i Characteristic of Orangutan Habitat n Coal Mining Rehabilition Area in East Kalimantan, Indonesia

The majority of wild orangutans are found outside of the protected areas, including in coal mining areas which generally overlapping with orangutan habitat. Thereby, mining ensured a direct impact on orangutans. Opportunities orangutans to survive in the mining area depends on various factors, one of them is the ability of orangutan to adapt to habitat change. We investigated habitat characteristics in the coal mining area consist of land cover types, species composition, and the structure of vegetation. Data were collected from April to September 2014 in the coal mining rehabilitation area (CMRA) of PT KPC in East Kutai. Mining caused the natural habitat fragmented into smaller patches in the form of CMRA and natural forests remaining. The forest stand in CMRA compiled by the small trees of the same species and age class. It caused the canopy is not always continue. Food trees and nest trees were limited in CMRA. Exotic species dominated in CMRA, namely: Senna siamea, Falcataria moluccana, and Senna surattensis. CMRA is not the good habitat for orangutan if seen from the aspect of either structure or vegetation composition. The quality of habitat can be improved by modifying the structure and vegetation composition, build the ecosystem corridors, increase public awareness, and involve various stakeholders at the landscape level.


Introduction
Bornean orangutan faces a high risk of extinction in the wild due to ±78% of the wild population found outside of protected areas, namely: 29% in logging concessions, 19% in oil palm plantation concession, 6% in industrial timber plantation concessions, and 24% outside concessions (Wich et al. 2012). The main threats to the orangutan survival are habitat loss, habitat degradation, forest fires, habitat fragmentation, illegal hunting, lack of awareness, and climate change (Meijaard et al. 2001; . Ancrenaz et al. 2016) Based on spatial models, Struebig et al. (2015) predicted many of orangutan habitat is no longer suitable in the future because of climate change. The number of bornean orangutan population is not precisely known. Wich et al. (2012) estimated the number of bornean orangutan populations are 104,700 in an area of ±155,000 km², the populations predicted are continuously declining to 47,000 orangutans in 2025. If there are no right conservation efforts, within the next 50 years many populations will be decreased or become extinct (Abram et al. 2015). The combined impacts of habitat loss, habitat degradation, and illegal hunting have caused the bornean orangutan populations declined sharply so that the bornean orangutan has been upgraded from endangered category becomes ritically " " "c e " ndangered on the Red List of Threatened Species IUCN (Ancrenaz et al. 2016).
Expansion of the area for economic development in many sectors can not be prevented because the human population continues to increase. It poses a major threat to orangutans and another species, either through the direct cause such as hunting and killing as well as the indirect causes such as degradation and fragmentation of habitats (Meijaard et al. 2001;Hockings & Humle 2010;Soehartono 2009). The et al. coal mining areas in East Kalimantan developed rapidly after the weakening of the era of forests exploitation and the timber industr . Since that time, the mines sector has been a ies major driver of economic development in East Kalimantan. East Kutai Regency has the largest coal reserves (52.67%), followed by Kutai Kertanegara (21.01%), and smaller reserves distributed in other regenc /cities. Interpretation ies of Landsat imagery in 2014 showed that the land has been used for mining only 0.7% of 22,410.51 ha of the total area of East Kutai or ±20% of the total area of the mining concession permits. Although the mining areas are relatively smaller than oil palm plantations which reached 296,119.33 ha (±9.28%), the impact of open pit mining on biodiversity could result in tremendous damage.
