Not Bot Horti Agrobo, 2013, 41(2): 613-625Print ISSN 0255-965X Electronic 1842-4309Available online at www.notulaebotanicae.r o [603009]

Not Bot Horti Agrobo, 2013, 41(2): 613-625Print ISSN 0255-965X; Electronic 1842-4309Available online at www.notulaebotanicae.r o
Notulae Botanicae Horti Agrobotanici
Cluj-Napoca
Forest Monitoring – Assessment, Analysis and W arning
System for Forest Ecosystem Status
Ovidiu BADEA1,2, Diana SILAGHI1,2*, Ioan TAUT1,3, Stefan NEAGU1, Stefan LECA1,2
1Forest Research and Management Institute, Eroilor Bld. 128, 77190 V oluntari, Ilfov, Romania; badea63@yahoo.
com, [anonimizat] (*corresponding author), [anonimizat] , [anonimizat]
2Transilvania University of Brasov, Faculty of Silviculture and Forest Engineering, 500068, Brasov, Romania
3University of Agricultural Science and V eterinary Medicine, Cluj-Napoca, Calea Mănăștur
3-5 Str., 400372, Cluj-Napoca, Romania; [anonimizat]
Abstract
Forests provide essential benefits and services as an important component of terrestrial ecosystems. Their functionality and health
result from multiple and cumulative interactions of biotic and abiotic stress factors such as air pollution, climate change, changes in
land use, and poor management practices. A forest monitoring system was established to identify, analyze and assess the degradation
of European forests. Two levels of forest monitoring were developed: I) large-scale forest condition surveys, based on an European grid
system starting in 1986 and II) an intensive non-systematic survey network placed in representative forest ecosystems starting in 1994.
Romania implemented both level I (1990-1991) and level II (1991-1992) forest monitoring surveys with the results showing the effects
of increased air temperatures and a drastic decrease of precipitation since the decade of 1971-1980. Thus, the highest values of damaged
trees (crown defoliation >25%) percent were recorded in 1993, 1994, 2000 and 2003 both in the national and European networks.
Also, in southern and South-Eastern Romania the forests are more frequently damaged as a response to worsening of climatic factors
in this region in recent decades, with temperatures rising 0.7-0.8 °C. In general, in Romania, ozone concentrations remained below the
critical threshold (40-50 ppb) for affecting growth or health of trees. The levels of S-SO4 and N-NO3 declined in the atmosphere but
the accumulation continued to increase in the soil, leading to soil acidification, mainly at depths of 10-40 cm). In general, during the last
decade, Romanian forests were affected at low to medium intensities with damage rate up to 11% of the trees and the status of general
forest health improved slightly.
Keywords: air pollution, climate change, crown condition, forest monitoring, national and transnational network
Introduction
Forests exhibit the highest levels of biodiversity of all
types of ecosystems, providing habitats for a wide range
of animal and plant species. With their considerable po –
tential for carbon sequestration, they constitute one of the
most important elements of the global carbon cycle. In ad –
dition to their great importance to the earth’s climate and
biodiversity, forests play a significant role in the develop –
ment of rural areas and provide many recreational oppor –
tunities for people as well as protective functions for soil,
water and infrastructure and contribute goods and services
to the economic sector (Badea et al ., 2005).
The decline of forest ecosystems health, reported in the
early 1980s and highlighted through research undertaken
at international level (Vins and Mrkva, 1973; Symeonides,
1979; Thompson, 1981; Lorenz, 1991; Giurgiu, 1979,
1988; Ianculescu, 1990) has been mainly caused by the
interaction of atmospheric pollution and various biotic
and abiotic factors as well as other disturbances, such as
anthropogenic disturbances or fires. The results obtained
from these studies clearly demonstrated pollutants and other stress factors have had a negative influence on forest
growth and in many cases caused an abnormal dieback of
trees and declines in forested ecosystems as a whole. Also,
multiple cumulative effects have had a considerable influ –
ence on the status of forest ecosystems at local, regional
and global scales. Major consequences of the changes in
forested ecosystems include the rapid shifting of vegeta –
tion boundaries toward higher altitudes, increases in the
intensity of processes which are damaging the trees, in –
creases in tree mortality and declines of other ecosystem
parameters, all of which pose threats to ecosystem biodi –
versity and forest habitats.
