Deforestation Characteristic during a Period 2006 - 2020 over Tropical Forest in Central Kalimantan, Indonesia

1. Introduction

The tropics are seeing fast economic growth, which naturally puts great strain on the region's natural resources, most notably its forests. Pressures on the land have massive effects on ecosystem resilience, soil and water sustainability, and tropical peatland in Indonesia, all of which have significant social and economic effects. Reducing deforestation can generate multiple economic, social and ecological benefits by safeguarding the climate and other ecosystem services provided by forests. Understanding the relative contribution of different drivers of deforestation is needed to guide policies seeking to maintain natural forest cover [1,2,3]. Therefore, monitoring land status or condition is desired in the context of sustainable land use. The only practical and affordable way to get the essential data on the environment is through satellite remote sensing, given the geographical and temporal scales of relevance [4,5].

For at least the next 100 years, the biggest threat to ecological systems will come from changing land cover, one of the most significant drivers of environmental change. The serious degradation of the vast peatlands of Indonesia since the 1990s is the proximate cause of the haze that endangers public health in Indonesian Sumatra and Borneo, and also in neighbouring Singapore, Malaysia and Thailand. Moreover peatlands that have been drained and cleared for plantations are a major contributor to greenhouse gas emissions [6,7]. Remote sensing has been extensively utilized to track significant land cover changes, as those brought on by deforestation. But these are only some of the problems. Land cover change has two parts: those where the land cover is amended and those where the cover type is changed. The majority of remote sensing studies have concentrated on changes in land cover rather than those that could have an equal or greater environmental impact [8]. The soil and water systems are extremely vulnerable to changes in vegetation, and especially for forest covering, in tropical areas due to the large and frequently heavy rainfall as well as quick biochemical and mineral breakdown processes [9].

Based on studies by [10,11], deforestation is affected by policy, social economic, season of event and spatial aspects. The rate of deforestation strongly correlated to location, distance from village or city, road accesses and connectivity [12]. As result, the intensity of deforestation greatly varies between different location, regions, and period of time [13]. Some researchers analyzed that deforestation in Indonesia strongly influenced by legislation and law, and political setting [14].

Impact of deforestation is huge and covered multiple aspects including economy, biodiversity, and local communities’ livelihood [15,16]. Global communities are also affected by the deforestation as it accelerates climate change [17]. Furthermore, concern rises due to the increase of environmental disaster associate to climate change such as flooding, hurricane, and dryness [18,19,20,21]. Among anthropogenic activities, Land Use and Land Cover Change (LULC) and deforestation are the main triggered of biodiversity decline. The alteration of forests into plantation or cultivated area has created fragmentation and loss of habitat and resulted decline in biodiversity on earth. Furthermore, loss of biodiversity leads to loss of ecosystem services such as climate regulation, water purifying and many forest products [22].

Indonesia particularly Central Kalimantan has a central role in climate change mitigation due to its large forest cover [16,23,24]. As the largest province in Indonesia, Central Kalimantan owns more than 7 million ha forest cover that accounted approximately 49% from the total area of Central Kalimantan. On other hand, this province is also recognized as the largest Green House Gases (GHGs) emitter produced from deforestation and forest fire during a period 1990-2015 [23]. Beside large forest cover, Central Kalimantan also consists of 30% peatland which is rich in carbon stock. The carbon stored in peat has a positive correlation with the thick of the peat [23]. Thus, mitigation program in Central Kalimantan should focused on decreasing degradation and conserving forest carbon stock. Such kind of program will significantly mitigate the production of GHGs.

Government of Indonesia (GoI) develops some programs and initiative as a mean to tackle climate change. The commitment of GoI in mitigating climate change is reflected in the National Determined Contribution (NDC). Indonesia has strong commitment to reduce GHGs emission by 29% unconditionally and 41% with support from international funding. Some programs include Reduction Emission from Deforestation and Forest Degradation plus (REDD+), low carbon development program, peat restoration program and revegetation [25,26]. The program is run by various sectors encompassing government institutions, NGOs, private sector, universities, and local communities.

The management of areas, especially forests, has an influence on the occurrence of disasters in Central Kalimantan. Most of the disasters in Central Kalimantan were caused by anthropogenic activities such as the conversion of forest areas and damage to river basins. Natural disasters that often occur in Central Kalimantan in 2020 are floods and forest and land fires, while the types of natural disasters that rarely occur are landslides, tornadoes, and high tides. Floods most frequently occur in Kotawaringin Barat and Seruyan Districts, while forest fires in 2020 are relatively rare. The number of residents affected by floods in 2021 was recorded at 370,004 people spread across 725 villages/wards throughout Central Kalimantan. Forest and land fires have been relatively rare since 2020, one of the reasons being the high rainfall throughout the year and the short dry season [27,28,29,30].