Coal mining concessions in East Kalimantan are generally overlapping with orangutan habitat. Thereby, operations and infrastructure development ensured a direct impact on orangutans. Opportunities orangutans to survive in the coal mining area depends on various factors, one of them is the ability of orangutan to adapt, especially to changes in food resources. According to Campbell et al. (2008), foraging behavior and mating behavior can affect the fitness of animals directly, whose success is strongly influenced by moving behavior. In the habitats has changed, behavioral flexibility is very important for animals because it can improve the fitness of the animals that lived in the area (Reader & MacDonald 2003;Sol 2003). Psychological research showed that orangutans have the mental qualities to adapt to habitat changes, since orangutans are able to learn, make conclusions, set up and dismantle the equipment, have long-term memory, and it can understand the environment signs (Meijaard et al. 2001). In a certain degree, bornean orangutan (Pongo pygmaeus) has an ability to survive in the degraded habitat. For example, changes diet from fruit to an alternative food (fallback food) such as bark (Ancrenaz et al. 2007) and increases the terrestrial activity in a habitat which impaired canopy of anthropogenic (Ancrenaz et al. 2004). KPC (2011) and Rayadin and Spehar (2015) have confirmed the existence of orangutan population in the coal mining area, especially in any coal mining rehabilitation areas in East Kutai. During our research, we have documented 39 different individuals in the nine rehabilitation areas. They consist of 17.95% adult males, 38.45% adult females, 10.26% adolescents, and 23.08% infants). It's confirmed that bornean orangutan has an ability to adapt in those areas.
The aim of this research is to describe the characteristics of bornean orangutan (Pongo pygmaeus morio) habitat in the coal mining rehabilitation areas about changes in land cover, floristic composition, forest structure, food plants, and nest trees.  Figure 1).

Data collection
Variables which are used to describe habitat characteristics of orangutan habitat in CMRA consist of land cover types, species composition of trees with diameter at breast height (dbh) ≥ 5 cm (excluding shrubs), the vertical and horizontal structure of forest stand, orangutan food tree, and orangutan nest tree.
38 Figure 1 Location of coal mining study area. The data of land cover types was obtained through remote sensing, the method used was a visual classification to four Landsat imagery 8 path/row 116/59 acquisitions February 7th and March 11th, 2014 and path/row 116/60 acquisitions February 7 and July 1st, 2014. Four imageries were used to eliminate the appearance of clouds and cloud shadows on each imagery.
The trees composition data collection used a botanical sample plot of 0.2 ha (100 m x 20 m) in each CMRA. Sample plots were developed purposively. Each plot was subdivided into 20 m x 20 m quadrat for easy sampling of trees (dbh ≥ 5 cm). Thus, we used the total botanical plot of 0.4 ha and quadrats of trees were 10 quadrats. The total area of 0.4 ha sample plots have been considered to represent the condition of the forest stand was relatively homogeneous. We have recorded the species, number, and dbh of all trees (dbh ≥ 5 cm) for each quadrat. We also recorded species of plants lifestyles/habitus other than trees found in the study area. An expert helped for identified species. If possible, we identified each plant to species level or to genera level when the species could not be identified. Most of the trees in CMRA is not difficult to identify the species because these trees were cultivated and their species were known clearly.
The structure data collection used the same botanical plot. We were determined the number, total height (h), diameter at breast height (dbh), height of clear bole (hcb), the height of maximum crown width (hmcw), and the crown width of all tree species in each quadrat (Harja & Vincent 2008). We measured dbh using a phi band. We measured h, hcb, mcw, and crown width using a laser distance meter and a tape measure. Crown diameter was measured in two perpendicular directions. Crown projection diameter was first measured along maximum crown width axis and then perpendicularly to this first direction. The average was used for crown width. The radius projection of crown measured with eight radiuses to get a more accurate prediction of crown width. Tree parameters to be measured can be seen in Figure 2.
The data of food tree for orangutan was obtained based on the direct observation, the worker interview, and observed the after-eating signs of orangutan. Data of nest tree obtained based on direct observation by looking at the existence of nests on trees. The data of food tree for orangutan is obtained based on the direct observation, the worker interview, and observed the after-eating signs of orangutan. Data of nest tree obtained based on direct observation by looking at the existence of nests on trees.

Data analysis
We used spatial analysis with the geographic information system to determine the characteristics of the land cover in the study area. Visual classification is used to classify the homogeneous appearance, and then we interpret based on the elements that are recorded on an imagery (color, hue, texture patterns, shapes, sizes, as well as their association with the other land cover). Vegetation analysis is used to determine the composition of vegetation, abundance and distribution of the nest trees, food trees, and other food sources.
