.34 2.09Podu cu Flori 152.9 6.11 95.15 2.93 3.40 0.39 3.58 1.89 2.89 0.45 5.81
Fig. 5 Frequency of acidic rain (pH<5.5) at three research
locationsEnviron Monit Assess (2012) 184:7491 –7515 7501
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nutrient elements (total foliar form) against the aver-
age European data for the key tree species (Bauer et al.1997 ;S t e f a ne ta l . 1997 ) and for the Carpathian
Mountains (Mankovska et al. 2004 ). In general, levels
of foliar nutrients of the studied populations of treeswere not balanced, indicating their potential problems
with metabolic processes, lower resistance to stressors,
deterioration of tree health, and slower growth (Stefanet al. 1997 ).
Among the studied species, the nutritional status of
P . abies most adequately represents forests of the
Bucegi Mountains and samples from this species were
collected at seven sites dispersed throughout the study
area (Table 5). Compared to the normal macronutrient
concentrations for this species in Europe (Bauer et al.
1997 ), their limit values (Stefan et al. 1997 ), and
values previously determined in the Romanian Carpa-thians (Mankovska et al. 2004 ), the N foliar concen-
trations were normal, P concentrations were about
twofold higher than normal, while concentrations ofK, Ca, and Mg were below their normal values (about
fivefold, twofold, and twofold, respectively). Concen-
trations of micronutrients also significantly differedfrom the values typically found in the Carpathian
forests for this species (Mankovska et al. 2004 ), with
very low concentrations of Mn and zinc (Zn) (10- to15-fold and five times lower than normal values, re-
spectively), normal copper (Cu) levels, and concen-
trations of Na about two times higher than normal.
The elemental ratios (in grams per gram) also sug-
gest serious nutritional disturbances for P . abies in all
sites (Table 6). Typically, the N/P ratio ranges between
6 and 17 (Mankovska et al. 2004 ), but only the trees at
Observator Urs were at the typical recommended value.The recommended N/K ratio of 1.3 –5 was significant-
ly exceeded at all study sites. The N/Mg ratio did notdiffer much between the sites and was at the high end
of the recommended limit of 8 –28 (Stefan et al.
1997 ) but much higher than the values determined
in the Romanian Carpathians ( ∼14.5) in the late
1990s (Mankovska et al. 2004 ). The K/Ca ratio was
at the low end of the recommended values (Stefan etal.1997 ).P . abies needles showed a serious Mn
deficiency indicated by very high values at all sites
compared to the typical N/Mn ratio of 27.3 (Stefan etal.1997 ) and to the average ratio of 15.2 determined
in the Romanian Carpathians by Mankovska et al.
(2004 ). This deficiency was the highest at the
Timen-Grofi and Valea cu Brazi sites.
Results of elemental concentrations of P . sylvestris ,
A. alba , and F. sylvatica are presented in Table 7and
their foliar ratios in Table 8.
Similar to P . abies ,A. alba , and P. sylvestris also
had normal N and Ca concentrations, higher thannormal P concentrations, and the K, Mg, Zn, and Mn
concentrations were lower than recommended (Stefan
et al.
1997 ) or typically found in the Carpathian
Mountains (Mankovska et al., 2004 ). These general
trends seen in the studied coniferous species were also
determined for F. sylvatica , in which the N concen-
trations of 2.32 –2.44% were typical for various Euro-
pean forests; howeve r, P concentrations of ∼0.3%
were about two times higher than normal (Furst2006 ), while concentrations of K, Mg, Zn, and Mn
were lower (Bauer et al. 1997 ; Stefan et al. 1997 ) than
in other Carpathian stands (Mankovska et al. 2004 ).
These discrepancies between the study concentrations
of nutrients and the recommended values for theseTable 5 Average concentrations of nutrients in the Picea abies foliage in Bucegi Natural Park
Location N
(%g g−1)P
(%g g−1)K
(%g g−1)Ca
(%g g−1)Mn
(mg kg−1)Zn
(mg kg−1)Cu
(mg kg−1)Na
(mg kg−1)Mg
(mg kg−1)
Timen-Grofi 1.39 0.29 0.15 0.24 14.4 7.2 10.7 172.3 564.2
Observator Urs 1.24 0.21 0.13 0.26 23.4 9.8 11.0 183.6 515.9Salvamont Bran 1.42 0.29 0.11 0.34 37.6 7.6 14.9 199.6 555.4Valea cu Brazi 1.26 0.29 0.13 0.42 9.8 8.2 18.8 203.7 538.5Bătrana 1.26 0.36 0.15 0.23 17.4 8.7 15.0 195.3 564.9
Podu cu Flori 1.17 0.35 0.14 0.30 48.5 7.7 28.1 245.8 524.2
Brandu și 1.23 0.29 0.12 0.24 37.5 6.8 20.9 177.2 537.3
Average 1.28 0.30 0.13 0.29 26.9 8.0 17.1 196.7 542.97502 Environ Monit Assess (2012) 184:7491 –7515
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species were also reflected in the nutritional ratios
(Stefan et al. 1997 ; Mankovska et al. 2004 ).