Central Kalimantan Province, through various schemes has attempted to contribute to the achievement of emission reduction target or NDC. With a significant forested area, Kalteng has great opportunities in mitigating climate change in Indonesia. However, there is much that needs to be done, including preparing an emission reduction strategy, institutional strengthening, and the preparation of Forest Reference Level (FRL) using the latest methods according to guidance developed by the Ministry of Environment and Forestry [23,26].

Identify and characterize the cause of GHGs emission is crucial in determining the mitigations strategy. For instance, deforestation as the main cause of GHGs emission in Central Kalimantan need to be identify, measure and classified in order to find the best strategy to slow down the deforestation and rehabilitate degraded forest. Another benefit by characterized deforestation is the support of land-based data to measure the target of mitigation programs [31,32,33]. By implementing these approaches, the probability of achieving the NDC target will increase. The study aims to characterize deforestation in Central Kalimantan by assessing the trend of deforestation, the location, and the cause of deforestation.

2. Materials and Methods

2.1. Research Setting

This research was located in Central Kalimantan as unit analysis. Based on Indonesian Internal Affair Ministry Degree Number 58 in 2021, Central Kalimantan cover an area of 153.413,06 km², that divided into 13 Districts and 1 Municipal (shown in Figure 1). In 2021, the total residents of Central Kalimantan Province accounted for 2.70 million with the rate of resident increments 0.90% [29,30].

Central Kalimantan has a tropical climate with the temperature ranged from 21.2⁰ C to 34.8⁰ C [34,35,36,37]. The sunlight available abundantly ranged from 52% - 69%, creating favorable conditions for agriculture and plantations. The condition of social and ecosystem condition influenced by the river. 11 big rivers and 33 small rivers found in Central Kalimantan and the Barito rivers is the longest river that reach 900 km length. The south part of Central Kalimantan is flat low land with altitude 1-9 meter above sea level. Whist the north side is mountain area and hilly contour. Beside rivers, the altitude and contour also have influence on the type of ecosystem. Peat swamp forest and low land forest dominated South area and high land dipterocarps forest is dominant at north side [30].

Central Kalimantan's ecosystem is heavily influenced by the presence of rivers. From a socio-economic perspective, rivers also play an important role for the community. In some areas where there is no land access yet, rivers still play an important role in transportation so that in general, many settlements for the people of Central Kalimantan are located on riverbanks. Rivers also play an important role from an economic standpoint, rivers where people catch fish, look for gold and provide water for their daily needs. There are 11 major rivers and 33 tributaries spread throughout the Central Kalimantan region. The longest river is the Barito River with a length of 900 km, while the shortest river is the Kumai River with a length of 175 km. Central Kalimantan contains about three million hectares of peatland which is one of the largest unbroken peatland in the world and located between 0º 45’ N and 3º 3’ S, between 111º and 116º E [30,38].

Based on the Central Kalimantan Provincial Spatial Plan for 2021, the total allocation for protected forest is 3,630,142 ha and 12,120,330 ha for productive forest area. As shown in Table 1, from the proportion of protected forest areas, the provincial government allocated 600,000 ha for Customary Forests and 35,627 for Grand Forest Parks (or Taman Hutan Rakyat/TAHURA). It is hoped that in the future the role of indigenous peoples in managing and conserving nature will be increased [30,39,40].

2.2. Data and Analysis

We used land cover maps issued by Ministry of Forestry and Environment (MoFE) Republic of Indonesia. The period time of deforestation analysis followed procedure of the 2^nd FRL of Indonesia, which are 2006 – 2020 [41]. However, the MoEF did not publish land cover maps of 2007, 2008 and 2010. Deforestation in this study defined as the conversion of natural forest into other land covers, this imply that the logging in plantation forest do not considered as deforestations, otherwise, the conversion of natural forest into plantation forest count as deforestation [23,25,42].

MoEF classified natural forest land cover into 6 classes: primary dryland forest, secondary dry land forest, primary swamp forest, secondary swamp forest, primary mangrove forest and secondary mangrove forest. Meanwhile non-natural forest cover classified into 15 classes: plantation forest, pure dry agriculture, mixed dry agriculture, dry shrub, wet shrub, savanna and grasses, paddy field, open swamp, fishpond/aquaculture, transmigration areas, settlement areas, port and harbor, mining areas, bare ground, and open water [43].

