Ex situ genetic conservation of Gonystylus bancanus (Miq.) Kurz in PT. Arara Abadi, Riau, Sumatra

Ex situ genetic conservation refers to the conservation of species outside their natural habitats. In the case of Gonystylus bancanus (Miq.) Kurz, an endangered species listed on CITES Appendix II and the IUCN Red List as Critically Endangered, ex situ conservation effort has been undertaken by PT. Arara Abadi in Riau, Sumatra collaboration with the Centre for Forest Biotechnology and Tree Improvement Agency. This initiative aimed to preserve the genetic diversity of G. bancanus and ensure long-term survival by reducing the risk of extinction caused by habitat loss and other threats., Genetic material from G. bancanus populations in Sumatra and Central Kalimantan was collected during 2012 to 2016. The ex situ genetic conservation was established in PT. Arara Abadi, a private forest company. Each population was planted in two sites and each plot initially consisted of 456-546 plants covering an area of 1-1.3 hectares. After three years, the G. bancanus in ex situ conservation plot exhibited better growth in open areas than shaded ones, highlighting the species’ preference for exposed environments. The successful growth up to three-year-old plants demonstrates the effectiveness of ex situ conservation efforts of the G. bancanus and suggests the potential for future reintroduction or restoration programs.


Introduction
Gonystylus bancanus (Miq.)Kurz (Thymelaeaceae) also known in Indonesian as ramin, is a critically endangered tree species found in Southeast Asia [1].It is a large tree species which was one of the most abundant species of peat swamp forest in Sumatra and Kalimantan, Indonesia [2].G. bancanus wood is a valuable commercial wood mainly for furniture, interior decoration, stick, frames and other products because of its luxurious appearance, good wood properties and easy to work [2,3].The very high demand for the wood led to over-exploitation of the G. bancanus timber during the 1980s to early 2000s.Global concerns on the status of natural G. bancanus populations have led to the listing of this species on Appendix II of the Convention on International Trade of Endangered Species of wild flora and fauna (CITES) in 2005 [4] to reduce the pressure on the population in the natural distribution.Since 2018, G. bancanus is categorized as Critically Endangered A2cd ver 3.1 by the IUCN Red List of Threatened IOP Publishing doi:10.1088/1755-1315/1315/1/012019 2 Species due to the massive decline of timber and as well as a decline in the forest itself, its poor natural generation and slow rate of growth, habitat degradation, forest fragmentation and land clearance [5].
Conservation of the G. bancanus is priority in Indonesia and requires much effort, both in situ conservation and ex situ conservation strategies.Ex situ conservation is a complementary approach to in situ conservation, and the two strategies are often used together to achieve the best results in maintaining biodiversity.This paper presents an ex situ genetic conservation of G. bancanus initiated by the private sector, namely PT.Arara Abadi in collaboration with the government cq.The Center for Forest Biotechnology and Tree Improvement (CFBTI) Agency, The Minister of Environment and Forestry (Since Dec 2021, CFBTI has become The Centre for Forestry Instruments Standard Assessment).

Location of Study
Ex situ conservation plots of G. bancanus were established in the concession area of PT Arara Abadi -Rasau Kuning District, Siak, Riau Province.[7] have described the site as follows: climate A based on the Schmidt and Ferguson classification with rainfall ranging from 1,937-3,484 mm (average 2,456 mm/year).The average temperature was 27.7ºC, with a maximum average of 29.3ºC and a minimum average of 26.4ºC; the average humidity was 68.7%, with a maximum average of 75.1% and a minimum average of 63.0%.In general, the soil type at the study site is Ultisols, with a texture of sandy loam to sandy clay loam.

Materials
G. bancanus in Indonesia is naturally distributed in peat swamp forests on the islands of Sumatra, particularly in the provinces of South Sumatra, Jambi and Riau, and on the islands of Kalimantan, particularly in West Kalimantan and Central Kalimantan.The collection of G. bancanus genetic material for the purpose of establishing genetic resource conservation areas is carried out in the natural distribution of the two islands.The population of Kalimantan is represented by the population of Central Kalimantan, while the population of Sumatra is represented by the populations of Riau provinces (Figure 1a).Some references indicate that G. bancanus flowers and bears fruit every year, but based on data and information obtained from the field, the flowering and fruiting season has changed, making it very difficult to find fruits when collecting genetic material.The genetic material collected is in the form of wildlings (Figure 1b).Information on the collection of genetic material is given in Table 1.