Elemental foliar concentrations and ratios were
similar for the compared species, which suggests that
balanced nutrition resulted from cohabitation of treesin similar trophic and environmental conditions. The
improper K/Ca ratio shows an abundance of calcium
in substrate and of water stress at the foliar level. Highdifferences between the N/Mn ratios in various loca-
tions could possibly be explained by high variability
in various soluble forms of this mineral.
In general, several significant differences ( p00.05)
were found among the nutrient mean concentrations at
different locations (one-way ANOVA): Ca and Mnboth for P. abies and F . sylvatica , and N, P, K, Zn,
and Cu solely for P . abies . The cause of these differ-
ences may be a result of the distinct site conditions andstand parameters (structure, composition, age, yield
class). In addition, the Pearson correlation analysis
indicated a relatively high and significant correlation(p00.05) between altitude and P concentration for
both species (i.e., 0.760 for P . abies and 0.791 for F.
sylvatica ), and between altitude and N/P ratio, al-
though negative (i.e., −0.873 for P . abies and−0.885
forF . sylvatica ). Thus, at high altitude (over the uppervegetation limit) the health and growth of trees is
expected to be reduced (Badea and Tanase 2004 ) due
to the fact that N is less available, although P concen-
tration is higher than in lower altitudes.
Soil condition
The soils of the Bucegi LTER sites are of the following
types (according to the international WRB classifica-
tion): dystric Cambisols —CMdy (Salvamont Bran,
Observator Urs, Cariera-Lespezi, Brandu și), eutric
Cambisols —CMeu (Timen-Grofi, Poiana Stanii,
Dichiu), haplic Podzols —PZha (Podu cu Flori), entic
Podzols —PZet (B ătrana), and rendzinic Phaeozems —
PHrz (Valea cu Brazi).
The parent material on which these soils have de-
veloped is composed of typical Bucegi conglomeratesspecific to the mountainous area: micaceous sand-
stones, sericite –chlorite schists, limestone and lime-
stone sandstones, conglomerate sandstones and
micaschists.
The organic horizon is composed of three subhor-
izons, and their thickness depends on the effectiveness
of the humification process. Thus, the litterfall sub-
horizon (OL) has a thickness between 0.8 and 2 cm,Table 6 Elemental ratio in
Picea abies foliage in Bucegi
Natural ParkLocation N/P
(g g−1)N/K
(g g−1)N/Mg
(g g−1)K/Ca
(g g−1)N/Mn
(g g−1)
Timen-Grofi 4.8 9.1 24.6 0.62 967.0
Observator Urs 6.0 9.9 24.3 0.50 531.2Salvamont Bran 4.9 12.7 25.6 0.32 378.5Valea cu Brazi 4.4 9.4 23.4 0.31 1286.4
Bătrana 3.5 8.3 22.3 0.65 725.5
Podu cu Flori 3.3 8.6 22.3 0.47 241.7Brandu și 4.2 10.2 22.9 0.50 326.3
Table 7 Average foliar elemental concentration in Abies alba, Pinus sylvestris , and Fagus sylvatica stands in Bucegi Natural Park
Species (Locations) N
(%g g−1)P
(%g g−1)K
(%g g−1)Ca
(%g g−1)Mn
(mg kg−1)Zn
(mg kg−1)Cu
(mg kg−1)Na
(mg kg−1)Mg
(mg kg−1)
Abies alba (Observator Urs) 1.31 0.25 0.17 0.53 15.1 8.3 21.4 235.4 613.8
Pinus sylvestris (Timen-Grofi) 1.82 0.27 0.15 0.23 11.5 12.2 16.2 170.1 514.5
Fagus sylvatica (Poiana Stanii) 2.44 0.30 0.12 0.38 21.3 7.0 14.1 156.5 655.1
Fagus sylvatica
(Cariera-Lespezi)2.32 0.29 0.14 0.26 37.1 7.4 17.7 159.5 527.6Environ Monit Assess (2012) 184:7491 –7515 7503
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the fermentation subhorizon (OF) between 1.5 and
4 cm, and the humus subhorizon (OH) between 0.1
and 2 cm.
The rocky-gravel infill (5% –25%) appears on the
soil profile, especially at 30 –70 cm depth and the
parent material (bedrock) is below 60 to 150 cm depth.
Soil texture was generally loam, sandy-loam, and
loamy-sand. Structure is granular to subangular
blocky, small-medium, or medium-large aggregation.
In mineral horizons, the soil is very high to high acid,
whereas in the surface horizons, pH values increase with
depth, becoming moderate or low acid. Only in the
Dichiu site the soil is low alkaline in the first 40 cmand low acid between 40 and 125 cm depth.