In response to these events and conditions and based on
the United Nations Economic Commission for Europe’s
(UNECE) Convention on Long-range T ransboundary
Air Pollution (UN/ECE 1979), in United States, Canada
and in almost all European countries, concerns regarding
research and long-term monitoring of forested ecosystems
experiencing the effects of these various stress factors, es –
pecially air pollution, have intensified.
T o identify, analyze and monitor the degradation and
disruption of forested ecosystems across Europe, forest –

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2004; Ciais et al ., 2005), can cause declines in tree growth
(Piovesan et al ., 2008; Granier et al ., 2007), high levels of
tree mortality (Carnicer et al ., 2011; Allen et al ., 2010)
and other delayed multiannual effects (Bigler et al ., 2007).
Also, limited water availability is considered the most se –
rious threat for forests at a global scale (Allen and Bres –
hears, 1998). Predictions on the evolution of climate can
be made using specific modeling procedures.
Assuring the persistence of high levels of biodiversity in
forested ecosystems is widely acknowledged to be the best
way to guarantee that forests will be capable of adapting to
present and future climatic changes (Lindner et al ., 2010).
Knowing the existence of these threats, there has been a
consistent preoccupation at the international level for
maintaining forest health so as to conserve forests, to pro –
mote sustainable management of forests and to enhance
forest functions by maintaining a high level scientific in –
formation, which can be obtained in the well-organized
system used to monitor the European forests.
Monitoring networks and methods
From its infancy in 1985, the main causes of declines
in forest ecosystems were high concentrations of sulfur
(S) and related compounds, which determined the occur –
rence of acid rain and subsequently, the intensification of
soil acidification. These alarming processes and signals had
highlighted the need to develop a strategic policy regard –
ing atmospheric pollution. All these actions were imple –
mented under the UNECE-CLRT AP program and un –
der the EU policies related to “clean air, ” and resulted in
a greater than 70% reduction in sulfur deposition. Since
1985, the International Co-operative Programme on As –
sessment and Monitoring of Air Pollution Effects on
Forests (ICP-Forests) can be credited with providing a
considerable share of the effort needed to highlight these
actions, through providing scientific information. This
program has been providing regular updates on the con –
dition of forests in Europe for over 27 years. Since 1986,
after its first year of operation, the ICP-Forests program
has been cooperating with the European Union (EU). Ini –
tially, this cooperation was based on the EU Scheme (EC
Regulation No. 3528/1986) and Forest Focus Regulation
(EC No. 2152/2003). The last of these regulations consti –
tuted the legal basis for the co-financing of forest monitor –
ing activities, which continued until 2006. Since then, the
Regulation (614/2007) “LIFE+” has provided the legal
basis for co-financing of the future development of for –
est monitoring at the European level (Fig. 1). The main
purpose of the large-scale forest monitoring (level I) is to
assess the dynamics and spatial distribution of tree damage
and to analyze long term data series related to forest health
status and vitality. At the European level, 7,500 permanent
and representative plots within a 16 × 16 km grid system ers and forest scientists have developed specific methods
and procedures for continuous monitoring of the factors
which influence the quality of forested ecosystems and
specifically across Europe, the forest monitoring system.
The main objectives of forest monitoring are: (i) imple –
menting of priority actions included in policies and strate –
gies designed to protect forests against the impacts of air
pollution, climate change and other biotic and abiotic
stress factors; (ii) improving the coordination and integra –
tion of forest monitoring activities to assist land managers
in assessing the vulnerability and adaptive capabilities of
forest vegetation under the combined effects of climate
change and air pollution; (iii) harmonizing forest moni –
toring methodologies used at national and European lev –
els; (iv) providing information for criteria and indicators
for sustainable forest management as defined by the Min –
isterial Conference on the Protection of Forests in Europe;
(v) highlighting the effects of climate change, air pollution
and other stress factors on forest status and biodiversity,
by means of annual reports documenting critical events
identified at local, regional and European levels, and (vi)
creating a common database on forest status at national
and European levels.
