| Jacobson caterpillar butterfly is a monophagous insect with a development cycle of one year quite widely spread in forests of Mongolia.An over-increase was recorded firstly in territory of Buryat, Russian Federation in 1959-1962 (Raigoradskaya,1966; Boldaruyev,1969). The butterfly is spread from Altai remote region to Amur River lands, or north latitude of 630, south latitude 450 (Boldaruyev, 1969). Over-increase roundup shows the butterfly is increased and spread at Altai region-Amur River vicinity-Irkutsk-Buryad-Mongolian central part. According to geographic region the territories involve coniferous forest of Southern Syberia and Mongolian forest-steppe. Dr. D. Tegshjargal recorded an over-increase occurrences in north-eastern part of Khentii Mountains (1991) and in Central and Khentii province in 1988-1989. So, Jacobson caterpillar butterfly is spread in syberian larch dominated forests of taiga forest and vegetation zones of Khangai and Khentii regions of our country, and over-increased in number periodically.As Jacobson caterpillar butterfly feeds only on needle of syberian larch, its spread mainly accords to spread of larch trees. Spread of Jacobson caterpillar butterfly occurs in larch-cedar and cedar-larch forests in north part of Tarvagatai Ranges of Zavkhan province, eastern part of Khuvsgul province, and southern part of Khentii Mountains with larch forests of taiga vegetation zones. Over-increase occurred in last years in Khangai regions of Mongolia has caused damages to the forest. Two research fields had been selected and processed in this study when determining disaster scope of the year of Jacobson caterpillar butterfly over-increase, as follows:1. Images of June, July, August and September,2013 when an over-increase occurred in Bayan-Agt and Khutagt-Undur soums of Bulgan province.2. Images of Bogd-Khan Mountains from 1989,1994,2000,2004,2008,2013, 2015.These images had been taken and processed at ARCGIS 10.3, ENVI 5.1 program, and found out in which months the damage of spread point is highest out of a period between June and September in forests of Bayan-Agt and Khutagt-Undur soum.From the image of Bogd-Khan Mountain it was found out which altitude zone and which trees are mostly spread and damaged by Jacobson caterpillar butterfly taking altitude numerical model DEM and age classification of trees into consideration.Based on this results had been achieved and a map of disaster scope had been created for each study field. Results had been achieved deducting results of July, August and September respectively taking into consideration fall study of Geo-ecological institute of 2013, butterfly development calendar of Bayan-Agt and Khutagt-Undur soums of Bulgan province, and larva period or June-the most forest devastating month.Total area of study is 182536.29 ha. From which in July:169134.75 ha area had not been hit by disaster or healthy,4654.17 ha area been affected to low extent,5842.26 ha area affected to medium extent, and 2905.11 ha area affected to severe extent.73705.68 ha area hit by disaster to a lower extent,1992.87 ha area to medium extent, and 825.12 ha area to large extent respectively of total area in August. In September,71550.09 ha area hit to low extent,26154.72 ha area to medium extent, and 5127.57 ha area to large extent respectively. Results show larva of Jacobson caterpillar butterfly damaged over 50% of total area to certain extent. Summarizing these results an over-increase of Jacobson caterpillar butterfly occurred in spread areas of Bayan-Agt and Khutag-Undur soums of Bulgan province in 2013 causing damages to the forest.Total larch forest area of Bogd-Khan Mountain covered 12398 hectares of land. When determining extent of the disaster, the whole area was classified as per extent, namely, not hit by disaster, hit to low extent, hit to medium extent and hit to large extent. In 1989, as result of disaster study, it was found out 5208.84 ha area or 42% not hit-healthy,2882.82 ha area or 23% hit to low extent,2604.6 ha area or 21% hit to medium extent, and 1712.43 ha area or 14% to severe extent respectively of total area.As for age classification of trees, while young larch trees in 30.42 ha area hit by disaster to low extent,3.42 ha area to medium extent, and 3.51 ha area to large extent respectively of total area in 1989, mid-age larch trees in 826.56 ha area hit to low extent, 277.11 ha area to medium extent, and 75.15 ha area to large extent respectively of total area. As for old larch trees, it hit by disaster to largest extent or 1202.22 ha area to low extent,289.8 ha area to medium extent, and 74.16 ha area to large extent respectively of total area. When determining how it's spread in highland areas, and in which areas it hits to most extent:Bogdkhan Mountain reserve is elevated 2256 m above sea level, and absolute height of the plateau surface builds four levels at 1600,1800,2000, and 2200 m respectively. It was found out in which elevated zones Jacobson caterpillar butterfly causes more damage as per disaster extents of low, medium and high for these elevations. In elevated zones:in 1989 increase of Jacobson caterpillar butterfly caused damages to 233.19 ha area to low extent,100.89 ha area to medium extent, and 29.07 ha area to large extent respectively in highland zone#1 or 1600 m above sea level. In zone#2 or 1800 m above sea level it caused damage to 1464.57 ha area to low extent,1138.77 ha area to medium extent, and 413.65 ha area to large extent respectively. In zone#3 or 2000 m above sea level it caused damage to 1080.27 ha area to low extent,1212.3 ha area to medium extent, and 112.25 ha area to large extent respectively. In zone# 4 or 2200 m above sea level it caused damage to 114.84 ha area to low extent,152.64 ha area to medium extent, and 143.46 ha area to large extent respectively.In 1989 and 2004 Jacobson caterpillar butterfly over-increase occurred in Bogd-Khan Mountain. In 1994 and 2000 Jacobson caterpillar butterfly had been at normal level causing no damage, and in 2008 and 2013 low spread and damage had been recorded as concluded. |
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