In order to study the influence of atmospheric pro-
cesses on soil properties, and the differences in soilchemical characteristics between sites, and especially
their dominant species, a table was established (Table 9),
where the soils were grouped based on the stand cate-gory that vegetates on them. Furthermore, this table
comprises the main chemical elements that were ana-
lyzed on the organic horizons and on the standard depthsframing the mineral horizons used in other projects
(Biosoil, Futmon). It was ascertained that for each type
of stand from the studied area (pure spruce stand, mixedbeech-silver fir stands and pure beech stands), there is a
common CMeu and CMdy soil type.
From the pH variation depicted in Table 10,i tc a nb e
observed that the acidity grows from beech stands to-
wards the spruce ones especially for the litter and in the
first centimeter of the mineral soils (normally, the influ-ence of the type of litter) but is relatively constant at
higher depths. This fact demonstrates that the nature of
the stand does not influence the pH at the depths >20 cm.
Thenceforth, in order to study the possible acidifi-
cation of the soils from this area it is necessary to
remove the influence of the type of stand (this is thereason why only the pure spruce stand and pure beech
stands were taken into consideration because for the
mixed stands the percentage of resinous/broad-leaved
participation is important) and that of the type of soil(this is the reason why only the two soil types that
appear in all the stand versions and only their mineral
soil were taken into consideration). Thus, the values ofthe pH resulted from this method are presented in
Table 11.
It can be ascertained that the pH decreases from the
soil depth (where it can be influenced by the nature of
the rock) towards the surface. This decrease can also
be observed in the case of the first 10 cm from eutricCambisols on pure beech stands, where the vegetation
(not acid) does not influence the acidification. The
decrease of these values (acidification), certifiable bothfor the soil types as well as for the stands, might be
partially attributed to atmospheric deposition of S and N
in precipitation and as dry deposition of NO
3−,S O 42−,
and NH 4+ions. This in turn could affect nutrient uptake
and possibly contribute to the observed nutritional
imbalances of the studied trees. We can make thisobservation without having information concerning
the evolution of the pH in the same locations in
different years.
Crown condition
Based on field assessments of the crown condition in
the (LTER) sites in 2006 –2009, the ranges of the
proportion of damaged trees (defoliation classes 2 –4)
varied between 18.4% and 45.6% in 2006, between
11.4% and 47.5% in 2007, between 14.6% and 47.5%
in 2008, and between 18.6% and 54.3% in 2009(Table 12).
In the pure or relatively pure P . abies stands, the
proportion of damaged trees increased in 2008 comparedTable 8 Elemental ratios in
Abies alba ,Pinus sylvestris , and
Fagus sylvatica stands in Bucegi
Natural ParkSpecies (Location) N/P
(g g−1)N/K
(g g−1)N/Mg
(g g−1)K/Ca
(g g−1)N/Mn
(g g−1)
Abies alba (Observator
Urs)5.3 7.8 21.3 0.32 865.5
Pinus sylvestris
(Timen-Grofi)6.7 12.3 35.4 0.65 1586.1
Fagus sylvatica
(Poiana Stanii)8.1 20.1 37.3 0.32 1141.0
Fagus sylvatica
(Cariera-Lespezi)8.1 16.2 44.0 0.54 626.07504 Environ Monit Assess (2012) 184:7491 –7515
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to 2007 at the Timen-Grofi, Valea cu Brazi, Brandu și,
Podu cu Flori sites, but approximately the same values
were maintained in Salvamont Bran and B ătrana. The
same increasing trend was observed in the case of F.