The successful implementation of the protocols regard –
ing the control of pollutant emissions by the CLRT AP
signatory countries and of special monitoring programs
(ICP-Forests, European Union (EU) Scheme, Forest Fo –
cus Scheme and LIFE+) has led to a significant reduction
of industrial pollution in most European countries in the
last few decades, and also led to the establishment of a
well-organized trans-disciplinary monitoring system of
forest ecosystems and efforts to determine the effects of
the main factors disrupting forested ecosystems, especially
air pollution and climate changes.
One of the most important achievements of the Eu –
ropean Forest Monitoring System is the development of
specific, well-developed and uniform indicators and crite –
ria related to forest health, as well as the development of
common forest monitoring methodologies. Their uniform
application allows the comparison of results and the devel –
opment of long-term data series. Currently, atmospheric
pollution and pollutant depositions in forests and forest
soils continues to be an important issue, while nitrate depo –
sition is still a serious threat because of its effects on forest
ecosystems (Thimonier et al ., 2010). The increasing ozone
concentrations (V olz and Kley, 1988; Fowler et al ., 1999)
combined with a decline in biodiversity and basic changes
in the environment are processes that produce significant
changes at the global level, such as the increase in mean
air temperatures as well as an increase in the frequency of
extreme weather events, drought, and other catastrophic
weather related phenomena (IPCC, 2007; Jentsch et al .,
2007; Sterl et al ., 2008). Limited water availability can af –
fect either forests as a whole or individual trees. Singular
events, like extreme drought or heat waves such as the ones
which occurred during the summer of 2003 (Stott et al .,

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(herein called the European grid system) have been used
for annual data collection.
Fig. 1. Functioning of forest monitoring at the European level
(European grid system)
T o determine the influence of various stress factors
on forest ecosystem status and to better understand in –
teractions between these plots as well as their cumulative
changes, 500 monitoring plots were designated for inten –
sive, permanent and continuous data collection.
Over the years, a two-level survey system has been de –
veloped: level I refers especially to general information
gathering related to annual forest health status, while level
II refers to intensive scientific research in representative
forest ecosystems. Furthermore, most of the European
countries are monitoring their forest resources at the na –
tional level, using specific methodologies.
In Romania, during 1990-2006, level I monitoring has
consisted of a mixed network, having two roles: (i) moni –
toring of forest ecosystem health and (ii) performing a
National Forest Inventory, although the network has been
abandoned because of the lack of financing.
The negative impact of environmental factors on for –
ests was similar in Romania to what has been described
as occurring in most European countries, where damaged
forests and those with abnormal dieback were becoming
progressively predominant until the 1980s; the assessment
of the status of certain factors (including forest health)
had seen conducted using non-systematic methods at that
time. These monitoring methods were focused on (i) the
revision of forest management plans every 10 years, (ii)
the initial forest inventories based on those management
plans, and (iii) the specific research and studies. These
methods were deficient due to the fact that (i) the infor –
mation gathered was insufficient because it came from dif –
ferent sources and was collected using different methods,
and (ii) the information was recorded at different points
in time. T o improve this situation, the development of a
single, uniform forest survey system for both national
and European levels was initiated. In 1990, this system
and concept was adopted and correlated with the one ap –
plied by the member countries of ICP-Forests and was the
applied across the entire Romanian forestry system (Or -der No. 96/1990 of the Deputy Minister of Silviculture;
Badea and Patrascoiu, 1998) (Fig. 2).
Fig. 2. Functioning of forest monitoring system in Romania (na –
tional grid system)
The survey system was developed and improved when
the “Regulation of the Organization and Functioning of
Forest Monitoring in Romania” was applied (Order No.
