Plant Species Richness After Revegetation on The Reclaimed Coal Mine Land of PT Adaro Indonesia , South Kalimantan

The focus of monitoring was the plant purposely cultivated because after re-vegetation, there were a very few of other plants growing naturally on reclimed coal mining area which were recorded, whereas these plants had important values. The research aimed to record all plants and to identify predominant plants over the reclaimed land of PT Adaro Indonesia. There were four sampling locations with 13 squares of 50 × 20 m on each location established and 2 on each square there were 5 plots of 2 × 2 m plotse made. Both plant species and its individual number of woodyplant saplings were recorded on each square, so in each plot, there were small species and its individual number of either woody-plant seedlings or non-woody plants (herbs/shrubs, grasses, ferns). The relative density and the relative frequency of woody or non-woody plants were summed to obtain the important value index (IVI) of each successional stage. There were 107 plant species consisting of 32, 43, 27, and 5 species of saplings, seedlings/herbs/shrubs, grasses, and ferns respectively. From those species, 16 species of woody plants and 2 species of herbs were planted purposely, other species grew naturally and even some of them were dominants. Either the number of plants or the dominating plant is varied according to the sampling location and the growing stage.


Introduction
Almost all coal minings in Indonesia use open mining system.The system converts the landforms and influences the biotic components (plants, animals), the abiotic components (physical, chemical), and the community (social, economics, culture).According to Subowo (2011), open coal-mining should be conducted carefully, due to the conversion of the landform, the damage of soil structure, the lack of top soil, the change of top soil ecosystem equilibrium, the decrease of land productivity, and the reduce of the environmental quality.
Based on Perjanjian Karya Pengusahaan Pertambangan Batubara (PKP2B) with Indonesian Government, PT Adaro Indonesia, the coal-mining company operating in Balangan Regency and Tabalong Regency, South Kalimantan Province, commits to reduce the negative impact of coal mining as maximum as possible.Basically the commitment is an obligatory and has to be realized by all coal-mining companies.After mining coal, the company has to reclaim the ex-coal-mining area and then conducts re-vegetation on this area.The plants for re-vegetation have to fulfil the conditions of government's regulations.The development of vegetation is monitored periodically suitable with the guidances mentioned in the environmental documents.Monitoring results are reported to the related institution (Ministry of Environment, Ministry of Forestry).
The main focus of environment monitoring by the coal companies in Indonesia is the plants planted purposely.Not many plants growing naturally after re-vegetation are recorded.In fact, such plants are not less important than the plants for re-vegetation.The research was conducted not only to entirely record all plants growing after re-vegetation on the reclaimed coal mininge land, but also to identify the predominant ones based on the successional stage.
Data on plants after re-vegetation is necessary.They can be used as an initial standard relation with what the company will do or what it has to do later.In the other words, it is necessary to develop a standardation to evaluate the success of re-vegetation and to soundly plan the next treatments (planting, replanting, enriching, maintaining) on the reclaimed land.
Data were collected in December 2013 on the reclaimed ex-coal-mining area of PT Adaro Indonesia.There were four sampling locations representing the area.The coordinate of the sampling locations and the date of planting were presented in Table 1, but the positions were shown in Figure 1.square and the others were on each corner of the square.Data recorded on each square were about both the plant species and the number of sapling species, but on each plot, the data were about the plant species and the number of seedling species for woody plants and herb/bush, grass, or fern for non-woody plants.The initial survey showed that no woody plant was pole (diameter 10 − < 20 cm) or even tree (diameter ≥ 20 cm).The existing woody plants were seedlings (height < 1.5 m) or saplings (height ≥ 1.5 m with diameter < 10 cm).
Data were analyzed to obtain important value index (IVI) for each growing stage.IVI of seedling is the sum of RD (relative density) and RF (relative frequency).The similar way is for both IVI of sapling and IVI of non-woody plant.The formulas are as shown in Equation [