We calculated deforestation in each year by overlaying the landcover map of the previous year (T0) with the landcover map of following year (T1). Using ArcGIS version 10.2, we measured the conversion from natural forest category into non-natural forest category. We also identified the land cover post deforestation to tract the cause of deforestation. The interpretation of the Landsat LDCM (Landsat Data Continuity Mission) data served as the basis for the estimation of the deforestation rate for the years 2006 – 2020 [44]. Field observation was conducted to identify the land use type and validate the result from satellite images. Result from land cover change analysis then analyzed further using statistic descriptive to calculate the average deforestation each year and the standard error.

3. Results

Data indicated that deforestation rates in Central Kalimantan had fluctuated in each computation. This takes place because of the dynamic changes in land cover brought on by human activities that result in the loss of forest cover. In total, between the period 2006 – 2020 natural forest in Central Kalimantan has reduced 1.5 million hectares. Swamp secondary forest and dry secondary forest experienced deforestation the most, while mangrove primary forest and mangrove secondary forest less deforested (see Figure 3). The rate of deforestation fluctuated during the period of analysis, however in general showed a decreasing trend. As Table 2 shows between 2006 – 2009 to 2011 – 2012 deforestation decrease sharply, falling from 418,524 ha/year to 56,421 ha/year. The trend then rises slightly to 86,305 ha/year in 2012 – 2013.

Considering the rise and the down of the trend, deforestation in Central Kalimantan could categorized into decrease period and increase period. Decreased era occurred in period 2006 – 2012, 2013 – 2014, 2015 – 2016 and 2018 – 2020. On other hand, Figure 2 shows increasing trends take place in 2012 – 2013, 2014 – 2015, and 2016 – 2018. Interesting phenomena occurred between 2019 – 2020 where deforestation rate recorded negative 35,812 ha. This indicated that between this period covered natural forest is increasing.

Total rate of deforestation in Central Kalimantan was 117,445 ha/yr. Usually the process of deforestation initiates forest degradation, the change from primary forest into secondary forest. When the detriment continues, the secondary forest converts into other land covers such as plantation and agriculture (see in Table 3). However, deforestation also could happen from primary forest that change into other land cover type. Our analysis found that dry primary forest and swamp primary forest experienced deforestation. All natural forest criteria, mangrove forest experienced a relatively small rate of deforestation.

Analysis on the change of land cover, this research found that natural forest in Central Kalimantan had converted into 15 land use types. The dominant land use resulting from deforestation were shrubs, open area, plantations, and agriculture land. Besides that, natural forest clearing especially in swamp forest generates swamp area and water body such as lake and water pond.

The average amount of deforestation in each forest category is presented in Table 4. As we can see from that table swamp secondary forest and dry secondary forest had the highest deforestation rate 59,317.81 ha/year and 55,938.56 ha/year respectively. Mangrove forests suffered less from deforestation because mangrove ecosystem was less favorable for plantations. Large scale oil palm plantations or forest plantations require fertile soil with sufficient water supply, thus low land and dry land forest are favorable.

Of the 1.5 million natural forests that converted into other land use system 373,816.39 hectare were taken in peatland soil. On other words, as much as 24% of deforestation in Central Kalimantan targeted peat ecosystem that rich in carbon stock and as consequences, emit higher GHGs into the atmosphere. Figure 3 shows comparing the proportion of forest on peat soil and mineral soil, we found that forest in 2006 has slightly different from forest in 2020. In 2006 the proportion of forests on peat soil was to some extent higher than forest on peat soil in 2020.

Figure 3. Comparison of deforestation on mineral soil and peat soil between 2006 and 2020 in Central Kalimantan (Indonesia). This figure shows that mineral soil is more desirable than peat soil due to forest clearing for various purposes.

Figure 3. Comparison of deforestation on mineral soil and peat soil between 2006 and 2020 in Central Kalimantan (Indonesia). This figure shows that mineral soil is more desirable than peat soil due to forest clearing for various purposes.

4. Discussion

This research found that most of deforestation in Central Kalimantan within range time 2006 – 2020 arisen in secondary swamp and dry forest, which is located mostly at low land area in south part as shown in Figure 4. This finding is consistent with the finding that from 2010 to 2015, just 18% of forests were replaced by plantations, down from 54% between 1995 and 2000. Additionally, it is estimated that 30.2 million hectares of non-forest land across the country match the biophysical requirements for oil palm development [12,45].

The low land forest is inhabited more than high land parts. In addition, low elevation, access and soil condition make lowland forest of Central Kalimantan favorable for oil palm and timber plantations [42,43,46,47]. Protected forest in lowland Kalimantan decreased by 56% in period of 1985 – 2001 [46]. The rate of oil palm plantation expanded was 450,000 ha/year and replacing forested area in lowland area [42,45].