Vegetation species diversity and its distribution are the useful variables to assess habitat quality. A good orangutan habitat is usually in the forms of small forest slot mosaic with its different species of woody plants, it also has species fruit trees. Vegetation analysis is used to gain species composition, the tree density (D), frequency (F), basal area (BA), important value index (IVI).

D of a species is a and
The count of the number of individuals of a species within the botanical plot. Afterwards, the sum of D is calculated in terms of species density per hectare.
F is the probability The or chance of finding a species in a given sample area. BA The per tree was formulated with 0.25 d in which d is the dbh 2 π and is the constanta (3.1416). BA (m ha ), was 2 -1 π The calculated by summing the BA of all trees found within the botanical plot.
IVI is the pattern of calculation used to determine the The dominant vegetation ecologically for each level of growth in every observation plot. It is the result of summation of relative density (RD, %), relative frequency (RF, %), and relative basal area (RBA, %) (Curtis 1959). RD = D of a The species/total D of all species × 100. RF = F of a The species/sum of F of all species × 100, The RBA = BA of a species/total BA of all species x 100.
The architecture profile analysis is used to obtain the description of vertical and horizontal structure of forest. The structure of forest stand was described in the form of architecture profile by projecting the result of tree measurement, the total height, clear bole, the canopy i.e., diameter, and the position of a tree in the botany plot. The parameters derived from measurement were processed by using the software SexI-FS (Spatially Explicit Individual-Based Forest Simulator), 2.1.0 version to describe the vertical and horizontal structure of forest stand (Harja & Vincent 2008). We divided the height of the canopy into 5 of high-class, namely: 5 m, 5−10 m, 10−15 m, 15−20 m, and >20 m. We also drew the canopy into five layers: A (> 30 m), B (20−30 m), C (4−20 m), D (1−4 m), and E (0−1 m) (Soerianegara & Indrawan 1998).

Results and Discussion
Overall study sites Coal mining area adjacent to the Prevab Orangutan Research Station of the Kutai National Park. Both locations are separated by the Sangatta River as the northern boundary of the Kutai National Park (KNP).  Taman Payau CMRA is reclamation planted in 1998 with an area of 162.74 ha, while Gajah Hitam CMRA planted in 2002 and it has an area of 22.97 ha. Based on Schmidt-Ferguson climate classification, study areas including type A is very wet. Annual rainfall was in the range of 1,549.5−2,993.4 mm with mean annual was 2,558 mm. The mean annual temperature was 26 ºC between 21 ºC and 34 ºC, -1 The normal wind speed was 2−4 knot hour (Ferisa 2014;KPC 2015).
nine During 2014, Gajah Hitam CMRA suffered wet months and moist months, the average rainfall per rain three day was 13.42 mm. Mean monthly rainfall in Gajah Hitam CMRA was 188.2 mm, ranging 73.0 mm ( rain days) from six in October until 376.5 mm (19 rain days) in December. Taman Payau CMRA has 10 wet months, moist months, one and dry months in 2014, maximum rainfall in December one (536.0 mm and 21 rain days), while minimum rainfall in October (35.0 mm and 3 rain days). These data were the result of measurement in the study site in 2014, derived from the Environment Department of PT KPC.

Land cover Interpretation of landsat coverage in 2014
showed that the orangutan habitat in the coal mining area has undergone constriction and fragmentation within a period of >30 years. Mining and construction of supporting infrastructure have changed the wet rain forest intact and compact into smaller and isolated patches. Mining activities have led partly of orangutan habitat were lost, and the remaining area is divided into smaller habitat fragment. Of the 90,938 ha concession area of PT KPC, the total area that has been mined is ±26% (24,553.19 ha). The land cover of the 26% PT KPC areas have been mined has presented in Figure  3 and Table 1.
Comparison of land cover by Sihombing (2012) in two periods (2002 and 2012) in the coal mining area of PT KPC showed the degradation of the land cover quality. It is evidenced by the increase in the total degraded area ( Table 2).