sylvatica at the Poiana Stanii and Cariera-Lespezi sites,
an exception being noticed in Dichiu and ObservatorUrs, where the proportion of damaged trees remained
the same or significantly reduced, respectively. In this
last case, F . sylvatica is less represented in the mixture
with A. alba and other species.In 2009 at the Brandu și site, a very significant
increase in the percentage of damaged trees was
noticed (54.3%), which was caused by windfall pro-duced at the end of 2008. The density of the stand
was very much reduced and foliar insect ( Lymantria
monacha ) and bark beetle ( Ipssp.) populations de-
veloped. At whole network level, in the same year
(2009), as compared to 2008, at F . sylvatica ,a
decrease of a percentage of damaged trees wasrecorded (Table 12).Table 9 General table with the repartition of chemical properties on types of stands and standard depths
Stand type Location Soil type Chemical
propertiesOrganic and mineral fix depth (cm)
OL OF OH 0-10 10-
2020-
40>40
Pure spruce stands Timen-
GrofiEutric Cambisol
(CMeu)pH (CaCl2) 4.66 4.26 3.91 3.72 4.3 4.44 5.02
organic C (g/kg) 240.4 187.86 93.07 47.33 12.06 7.77 7.54
organic N (g/kg) 15.41 15.41 7.71 5.04 1.96 1.12 1.12
Salvamont
BranDystric Cambisol
(CMdy)pH (CaCl2) 4.61 4.45 3.99 3.65 4.19 4.34 4.46
organic C (g/kg) 247.34 190.94 66.97 60.5 28.19 21.29 6.73organic N (g/kg) 12.61 11.91 4.2 5.88 3.08 2.52 1.4
Batrana Entic Podzol (PZet) pH (CaCl2) 4.67 4.33 3.37 3.09 3.34 3.71 4.33
organic C (g/kg) 258.3 249.96 133.87 90.72 65.31 43.68 21.63organic N (g/kg) 11.91 16.1 11.2 7 3.92 2.52 1.12
Podul cu
FloriHaplic Podzol (PZha) pH (CaCl2) 4.83 4.43 3.52 2.99 3.27 3.7 4.01
organic C (g/kg) 257.65 248.29 207.72 120.4 31.5 19.95 7.54organic N (g/kg) 12.61 15.41 16.8 8.68 2.52 2.24 1.4
Brandusi Dystric Cambisol
(CMdy)pH (CaCl2) 4.53 4.27 3.79 3.6 3.92 4.25 4.45
organic C (g/kg) 253.28 240.06 198.47 149.1 34.22 17.69 7.85organic N (g/kg) 15.41 15.41 15.41 8.96 3.36 2.24 2.61
Valea cu
BraziRendzinic Phaeozem
(PHrz)pH (CaCl2) 5.07 5.24 6.41 7.03 7.13 7.14 7.37
organic C (g/kg) 244.58 191.54 72.54 44.02 42.92 36.77 17.46
organic N (g/kg) 11.91 11.2 6.3 4.76 3.92 4.48 1.96
Mixed beech-silver
fir standsDichiu Eutric Cambisol
(CMeu)pH (CaCl2) 5.97 6.17 6.17 7.17 6.87 6.67 5.2
organic C (g/kg) 247.72 167.27 167.27 25.87 10.56 6.55 3.25organic N (g/kg) 10.5 9.8 9.8 2.52 1.68 1.12 0.47
Observator
UrsDystric Cambisol
(CMdy)pH (CaCl2) 4.94 4.82 3.85 3.67 4.03 4.23 4.34
organic C (g/kg) 240.74 214.78 96.24 63.57 30.28 4.58 3.13
organic N (g/kg) 12.61 13.31 7.71 3.92 2.24 0.84 0.65
Beech stands Poiana
StaniiEutric Cambisol
(CMeu)pH (CaCl2) 5.94 5.63 5 5 5.14 5.34 5.93
organic C (g/kg) 253.42 206.86 102.67 41.39 11.89 4.29 4.26organic N (g/kg) 14 15.41 9.8 4.34 1.68 0.84 0.84
Cariera-
LespeziDystric Cambisol
(CMdy)pH (CaCl2) 5.77 5.32 4.48 4.09 4.18 4.3 4.43
organic C (g/kg) 252.71 253.04 152.06 52.26 32.8 19.37 8.93
organic N (g/kg) 11.2 16.8 13.31 5.6 3.64 2.52 1.68Environ Monit Assess (2012) 184:7491 –7515 7505
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Table 10 Influence of stand
type on chemical characteristicsof soilsOrganic and mineral fix
depth (cm)Stand type pH
(CaCl
2)organic C
(g/kg)organic N
(g/kg)
Eutric Cambisols (CMeu)
OL Pure spruce stands 4.66 240.4 15.41
Mixed beech-silver fir stands 5.97 247.72 10.5Pure beech stands 5.94 253.42 14
OF Pure spruce stands 4.26 187.86 15.41
Mixed beech-silver fir stands 6.17 167.27 9.8Pure beech stands 5.63 206.86 15.41
OH Pure spruce stands 3.91 93.07 7.71
Mixed beech-silver fir stands 6.17 167.27 9.8
Pure beech stands 5 102.67 9.8
0–10 Pure spruce stands 3.72 47.33 5.04
Mixed beech-silver fir stands 7.17 25.87 2.52Pure beech stands 5 41.39 4.34
10–20 Pure spruce stands 4.3 12.06 1.96
Mixed beech-silver fir stands 6.87 10.56 1.68
Pure beech stands 5.14 11.89 1.68
20–40 Pure spruce stands 4.44 7.77 1.12
Mixed beech-silver fir stands 6.67 6.55 1.12Pure beech stands 5.34 4.29 0.84
>40 Pure spruce stands 5.02 7.54 1.12
Mixed beech-silver fir stands 5.2 3.25 0.47
Pure beech stands 5.93 4.26 0.84
Dystric Cambisols (CMdy)OL Pure spruce stands 4.57 250.31 14.01
Mixed beech-silver fir stands 4.94 240.74 12.61
Pure beech stands 5.77 252.71 11.2
OF Pure spruce stands 4.36 215.5 13.66
Mixed beech-silver fir stands 4.82 214.78 13.31Pure beech stands 5.32 253.04 16.8
OH Pure spruce stands 3.89 132.72 9.8
Mixed beech-silver fir stands 3.85 96.24 7.71
Pure beech stands 4.48 152.06 13.31
0–10 Pure spruce stands 3.63 104.8 7.42
Mixed beech-silver fir stands 3.67 63.57 3.92Pure beech stands 4.09 52.26 5.6
10–20 Pure spruce stands 4.06 31.2 3.22
Mixed beech-silver fir stands 4.03 30.28 2.24
Pure beech stands 4.18 32.8 3.64
20–40 Pure spruce stands 4.3 19.49 2.38
Mixed beech-silver fir stands 4.23 4.58 0.84Pure beech stands 4.3 19.37 2.52
>40 Pure spruce stands 4.46 7.29 2
Mixed beech-silver fir stands 4.34 3.13 0.65
Pure beech stands 4.43 8.93 1.687506 Environ Monit Assess (2012) 184:7491 –7515
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Over the entire network for all species, the propor-
tion of damaged trees was slightly higher in 2008
(33.9%) compared to the previous years when thevalues were approximately the same (30.6% in 2006
and 30.5% in 2007) and with 2009 when an improved
forest health was found (percent of damaged trees was28.0%).