As of 2015, Central Kalimantan, the largest of the five provinces in Kalimantan/Borneo (~15.3 million hectares), still had the third-largest relative forest cover (~49% of the total provincial area), the greatest absolute forest cover (~7.5 million ha), and the highest percentage of forests (~7.5 million ha). Additionally, it is the province that contributed the biggest percentage (38%) of all emissions from deforestation for the whole analyzed period from 1990 to 2015 [23,30]. Central Kalimantan has two national parks in the lowland area, Sebangau National Park, and Tanjung Puting National Park. The two protected areas play as bulwark, holding and resisting deforestation. However, concern arises for the conservation of these two national parks since rapid deforestation occurred in surrounding and buffer zone areas.

The deforestation rate was relatively high in the period 2006 – 2011 because of policy and development priority from the government. During this range of time, the government is creating investment ambience, high incentive and attractive leases inviting investors to develop large scale oil palm and timber plantations [48]. In comparison to what actually happened, it was estimated that a European ban on high-deforestation palm oil from 2000 to 2015 would have resulted in a global price premium of 8.9% on low-deforestation palm oil, preventing 21 374 ha (1.60%) less deforestation and 21.1 million tCO₂ (1.91%) less deforestation-related emissions in Indonesia [41,49].

Oil palm is a lucrative and highly profitable commodity and has become the main reason for the expansion of this commodity in Kalimantan. It works closely with the cooperative sector and individual farmers, producers of palm oil production (Indonesia is the world’s largest producer and plans to increase its production up to 40 million tons annually by 2020) [50]. After 2011, deforestation rate slowed down, following moratorium policy. Government banned the establishment of oil palm plantation on primary and peatland [41]. However, deforestation rose again between 2015 – 2019 as a result widespread forest fire that triggered by ENSO (El Niño–Southern Oscillation) condition [51]. It has become obvious that the incidence of more frequent ENSO events, coupled with major land development projects that involve drainage of the surface peat, is leading to an increased risk of repeated fire events in tropical peatland areas [34]. Furthermore, forest fires are an important cause of environmental alteration and land degradation or conversion through human activities.

The combination of degraded ecosystem generated from previous deforestation and long dry season caused forest fire uncontrolled. Even though Kalimantan's deforestation and emission rates have decreased overall from 1990 to 2015, this trend is not uniformly present across the five provinces. Even the rates in West and North Kalimantan appear to be rising. Thus, each province on Kalimantan Island has a different chance of meeting its carbon reduction goals [23]. After 2019, the deforestation in Central Kalimantan slowed down and even negative that associated with the absence of long dry season and the occurring of COVID-19 pandemic. But otherwise, evidence reveals that the COVID-19 epidemic has prompted illegitimate, opportunistic forest cutting and mining in tropical nations, endangering forest ecosystems and the inhabitants that depend on them [52,53,54,55,56,57].

Considering the negative effect of deforestation, recently The Government of Indonesia launched program called FOLU Net Sink. This program aims to sequestrate GHGs bigger than the emission from forestry and other land use sectors. The goal of FOLU net sink articulate in 5 main strategies: reduction emission from deforestation and forest degradation, establishment of forest plantations, sustainable forest management, forest rehabilitation and management of peat ecosystem[30,58]. Forest vegetation and soils continue to be important on carbon sinks, even though deforestation and forest degradation contribute to around 17% of the world's greenhouse gas emissions. Together, tropical and subtropical forests hold more than half of the carbon dioxide (CO₂) in the atmosphere.

The result of this research may contribute to the achievement of the Indonesia NDC by inform the decision makers about the characteristic of deforestation in Central Kalimantan as the largest province in Indonesia. Additionally, the primary causes of land-use changes are the increase of agriculture and deforestation. Given that peat swamp forest ecosystems in Central Kalimantan also could support extraordinarily high biodiversity and enormous amounts of carbon, deforestation in this area has the potential to have negative effects on the entire planet [59,60]. Research on the causes of the unsuccessful forest law enforcement policies and initiatives over the past 20 years, beginning with the first Forest Law Enforcement, Governance and Trade conference held in Bali in 2001, would help Indonesia's efforts and those of other nations [42,50,61].

5. Conclusions

Deforestation in Central Kalimantan as the largest province in Indonesia in the period 2006 – 2020 has shown a decline trend that influenced by policy and anthropogenic activities. From the total of 1.5 million ha forest loss within the analysis period, deforestation mostly occurred in peat swamp and dry secondary forest were human activities relatively high. Deforestation resulted in degraded areas such as shrubs, open areas and savanna and cultivated systems including agriculture and plantations.

Government policies, especially regulations regarding the eradication of illegal logging, forest and land fires, social forestry, carbon economic value, and the involvement of all forestry related stakeholders are at least able to reduce deforestation and changes in land use in the study area from forest to non-forest. The finding of this research could be used as a base to determine the target location for rehabilitation strategy and approach to prevent further deforestation.