Analysis of land cover changes on the Sumatran Orangutan (Pongo abelii) habitat due to forest fires in Gunung Leuser National Park

Gunung Leuser National Park (GLNP) is home to Indonesia’s native species, the Sumatran orangutan (Pongo abelii). The GLNP in some of its areas has experienced forest degradation, one of which is by land clearing activities by burning. The purpose of this study is to analyze land cover changes due to forest fires in the habitat of Sumatran orangutans in GLNP, Langkat Regency, North Sumatera Province. This study used temporal and spatial analysis of fire hotspot data with land cover. Temporal analysis of land cover changes was conducted between before and after forest and land fires in the study area. There are at least 6,783 ha of forest fires, of which 1,541 ha were habitat distribution areas for Sumatran orangutans. From 2000-2019, 158 hotspots were detected, of which 36 hotspots were in the distribution area of Sumatran orangutan habitat. Land cover in the study area has mostly changed from primary dryland forest to plantations. The primary dryland forest that remained in the study area only 483.51 Ha in 2019 after converting since 2000. Communities around GLNP need to be assisted in the process of ecosystem restoration through a conservation partnership pattern to restore the function of the area, one of which is as a habitat for Sumatran orangutans.


Introduction
Forest cover is decreasing every year due to land use conversion.The increasing need for land due to population growth pressures forest areas to convert to non-forest functions.Forest fires are carried out, among others, due to forest land clearing activities which have caused very serious problems to date and have not even been properly addressed by the government.The problem of forest fires always increases every year [1].
One of the areas affected by forest fires is Gunung Leuser National Park (GLNP) which is one of the conservation forest areas that is also experiencing degradation [2].One of the areas that experienced severe disturbance was the GLNP of Sekoci Lepan Resort area.In this area the number of hostpots found is very large [3].In addition, the results of monitoring through satellite imagery show that in the GLNP of Sekoci Lepan Resort many hotspots were found which identified forest fires with the motive for encroachment activities which resulted in changes in land cover.
Sumatran orangutan (Pongo abelii) is one of the key species in GLNP.The latest data states that currently the Sumatran orangutan is threatened with extinction [4] due to habitat changes and declining forest quality due to illegal activities.The increasing human need for land to sustain life and the economy has resulted in some areas of GLNP being degraded.This directly affects the orangutan habitat found in the GLNP area, especially in the GLNP of Sekoci Lepan Resort which is a habitat pocket for Sumatran orangutans (Pongo abelii).With the right information about land cover changes in the Sumatran Orangutan distribution area in the GLNP area of North Sumatra, it will be easier to carry out monitoring in GLNP which is the main habitat of animals in critically endangered conservation status [4].The purpose of this study is to analyze land cover changes due to forest fires in the habitat of Sumatran Orangutans (Pongo abelii) in GLNP, Langkat Regency, North Sumatra.

Research site
This research was conducted in the GNLP of Sekoci Lepan Resort (Figure 1).The research location is in Besitang District, Langkat Regency, North Sumatera Province, Indonesia.This research was carried out January-June 2021.Research data is processed at the Forest Resources Conservation Laboratory, Faculty of Forestry, Universitas Sumatera Utara.

Tools and materials
The hotspots as fire indication 2001-2019 is taken from the Terra/Aqua satellite with the Moderateresolution Imaging Spectroradiometer (MODIS) sensor.The data can be accessed from the NASA Active Fire Data website at https://firms.modaps.eosdis.nasa.gov/download.In addition, this study also used the TNG area boundary map, Sumatran Orangutan habitat map obtained from the Ministry of Environment and Forestry (KLHK) and Landsat 5 and Landsat 8 OLI images of 2000, 2005, 2010, 2013, 2016 and 2019 which can be downloaded at https://earthexplorer.usgs.gov.
These hotspots are monitored from remote sensing satellite by MODIS Sensor.The higher the confidence level, the higher the indication that the hotspot is a forest and land fire.Hotspots that have a strong indication of fire occurrence have a confidence level above 50% [5].Hotspots data were reclassified using a Geographic Information System (GIS) tool, ArcGIS 10.8, to separate hotspots with a confidence level above 80.To determine locations that have strong indications of forest and land fires and land cover dynamics is conducted groundcheck.ArcGIS 10.8 was also used to conduct land cover classification and land use change analysis.