The combined impact of habitat constriction and fragmentation be able to cause the collapse of the ecosystem as a whole (Gunawan & Prasetyo 2003), this case applies to orangutan habitat in the coal mining area. According to Forman (1995), fragmentation begins with dissection, then perforation, fragmentation, and habitat attrition, which causing the habitat becomes unsuitable or have a low suitability. Habitat degradation in the coal mining area started with dissection when the road network built for coal exploration, followed by perforation when concession holders started exploitation coal. In line with the increased production capacity and growing extent of disturbed areas, the frequency of small bags habitat has increased, so fragmented habitats dominated the landscape in the coal mining area. Further small habitat remaining suffered attrition, become smaller and isolated.
Reclamation and revegetation by concessionaires led to the emergence of new bags habitat, it has the structure and floristic composition is very different from the natural habitat. Ultimately, coal mining operations have produced a landscape with some land cover types, namely: remaining natural forests, CMRA forest with trees dbh ≥5 cm, CMRA with small trees (dbh <5 cm), pit, road network, office area, water, etc.
Land cover changes have caused a large negative impact on the orangutans and another biodiversity. Despite massive habitat destruction occurred in coal mining area, orangutans are known to survive in patches of natural forest remaining and have confirmed colonize some CMRA. The remaining natural forests in the mining area generally have lost the big trees which are very important for the orangutan as food resources and place to build the nest. The structure and floristic composition in CMRA are tended to be similar, almost the same as the forest plantations. Floristic composition and structure of forest stands in CMRA will be described hereinafter.
Floristic composition Most of the total numbers of trees which frames the forest stand in Taman Payau CMRA and Gajah Hitam were trees from exotic species (79.83%) and there was only 20.17% of local species. There were at least 18 species of tree from 16 genera and 9 different families met in both botany plots. The both study plots are dominated by johar (Senna siamea) Johar has the highest density (405 trees -1 2 -1 ha ), the biggest basal area (2.15 m ha ), and the most prevalent distribution. Summary of botanical analysis of trees (dbh ≥5 cm) in Taman Payau CMRA and Gajah Hitam is presented in Table 3, while the analysis results in each CMRA is presented in Table 4 and Table 5. Some species of trees in Taman Payau CMRA and Gajah Hitam have a very low density and distributed randomly, that was why these species were not found in the botanical plot. A number of species found within study plot of Taman Payau are 9 species from 9 genera and 7 families, while outside the plot, there are 8 species of trees, namely: S. surattensis, Vitex pinnata, Acasia auriculiformis, Terminalia catappa, Swietania mahagoni, Delonix regia, Gmelina arborea, and Hibiscus macrophylla. Thus, in Taman  families. This number is more than that of research conducted by Rayadin (2012) which only found three species of trees within botany plot in which the width was the same as Taman Payau CMRA. The number of tree species found within the botany plot of Gajah Hitam were 11 species from 10 genera and 8 families, while outside the botany plot, there were eight species of trees, namely: A auriculiformis, Ficus sp., . Geunsia pentandra, Mallotus dispar, Neolamarckia cadamba, Samanea saman, Syzygium sp., and V pinnata.
. Thus, there were minimum 19 species of trees from 17 genera and 11 different families in Gajah Hitam CMRA.
The research results in CMRAs showed that the orangutan habitat were lack of tree species compared to its natural habitat. Niningsih (2009) recorded that there are 78 species consisting 59 genera and 35 families in natural habitat in Prevab Area KNP, while Wahyudi (2009) found there are 98 species from 82 genera and 38 families in that area. In general, orangutans prefer natural habitat, intact, and have the higher food availability (van Schaik 2001; Soehartono et al. 2009). The higher the diversity of vegetation, it will provide food more abundant and varied for orangutans. Changes in composition floristic ensured a serious impact on orangutans. In CMRA, only five of the 28 species that are orangutan food trees. Yet, five of these species were not the dominant in CMRA, even three species of them confirmed were not important food trees for the orangutan (Niningsih et al. 2016), it was because orangutan prefers fruits with soft pulp (Meijaard et al. 2001;Kanamori et al. 2010). Orangutans have to adjust their food composition on species available in the mining area to survive (Campbell et al. 2008). According to Suhud and Saleh (2007), if fruits availability is reduced in an area, the orangutan will migrate to other areas or they try to adapt to change their feeding behavior as an adaptation to environmental changes. Twenty three of the total 28 species found in the both CMRAs are cultivated and the others growing naturally. Trees growing naturally were pioneer trees, such as, Macaranga gigantea, M. hypoleuca, and Mallotus dispar. Soendjoto et al. (2014), recorded a lot of plant species growing naturally are able to grow and progressed in less than two years after reclamation and revegetation on the reclaimed coal mining land of PT Adora Indonesia, because their seeds, rhizomes, or seedlings are dormant on the surface and in the top soil. According to Whitmore (1975), the seed dispersion of pioneer tree species is very effective. Pioneer species is often characterized as having early and frequent flowering and the copious production of small and easily dispersed seeds (Swaine & Whitmore 1988). Pioneer species vary in a range of ecophysiological and demographic traits, yet many species successfully colonize and co-occur in the forest (Davies 1998). The pioneer species that grown naturally can use as an indicator that the succession in progress in CMRAs.