Methods
The first attempt to collect genetic material from the Central Kalimantan population was carried out in February 2013.The exploration was conducted in Tanjung Puting National Park, which was known as one of the natural distribution areas of G. bancanus in Central Kalimantan.However, only 335 wildlings were collected during the survey.According to local people and a Tanjung Puting National Park staff member who assisted the team in this survey, this was probably due to wildlings in the area being collected by other people, as the demand for the wildlings was high.G. bancanus stand contain a lot of wildlings with about 50-80 cm high.A total of about 2,000 wildlings were collected from 10 mother trees.Another population, Lahai, Kapuas, Central Kalimantan were experienced mass flowering and abundant seed production in the end of 2013 at ex. PT Kayu Lapis Indonesia.From this location 5,000 wildlings can be collected.The G. bancanus in Humus-Giam Siak Kecil, Bukit Batu, Bengkalis District, Riau has no flower or seed.Wildlings around 50 cm tall can be found in this area, and small newly germinated seedlings are limited.At this stage, collecting as many wildlings as possible from many unrelated mother trees in this area is the only way to capture the genetic variation in this population for establishing ex situ genetic conservation.In this exploration, 1,090 wildlings from 10 mother trees were collected from this population.The minimum number of mother trees to represent the population refers to [8] which is 10-50 mother trees.All wildings were transported to PT Arara Abadi.

Seedlings Production
The wildlings from the natural forest were maintained and propagated in the nursery until they were ready for planting (Fig. 2a).The green house was topped with 14% ultra violet plastic, and 60% paranet was added on top.The planting medium used was cocopeat: top soil = 2:1.NPK fertilizer was applied to accelerate plant growth.Vegetative propagation was applied with shoot cuttings technique (Fig. 2b).The cuttings were placed in a greenhouse with a temperature of 30.3°C, humidity of 72%, light intensity of 559.8 lux.Cuttings in the beds were covered with transparent plastic for 1-1.5 months depending on the condition of the cuttings.Once shoots appear, the lid is removed.G. bancanus plant propagation with shoot cuttings is constrained by the limited number of shoots available, where each stool plant only produces about 1 to 3 shoots per 3 months.Another problem that arises is when the size of the cut is large enough (diameter ± 8.0 mm) and has sprouted then the shoots will wither again.This is different when the cuttings used are still small.The success of shoot cuttings reached 85%.Seedlings are ready for planting when they reach 30-40 cm in height.

Establishment of Ex situ Conservation
The G. bancanus ex situ conservation plot refers to the third era genetic conservation concept, namely by planting a separate population system to prevent hybridization between populations, while maintaining individual identity within the population [9].The first step in establishing ex situ genetic conservation and demonstration plantations is site selection.The adaptability of G. bancanus to the site must be the main consideration and the stand should be able to a b produce reproductive material under the environmental conditions.Ex situ conservation stands of the species should be established in suitable areas potential to support tree growth that meets the objectives of the plantation.Access to the plantation should be reasonably easy for maintenance, protection and other essential activities.Genetic material collected from three G. bancanus populations (two from Borneo and one from Sumatra) was planted in ex situ conservation plots in Rasau Kuning District, PT Arara Abadi, Riau, Sumatra during 2014-2016.The three populations were established in three separated locations usinga strip planting silviculture system.Within location, each population was planted in two sites.Fertilizer was applied with KCa 2 kg/tree, CIRP 0.2 kg.tree-1 and NPK 0.1kg.tree-1.Information of the G. bancanus ex situ conservation plots is presented in Table 2. Light Intensity was measured using an Extech Instrumens Type HD 450.The value of light intensity (in lux) can be seen on the instruction board.Tree height was measured from the ground to the tip of the tree using a measuring pole (in centimeter).