Data anaysis
Image data processing of Landsat 5 (OLI) and Landsat 8 (OLI) image is started by band composite process.The next process is raster processing, compositing bands, clip raster and geoprocessing.The next step is image classification using visual interpretation with the digitizing on screen method or by manual interpretation on a computer screen.Image classification is carried out to determine the land cover class along with information on the type of land cover.Image classification is carried out using visual interpretation or manual classification using the Technical Guidelines for Interpreting Medium Resolution Satellite Imagery for the 2020 National Land Cover Data Update [6].The visual interpretation method is a land cover classification technique of land cover classification techniques from satellite imagery by inferring the specific characteristics of objects in the image based on color, shape, size, pattern, shadow, texture, and location.The visual interpretation use on screen digitizing technique for determining the land cover classification map.
Whether or not changes to land cover data are logical in this technical guide refers to the general conditions that occur.Illogical changes can occur and are categorized in extraordinary events, for example due to natural disasters (fires, floods, landslides, etc.) as well as for development reasons (for example: road construction, dams, etc.).For these illogical changes, it is necessary to recheck using data sources (very high resolution satellite images) and/or groundcheck [6].Analysis of attribute data is carried out to make it easier to analyze changes in the type and extent of land cover.After digitizing, data in the form of land cover was obtained from each land cover map starting from 2000, 2005, 2010, 2013, 2016 and 2019.

Temporal distribution of hotspot
The area studied was 1,541 ha.Land cover change analysis was conducted in the GLNP area, which is the distribution area of the detected Sumatran orangutan habitat.The number of hotspots in the study area 2001-2019 was 36 hotspots.The temporal distribution of hotspots as an indication of forest fires in the Sumatran Orangutan habitat area in the study area is shown in Figure 2.   2).The number of hotspots as an indication of forest fires also generally increased in 2010 in GLNP areas outside the Sumatran Orangutan habitat.

Land cover change in Sumatran Orangutan habitat in GLNP
Land cover in the GLNP area is naturally primary dryland forest.In its development due to human activities in the forest area there is a change from primary dryland forest to other land cover.The development of land cover change in Sumatran orangutan habitat in the study area is shown in Figure 3.

Land cover changes of Sumatran Orangutan Habitat in GNLP of Sekoci Lepan Resort
Land cover changes may follow the pattern of detected forest fires.Forest fires can also indicate forest clearing for land tenure using slash and burn methods.After a large number of hotspots were detected in 2010, in the following period, forest cover decreased (Figure 4).This was triggered by degraded lands after burning, such as shrubs, which are easily converted into land rather than forests.Shrubs have finer and more flammable fuels than forests.
A study conducted by [7] found a strong relationship between forest loss and increased fires in the region.The land that converted land cover change to non-forest experienced increased fire activity.Based on study [8,9] also confirmed that non-forest land namely shrubs, reeds and dryland farming, are the main source of land fires in North Sumaetra region.A study by [10] found that land cover change after forest and land fires, where forest and shrub cover turned into plantations.According to Thoha et al. [11], the most common cause of fires was land conversion to plantations.Land that had been burnt became plantations in the following period.Forest encroachment has long occurred in the GNLP area but is decreasing day by day.Dwiprabowo et al. [12] stated that encroachers are people who illegally cultivate land within the GLNP area.They may live and farm adjacent to the National Park (NP) area or live in villages adjacent to the NP where at least some of the land they control is within the NP.The characteristics of encroachers vary between regions and can be categorized into 5 types, namely: landless natives, local migrants, Javanese immigrants, landless poor migrants, and cunning opportunists.
Jayanthi [13] found that the GLNP area is one of the forest areas that is experiencing severe degradation.One area that is experiencing severe disturbance is in the Besitang area.She also found that up to 2000, the GLNP area has been degraded by 18,089 ha, while the GLNP area that has decreased in quality due to various disturbances is 142,087 ha.Thoha and Ahmad [8] found that in the GLNP of Sekoci Lepan Resort, forest encroachment was also found.Forest encroachment in the Besitang area has had a major impact on changes in forest cover in the Langkat Regency.
There is a human influence on changes in land cover and use from forests and agricultural land to plantations [14].This directly affects the habitat of orangutans in the GLNP area.Because of this, the orangutan as a protected species and has a native habitat in GLNP must lose its habitat as stated by Kuswanda and Satyawan [15] that the Sumatran Orangutan is estimated to only use space between 35- 60% of its habitat area.They also stated that a decrease in habitat quality and quantity is thought to cause behavioral changes in Sumatran Orangutans.Sumatran orangutans must be able to adapt to habitats that are narrow and insufficient to meet their needs.In the adaptation process, it is estimated that orangutans will choose ideal habitat types that are more favorable to them.
Thoha et al. [16] in the GLNP area of Langkat Regency found that primary dryland forests after the 2010 forest fires only remained 6% of the initial area.About more than 200 ha of forest area is reduced in the forest area in the study area every year.The lands after 2010 tend to become plantation lands.Plantation land cover increased by about 90% during 2000-2019.
Based on interviews with Non-Governmental Organizations at the study site, it was stated that the community around GLNP of Sekoci Lepan Resort cleared land by cutting down trees, cutting down undergrowth and then burning the trees they cut down or the community called it "nyimas".Nyimas is done by the community to clear land and planted with plantation crops and dry agricultural crops.The large number of encroachment activities using the slash and burn method or Nyimas has led to the detection of hotspots and changes in land cover from forest to non-forest.
One way to restore the condition of forest cover back to its original condition of forest is to restore the ecosystem.Ecosystem restoration needs to consider the types of native plants that exist in the reference forest, especially the types of food for Sumatran Orangitans.The selection of the right plant species in accordance with the characteristics of the Sumatran Orangutan habitat is the key to successful ecosystem restoration.In addition, communities around GLNP need to be assisted in the ecosystem recovery process through a conservation partnership pattern.