249/1994 of Minister of W ater, Forests and Environmen –
tal Protection). In 2002, a special law related to forest
monitoring was adopted (Law No. 444/2002) followed
by the Governmental Decision No. 1003/2003 related to
the functioning and financing of forest monitoring in Ro –
mania. As in all ICP-Forests European member countries,
forest monitoring activity was carried out at a large scale;
the forest condition surveys were based on a permanent
national (2 × 2 km and 2 × 4 km) and European grid sys –
tem plots (level I) (Fig. 3a) and on intensive plots placed
in representative forest ecosystems within a nonsystematic
network (level II) (Fig. 3b). Additionally, in Romania,
long term ecological research was developed in two LTER
sites (Retezat and Bucegi – Piatra Craiului) (Badea et al .,
2011).
Fig. 3. Romanian ICP-Forests Large Scale European grid system
network (a) (16 × 16 km; (252 permanent plots) and intensive
monitoring network (b): 12 permanent plots in representative
forest ecosystems in place since 1992
The Romanian forest survey through the national per –
manent plot network (2 × 2 and 2×4 km) was based on:
(i) annual records including information on the status of
tree crowns and damage caused by different factors (e.g.
biotic, abiotic, anthropogenic, pollution or fires); (ii) peri –
odical records collected every 5 years related to the devel –

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(UN/ECE 1991-1998). Since 1998, after statistical opti –
mization of the national network, the number of plots and
trees assessed were reduced by a factor of four (4 × 4 km)
(Badea, 1998).
In 2010, in the framework of the LIFE+ Further De –
velopment and Implementation of an EU-level Forest
Monitoring (FutMon) project, a large scale systematic
crown condition monitoring network was created by plac –
ing a southeastern plot of the NFI tract in the center of the
former European level I plots (Fig. 6). For this purpose,
over 20 years of data on crown condition assessment at lev –
el I are available, and starting with 2010, this database has
been includind information specific to NFI, which can be
useful, comparable, and compatible at the European grid
system (16 × 16 km) scale.
Fig. 6. Design of the uniform NFI and ICP large scale plots
(FutMon large scale plot)
Research of an intensive nature in a nonsystematic
survey network placed in representative forest ecosystems
(level II), suitable for cause-effect relationship studies
started in 1989 and developed in 1991 and 1992. Thirteen
intensive permanent plots (IPP) were chosen in represen –
tative forest ecosystems near meteorological stations and
were situated in historical impact zones subject to pollu –
tion and/or long recurrent droughts.
An IPP consists of five permanent sample plots (PSP)
placed 30 m from each other in a crosswise direction in
the cardinal directions from the plot center (N, E, S, W)
and to the center of the plot. All five PSPs are placed in the opment of a National Forest Inventory (NFI), regarding
the status and evolution of the primary parameters related
to forest condition assessment and measures of the forests
capacity to fulfill socio-economic services at both national
and international levels.
T o assess tree crown condition and mechanical dam –
age, 30 (15 in every permanent subplot-PSP) predomi –
nant, dominant and co-dominant trees were initially cho –
sen in every plot (Fig. 4), representing trees with moderate
to strong mechanical damages (Patrascoiu and Badea,
1990).
Until 2006, for these 30 trees, defoliation and discol –
oration were evaluated annually (UN/ECE 1989, 2004)
and the presence of the damage caused by abiotic factors
(wind, snow, frosts), biotic factors (game, insects, fungi)
and anthropogenic factors (e.g. pollution, fires) were ob –
served.
Beginning with 2007, this national forest monitoring
network consisting of the 2 × 2 and 2 × 4 km grid systems
was abandoned and the assessment of crown condition has
focused on the European grid system only, which included
252 plots in Romania, based on the geographical coordi –
nates received from the ICP-Forests program (Program
Coordinating Centre, Hamburg, Germany). This was
done using the methodology adopted by the participating
countries in the ICP-Forests and in the European Union
scheme (EU Scheme).
