**2.1.2 Forest wildfire and the timing of spring**

There has been a remarkable increase in the incidence of large forest wildfire in some of the countries in the South East Europe since the early 1980s (Table 2). Understanding the factors behind such increase in forest wildfire activity is key to understanding the recent trends and inter-annual variability in forest wildfire. According to Westerling et al. (2006b) the length of the average season completely free of snow cover is highly sensitive to variability in regional temperature, increasing approximately 30 percent in the latest third of snowmelt years and this has a positive effect on wildfire incidence. In years with an early spring snowmelt, spring and early summer temperatures were higher than average, winter precipitation was below average, the dry soil moistures typical of summer in the region came sooner and were more intense, and vegetation was drier (Westerling et al., 2006b).


Table 2. Fire statistical data of the SE Europe. Source: GFMC.

The statistics presented here are for only those wildfires greater than 400ha that burned primarily in forests, of which there were 676 in South East Europe since 1970. This region has experienced a number of large wildfires that ignited spread to and burned substantial forested area (Table 2). The consequences of an early spring for the fire season are profound.

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

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.

There has been a remarkable increase in the incidence of large forest wildfire in some of the countries in the South East Europe since the early 1980s (Table 2). Understanding the factors behind such increase in forest wildfire activity is key to understanding the recent trends and inter-annual variability in forest wildfire. According to Westerling et al. (2006b) the length of the average season completely free of snow cover is highly sensitive to variability in regional temperature, increasing approximately 30 percent in the latest third of snowmelt years and this has a positive effect on wildfire incidence. In years with an early spring snowmelt, spring and early summer temperatures were higher than average, winter precipitation was below average, the dry soil moistures typical of summer in the region came sooner and were more intense, and vegetation was drier (Westerling et al., 2006b).

of fires

95 318

Albania 1981-2000 667 21456

Croatia 1990-1997 259 10000 Cyprus 1991-1999 20 777 Greece 1990-2000 4502 55988 Romania 1990-1997 102 355 Slovenia 1991-1996 89 643

The statistics presented here are for only those wildfires greater than 400ha that burned primarily in forests, of which there were 676 in South East Europe since 1970. This region has experienced a number of large wildfires that ignited spread to and burned substantial forested area (Table 2). The consequences of an early spring for the fire season are profound.

Average area burned, ha

> 572 11242

Country Time period Average number

1991-2000

Table 2. Fire statistical data of the SE Europe. Source: GFMC.

to be somewhat wetter than conditions were at the time of ignition.

**2.1.2 Forest wildfire and the timing of spring** 

Bulgaria 1978-1990

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.

Climate Change: Wildfire Impact 9

No of fires (forest +pastured forest)

No of fires (forest +pastured forest)

No of fires (forest +pastured forest)

Albania

Bosnia

Romania

Fig. 6. Forest fire numbers (to include forested pastures) in Albania, Bosnia Herzegovina

2004 2005 2006 2007 2008 2009

Looking across South East Europe it is obvious that land uses changes have determined significant, often cascading impacts to biodiversity and ecosystems – and more recently it was witnessed how these have threatened the quality of life for the human residents as well. Ecological impacts of land use have been well documented through pioneering research on habitat fragmentation. Fragmentation can affect communities from the "bottom up". Suarez et al, (1998) research on habitat fragmentation, showed how when non-native species invade, and native ant species disappear other species up the food chain will soon also disappear because they have lost the native species that are their main food resource (Chen et al., 2011). Such "ecosystem decay" leading to loss of biodiversity may take decades to complete following the fragmentation. The cahoots between climate change and habitat fragmentation is the most threatening aspect of climate change for biodiversity, and is a

As the human population grows, there will be increased competition for resources (like space and water) with plants and animals. Demand for housing will displace rural land uses like farming that can provide important habitat for some native species. With increased development we will witness more introduction, establishment, and invasion of habitat altering non-native species. More people will demand more opportunity for recreation – yet low intensity recreational uses like hiking when is done is an intensive way can damage

Increased demand for resources, goods, and services will increase demand for transport infrastructure (roads, power lines, pipelines, etc.) which may fragment otherwise intact landscapes and provide an entry point for non-native species such as weeds. More people

and Romania between 2004 and 2009.

central challenge facing conservation (Ioras, 2006).

