Current Challenges and Prospects of Indonesian Non-Timber Forest Products (NTFPs): A Review

: Non-Timber Forest Products (NTFPs) management can lead to various beneﬁts for community livelihood and forest sustainability. However, such management has not been carried out optimally and sustainably in Indonesia, due to various limiting factors including ineffective policies, undeveloped cultivation technologies, and inadequate innovation in processing technologies. Further, the diversity of NTFPs species requires that policy-makers determine the priority species to be developed. Agarwood ( Aquilaria spp. and Gyrinops spp.), benzoin ( Styrax spp.), sandalwood ( Santalum album L.), and cajuput ( Melaleuca cajuputi Powell) are aromatic NTFPs species in Indonesia that forest-dwellers have utilized across generations. This paper reviews the current governance, cultivation systems, processing and valuation, and beneﬁts and uses of these species. We also highlights the future challenges and prospects of these NTFPs species, which are expected to be useful in designing NTFPs governance, in order to maximize the associated beneﬁts for the farmers and all related stakeholders.


Governance
The governance of NTFPs is often considered to be embedded in forestry governance in general. In contrast, the management of NTFPs has some different characteristics, associated with the number of parties or the human resources involved; the uncertainty of land or trees rights; traditional cultivation, harvesting and processing technologies; the short storage time of the products; and limited market access. Governance creates mutual interactions among parties in applying governance institutions and arrangements to result in better value chains [114,194]. Beyond timber benefits, NTFPs provide ecological, social, and economic dimensions. Therefore, the integration of NTFPs utilization in forest management should support community livelihood, conservation, and socio-cultural means [14].
Forest governance can be defined as the act of implementing the forest policy [71], as a part of social science [66]. Forest governance is an attempt to regulate the use, access, management, and conservation of forest resources by using a social approach, considering social, economic, and governmental interests [66]. Forest governance encompasses agreements to achieve the accepted goals among stakeholders, based on rules and norms, the rights and obligations of the owners, how to participate in the decision-making process, the shape of the distribution of benefits, the responsibility of labor, and the position of the roles, work, and accountability [66]. Consequently, all stakeholders must be responsible and respectful to the agreement, whether written or verbal [66,70].
Good forestry governance is formulated as institutional mechanisms in the management of forest resources according to applicable law, accountability, transparency, democracy, fairness, decency, efficiency, equity, sustainability, and the participation of stakeholders [52,71,72]. In practice, forest governance is associated with the government, authority, and territoriality. The concept of territorial boundaries includes the actual technical and administrative processes, which includes the forest resources [69]. Conceptually, governance is determined with respect to the actor's roles, authority, and resources; rules or regulations; and discourse related to the management system [67]. Forest governance at the global level is likely to be too technical and bureaucratic, and is still significantly lacking in the inclusion of social-ecological perspectives [68]. Likewise, forest governance in Indonesia has been characterized by legal uncertainty on access to resources and land ownership [69] in the past. A centralized system characterized forest management in Indonesia in the colonial period, with a main focus on timber extraction, which was continued in the New Order through the Mining Law 1967 and Forestry Law 1967 [53]. Forest management was very commercial, and the government generally granted forest concession rights to companies. After the reformation in 1998, the government has paid more attention to community rights, granted new access rights, and has followed land reform policy over the past ten years [67,69].