Each permanent sample plot (PSP) contains four sub –
plots placed crosswise on the direction of cardinal points,
at 25 m from the plot’s center. Each subplot includes the
six trees closest to its center (Fig. 5). Compared with the
national network, the number of trees evaluated annually
in the European grid system is constant (24). Any trees
which had been damaged by being broken or have been re –
moved (cut) are replaced by others during the annual eval –
uation (UN/ECE, 1989; Badea and Patrascoiu, 1992).

This transnational network has been also designated
for the assessment of soil conditions every 10 years. An –
nual results related to crown condition from both the na –
tional and transnational plot networks are reported and
included in the Annual Reports on Forest Condition in
Europe, developed by the ICP-Forests program.
Because of the very high number of trees assessed in
the national network, Romania has made a consistent con –
tribution at the European level between 1990 and 2006
Fig. 4. Design of a national forest monitoring plot
Fig. 5. Design of a forest monitoring level I plot (16 × 16 km
European grid system)

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foliation > 25%) recorded in both systems of plots (Fig.
8). In general, the maximum (21.3%, 14.3% and 39.9%,
36.5%, respectively) and the minimum (9.7%, 8.1% and
30.1%, 24.3%, respectively) values were recorded in the
same years (1994, 2000 and 1991, 2005 respectively);
these were mainly believed to be an effect of precipitation
deficits and high temperatures, respectively (Badea, 1998;
Badea and Neagu, 2007). A similar situation was encoun –
tered at European grid system level for all species (Fig. 9).
Fig. 8. Dynamics of forest health status in Romania (all species)
Fig. 9. Dynamics of forest health status in Europe
Also, the dynamics of the percentage of damaged trees
for each main group of species (conifer and broadleaf spe –
cies) has followed almost the same trend in both networks
(Fig. 10, 11).
Fig. 10. Dynamics of forest health status in Romania (conifers)same stand conditions and their land surface together with
the IPP’s buffer zone cover about 0.7 ha (Fig. 7).Until now,
date related to: (i) crown condition using defoliation per –
centage (yearly); (ii) soil analysis (every 10 years); (iii) soil
solution using lysimeter method (continuous); (iv) foliar
analysis (every 2 years); (v) growth (permanent, continu –
ous, every 5 years); (vi) atmospheric deposition in open
field and under the canopy – bulk and throughfall (con –
tinuous); (vii) meteorology (continuous); (viii) ground
vegetation (every 5 years); (ix) phenology (continuous);
(x) air quality using passive samplers during the growing
season and collocated ozone active monitor (continuous)
and (xi) litterfall (continuous) have been collected.
The applied methodology followed the 1986, 1989,
1994 and 2010 versions of the ICP-Forests Manuals,
the last one being revised during FutMon project period
(2009–2011).
Statistical analyses of monitoring data were performed
using Excel and SPSS software. Geospatial distribution of
forest health status dynamics was achieved using ArcGis
9.2-Geostatistical software.
Results
The results on forest condition in Romania have been
based on information collected from a national optimized
network (4 × 4 km; or herein, the national grid system).
The representativity error (e%) was ± 1.02% (p < 0.05)
(Badea, 1998), which is comparable with the ones calcu –
lated at European grid system level (16 × 16 km) of e% =
± 1.31% (Badea et al ., 2005).
The European grid system plots placed in Romanian
forests (about 252 permanent plots) are not representative
of the forest conditions in Romania (e% >20%, p >0.05)
(Badea, 1998). Y et, it was noticed that the temporal trend
of results dynamics could be compared with the more ac –
curate ones recorded in the national grid system network.
By comparing the dynamics of the multiannual results
at an “all species” level, one can observe considerable dif –
ferences between the percentages of damaged trees (de –
Fig. 7. Design of a Romanian intensive forest monitoring (level
II) plot

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618
recorded in existing European grid system plots placed in
Romanian forests.