Individually, P . abies was the least affected species,
showing relative stability in the research period, withthe proportion of damaged trees between 27.9% in
2007 and 31.8% in 2008 (Table 12).A. alba andF.
sylvatica showed significant temporal fluctuations in
the proportion of damaged trees: between 27.7% in
2009 and 41.5% in 2007 for A. alba and between
16.6% in 2009 and 36.6% in 2008 for F. sylvatica .
Evaluation of crown condition during 2006 –2009
showed that the Bucegi Mountains forests wereseverely damaged with generally more than 20% of
trees assessed at classes 2 –4 for all the species (Badea
et al. 2004 ).F. sylvatica was the healthiest species,
followed by P. abies , which showed a relative stability
in the study period. P . abies was least affected at high
altitudes (over 1,500 m) where the effects of hightemperature and excessive drought in the summer
seasons of 2007 and 2008 were weaker than for the
lower altitude species ( F. sylvatica andA. alba ) grow-
ing at their upper natural vegetation limit (higher than
1,000 –1,200 m).
The significant fluctuation of health status recorded
forF . sylvatica andA. alba may be explained by the
effects of changing weather conditions, especially for
A. alba , which is very susceptible to excessive drought
and high temperatures due to its specific ecological
conditions (Sofletea and Curtu 2001 ). These speciesTable 11 pH variation of the
soils from CMeu and CMdycategories based on depth andtype of standDepth (cm) Pure spruce stands Pure beech stands
Eutric Cambisols
(CMeu)Dystric Cambisols
(CMdy)Eutric Cambisols
(CMeu)Dystric Cambisols
(CMdy)
0–10 3.72 3.63 5.0 4.09
10–20 4.3 4.06 5.14 4.18
20–40 4.44 4.3 5.34 4.3
>40 5.02 4.46 5.93 4.43
Table 12 Proportion of healthy trees (defoliation classes 0 –1) and damaged trees (defoliation classes 2 –4) for all species in the Bucegi
forests in 2006 –2009
Site Main species Group of defoliation classes 2 –4 (damaged trees)
2006 2007 2008 2009
1. Salvamont Bran Picea abies 28.9 23.5 23.0 18.6
2. Observator Urs Picea abies, Fagus sylvatica, Abies alba 18.4 22.7 15.9 18.9
3. Timen-Grofi Picea abies 31.6 31.7 34.4 39.3
4. Poiana Stanii Fagus sylvatica 19.0 14.3 26.7 14.3
5. Valea cu Brazi Picea abies 34.7 35.6 43.4 34.6
6. Dichiu Fagus sylvatica 31.4 47.5 46.9 23.2
7. Brandu și Picea abies 24.0 11.4 25.0 54.3
8. Cariera-Lespezi Fagus sylvatica 29.7 40.3 42.7 23.6
9. Podu cu Flori Picea abies 45.6 41.1 47.5 29.6
10. B ătrana Picea abies 22.3 14.0 14.6 17.6
Whole network Picea abies 30.7 27.9 31.8 30.1
Abies alba 33.3 41.5 31.8 27.7
Fagus sylvatica 23.9 31.2 36.6 16.6
All species 30.6 30.5 33.9 28.0Environ Monit Assess (2012) 184:7491 –7515 7507
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responded quickly to the amount of precipitations during
the previous year ’s autumn and the spring of the same
year (Badea 1998 ). Compared with the results on forest
health status in the Romanian Carpathian Mountains
10 years ago (Badea et al. 2004 ), when the percentage
of damaged trees for all species varied between 31.4%
(1997) and 32.3% (1998), forest health in the Bucegi
Mountains remained approximately the same (30.6% in2006, 30.5% in 2007, 33.9% in 2008 and 28.0% in
2009). Also, compared with forest health status recorded
in the Retezat Mountains in 2000 –2002 and 2009, the
forests of the Bucegi Mountains are more damaged
(Badea et al. 2011).