**3. Land use patterns** 

0

200

400

600 800

1000

1200

1400 1600

1800

**3.1 Increasing population** 

fragile environments (Ioras, 1997).

Fig. 5. The forest fire spread in the South East Europe on 25 July 2007 as seen by the Terra Satellite (Source GFMC).

Fig. 5. The forest fire spread in the South East Europe on 25 July 2007 as seen by the Terra

Satellite (Source GFMC).

Fig. 6. Forest fire numbers (to include forested pastures) in Albania, Bosnia Herzegovina and Romania between 2004 and 2009.

#### **3. Land use patterns**

Looking across South East Europe it is obvious that land uses changes have determined significant, often cascading impacts to biodiversity and ecosystems – and more recently it was witnessed how these have threatened the quality of life for the human residents as well. Ecological impacts of land use have been well documented through pioneering research on habitat fragmentation. Fragmentation can affect communities from the "bottom up". Suarez et al, (1998) research on habitat fragmentation, showed how when non-native species invade, and native ant species disappear other species up the food chain will soon also disappear because they have lost the native species that are their main food resource (Chen et al., 2011). Such "ecosystem decay" leading to loss of biodiversity may take decades to complete following the fragmentation. The cahoots between climate change and habitat fragmentation is the most threatening aspect of climate change for biodiversity, and is a central challenge facing conservation (Ioras, 2006).

#### **3.1 Increasing population**

As the human population grows, there will be increased competition for resources (like space and water) with plants and animals. Demand for housing will displace rural land uses like farming that can provide important habitat for some native species. With increased development we will witness more introduction, establishment, and invasion of habitat altering non-native species. More people will demand more opportunity for recreation – yet low intensity recreational uses like hiking when is done is an intensive way can damage fragile environments (Ioras, 1997).

Increased demand for resources, goods, and services will increase demand for transport infrastructure (roads, power lines, pipelines, etc.) which may fragment otherwise intact landscapes and provide an entry point for non-native species such as weeds. More people

Climate Change: Wildfire Impact 11

Mediterranean climate, this coastal sage and chaparral vegetation rapidly grows fine new twigs and leaves during the moist winters. This new growth then dries to a highly flammable state during the arid summer-fall season. Consequently, most fires burn during summer when fine, dry fuels become abundant, whereas the greatest total acreage burns in

Different climate change models yield somewhat different predictions about the frequency, timing, and severity of future region wind conditions, leading to uncertainty about just how fire regimes may change in the future. However, preliminary analyses for the period 2002- 2006 suggest that wind conditions may significantly increase earlier in the fire season (especially end of July- start of September) while they may decrease somewhat later in the season (especially towards the end of September). This predicted change to earlier winds occurrences would likely increase the frequency of huge fires as severe fire weather would

Of course, fires also require an ignition source. Fires started naturally, by lightening strikes, are actually quite rare during the most dangerous autumn fire weather—when the hot, dry sea winds blow. Nowadays, however, the vast majority of ignitions are caused by humans or their inventions; and even without climate change, the number of fires in southern part of

coincide more closely with the period of most frequent fire ignitions (Fig. 7).

fall, when the largest fires are driven by winds.

means increased susceptibility to fire ignitions – and subsequently more restrictions on fire management for ecological outcomes. More people will also increase the potential for human-wildlife conflicts in the remaining wildlands (e.g. interactions with predators like bears, wolfs; biodiversity impacts from efforts to control insect-borne disease vectors). Hence, even distant human land uses can damage natural resources. Pollution, for example – whether it is represented by airborne toxins when wildfires burn, or nitrogen, ozone from urban areas, or wastewater that fouls beaches and other coastal areas – will pose great challenges for the health of the ecosystems.