Results and Discussion
There were 107 plant species found in four sampling locations namely 32 woody sapling species, 43 species of seedlings/herbs/shrubs, 27 species of grasses, and 5 species of ferns (Table 2).From this number, there were 16 woody plant species and 2 species of herbs which were proposely planted.The others were the wild plant species which grew naturally.Plant species number varied according to the location and the growing stage (Figure 2).The number of species of Location 4 (64 species) was the highest of all locations, where the number of species in Location, Location 2, and Location 3 was 59, 58, and 54 species, respectively.
The plant species number in the reclaimed ex-coalmining area of PT Adaro Indonesia was relatively higher than the research results on the other coal mining areas.Akbar et al. (2005) identified 11−16 understorey and seedling species under stands growing on the reclaimed areas of two coalmining companies in South Kalimantan.Adman et al. (2012) recorded 58 plant species on the pre-coal-mining area in East Kalimantan.Solviana et al. (2012) found 6 seedling species and 43 sapling species on the pre-coal-mining area, but 5 seedling species and 10 sapling species on the post-coalmining area in West Sumatera.Hilwan et al. (2013) found 24 understorey plant species under 6 year stands; 22 species under Enterolobium cyclocarpum stand and 17 species under Samanea saman stand on the reclaimed coal mining land in East Kalimantan.Wiryono and Siahaan (2013) recorded 16 understorey plant species growing under 1.5 year old Gmelina arborea stand of the coal mining land.In spite of the different condition, approximately one year after the eruption of Mt.Merapi, Sutomo and Fardila (2013) found 72 species in the burnt site and 79 species in the unburnt site.
The plant species can grow and develop on the reclaimed land, because their seeds, rhizomes, or seedlings are supposed to be present or dormant on the surface and in the top soil.Those grow slowly as top soil is returned to the excoal-mining area.If the environment supports, they will form the complete individuals and even simultaneously a forest ecosystem.Gulshan et al. (2013) state that soil seed bank reserves viable seeds present on the surface and in the soil and provides an immediate and main source of propagules for recruitment after disturbance.Zhang et al. (2013) conclude that firstly, plantation soil seed banks are the potential for regenerating understorey vegetation.
Thirdly, they are dispersed after being transported by human activities and by animals which have high mobility, such as insects, birds, and mammals.Fruits of Melastoma, Ficus, Vitex, and grasses are diets for birds, whereas those of Trema and Passiflora are diets for small mammals.Seeds are dispersed to other locations by frugivore birds, such as Pycnonotus (Spiegel & Nathan 2007;Kunz et al. 2008;Kerdkaew et al. 2014) through faeces or vomit.In Nigeria, seeds of Ageratum conyzoides, Amaranthus spp., Centrosema pubescens, and C. rotundus are disseminated to other areas through the faeces of ruminant animals (Jolaosho et al. 2006).
Based on dispersal mechanism, vegetation surrounding the mining land, the land where top soil and overburden are piled temporarily, should be in a good condition.The vegetation could be a source of both seeds and seedlings.According to Boer (2009), the primary forest surrounding the reclaimed land is a source of species which plays an important role for succession and accelerates the growth of plants on the area.Widyati (2011) stated that the healthy forest could be developed to produce seeds of hyperaccumulator plants for neutralizing toxic metals ofex-coalmining area.Some planted plants were not recorded on the locations because of three causing factors.Firstly, the plant died or did not grow, because it was not able to adapt to the reclaimed land which was marginal.It was no cover crop, lack of organic matter, and lack of nutrient.The health of plant would be disturbed, if land nutrients, i.e.N, P, K, and Ca, reduce (Setiadi & Adinda 2013).Lack of P constrains the development of new plant species or natural succession (Yassir & Omon 2003).Secondly, there was no plant on the sampling plot/square.Plant could be present, but it was on outside plot/square.Thirdly, plant was recorded with other name, because it was morphologically similar (particularly in seedling or sapling) to other plant which was known by a researcher.
On the other hand, a lot of plant species growing naturally The development of plant Plants planted purposely (woody plants were mentioned on the board which was stuck into the ground of the location, but no non-woody plant was) 3) The plant's name written on the board was the Indonesian name, including akasia and eukaliptus consisting of 2 species each.4) No board was on Location-4.5) The bold number is the highest IVI.█████ JMHT Vol. XX, (3): 150-158, December 2014EISSN: 2089-2063 DOI: 10.7226/jtfm.20.3.150 were able to grow and develop in less than 2 years after reclamation and re-vegetation.Even on the suitable location, those were most noticeable on the location as shown with the highest IVI (Table 2).The predominating plant differed according to the successional stage and the location.The predominant plant of Location-1 was Cassia siamea as woody plants, Crotalaria micans as herbs, Cyperus difformis as grasses, and Lygodium scandens as ferns.On Location-2, the predominant plants in accordance with the successional stage were respectively Paraserianthes falcataria, Pueraria phaseoloides, Paspalum distichum, and Dicranopteris linearis.On Location-3, the plants were Sesbania grandiflora, C. micans, P. distichum, and on Location-4, the plants were Leucaena glauca, Melastoma affine, E. dulcis, D. linearis.There was no fern on Location-3.
