Interpretation of Wildland fires in the Boreal Ecoregion

Boreal and subarrctic wildland fires in Northern Manitoba

 

 

 

Link to Map Overlay on Google Earth

 

 

 

 

 

 

 

To better understand the maps: Using the time-since-fire dates from 1497 sampling points, Thiessen polygons were calculated using ArcView GIS 3.3 and no attempt to adjust polygon boundaries to those of the
forest inventory was done. Since fewer sample points were available for the 1720-1890 and the 1670-1720 periods, the polygones become more angular and larger

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Additional time-since-fire maps were made to provide a better view of the landscape in 1880 and 1900.

The first one aimed at providing a view of the landscape in 1880 and was constructed using time-since-fire dates from 232 points with fire dates. Figure 2

The second map aimed at providing a view of the landscape in 1900 and was constructed from a total of 1147 points. Figure 3

 

EXPLORING LANDSCAPE ECOSYSTEMS WITH GOOGLE EARTH:

BOREAL WILDLAND FIRE HISTORY:

DUCK MOUNTAINS, MANITOBA

An intresting study carried ou by Jacques Tardiff at the Centre for Forest interdisciplinary Research (C-FIR), University of Winnipeg provides a unique 300 year perspective of fire history in the Duck Mountain Provincial Forest (DMPF), Manitoba. The results are reported in Project Report 2003-2004 - Fire history in the Duck Mountain Provincial Forest published in 2004 as part of the Sustainable Forest Management Network Reserach projects. Link:

Some Key Results of this Study:

    This study presents a 300-year fire history reconstruction for the Duck Mountain Provincial Forest (DMPF) located in the boreal plains of western Manitoba.

    Results indicated that the fire cycle in the DMPF has dramatically changed since the early 1700. In the pre-settlement period (1700-1880), which corresponded to the late portion of the Little Ice Age, the fire cycle may have been around 55-years with, on average, up to 1.8% of the area burning each year.

    Throughout that period, the authors speculated that large, infrequent fires have occurred in conjunction with prolonged droughts.

    Such an extreme drought was observed from 1885 to 1895 and coincided with about 83% of the DMPF burning, i.e., an area equal to 283,580 ha.

    During settlement, numerous small fires were observed at the periphery of the DMPF and were speculated to origin from land clearing. Despite these frequent fires, the length of the fire cycle has increased to about 200 years. On average, about 0.5% of the landscape was burning every year.

    Since the last major fire to occur in 1961 the length of the fire cycle has been estimated to be over 15,000 years.

    The year 1961 coincided with the most severe drought in the 20th century for that region of Manitoba. At no other time in the 300-year record was there a period of 40-years or so with so little area burned

    The impact of fire suppression needs to be further investigated but is speculated to play a major role in the lengthening of the fire cycle. The current time-since-fire distribution and age structure observed in the landscape are probably unprecedented. The imprint of the late 19th century fires coupled with settlement and fire suppression have been the dominant forces structuring the ecological processes of today..

 

Figure 1. Time-since-last-fire map for the Duck Mountain Provincial Forest as of 2002

Time-since-last-fire map for the Duck Mountain Provincial Forest as of 2002 and including data obtained from Manitoba Conservation’s archives. One can observe the numerous small fires occurring at the perimeter of the DMPF in the early 20th century and the area burned in 1961 in brown at the centre of the map.

The Google Earth image below provides a somewhat broader overview of the Duck Mountain Area, which is essentially a higher plateau surrounded by an agriculturally dominated areas. Because of plateau, the Duck Mountains show a more typical boreal ecosystem than the surrounding areas. Recnet logging activities can be seen around D. The area near B is one of the oldest fire history sites (see purple- 1720 on figure 1). The area around A is the last prominent burn (1960). The Wisconsin ice sheet was responsible shaping the topography of plateau and leaving a ground and dead ice moraine. Glacial lake Agassiz, during shaped the slopes of the plateau and left numerous beachlines during its retreat ( see around C)

 

This NASA WorldWind satellite image composite shows the area near A,B,C for the time period around 2000. The pink areas on the plateau are recent logging areas, in the lowlands agricultural crops.

 

Figure 2 Time-since–last-fire map for the Duck Mountain Provincial Forest as if one was standing in the early 1900.

Time-since–last-fire map for the Duck Mountain Provincial Forest as if one was standing in the early 1900, immediately after the catastrophic burns of the 1885-1895 decade. The
area burned in both 1880 and 1890 classes totalized 83% of the DPPF.

 
 
 

Figure 3 Time-since-last-fire map for the Duck Mountain Provincial Forest as if one was standing in the early 1880.

Time-since-last-fire map for the Duck Mountain Provincial Forest as if one was standing
in the early 1880, i.e. before the catastrophic burns of the 1885-1895 decade. Large-scale fires may
have occurred throughout the period covered as indicated by the colour scale..