#### **3.2 Interaction of climate, land use, and wildfire**

Fire in the recent years has become a key ecological process in South East Europe. Many plant species display adaptations that are finely tuned to a particular frequency and intensity of fire. Some plants may re-sprout from roots following fire. The seeds of other plants may require heat or chemicals from smoke to germinate. Some animals may be especially suited to invade recently burned areas; others may only succeed in habitats that have not burned for a relatively long time. In some cases species that are highly adapted to – even reliant on – fire can also be put at risk by fire. If fire behaviour is changed by human activities such that it is outside of its natural range of variation, it can have great significant adverse impact on native species. For example Pinus heldreichii H. Christ requires fire to reproduce, but if fires recur too frequently (i.e., before the trees have a chance to mature to reproductive age) fire can kill the young trees and break that finely-tuned life cycle. Its areal covers Albania, Bosnia Herzegovina, Bulgaria, Greece, Macedonia and Serbia (Critchfield et al 1966).

Due to human activities the fire behaviour of the entire region have greatly altered – fires generally occur too frequently in the coastal areas and too infrequently in the higher elevation forests. Fires set during wind conditions can have enormous ecological consequences (see the fire that engulfed Dubrovnik coast during of summer 2007); for some highly restricted species, an individual fire could lead to extinction. Future land use and climate changes will only exacerbate the alteration fire regimes in South East Europe. These have consequences not only on biodiversity conservation but there are also important implications for public safety, the quality of our air and water, and the economy.

Some parts of Croatia, Bulgaria already have the most severe wildfire conditions in the region, and the situation is only likely to worsen with climate change—meaning dangerous consequences for both humans and biological diversity. South East Europe's coastal area exceptional combination of fire-prone, shrubby vegetation and extreme fire weather means that fires here are not only going to become very frequent, but occasionally huge and extremely intense. The combination of a changing climate and an expanding human population threatens to increase both the number and the average size of wildfires even more. Increasing fire frequency--or ever shortening intervals between repeated fires at any particular location--poses the greatest threat to the region's coastal natural communities (except perhaps in high altitude forests), whereas increasing incidence of the largest, most intense fires poses the greatest threat to human communities.

A region's fire regime is defined by the number, timing, size, frequency, and intensity of wildfires, which are in turn largely determined by weather and vegetation. Vegetation on the region's coastal plains and foothills—where humans are most concentrated—is dominated by shrub species that burn hot and fast, and that renew themselves in the aftermath of fire (so long as inter-fire intervals are sufficiently long to allow individual plants to mature and reproduce by resprouting or setting seed between fires). In the

means increased susceptibility to fire ignitions – and subsequently more restrictions on fire management for ecological outcomes. More people will also increase the potential for human-wildlife conflicts in the remaining wildlands (e.g. interactions with predators like bears, wolfs; biodiversity impacts from efforts to control insect-borne disease vectors). Hence, even distant human land uses can damage natural resources. Pollution, for example – whether it is represented by airborne toxins when wildfires burn, or nitrogen, ozone from urban areas, or wastewater that fouls beaches and other coastal areas – will pose great

Fire in the recent years has become a key ecological process in South East Europe. Many plant species display adaptations that are finely tuned to a particular frequency and intensity of fire. Some plants may re-sprout from roots following fire. The seeds of other plants may require heat or chemicals from smoke to germinate. Some animals may be especially suited to invade recently burned areas; others may only succeed in habitats that have not burned for a relatively long time. In some cases species that are highly adapted to – even reliant on – fire can also be put at risk by fire. If fire behaviour is changed by human activities such that it is outside of its natural range of variation, it can have great significant adverse impact on native species. For example Pinus heldreichii H. Christ requires fire to reproduce, but if fires recur too frequently (i.e., before the trees have a chance to mature to reproductive age) fire can kill the young trees and break that finely-tuned life cycle. Its areal covers Albania, Bosnia

