**1. Introduction**

The European forests harbour biological wealth of international importance (circa 6,000 species are of conservation importance according to IUCN). Changes to come in climate are challenging science, governments, and local communities in order to sustain the health of its ecosystems, which will, in turn, also help protect the quality of life.

European climate system are supported by various factors such as soils, topography, available plant species. Some of these factors are contributing to both natural ecosystems and their fire regimes. Long-term patterns of temperature and precipitation determine the moisture available to grow the vegetation that fuels wildfires (Stephenson, 1998). Climatic inconsistency on inter-annual and shorter scales governs the flammability of these fuels (Westerling, 2003; Heyerdahl et al., 2001). Flammability and fire frequency in turn affect the amount and continuity of available fuels. Therefore, long-term trends in climate can have profound implications for the location, frequency, extent, and severity of wildfires and for the character of the ecosystems that support them (Westerling, 2006a). Human determined climatic change may, over a relatively short time period (< 100 years), give rise to climates outside anything experienced in Europe, since the establishment of an industrial civilization, currently sustaining a population that has increased approximately 270% since 1850. Changes in wildfire regimes driven by climate change are likely to impact ecosystem services that European citizens rely on, including carbon sequestration; water quality and quantity; air quality; wildlife habitat; and recreational facilities. In addition to climate change, the continued growth of continent's population and the spatial pattern of development that accompanies that growth are consequently affecting wildfire regimes through their impact on the availability and continuity of fuels and the availability of ignitions.

South East Europe ecosystems are a vast mosaic of different habitat types. The biodiversity patterns we encounter today are a result of millions of years of climatic and geologic change.

Climate Change: Wildfire Impact 3

impacts may have undermined the resilience of some species to adapt to the change (e.g., by lowering their overall population). Human land uses also may have disconnected the ecological connectivity in the landscape that would provide the movement corridor from the

This degree of alteration of ecological processes and jeopardise of native species will complete the transformation of the entire region to a "managed ecosystem"(Ioras, 2009). This reality will require that the local politicians articulate what the wanted future condition is for the area in question. Only with an informed thorough assessment of the current and future challenges confronting native species, and a clear articulation of ecological and socioeconomic goals, we will be able to manage South East Europe native species and systems

Climate increases wildfire risks primarily through its effects on moisture availability. Wet conditions during the growing season promote fuel—especially fine fuel—production via the growth of vegetation, while dry conditions during and prior to the fire season increase the flammability of the live and dead vegetation that fuels wildfires (Swetnam and Betancourt 1990, 1998; Veblen et al. 1999, 2000; Donnegan 2001). Moisture availability is determined by both precipitation and temperature. Warmer temperatures can reduce moisture availability via an increased potential for evapo-transpiration (evaporation from soils and surface water, and from vegetation), a reduced snowpack, and an earlier snowmelt. Snowpack at high altitude is an important mean of making water available as runoff in late spring and early summer (Sheffield et al. 2004), and a reduced snowpack and earlier snowmelt potentially lead to a longer, drier summer fire season in many mountain

For wildfire risks in most Eastern European forests, inter-annual variability in precipitation and temperature appear to be determinant on forest wildfire through their short-term effects on fuel flammability, as opposed to their longer-term affects on fuel production. One way of illustration this is with the use of average Palmer Drought Severity Index (PDSI). The Palmer Drought Severity Index (PDSI) was developed by Palmer (1965) based on monthly temperature and precipitation data as well as the soil-water holding capacity at that location to represent the severity of dry and wet spells over the U.S. The global PDSI data (Dai et al., 2004) consist of the monthly surface air temperature (Jones and Moberg 2003) and precipitation (Dai et al., 1998; Chen et al., 2002) over global land areas from 1870 to 2006.

The time series of the PDSI variations are determined by the mean values from all grid data from the selected area. The mean values are computed by means of the robust Danish method (Kegel, 1987). This method allows to detect and isolate outliers and to obtain accurate and reliable solution for the mean values. The global PDSI variations for the period 1870-2006 are between +1 in the beginning and -2 in 2002. The Palmer classification of drought conditions is in terms of minus numbers: between 0.49 and -0.49 - near normal conditions; -0.5 to -0.99 -incipient dry spell; -1.0 to -1.99 - mild drought; -2.0 to -2.99 moderate drought; -3.0 to -3.99 - severe drought; and -4.0 or less - extreme drought. The

The PDSI variations over the South-East Europe are determined for area between longitude 10°30' E and latitude 32.5°50' N (Fig.1). This area consists of 44 grids of the global PDSI data.

current to the future range.

through the transformation ahead.

**2.1 Climate and forest wildfire** 

forests (Westerling, 2006b).