The accuracy of these results is mainly influenced
by the number of plots where tree condition was
assessed. Thus, for forest health status in the Bucegi
Mountains, the representative error ( e
%) is 17.2%, for
α00.05. Nevertheless, the information related to tree
condition is very useful in finding a trend in thedynamics of forest health at the regional level. Addi-
tionally, these results may be used at the plot (site)
level to evaluate changes of various factors (air pollu-tion, climatic parameters, precipitation chemistry) af-
fecting forest health status and growth of trees and
forest stands.
High frequency of acidic throughfall had a signifi-
cant negative effect on crown condition (Pearson cor-
relation coefficient r00.662; α<0.01). Similarly, high
frequency of alkaline throughfall ( r00.644; α<0.01),
and high Ca concentrations ( r00.729; α<0.05) also
had significant effects on crown defoliation. In addi-tion, the high frequency of acidic rain can affect soil
chemistry with negative influence on the physiological
processes of trees and forest stands (Edzards et al.1997 ; Bytnerowicz et al. 2005 ).
Regarding the influence of soil solution pH on crown
condition, a negative correlation was found that signifi-cantly increased with depth. Thus, up to 20 cm, Pearson
correlation coefficient “r”has values of −0.687 (0 –
10 cm) and −0.692 (11 –20 cm) with a significance level
α<0.05 and for higher depths r0−0.742 (21 –40 cm) and
r0−0.819 (41 –60 cm) for α<0.01. Considering that at
the soil depths of 46 –60-cm tree roots are characterized
by high physiological activity, increasing acidity may
have pronounced effects on tree health.
Forest health status described as mean tree crown
defoliation percent within selected forest stands was
insignificantly correlated with the main nutrients and
with their ionic ratios. Even though the correlationswere not statistically significant ( α>0.05), correlation
coefficient values were positive for P, K, Ca, Mn andnegative for N and for the ionic ratios (N/P, N/K, K/
Ca, and N/Mn). This indicates that at higher N levels
and balanced nutrition the mean defoliation and healthof forest stands improve. However, higher than opti-
mal P and Ca concentrations and a simultaneous lower
than normal K, Mg, and Mn concentrations could alsobe responsible for worsening tree health manifested by
higher defoliation.
In general, as stated above, the O
3concentrations
were too low to cause negative effects on forest health,
a n dt h u sn os p e c i f i cO 3injury symptoms were
detected on foliage of the main tree species in theBucegi Mountains. However, it may be expected that
acidic rain events will continue to contribute to forest
soil acidification with a negative effect on forest
health. Also, an increase in air pollutant levels, espe-
cially the predicted increase of background O
3levels
(Fowler et al. 1999 ) combined with changing and
variable climates, such as severe drought and high
temperatures Bytnerowicz et al. ( 2008b ), could have
even more pronounced effects on forest health in the
Bucegi Mountains.
Biodiversity
The composition of studied forest stands varied from
the pure P. abies orF. sylvatica stands to the mixed
forests of P. abies andF . sylvatica ,o rF. sylvatica with
A. alba and other conifers ( Larix decidua andPicea
sp.) and broadleaves species ( Acer pseudoplatanus ,
Betula pendula ,Sorbus aucuparia ). The number of
plant species varied from 33 to 47 per studied forest
stand. Mixed and pure F. sylvatica forests were richer
both in species number and their value. Diameter and
height of trees varied from site to site according to thestand type, its structure to the local environmental, and
vegetation conditions. Based on inventory of species
in each layer (A —trees, B —shrubs, C —herbaceous
plants, D —mosses), six major plant communities were
identified (Badea et al. 2011 ). Also, for each level (A,
B, C, D), the Shannon –Wiener diversity index and
Shannon evenness was determined. According to the
values of this index, the lowest diversity (<2) was
recorded at the tree level (Fig. 6) followed by moss
layer (2 –3). A high diversity was observed within the
herbaceous layer (>3). A good development of herb
diversity was allowed by the vertical distribution and7508 Environ Monit Assess (2012) 184:7491 –7515
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coverage of tree layer (Fig. 7). Vascular plant commu-
nities were characterized by a high diversity and even-
ness (Fig. 8). Because of its essential contribution to
forest ecosystems functioning, ground vegetation
structure and composition is an expression of the
relationship between tree layers and environmental
and vegetation conditions (Vadineanu et al. 2008 ).
A significant amount of aboveground biomass and
nutrients are contained in the ground vegetation layer ’s
richness and productivity (Bytnerowicz et al. 2005 ).
High diversity and evenness was observed within theherbaceous layer, indicating that biodiversity of the vas-
cular plant communities of the studied forest sites was
substantial. All the vegetation biodiversity componentsof the forest ecosystems were specific to the stand type ’s
structures and local climate conditions. Furthermore,
there was no evidence of accelerated environmentalmodifications and significant reduction of biodiversity.