The analysis of the correlation between the percentages
of damaged trees recorded in the national network com –
pared with those recorded in the European grid system
network was significant (r = 0.74 for all species, r = 0.79
for broadleaf species and r = 0.47 for conifers). The regres –
sion is represented by an exponential function, which may
be used to estimate the intensity of forest damages with a
lower accuracy (Fig. 14).
Fig. 14. Distribution of damaged trees (percent defoliation
>25%) from the national grid system in relation to those regis –
tered in the European grid system (all species)
A similar situation, statistically confirmed, can also be
observed for broadleaf species, which represents a high
percentage (over 65%) of the total number of assessed
trees (Fig. 15a); the same situation is not statistically sig –
nificant for conifers (Fig. 15b).
Comparing the adjusted values calculated for all spe –
cies using these exponential functions, presently estab –
lished based on experimental distribution (variation of
multiannual percentages of damaged trees recorded in the
national network), with the real values, no significant dif –
ferences were found (texp = 0.335, p > 0.05). So, from a
statistical point of view, this type of pattern can be used
to document the trend of Romanian forest health based
on information from the European grid system network of Individually, the main species ( Picea abies , Abies alba ,
Fagus sylvatica , Quercus robur , Quercus petraea , Quercus
pubescens + Quercus pedunculiflora , Robinia pseudoacacia )
followed the same dynamics (Fig. 12). The highest and
the lowest percentages of damaged trees were recorded
at about the same time, with small deviations (1–2 years)
depending on species reaction to the quantity of precipita –
tion or to temperatures from the previous year (autumn
season) or current year (spring and vegetation season)
(Badea, 1998; Badea and Neagu, 2007).
Fig. 12. T emporal trendline of forest health status dynamics in
Romania during 1990-2006
By adjusting the multiannual variation (1991-2006)
in the percentage of damaged trees (defoliation >25%)
recorded in the two monitoring networks (the national
and the European grid systems), it was noticed that the
difference between temporal trend line slopes were not
significant (p <0.05). The increasing/decreasing trends are
insignificantly different. The linear slopes are practically
the same (Fig. 13).
Univariate covariance analysis (ANCOVA) empha –
sized the differences recorded between national and Eu –
ropean grid system networks. Therefore, without informa –
tion from the national grid system we would be able to
know the trend of forest health dynamics at the national
level (especially because the national network was aban –
doned in 2008), taking into consideration only the results
Fig. 11. Dynamics of forest health status in Romania (broadleaf
species)Fig. 13. T emporal trendline of forest health status dynamics in
Romania, during 1990-2006

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619
Regional warming and consequent increases in water
deficits are, most likely, the main contributors to the dy –
namics of this indicator, as well as to forest health status
dynamics. One can observe that the main causes influenc –
ing forest health status since the year 1990 until the pres –
ent day were represented mainly by air pollution combined
with climate change effects, especially the precipitation
deficit and extreme temperatures, and these phenomenons
were more intense in the south and southeastern Romania
(Fig. 18 a, b). Therefore, in those parts of Romania, during
1981-2010, in relation to the 1961-1990 reference period
the temperature has raised as much as 0.7-0.8°C and the
precipitation quantities dropped about 20-80 mm. Dur –
ing the last decade (2001-2010), some recovery of precipi –
tation rates (37-60 mm) was noticed compared with the
same reference period (1961-1990) (Fig. 18 b).
Fig. 18. The extent of climate change: (a) air temperature, (b)
precipitation in southern and southeastern Romania during the
last three decades (reference period 1961-1990)
As representative examples for the southern part of Ro –
mania, the data coming from two meteorological stations
(Caracal and Alexandria) related to decennial dynamics of
average air temperatures during 1961-2008 showed an ob –
vious increasing trend since 1971 (around 1°C) (Fig. 21 a,
b). Also, we can observe a decreasing trend in precipitation
quantity, beginning in 1981 and recovery during the last
decade after 2001 (Fig. 22 a, b).
Fig. 19. Decennial dynamics of air temperature, during the
1961-2008 period at the Caracal (a) and Alexandria (b) meteo –
rological stations in southern Romaniaplots. In this way, an image of the share of damaged trees
values (adjusted) could be obtained (Fig. 16).