**2.1.1 Moisture, fuel availability, and fuel flammability** 

These date is represented as PDSI values in 2.5x 2.5 global grids.

positive values are similar about the wet conditions.

Over years, populations of their native biota expanded and contracted in range – some at local scales, others at hemispheric scales, some up and others down slopes – to find and adapt to the local conditions that allowed them to persist to this day. During drier periods, for example, some species seek out the refuge of mountaintops that provided the conditions necessary for survival; on contrary during wetter periods, those species may have moved from those refuges to re-sort across the landscape that is now found in Europe.

What this dynamism demonstrates us is that change occurs at various temporal and spatial scales, and that while today's climate may be our baseline, our climate has not been and will not be static. It also highlights how critical connectivity is in our landscape: the extraordinary biological richness is to a great degree a product of species being able to shift in their range and adapt to changing climatic conditions. If that landscape connectivity is lost, or if the climate changes overtakes the ability of species to respond, or if populations are already reduced or stressed by other factors, species may be unable to survive through the climate changes to come.

In the case of many species and ecological processes, the effect of past and future land use change may induce significant stresses, that left unmanaged could see species to extinction. Some of these land use impacts may have a more significant impact than a changing climate. The challenge for South East Europe is to describe out the anticipated effects of past and future land use change from those of climate change – so that we can better plan our strategies to protect ecosystem health and conserve the native biodiversity for future generations.

This chapter endeavours to investigate what impact has the climate change, with specific reference to wildfire, on biodiversity and ecological processes in South East Europe and is presenting some considerations on how species native to the region will have to adapt.

### **2. Climate change**

A changing climate will interact with other drivers in pertaining ways and generate feedback cycles with significant consequences. The effects of habitat fragmentation on native species may be dependent on intra- and inter-annual variation in rainfall (Morrison, 2000); so changes in rainfall and development patterns may deepen impacts. Increasing fires, in combination with increasing nitrogen deposition as a result of ash deposition on soil, may facilitate invasive of non-native weeds that in turn increase fire risk. Decreasing water supplies due to human pressure may have negative effects on native plants and animals, like species found in rivers. Meanwhile, increased irrigation run-off from non-porous soil in an urbanized watershed can fundamentally alter hydrological regimes in other ways (White et al, 2002).

These threats may lead to population pressure for native species, and possibly lead to extinction. The urbanization stress on southern part of South East Europe has increased recently, and most of the direct impacts to resources have occurred in the recent past. This means that the indirect effects have yet to be seen. Once these changes have occurred, it is expect that in some areas of South East Europe (eg Croatia, Bulgaria) it will only accelerate. Compounding the ecological impacts of land use change is perhaps an unprecedentedly rapid change in climate. The "climatic envelopes" species need (the locations where the temperature, moisture and other environmental conditions are suitable for persistence) will shift. For many species, a changing climate is not the problem, per se. The problem is the pace of the change: the envelope may shift faster than species are able to follow. For some species, the envelope may shift to areas already changed to human land use. Human

Over years, populations of their native biota expanded and contracted in range – some at local scales, others at hemispheric scales, some up and others down slopes – to find and adapt to the local conditions that allowed them to persist to this day. During drier periods, for example, some species seek out the refuge of mountaintops that provided the conditions necessary for survival; on contrary during wetter periods, those species may have moved

What this dynamism demonstrates us is that change occurs at various temporal and spatial scales, and that while today's climate may be our baseline, our climate has not been and will not be static. It also highlights how critical connectivity is in our landscape: the extraordinary biological richness is to a great degree a product of species being able to shift in their range and adapt to changing climatic conditions. If that landscape connectivity is lost, or if the climate changes overtakes the ability of species to respond, or if populations are already reduced or stressed by other factors, species may be unable to survive through

In the case of many species and ecological processes, the effect of past and future land use change may induce significant stresses, that left unmanaged could see species to extinction. Some of these land use impacts may have a more significant impact than a changing climate. The challenge for South East Europe is to describe out the anticipated effects of past and future land use change from those of climate change – so that we can better plan our strategies to

This chapter endeavours to investigate what impact has the climate change, with specific reference to wildfire, on biodiversity and ecological processes in South East Europe and is

A changing climate will interact with other drivers in pertaining ways and generate feedback cycles with significant consequences. The effects of habitat fragmentation on native species may be dependent on intra- and inter-annual variation in rainfall (Morrison, 2000); so changes in rainfall and development patterns may deepen impacts. Increasing fires, in combination with increasing nitrogen deposition as a result of ash deposition on soil, may facilitate invasive of non-native weeds that in turn increase fire risk. Decreasing water supplies due to human pressure may have negative effects on native plants and animals, like species found in rivers. Meanwhile, increased irrigation run-off from non-porous soil in an urbanized watershed can fundamentally alter hydrological regimes in other ways (White