Generally, plant communities play an important role as
indicators of local environmental and vegetation condi-tions (microclimate, soil acidity, nitrogen availability) of
the forest types and site types (Donita et al. 2005 ).Growth
The entire LTER network of the Bucegi Mountains with
an average altitude of 1,300 m had a yield class of 2.8
(medium productivity) and an average age of 90 years,which are typical to these areas for all species. The
average annual volume growth over the 1996 –2005 pe-
riod of review was 11.1 m
3year−1ha−1.F o rt h em a i n
species, the annual volume growth for P . abies was
14.3 m3year−1ha−1,f o r F. s y l v a t i c a 9.5 m3year−1ha−1,
and for A. alba 5.3 m3year−1ha−1(Table 13). The highest
values of the average annual volume growth were
recorded in pure stands of P . abies of high productivity
(Salvamont Bran and Timen-Grofi) and young over-stocked stands without silvicul tural interventions (thin-
nings; Valea cu Brazi).
In cases where the main species representation was
low in the composition of mixed forest stands, the
annual volume growth was the lowest (F . sylvatica in
Observator Urs, P . abies in Cariera-Lespezi, and A. alba
in Dichiu). In addition, F. sylvatica recorded a low
relative annual volume growth (7.0 m
3year−1ha−1)i n
Fig. 6 Shannon –Wiener
diversity of different vege-tation layersEnviron Monit Assess (2012) 184:7491 –7515 7509
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a pure >140-year-old forest stand (Poiana Stanii), locat-
ed above the optimal altitudinal limit (above 1,300 m).In this case, age, altitude, and vegetation conditions are
the main limiting growth factors. However, F . sylvatica
Fig. 7 Cover distribution
of different vegetation layers
Fig. 8 Evenness of different
vegetation layers7510 Environ Monit Assess (2012) 184:7491 –7515
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recorded higher values of annual volume growth
(Dichiu and Cariera-Lespezi) in mixed stands with A.
alba orP . abies as secondary species. In the mixed
stands of F . sylvatica with conifers, the average annual
volume growth per ha was between 11.7 m3year−1ha−1
(Observator Urs) and 18.2 m3year−1ha−1(Cariera-
Lespezi), confirming the structural stability and growth
efficiency of these mixed stands in the mountain region(Table 13).
The annual volume was determined for defoliation
group classes 0 –1 and 2 –4, both for individual sites
and for the entire research network within the Bucegi
Mountains (Table 13). Results are quite typical (Badea
and Neagu 2011 ), both for each site and for the entire
study area, demonstrating significant differences be-
tween real ( I
v) and normal ( Iv1) annual volume growth
per hectare. These differences ( Δiv) may be explained
in terms of annual volume growth losses recorded by
forest stands in real life conditions (having in theircomposition both healthy trees of defoliation classes
0–1 and damaged trees of defoliation classes 2 –4),
given the normal (theoretical) conditions (having incomposition only healthy trees). These volume growthlosses (%) are different from site to site and dependent
on forest stand composition, age, productivity, alti-tude, and especially the proportion of damaged trees
in each stand.
At the whole study area level, for all species, the
annual volume growth losses per hectare ( Δi
v%)w a s
25.4% (Table 13) and well reflect the influence of tree
condition on the bioaccumulation processes inside theforest ecosystems. Such information may be considered
important for establishing the dynamics of growing
stock and the allowable cutting volume. Additionally,it might be taken into consideration as a main indicator
for management programs from a perspective of man-
agement and control of air pollution, pathogens, pests,and anthropogenic activities.
The variation of annual average ring width showed
the typical downward increment trend of the damaged
trees (defoliation >25%) compared with the healthy
ones (Bytnerowicz et al. 2005 ; Badea et al. 2011 ). The
average annual increment was significantly lower for
damaged trees compared to the healthy trees in all sites
(Fig. 9) and for each main species at the entire study
network level (Fig. 10).