Due to human activities the fire behaviour of the entire region have greatly altered – fires generally occur too frequently in the coastal areas and too infrequently in the higher elevation forests. Fires set during wind conditions can have enormous ecological consequences (see the fire that engulfed Dubrovnik coast during of summer 2007); for some highly restricted species, an individual fire could lead to extinction. Future land use and climate changes will only exacerbate the alteration fire regimes in South East Europe. These have consequences not only on biodiversity conservation but there are also important

Some parts of Croatia, Bulgaria already have the most severe wildfire conditions in the region, and the situation is only likely to worsen with climate change—meaning dangerous consequences for both humans and biological diversity. South East Europe's coastal area exceptional combination of fire-prone, shrubby vegetation and extreme fire weather means that fires here are not only going to become very frequent, but occasionally huge and extremely intense. The combination of a changing climate and an expanding human population threatens to increase both the number and the average size of wildfires even more. Increasing fire frequency--or ever shortening intervals between repeated fires at any particular location--poses the greatest threat to the region's coastal natural communities (except perhaps in high altitude forests), whereas increasing incidence of the largest, most

A region's fire regime is defined by the number, timing, size, frequency, and intensity of wildfires, which are in turn largely determined by weather and vegetation. Vegetation on the region's coastal plains and foothills—where humans are most concentrated—is dominated by shrub species that burn hot and fast, and that renew themselves in the aftermath of fire (so long as inter-fire intervals are sufficiently long to allow individual plants to mature and reproduce by resprouting or setting seed between fires). In the

Herzegovina, Bulgaria, Greece, Macedonia and Serbia (Critchfield et al 1966).

implications for public safety, the quality of our air and water, and the economy.

intense fires poses the greatest threat to human communities.

challenges for the health of the ecosystems.

**3.2 Interaction of climate, land use, and wildfire** 

Mediterranean climate, this coastal sage and chaparral vegetation rapidly grows fine new twigs and leaves during the moist winters. This new growth then dries to a highly flammable state during the arid summer-fall season. Consequently, most fires burn during summer when fine, dry fuels become abundant, whereas the greatest total acreage burns in fall, when the largest fires are driven by winds.

Different climate change models yield somewhat different predictions about the frequency, timing, and severity of future region wind conditions, leading to uncertainty about just how fire regimes may change in the future. However, preliminary analyses for the period 2002- 2006 suggest that wind conditions may significantly increase earlier in the fire season (especially end of July- start of September) while they may decrease somewhat later in the season (especially towards the end of September). This predicted change to earlier winds occurrences would likely increase the frequency of huge fires as severe fire weather would coincide more closely with the period of most frequent fire ignitions (Fig. 7).

Of course, fires also require an ignition source. Fires started naturally, by lightening strikes, are actually quite rare during the most dangerous autumn fire weather—when the hot, dry sea winds blow. Nowadays, however, the vast majority of ignitions are caused by humans or their inventions; and even without climate change, the number of fires in southern part of

Climate Change: Wildfire Impact 13

the region has been steadily increasing in direct proportion to human population (www.effis.jrc.ec.europa.eu/reports/category/40/fire-reports). This increase in ignitions, especially if coupled with a longer fire-weather season, creates more opportunities for fires to start when conditions are most extreme, however, huge firestorms such as those during 2003 and 2007 are not new phenomena in this region. Studies of charcoal layers deposited on the sea floor near the Cyclades Islands indicate that such major fire events have recurred on average every 20 to 60 years, or roughly two to five times per century over the past 12 to 13 centuries (Bryne et al., 1977). These huge firestorms inevitably occur following very wet years, at the beginning of drought periods (Mensing et al., 1999). How these inter-annual

Due to the combined forces of changing climate, increasing fire ignitions, and invasive weedy species, fires are likely to burn ever more frequently in a positive feedback loop. Studies have shown that frequent fires over short time intervals increase invasions by weedy annual plants into native communities. These weedy invaders then set seed, die, and dry out earlier than the natives, thereby starting the fire season even earlier and increasing chances of another fire. These weedy annuals, referred to as "flash fuels" by firefighters, also ignite more readily and burn more rapidly than native perennial plants, thus creating a more favourable environment for themselves at the expense of the natives, which evolved under longer fire-return intervals. The potential for these interactions between climate change, weedy invasions, and changing fire regimes paints a grim picture for South East Europe's biological diversity and watershed quality, as vast stands of rich biodiverse and soil-holding shrub communities are replaced by biologically sparse, shallow-rooted, fire-

**4. Specific challenges of climate change in South and Eastern Europe** 

temperature, but also by conditions like interactions with other species.

is not currently known where such thresholds in the system might be.

require assistance moving to new regions.