Survival and growth evaluation Site 1: RSKH -9254
At this site the depth of peat is around 3 m with the dominant vegetation in the site is mahang (Macaranga triloba), meranti (Shorea sp.), Pasir-pasir (Stemonurus secundiflorus), kelat (Dillenia reticulata KING), Artocarpus and geronggang (Cratoxylon cuncatum).Stand conditions were dense with light intensity of 1154 lux.This site has the least light intensity compared to the other two sites (Table 2).The G. bancanus planted in this site is from populations of Tanjung Puting 1 (Central Kalimantan).Up to 3 years of age, the survival rate was 54.94% and the average plant height was 67.85 cm with height increment of 22.62 cm.yr-1 (Fig. 3).The low survival rate at this site is due to the fact that the planting was done under the shade of natural forest, which still has a dense canopy.At site 2, G. bancanus populations from Humus 1 and Kapuas 1 were planted.The dominant vegetation in the RSKH 930040 plot area (Rasau Kuning District) was mahang (Macaranga triloba), meranti (Shorea sp.), balam (Palaquium walsurifolium) and kelat (Dillenia reticulata KING) with a peat soil depth of less than 1 m.The water table was 30 cm.Mortality in these two plots was very high with survival rates at 3 years of age for Humus 1 and Kapuas 1 populations of 32.4% and 18.5% respectively or an average of 25.45% (Fig. 4).This was due to the dry season in October 2015 while planting took place in that month.During the dry season, the water table was 1.5 m high.In addition, a deep flood of over 1.5 m occurred in 2016 when the plants were still small.At 3 years of age, the mean population heights of Humus 1 and Kapuas 1 were 118.4 cm and 141.3 cm, respectively, or height increments of 39.46 cm.yr-1 and 47.10 cm.yr-1, respectively or two plots mean 43.28 cm.yr-1.At site 3, G. bancanus population from Tanjung Puting 2, Humus 2 and Kapuas 2 were planted.The dominant vegetation in plot area 51102 of Rasau Kuning District is mahang (Macaranga triloba), meranti (Shorea sp.), geronggang (Cratoxylon cuncatum) and kelat (Dillenia reticulata KING) with a peat soil depth of more than 4.5 m.The water table 90 cm high.Survival rates at 3 years of age for Tanjung Puting 2, Humus 2 and Kapuas 2 populations were 41.6%, 31.4% and 40.6%, respectively, or an average of 37.87% (Fig. 5).The survival rate is quite low because this site also experienced flooding for 2 weeks as in site 2. At 3 years of age, the mean height of Tanjung Puting 2, Humus 2 and Kapuas 2 populations was 154.8 cm, 142.1 cm and 123.8 cm, respectively, or a three-plot mean of 140.23 cm or a height increment of 34.74 cm.yr-1.Of the three locations mentioned above, the fastest height growth up to 36 months was the location of site 2 (43.28 cm.yr-1), followed by site 3 (34.74cm.yr-1) and site 1 (22.62 cm.yr-1).Our result was similar to previous study that the best increment of height G. bancanus was obtained in a rather open area site planting (light intensity between 35 to 65%) [10].The G. bancanus planted in PT.Diamond Raya Timber, Riau Province showed an average height of 34.24 cm.yr-1 with the site characteristics: depth of the peat is 3.5 to 5 m; height of water table was 0 to 15 cm; vegetation was secondary forest with light intensity of 40 to 80% [3].Therefore, the lowest growth of G. bancanus in site 1 was probably due to a dense shade of site that affected the less intensity of sunlight.This is because G. bancanus is a semi-tolerant species [11].Ramin growth in an open area site tend to become tolerant for light [12].

Figure 2 .
Figure 2. Seedlings (a) and cutting 2.5 year (b) of G. bancanus Survival was calculated by dividing the number of plants at initial planting by the number of plants at evaluation.Height growth and survival data were compared across the three sites at 3 years of age.a b a

Table 1 .
Genetic materials information used to genetic conservation plot

Table . 2
. Information the G. bancanus ex situ conservation plot at PT. Arara Abadi, Riau Parameters Measurement Parameters observed directly in the field were peat depth, light intensity level, tree height and survival rate.Peat depth was measured with a peat drill Eujkelkamp (in meter).