Table 13 Volume growth of main species and groups of defoliation classes (0 –1 and 2 –4) in LTER sites in Bucegi Natural Park
Location Species Average annual volume growth per year and per ha (m3year−1ha−1) Volume growth osses
Total real volume
growth per speciesReal volume growth
per speciesTotal normal volume
growth per speciesΔiv Δiv%
0–12 –4m3year−1ha−1%
Salvamont Bran Picea abies 20.3 16.8 3.5 28.3 8.1 28.6
Observator Urs Fagus sylvatica 5.1 4.3 0.8 5.8 0.7 12.5
Abies alba 5.6 5.1 0.5 6.5 0.8 13.0
Timen-Grofi Picea abies 27.4 20.0 7.4 39.1 11.8 30.0
Poiana Stanii Fagus sylvatica 7.0 6.5 0.5 9.1 2.1 23.4
Valea cu Brazi Picea abies 16.9 12.0 4.9 24.8 7.9 31.9
Dichiu Fagus sylvatica 9.4 6.1 3.3 10.6 1.2 11.4
Abies alba 4.9 2.8 2.1 6.3 1.4 22.3
Brandusi Picea abies 13.2 9.9 3.3 17.1 3.9 23.0
Cariera-Lespezi Fagus sylvatica 16.4 13.5 2.9 21.9 5.5 25.2
Picea abies 1.8 1.4 0.4 2.7 0.9 34.3
Podu cu Flori Picea abies 12.8 7.6 5.2 19.8 7.0 35.5
Batrana Picea abies 7.7 6.1 1.6 8.6 0.9 10.6
Average Picea abies 14.3 10.5 3.7 20.1 5.8 28.9
Abies alba 5.3 4.0 1.3 6.4 1.1 17.6
Fagus sylvatica 9.5 7.6 1.9 11.8 2.4 20.2
All species 11.0 8.3 2.8 14.7 3.7 25.4Environ Monit Assess (2012) 184:7491 –7515 7511
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For the entire LTER network, the declining auxo-
logical (growth) tendency of the average annual radialincrement for the damaged trees is clear (defoliation
group classes 2 –3), starting from a certain defining
moment that denotes the “no turning back ”point of
the declining process, caused by a combination of
factors such as acidic precipitation, air pollution,
drought, nutritional imbalances, and other abiotic andbiotic predisposing or triggering factors.
Although the correlation between measured air pol-
lutant concentrations (O
3and NH 3) and annual volume
growth of studied stands (Badea et al. 2011) was not
significant ( α>0.05), the Pearson correlation coefficientsh a dn e g a t i v ev a l u e s( r0−0.382 for O 3andr0−0.273 for
NH 3, respectively). However, at higher air pollutants
levels, a significant reduction in volume growth can
appear (UNECE 2004 ). This is a hypothesis to be studied
in future research, in natural ambient conditions(Manning 2005 ).
Conclusions
Based upon the obtained results and analysis, the
Bucegi Mts. have relatively good air quality, although
Fig. 9 Mean radial
increment ( bars) for the
Picea abies ,Abies alba , and
Fagus sylvatica by defolia-
tion group classes (0 –1 and
2–3) for all studied sites in
the Bucegi Mountains, with
95% confidence intervals
(lines)
Fig. 10 Mean radial
increment ( bars) for main
species by defoliation group
classes (0 –1 and 2 –3) in the
Bucegi Mountains, with95% confidence intervals
(lines)7512 Environ Monit Assess (2012) 184:7491 –7515
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in some cases, slightly high ambient O 3and NH 3
concentrations were found.
Spatial and temporal ambient O 3concentrations
patterns are distinct, and for that manner, the ozone
concentration variation could be explained by altitudeup to 50%, and by mean temperature up to 20%, for
each exposure period during the 2006 –2009 growing
seasons.
Bulk precipitation, throughfall, and soil solution
were acidic in most of the studied sites. Concentra-
tions of acidic ions (NO
−,S O 42−,N H 4+) were below
their critical limits, but could have significant long-
term cumulative effects on soils and forest vegetation,
especially in the context of changing climate.
The nutritional status of trees was imbalanced with
higher than normal foliar concentrations of P and Ca
and lower than typical concentrations of K, Mg, and
Mn in all species.
There were no indications of decreased biodiversity
of the forest ecosystems representative for Bucegi
Natural Park. The studied plots were rich in floristi-
cally important species and had distribution of vege-tation layers in accordance with their geological and
ecological characteristics.
In general, forest health in the Bucegi Mountains
was moderately affected. While O
3and NH 3had no
direct effect on forest health and no specific foliar O 3-
injury symptoms were detected, these pollutants to-gether with other stressors could contribute to integrat-
ed negative stress.
Both high frequencies of acid and alkaline precip-
itation had significant effects on tree crown defolia-
tion. Increased acidity of soil solution in the 40 –60 cm
soil layer, where root physiological activity is high,could affect nutrient uptake, tree health, and crown
condition.
In general, the health of Bucegi forests was similar
to the other Carpathians regions. Damaged trees grew
less than healthy trees (crown defoliation ≤25%), and
the differences between their mean annual volumegrowth was about 25%.
Acknowledgments We acknowledge financial support from
the Romanian Research Agency ’s Excellence Research Pro-
gram, in the framework of the project “Long-term effects of
air pollution on selected forest ecosystems in the Bucegi NaturalPark–EPAEFOR, ”which is an ongoing and fruitful consortium
collaboration between the Forest Research and Management
Institute (ICAS), USDA Forest Service, Transylvania Universi-
ty, Bucharest University, and National Forest Administration(Romsilva). Since 2010, this research has been conducted with
the support of the European Commission and the RomanianNational Forest Administration (Romsilva), under the LIFE+program (EnvEurope project). The authors thank Ms. Laurie
Dunne for technical editing.
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