Long term non-catastrophic damages highlighted by
the annual tree mortality rates (%) can alter forest structure
and, consequently its functions (Allen et al ., 2010). In Fig.
19, only predominant, dominant and co-dominant trees
are represented, which rules out incidence of tree mortal –
ity caused by competition. During 1992-2011, the annual
mortality rates as a biological reaction of forest ecosystems
to the damage occurring in the environment varied from
0.1 (in 1992) to 0.7 (in 1994), dramatically reaching maxi –
mum values with a delay of 1-2 years after severe drought
events such as occurred in 1994, 2000, 2005, 2009.
Fig. 17. T ree mortality as a biological reaction of forest ecosys –
tems to the changing environment
Fig. 15. Distribution of damaged trees (percent defoliation >
25%) from the national grid system in relation to those regis –
tered in the European grid system (broadleaf species (a) conifers
(b))
Fig. 16. Distribution of damaged trees (percent defoliation
>25%) from the national grid system in relation to those regis –
tered in the European grid system (broadleaves)

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here and on the results for all species (broadleaf species
being the majority, about 2/3 of total number of trees as –
sessed).These climatic conditions from south and southeastern
Romania have had a very strong influence on forest health
status of broadleaf species, especially, which are growing
Fig. 21. Dynamics of the share of damaged trees (defoliation >25%) in the European grid system during 1992 (a), 1993 (b), 1994
(c), 2001(d), 2003 (e), 2005 (f ), 2009 (g) and 2010 (h)Fig. 20. Decennial dynamics of precipitation, during the 1961-2008 period at the Caracal (a) and Alexandria (b) meteorological
stations in southern Romania

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Romania, directly influenced forest health in this region.
At a national scale, the mean annual air temperature rose
by 0.6 °C in the last 100 years (Fig. 24); the evolution by
decades of mean multiannual air temperature from 1961
to 2010 show the average air temperature rose by 0.4-0.6
°C during 2001-2010 when compared with every other
decade. The increasing trend is obvious especially begin –
ning with 1971 (Fig. 24).
In the Romanian intensive forest monitoring network
(level II), but also in other Long T erm Ecological Research
sites (LTER), the results showed that the percent of dam –
aged trees (defoliation >25%) is not influenced by the
concentrations of monitored pollutants (O3, NO2, NH3)
(Bytnerowicz et al ., 2005; Silaghi et al ., 2011; Badea et al .,
2012; Silaghi and Badea, 2012).
Ozone concentrations, higher than the phytotoxic lev –
el and with high levels of nitrogen and sulfur deposition,
can have significant consequences on the health status and
biodiversity of forest ecosystems, similar ones registered in
other European countries (Bytnerowicz et al ., 2002).
In general, in the Romanian monitoring networks
(level II, LTER Retezat and LTER Bucegi-Piatra Craiu –
lui sites, Carpathian network), high ozone concentrations
had no negative effect on forest health and tree growth.
Also, specific ozone injuries weren’t observed. However,
the pollutant levels (Fowler et al ., 1999) accompanied by
the variation of climatic parameters through severe deficit A very good image of the influence of climatic condi –
tions on dynamics of the damaged trees is given by results
obtained during the period 1992-2001 (Fig. 21 a-e); the
high intensity of the tree damaging process could be
correlated with increasing of temperatures during 1981-
2010 (Fig. 22 a-c) and decreasing of precipitation during
1981-2000 (Fig. 22 d, e). A slight increase in the amount
of precipitation was recorded starting with 2001 (Fig. 22
f ).
The deterioration of forest health status continued into
2003, but after that an improving trend of forest health
status was seen after 2005 (Fig. 21 f-h). Regarding the as –
sessment of biotic and abiotic damage factors, in the last
three years (2009-2011), most of the observed damage
symptoms were attributed to insects (12-16%), abiotic
factors (9-10%), fungi (3-4%) and anthropogenic factors
(2-3%) (Fig. 23) (Neagu et al ., 2011).