Non-tree vegetation in CMRAs are also the important habitat component for any wild animals as food source and cover. It was grew both cultivated and naturally. Whereby, the result its showed in Table 6.
Food plant Orangutans were primarily frugivorous, spending a majority of their total foraging time feeding on fruits ). The fruit was preferred over leaves and vegetable matter (Bastian et al. 2010). Orangutans in Danum Valley spent 60.9% of the feeding times on fruits (Kanamori et al. 2010    feeding on fruits (Bastian et al. 2010).
In CMRAs, most of the trees found in CMRAs are unusual crop for orangutan which eaten in its natural habitat. There were only species of trees is known as the five orangutan food tree in their natural habitat, namely, Croton argyratus, Syzygium Ficus M. gigantea G. sp., sp., , and pentandra five . However, it must be remembered that the species of trees were not the dominant species in that area. In addition, the trees were not the species of important food plants for orangutan. Therefore, it could be assured that the 5 species of trees were not the reliable species for orangutan to survive in CMRA.
Based on the direct observations and interview result several workers, it found that orangutan adapted to eat species of the trees growing there. Several species eating by orangutan, among others, johar ( sengon S. siamea), ( ), lamtoro ( ),

Falcataria moluccana
Leucaena leucocephala flamboyan ( ), akar belaran ( ), D. regia Merremia peltata kaliandra ( ), Calliandra calothyrsus Calopogonium caeruleum, Centrocema acutifolium and . It species were exotic species that are not found in the natural habitat of orangutan. The plants were also not the fruit trees which had soft flesh favored by orangutan (Meijaard 2001). et al. According to Ancrenaz et al. (2007), bornean orangutan species at a certain degree had an ability to survive at disturbed habitat by eating alternative/fallback food available in that area. For example, when the natural food was not enough, orangutan living within and outside the palm tree plantation and they ate young palm (Yuwono et al. 2007;Ancrenaz et al. 2010), orangutan living at and around the pulp and paper plantation ate the bark of A mangium (Denis . et al. 2010;Meijaard et al. 2010), orangutan living in the area of agriculture changed their active eating time and ate the crop yield that belonged the society, like star fruit, jack fruit, durian and pete (Campbell-Smith et al. 2011). Marshall and Wrangham (2007) define fallback food as foods whose use is negatively correlated with the availability of preferred foods. Fallback foods shape primate food processing adaptations, that the dietary importance of fallback foods is central in determining the expression of a variety of traits (Harrison & Marshall 2011). Bornean orangutans typically consume bark and leaves as fallback food in Borneo, while sumateran orangutans with greater importance of figs (Harrison 2009;Vogel et al. 2008;Wich et al. 2006). The behavior flexibility shown by orangutan seemed one of the adaptation ways towards the less productive forest in Borneo (Hockings & Humle 2010).

Nest tree
Trees are not only the important food sources for the orangutan, but they are also the important need as the place build a nest (Prasetyo 2007). According to et al. Santosa and Rahman (2012), there were three dominant ecological variables that influence the presence or absence of orangutan nests, namely, the distance of nest trees with nearby sources of feed, the number of food tree close to the nest, and the presence of food trees near the nest.