The impact of climate change promises to be more visible in southern part of the region because there is such a great diversity of plants and animals. Every species has unique requirements for persistence. This means that species will respond differently to the same climatic change. The range of a species is determined by external conditions like

Thus, native species will face novel environmental conditions – and will have precious little time to adjust. Even if the changes in climate are gradual, it has been recognized that the changes will be steep. Species with limited ability to move will have an especially difficult time keeping pace as Chen et al. (2011) reported that the distributions of species have recently shifted to higher elevations at a median rate of 11.0 meters per decade, and to higher latitudes at a median rate of 16.9 kilometres per decade. Some species may even

Of greatest concern for local scientist, however, is that even with a gradual change there may be "tipping points" in the system, whereby ecological complexities interact and there is a dramatic "step change" in the system. These may include massive scale die-back of forests due to abnormal drought conditions, conversion of scrub habitat to non-native grassland with a few too frequent fires, and the scouring of watersheds, excessive erosion, and alteration of geomorphology of region's streams and rivers, with rain after catastrophic fire. Such fundamental conversion of the region's ecosystems could be abrupt and irreversible. It

wet-dry cycles may change with changing climate is as yet unclear.

perpetuating weeds.

Fig. 7. Fire risk trends (Fire Weather Index -FWI) between 2002 and 2006 in Bulgaria, Croatia, Romania and Turkey. Source EFFIS "Forest Fire in Europe 2006" (http://effis.jrc.ec.europa.eu/reports/fire-reports/doc/2/raw)

Fig. 7. Fire risk trends (Fire Weather Index -FWI) between 2002 and 2006 in Bulgaria,

Croatia, Romania and Turkey. Source EFFIS "Forest Fire in Europe 2006"

(http://effis.jrc.ec.europa.eu/reports/fire-reports/doc/2/raw)

the region has been steadily increasing in direct proportion to human population (www.effis.jrc.ec.europa.eu/reports/category/40/fire-reports). This increase in ignitions, especially if coupled with a longer fire-weather season, creates more opportunities for fires to start when conditions are most extreme, however, huge firestorms such as those during 2003 and 2007 are not new phenomena in this region. Studies of charcoal layers deposited on the sea floor near the Cyclades Islands indicate that such major fire events have recurred on average every 20 to 60 years, or roughly two to five times per century over the past 12 to 13 centuries (Bryne et al., 1977). These huge firestorms inevitably occur following very wet years, at the beginning of drought periods (Mensing et al., 1999). How these inter-annual wet-dry cycles may change with changing climate is as yet unclear.

Due to the combined forces of changing climate, increasing fire ignitions, and invasive weedy species, fires are likely to burn ever more frequently in a positive feedback loop. Studies have shown that frequent fires over short time intervals increase invasions by weedy annual plants into native communities. These weedy invaders then set seed, die, and dry out earlier than the natives, thereby starting the fire season even earlier and increasing chances of another fire. These weedy annuals, referred to as "flash fuels" by firefighters, also ignite more readily and burn more rapidly than native perennial plants, thus creating a more favourable environment for themselves at the expense of the natives, which evolved under longer fire-return intervals. The potential for these interactions between climate change, weedy invasions, and changing fire regimes paints a grim picture for South East Europe's biological diversity and watershed quality, as vast stands of rich biodiverse and soil-holding shrub communities are replaced by biologically sparse, shallow-rooted, fireperpetuating weeds.