The deterioration of forest health status continued into
2003, but after that an improving trend of forest health
status was seen after 2005 (Fig. 21 f-h). Regarding the as –
sessment of biotic and abiotic damage factors, in the last
three years (2009-2011), most of the observed damage
symptoms were attributed to insects (12-16%), abiotic
factors (9-10%), fungi (3-4%) and anthropogenic factors
(2-3%) (Fig. 23) (Neagu et al ., 2011).
Thus, high temperatures and low precipitation over
long time periods, especially in southern and southeastern
Fig. 22. V ariation of average decennial temperatures (a, 1981-1990; b, 1991-2000; c, 2001-2009) and precipitation (d, 1981-1990;
e, 1991-2000; f, 2001-2009) at the national level

Badea O. et al. / Not Bot Horti Agrobo, 2013, 41(2):613-625
622
Both for open field (TL), under canopy (SC) and in
soil depths, the ammonia (N-NH4) ions the fluxes show
more variable tendencies. Until 2005, the fluxes increased
(from 12 to 17 kg ha–1yr–1), while after 2005 a clear ten –
dency of reduction of flux (to 5 kg ha–1yr–1) was recorded
(Fig. 27).
The influence of S-SO4, N-NO3 and N-NH4 in the soil
acidification is well known. The effects on the soil are dif –
ferent related to critical loads calculated on the basis of the
soil substrate. For example, the comparisons of the mean
flux of sulfur (S-SO4) and nitrogen with the critical loads
for two core plots from level II show that soil and forest
from the Mihăești-sessile oak site are more exposed to
acidification than the soils at the Fundata-European beech
site where the soils and limestone are more resistant to
acidification (T ab. 1).of precipitation and a considerable increase in tempera –
tures (Bytnerowicz et al ., 2008) can produce significant
negative effects on forest health and the health of indi –
vidual trees.
The quantitative and qualitative analysis of pollutants
fluxes (atmospheric depositions) in the level II monitor –
ing network and in the other forest LTER sites (LTER
Retezat and LTER Bucegi – Piatra Craiului sites) showed
that from 1998 to 2009, the input of S-SO4 flux registered
a slow tendency to decrease in in concentrations in both
the open field (TL) and under the canopy (SC) (Fig. 25).
In soil, the tendency is increasing, mainly at 10 cm and 40
cm depths with an accumulation of S-SO4 in the upper soil
horizon from previous years. As for nitrate ions (N-NO3)
the trend of decreasing concentrations is more obvious in
the open field than under the canopy (Fig. 26).

PlotSoil
substrateCritical loads Mean flux registered
kg S*ha–1
yr–1kg N*ha–1
yr–1kg S*ha–1
yr–1kg N*ha–1
yr–1
Mihăești-
sessile oakLoessoid
deposits
and stony
deposits3-8 15-20 15 16
Fundata-
European
beechLimestone >32 15-20 11 8.5Fig. 25. V ariability of the yearly flux of S-SO4 (kg ha–1 yr–1) at
different levels in the ecosystem in a Mihaesti-sessile oak plot
during 1998-2009Fig. 26. V ariability of the yearly flux of N-NO3 (kg ha–1 yr–1) at
different levels in the ecosystem in a Mihaesti-sessile oak plot
during 1998-2009
Fig. 27. V ariability of the yearly flux of N-NH4 (kg ha–1 yr–1) at
different levels in the ecosystem in a Mihaesti-sessile oak plot
during 1998-2009
Fig. 23. Distribution of the most frequent causes of mechanical
damage to trees
T ab. 1. Critical loads for the level II core plots: Mihăiești-sessile
oak and Fundata-European beech
Fig. 24. Decennial evolution of mean multiannual air tempera –
ture: Romania (source Romanian National Administration for
Meteorology)

Badea O. et al. / Not Bot Horti Agrobo, 2013, 41(2):613-625
623
to thank everyone on the forest monitoring team from
ICAS for their work.
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