These threats may lead to population pressure for native species, and possibly lead to extinction. The urbanization stress on southern part of South East Europe has increased recently, and most of the direct impacts to resources have occurred in the recent past. This means that the indirect effects have yet to be seen. Once these changes have occurred, it is expect that in some areas of South East Europe (eg Croatia, Bulgaria) it will only accelerate. Compounding the ecological impacts of land use change is perhaps an unprecedentedly rapid change in climate. The "climatic envelopes" species need (the locations where the temperature, moisture and other environmental conditions are suitable for persistence) will shift. For many species, a changing climate is not the problem, per se. The problem is the pace of the change: the envelope may shift faster than species are able to follow. For some species, the envelope may shift to areas already changed to human land use. Human

protect ecosystem health and conserve the native biodiversity for future generations.

presenting some considerations on how species native to the region will have to adapt.

from those refuges to re-sort across the landscape that is now found in Europe.

the climate changes to come.

**2. Climate change** 

et al, 2002).

impacts may have undermined the resilience of some species to adapt to the change (e.g., by lowering their overall population). Human land uses also may have disconnected the ecological connectivity in the landscape that would provide the movement corridor from the current to the future range.

This degree of alteration of ecological processes and jeopardise of native species will complete the transformation of the entire region to a "managed ecosystem"(Ioras, 2009). This reality will require that the local politicians articulate what the wanted future condition is for the area in question. Only with an informed thorough assessment of the current and future challenges confronting native species, and a clear articulation of ecological and socioeconomic goals, we will be able to manage South East Europe native species and systems through the transformation ahead.

#### **2.1 Climate and forest wildfire**

#### **2.1.1 Moisture, fuel availability, and fuel flammability**

Climate increases wildfire risks primarily through its effects on moisture availability. Wet conditions during the growing season promote fuel—especially fine fuel—production via the growth of vegetation, while dry conditions during and prior to the fire season increase the flammability of the live and dead vegetation that fuels wildfires (Swetnam and Betancourt 1990, 1998; Veblen et al. 1999, 2000; Donnegan 2001). Moisture availability is determined by both precipitation and temperature. Warmer temperatures can reduce moisture availability via an increased potential for evapo-transpiration (evaporation from soils and surface water, and from vegetation), a reduced snowpack, and an earlier snowmelt. Snowpack at high altitude is an important mean of making water available as runoff in late spring and early summer (Sheffield et al. 2004), and a reduced snowpack and earlier snowmelt potentially lead to a longer, drier summer fire season in many mountain forests (Westerling, 2006b).

For wildfire risks in most Eastern European forests, inter-annual variability in precipitation and temperature appear to be determinant on forest wildfire through their short-term effects on fuel flammability, as opposed to their longer-term affects on fuel production. One way of illustration this is with the use of average Palmer Drought Severity Index (PDSI). The Palmer Drought Severity Index (PDSI) was developed by Palmer (1965) based on monthly temperature and precipitation data as well as the soil-water holding capacity at that location to represent the severity of dry and wet spells over the U.S. The global PDSI data (Dai et al., 2004) consist of the monthly surface air temperature (Jones and Moberg 2003) and precipitation (Dai et al., 1998; Chen et al., 2002) over global land areas from 1870 to 2006. These date is represented as PDSI values in 2.5x 2.5 global grids.

The time series of the PDSI variations are determined by the mean values from all grid data from the selected area. The mean values are computed by means of the robust Danish method (Kegel, 1987). This method allows to detect and isolate outliers and to obtain accurate and reliable solution for the mean values. The global PDSI variations for the period 1870-2006 are between +1 in the beginning and -2 in 2002. The Palmer classification of drought conditions is in terms of minus numbers: between 0.49 and -0.49 - near normal conditions; -0.5 to -0.99 -incipient dry spell; -1.0 to -1.99 - mild drought; -2.0 to -2.99 moderate drought; -3.0 to -3.99 - severe drought; and -4.0 or less - extreme drought. The positive values are similar about the wet conditions.

The PDSI variations over the South-East Europe are determined for area between longitude 10°30' E and latitude 32.5°50' N (Fig.1). This area consists of 44 grids of the global PDSI data.