This research also identified species of trees used by five orangutan as nest trees in Gajah Hitam CMRA and there were eight species of trees in Taman Payau CMRA used as nest trees. Therefore, there were minimum 10 species of trees used by orangutan as nest trees in both CMRA (see Table 7).
The above result showed that in CMRA where there were lack of trees, orangutan used the trees growing there and orangutan did not specifically choose the species of trees used as nest trees. Rayadin (2013) agreed with this in et al. which species of johar ( ), the most dominant ones in S. siamea the research location was the most species of trees used by orangutan as nest trees.
In richer habitat of tree species, a number of trees used by orangutan as nest trees were more various. For example, the sub species of morio in KNP Prevab area used minimum 49 species of trees as nest trees and there were 80 species in Bhirawa forest, Kutai Kertanegara Regency (Niningsih 2009). In Sebangau Central Kalimantan, there were minimum 52 species of trees used as nest trees by Pongo pygmaeus wurmbii et al.

Pongo pygmaeus morio
Forest structure Orangutan is arboreal mammals spending their time mostly on the trees, like eating, drinking and sleeping. This behavior is very influenced by the structure of vegetation in their habitat. The structure of vertical of forest would affect the height of orangutan to do an activity and horizontal structure would affect orangutan significantly when orangutan moved.
Thoroughly, the density of trees with dbh ≥ 5 cm in Taman Payau CMRA and Gajah Hitam was 880 trees ha , the -1 average dbh ± 12 cm, basal area ± 14.96 m ha . Trees 2 -1 of of arranging the stand in CMRA were almost in the same age. Therefore, they tended to have almost the same diameter, height, and canopy.
(dbh ≤ 20 cm) Small diameter trees dominated significantly in . There were a lot number of trees with CMRA dbh 5.1−10 m CMRA, dbh >20 cm in both while trees with were in small percentage. This condition was very different from the natural habitat of orangutan in in Prevab KNP, which there were big size trees with The dbh >50 cm. distribution of from both can be seen in Figure  dbh CMRA 5. Taman Payau CMRA had tree density of ±655 trees ha , -1 the average dbh of ± 13.25 cm, basal area of ± 11.97 m ha .  Figure 6. Vertical structure of forest in the area of research was very different from the previous condition before there was a mining activity. This area was wet tropical rain forest which was very dense inhabited by orangutan (Meijaard et al. 2001). There were five layers of canopy in the natural habitat in Prevab Kutai National Park, ., A (>30 m), B i.e (20−30 m), C (4−20 m), D (1−4 m), and E (0−1 m) layers (Niningsih et al. 2016). At the moment forest stand in CMRA had only three layers of the canopy with C stratum as the top canopy layer.
Horizontal structure of stand was very important for orangutan because the ability of orangutan to move from one tree to another depended on the continuity of canopy. Canopy continuity was very determined by the density and diameter of canopy from trees in the same height class.
dbh ≥5 (Ferisa 2014;Niningsih et al. 2016). 7 Taman Figure presents the stand horizontal structure in Payau CMRA Gajah Hitam. and The figure shows the forest canopy in both that is not always continue because CMRA the trees arranging the stand were not dense enough and their canopy was not wide enough. Canopy discontinuity was also caused by the present of liana in In the natural CMRA. habitat of woody was the important orangutan, liana connecting equipment for oran utan to move if the canopy of g trees did not intersect each other (Richard 1952;Rijksen 1978).
Mentoko Prevab In the area of and , KNP, the trees forming the C stratum mostly associated with epiphytic and liana (Ferisa 2014).