In general, the reclamation area is categorized as a marginal land due to various limiting factors for biomass production such as low soil pH, very low P O , and high Al 2 5 saturation (Table 3).However, the soil is potentially good enough to supply water and air for root growth as indirectly showed by its soil texture of loam.
Many plants growing naturally are positive for land surface covered and protected from rainfall which can easily break the soil to be smaller particles and transport them to a lower area.Both the physical and the chemical properties of lands are getting better.The bond of soil particles will be strong so that erosion reduces.The plants provide the various organic matters with various concentrationsas a result the land fertility improves.
The variety of plants triggers the variety of micro-climate under the plants and accelerates the animal biodiversity.The vegetation development is influenced by duration of ex-tinmining and the changes of soil both physical and chemical properties determine biodiversity of soil namely mesofaunas and macrofaunas (Hilwan & Handayani 2013).The longer age of vegetation is the more increase of organic matter and the Collembola's density (Nurtjahya et al. 2007).As vegetation is near 3 years old, the soil biology is getting  better; worms (Lumbricus sp.), termites (Macrotermus sp.), and ants are present (Yassir et al. 2011).However, plant species developing nearly 2 years after revegetation actually have not completely covered the area.Some parts of the reclaimed land were not covered.Plants, even understorey could not able to cover the area because of top soil which was not scattered evenly or not sufficiently enough to cover the surface of land.Top soil was also getting thinner and thinner then it was soon unavailable on the land, because it was eroded during the land open.The erosion paths were extremely obvious, moreover on the slope.
Other identified plants were Nepenthes mirabilis and Jatropha curcas.The Nepenthes grew naturally on Location 4 and Jatropha was planted on Location 3.However, both of -1 plants were outside of the sampling plots squares .A lot of Nepenthes were found in an area which was lack of nutrient (N, P, K), acidic soil (pH 2−4.5), and high humidity (Ellison & Gotelli 2001;Mansur 2006;Mardhiana et al. 2012).Jatropha is a pioneer plant and able to adapt to the environment which is ex-tin-mining land (Gedoan et al. 2011).
Land rehabilitation and re-vegetation remain necessary, particularly for opening spots of the reclaimed land.Land rehabilitation is directed to optimize top-soil availability, improve nutrient concentration or soil fertilization, and minimize erosion.The thickness of top soil in a reclaimed land should be more than 20 cm (Subowo 2011).The land fertility should be improved by fertilizing, liming, scattering organic fertilizer (Subowo 2011;Yassir et al. 2011), and increasing organic matter (Hadi & Sudiharto 2004;Subowo 2011).
Revegetation is directed to accelerate land covering, accelerate the plant growth, increase the species diversity, and conserve the local species, so land supports many important purposes.Oxygen cyclic operates and then oxygen is obtained chiefly and easily.There are potential plants functioning as hyper-accumulator and playing a role in phyto-remediationsuch as Ipomoea sp., Azolla, and Limnocharis flava for accumulating cyanide, Mikania cordata and Azolla for accumulating Pb (Juhaeti et al. 2005); and Brassicaceae family for accumulating more than one toxic metal (Gratao et al. 2005).In addition, the area could be developed as a habitat for many mammals (Rustam & Boer 2007), orangutan and birds (Puslitbanghutka 2009).In East Kalimantan Province, the reclaimed coal mining land which was revegetated in 16 years ago forms forest ecosystem supporting Pongo pygmaeus, the biggest non-human primate in Indonesia (Mukhtar & Heriyanto 2012).The similar case happens in South Kalimantan Province.The coal mining land of PT Adaro Indonesia (Paringin Site) that had also been reclaimed and re-vegetated in more than 16 years ago becomes a suitable habitat for proboscis monkey Nasalis larvatus, the non-human primate which is endemic to Borneo (Soendjoto & Gunawan 2012) and 69 avifauna species as well (Soendjoto & Riefani 2014).
There were 107 plant species growing on the reclaimed coal mining land in less than 2 years after re-vegetation.Eighteen of them were purposely planted, but others were grown naturally or as natural regeneration.The number of both plant species and the predominant species is varied according to the location and the growing stage.

2
On each location, 13 squares of 50 × 20 m were established systematically, and on each square, 5 plots of 2 × 2

Table 1
Coordinate of sampling locations and date of planting

Table 2
Plant species and its IVI in each sampling location

Table 3
Soil properties of each location