Conclusion
Land cover change from forest to non-forest in Sumatran Orangutan habitat occurs along with the increasing incidence of forest fires as indicated by the highest number of hotspots.Land cover in the study area mostly changed from primary dryland forest to plantations.In 2000 there were 4,547 ha of primary dryland forest that had been degraded into open land, plantations and shrubs so that in 2019 only 483.51 ha of primary dryland forest remained in the study area.Communities around GLNP need to be assisted in the process of ecosystem restoration through a conservation partnership pattern to restore the function of the area, one of which is as a habitat for Sumatran orangutans.

Figure 2 .
Figure 2. Analysis of the Temporal Hotspot Annual in the Habitat of Orangutan Gunung Leuser National.
by the number of hotspots in Sumatran orangutan habitat from 2001-2019 occurred mostly in 2010.In 2010, hotspots reached 21 in orangutan habitat and the number tended to continue to decline until 2019 (Figure

Figure 3 .
Figure 3. Land cover changes in Orangutan habitat of GLNP of Sekoci Lepan Resort.

Figure 4 .
Figure 4.The trajectory of land cover change from forest land secondary shrub, plantation and open land: landsat natural color in the habitat of the Sumatran Orangutan (Pongo abelii) in GLNP of Sekoci Lepan Resort in years (a) 2000 (b) 2005 (c) 2010 (d) 2013 (e) 2016.
1,509.90 ha.Meanwhile, open land was only 22.22-96.92ha.In 2010, when hotspots were detected to increase sharply, the area of primary dryland forest in Sumatran orangutan habitat began to decrease.Primary dryland forest was converted into plantations covering 3.91 ha, open land covering 22 ha, and shrubs covering 245.83 ha.This forest conversion continued until 2019, resulting in a further decline in the area of secondary dryland forest.In 2016, the area of non-forest land cover increased, with plantations reaching 827.47 ha, open land 155.19 ha, shrubs 91.16 ha and secondary land forest 467.91 ha.In 2019 the area of primary dryland forest began to increase to 483.51 ha, plantations 608.35 ha, open land 70.24 ha and shrubs 379.59 ha.Land cover change after 2010 tends to lead to non-forest cover.The numerous forest fires detected in 2010 severely degraded forests and opened up access to forests for communities.Burned forests generally turn into open areas and then develop into shrubs.If there is access to human activities, then the next development of burned land becomes a managed area in the form of a plantation.