Forest structure and support availability have important effects on orangutan locomotion (Manduell et al. 2012). Forest canopy discontinuity can certainly make orangutan go down to the to move f om one tree to another. ground r According to the increase of Ancrenaz et al. (2014), terrestriality would increase the risk of hunting and the new disease exposure because big ape was vulnerable towards most human disease. Moreover, it could be said that one of the reasons why still kept the arboreal bornean orangutan behavior was because orangutan wanted to decrease the risk of human activity exposure. Implication Orangutan habitat characteristics in are CMRAs very different from those of natural habitat.
is not the CMRA good habitat for if seen from the aspect of either orangutan structure or vegetation composition. Coal mining has removed the large trees are very important for the orangutan as the food resources, nest site, and as the tools to arboreal movement (Felton . 2003). et al Orangutan habitat in the coal mining area are fragmented into smaller patches, some of them suffered isolation (insularization). Fragmentation and isolation of patches can cause the ability of orangutans to move between patches is decreasing. Orangutans are isolated in the small patch is very susceptible to inbreeding depression, genetic drift, and other problems associated with small populations (Gunawan & Prasetyo 2013;Indrawan 2007;Aguilar 2008 CMRA is very lacking on fruit trees and habitat enrichment with the fruit trees can improve the quality orangutan habitat in the future. Ideally, the choice of plants should consider the ecological characteristics of the species (Dennis 2011), among other things: a food source has et al. been known, the food source for other species, fast growing species, as well as climatic and edaphic is suitable. Unfortunately, the most of the fruit trees which the natural food of the orangutan are unknown its ecological characteristics because it has never been cultivated or observed its increment and growth. The species of fruit trees recommended are the species is favored by orangutans but it is disliked by humans. Enrichment with tree species that its bark favored by orangutans is not recommended because of the tree which its bark consumed by orangutan will be death.
Sengkuang tree ( ) is one of the Dracontomelon dao species recommended for planting in the CMRA. Although the increment and age begin to bear the fruit of this species is unknown, sengkuang is the fruit which favored by the orangutan in the Prevab and Mentoko, K (Rodman 1977; NP Campbell 1992;Ferisa 2014). Sengkuang trees can found in almost all area of East Kalimantan, especially in riparian areas. It showed that sengkuang is suitable in edaphic and climatic. In addition, seeds of the sengkuang are not difficult to get. Figs ( spp ) also highly recommended. Figs are Ficus . most important food to many primates and the staple food for the orangutan (Mackinnon 1974;Rijksen 1978). Three species of ( , and Ficus F. rubiginosa F. uniglandulosa, F. pubilimba) were consumed most frequently by orangutans in Prevab area (Niningsih 2016).
Orangutan movement between habitat fragments assumed was very limited in this study and was not enough to prevent the effects of isolation. The company must make sure that each habitat patch, especially CMRA connect with the more spacious natural forests or other CMRA to prevent isolation. Orangutan needs the corridor to move from one patch to another patch (Luckett . 2004;Nasi . 2008).   Figure 5 The distribution dbh of trees in Taman Payau and Gajah Hitam.Taman payau ( ), Gajah Hitam ( ).
habitat patch isolated on the orangutan. Effective corridor is a corridor that has enough suitable habitat for the target species (orangutans) for lives permanently or passes normally (Harrison 1992). The minimum width of corridors for orangutans based on home range orangutans and sufficient to prevent the penetration of vegetation at the corridor edge (Harrison 1992). Construction of a corridor requires restoration as in low-quality habitat patches will be connected. The manager must plant the food trees and nest trees of the target species (orangutan) along the corridor (Bond 2003). Food trees, nest trees, and canopy connectivity are very important to consider in managing the corridor.

Conclusion
Coal mining operations caused the natural habitat of the orangutan which originally compact and intact fragmented into smaller patches in the form of CMRA and degraded  forests remaining that surrounded by large disturbed area. The structure of forest stands in the CMRA tended similarly and the forest canopy is not continued. It is because of the forest compiled by the small trees of the same species and the same age class. Exotic species dominate in the CMRA, no fruit tree and woody liana in that area. The most dominant species in the CMRA were S. siamea, F. moluccana, and S. surattensis. CMRA is not the good habitat for orangutan if seen from the aspect of either land cover as well as the structure and vegetation composition. The quality of habitat can be improved by modifying the structure of stand and vegetation composition, build the ecosystem corridors, increase public/workers awareness, and involve various stakeholders in the orangutan conservation at the landscape level. One of the ways recommended is to enrich with various fruit tree species whose fruit is favored by orangutan but contrary for the human. Habitat enrichment of tree species whose bark was liked by orangutan is not recommended.