Climate Change: Wildfire Impact 5

Fig. 3. Variations of the PDSI for South-East Europe (source Chapanov and Gambis, 2010). Positive values of the index represent wet conditions, and negative values represent dry conditions. This is used here as an indicator of the moisture available for the growth and

This analysis included all fires over 400ha -large wildfires threshold (Running, 2006) that have burned since 1970, and account for the majority of large forest wildfires in South East Europe. The fires have been aggregated for each country using the European Forest Institute

**Country/Decade** 1970-1979 1980-1989 1990-1999 Albania 009 Austria 100 Bosnia 0 0 12 Bulgaria 0 2 29 Croatia 10 37 66 Czech 846 Cyprus 12 10 4 Greece 60 33 46 Hungary 5 5 15 Italy 58 50 102 Macedonia 0 0 25 Moldova 000 Romania 006 Slovakia 13 1 3 Slovenia 0 0 13 Yugoslavia 12 17 2 Table 1. Number of forest fire that affected an area over 400ha in South East Europe between

wetting of fuels.

1970-2000.

Note: 0 means no reported data

Database on Forest Disturbances in Europe (Table 1).

The maximal errors are below 0.08 and the mean value of the all PDSI points is 0.02 (Fig.2). The PDSI variations over the South-East Europe from Fig.3 show several severe wet and dry events.

Fig. 1. Area of South-East Europe between longitude 10°-30° E and latitude 32°.5-50° N.

Fig. 2. Number of the grid points and errors of PDSI for South-East Europe (source Chapanov and Gambis, 2010).

The maximal errors are below 0.08 and the mean value of the all PDSI points is 0.02 (Fig.2). The PDSI variations over the South-East Europe from Fig.3 show several severe wet and dry

Fig. 1. Area of South-East Europe between longitude 10°-30° E and latitude 32°.5-50° N.

Fig. 2. Number of the grid points and errors of PDSI for South-East Europe (source

Chapanov and Gambis, 2010).

events.

Fig. 3. Variations of the PDSI for South-East Europe (source Chapanov and Gambis, 2010).

Positive values of the index represent wet conditions, and negative values represent dry conditions. This is used here as an indicator of the moisture available for the growth and wetting of fuels.

This analysis included all fires over 400ha -large wildfires threshold (Running, 2006) that have burned since 1970, and account for the majority of large forest wildfires in South East Europe. The fires have been aggregated for each country using the European Forest Institute Database on Forest Disturbances in Europe (Table 1).


Table 1. Number of forest fire that affected an area over 400ha in South East Europe between 1970-2000.

Note: 0 means no reported data

Climate Change: Wildfire Impact 7

Comparing fire seasons for the earliest versus the latest third of years by snowmelt date, the length of the wildfire season (defined here as the time between the first report of a large fire ignition and last report of a large fire controlled) was 45 days (71 percent) longer for the earliest third than for the latest third. Sixty-six percent of large fires in South East Europe occur in early snowmelt years, while only nine percent occur in late snowmelt years. Large wildfires in early snowmelt years, on average, burn 25 days (124 percent) longer than in late snowmelt years. As a consequence, both the incidence of large fires and the costs of suppressing them are highly sensitive to spring and summer temperatures. Both large fire frequency and suppression expenditure appear to increase with spring and summer average temperature in a highly non-linear fashion. In the case of Albania, Bosnia Herzegovina and Romania (Hoxhaj, 2005; Alexandru et al, 2007; Ciobanu and Ioras ed, 2007) suppression expenditure in particular appears to undergo a shift near 15°C during of 2007 (Figure 4 and 5). Year 2007 was used as reference year due to the significant increase of wildfire (Figure 6) and also this year was known to have had a heat wave. Temperatures taken separately above and below that threshold are not significantly correlated with expenditures, but the

mean and variance of expenditures increase dramatically above it.

Fig. 4. The annual number of large forest fires in Albania, Bosnia and Romania versus

average March–August temperature in 2007.

In the South, the frequency of large wildfires peaks in Italy and Greece, in the East in Bulgaria and Croatia often ignited by lightning strikes before the summer rains wet the fuels (Swetnam and Betancourt, 1998). Since the lightning ignitions are associated with subsequent precipitation, it is possible that the monthly drought index may tend to appear to be somewhat wetter than conditions were at the time of ignition.

In the two northern countries - Slovak and Check Republic-conditions also tended to be drier than normal in the 70s: extended drought increased the risk of large forest wildfires in these wetter northern forests for fires above 1700 meters in elevation, the importance of surplus moisture in the preceding year was greatest for the southern countries. According to Swetnam and Betancourt (1998) moisture availability in predecessor growing seasons was important for fire risks in open conifer forests as fine fuels play an important role in providing a continuous fuel cover for spreading wildfires, but not in mixed conifer forests. Looking at the western part of South East Europe more generally, the moisture necessary to support denser forest cover tends to increase with latitude and elevation. Consequently, the shift in forest fire incidence as one moves from the forests of the SW to those of the NE is broadly consistent with a decreasing importance of fine fuel availability—and an increasing importance of fuel flammability— as limiting factors for wildfire as moisture availability increases on average.