NTFPs governance requires a thorough understanding of the complexity of the NTFPs development problem [115]. Due to the complexity of the problem, the community and the government are not the only actors in NTFPs governance, although presence of a stable government can allow the NTFPs to not stay trapped in the gray economic status. Environmental and natural resources management requires the involvement of various stakeholders at different levels. It also requires an inter-village and outside village network, which is dynamic and involves different types of diverse actors with varying interests [54]. Previous research [16,55] have stated that governance challenges are more specific, requiring regional and inter-regional collaboration and involving private sectors that usually provide more innovation and entrepreneurship. The management of NTFPs in Indonesia is necessary due to their strategic social, economic, and ecological roles. The national policy is set through the Ministry of Forestry Regulation No. P. 35 In order to promote the contribution of NTFPs to economic development, the Government of Indonesia started to reorganize the management of NTFPs in 2007. However, before that, Indonesia had already ratified the Convention on Biological Diversity (CBD) in 1994 and the Convention on International Trade of Endangered Species of Flora and Fauna (CITES) in 1978, in order to regulate the international trade of NTFPs derived from plants that are classified as endangered species, including agarwood. Likewise, with sandalwood, the East Nusa Tenggara Provincial Government has regulated sandalwood exports since 1966, and the central government has regulated the trade of cajuput oil on Buru Island, Maluku, since 1956. The regulations issued since 2007 are more focused on defining NTFPs as a non-timber biological resource produced from both natural and cultivated forests, criteria for determining the priority of NTFPs development, NTFP development strategies, and permits, and quotas for the use of several NTFP commodities, such as rattan and agarwood.
These regulations have not yet established good NTFPs governance. The balance between utilization and conservation [198] has not been considered in the ultimate requirements of NTFPs sustainability. The regulations have not sufficiently strengthened the value chain of NTFPs to the farmers as producers [199], implemented adaptive management, strengthened the farmer economic institutions, enhanced trade and market information, set floor prices, provided incentives, and improved cross-sectoral coordination [195], as has been successfully conducted in rattan management. Such improvement to the NTFP regulations began in 2020, with the issuance of the Omnibus Law, and followed in 2021 with the issue of Governmental and Ministry of Environment and Forestry regulations which deregulated licensing (i.e., there is only one permit for both forest management and NTFP). The landscape-based multiple-use forest management is expected to promote the sustainability of NTFPs [200].
The policies and management strategies for agarwood, benzoin, sandalwood, and cajuput are based on central government regulations issued since 2007. However, considering that the four NTFP commodities have high economic values and involve many parties in their management and marketing, the regulations were preferably detailed at the Director-General and Local Government levels. Agarwood cultivation in Indonesia and benzoin in North Tapanuli, North Sumatra, were regulated by the relevant Director-General, while local governments issued utilization permits and quotas in the regions where these resources are being developed. The current condition indicates that cultivated agarwood resin has not yet been found in the export market, and wholesalers still rely on natural agarwood [73,192,201]. The price of benzoin resin also fluctuates sharply. The uncertainty of product grade is caused by farmers not being enthusiastic about growing benzoin plants and tapping their resin, especially younger benzoin farmers [65]. Regulations for the two NTFP commodities that led to improved management and development of NTFP plantations were ineffective, and wholesalers dominated the utilization of NTFPs, as they are the stakeholders that have access to international market information [28,202].
A similar circumstance has occurred for sandalwood where the East Nusa Tenggara Provincial Government Regulation in 1966 only provided 1%-10% benefits for farmers from the existing value chain [53], resulting in rising conflict and sandalwood overexploitation [183], which eventually led to the International Union for Conservation of Natural Resources (IUCN) categorizing sandalwood as vulnerable in Appendix II CITES [196]. Regulations that did not favor community strengthening led to the over-exploitation of sandalwood which had begun before the Portuguese and the VOC colonization, and which continued until the end of the New Order Era in 1999 [56]. On one hand, the local government did not recognize that the community's land was overgrown with sandalwood. On the other hand, sandalwood management was utilized as a state control to society [57]. The situation has led to prolonged conflicts, and the farmers no longer value sandalwood, culminating in collective action to fight through the extermination of natural sandalwood regeneration on their private land [58,183,196]. In the end, the Government realized this mistake and issued a Provincial Regulation in 2012, which aimed to build trust and heal traumatized farmers to realize sustainable sandalwood management.
The regulation of cajuput has been carried out since 1956 as the Applicability Statement of the "Ordonnantie Aetherische Olien" Regulation for cajuput oil [203]. This regulation aimed to stop monopolization and price manipulation of cajuput essential oil, which was detrimental to the community by traders on Buru Island [74]. To date, the cajuput oil trading system has not supported an efficient cajuput industry. Six parties are involved in this system, namely: (1) cajuput leaf producers (plantation forest manager), (2) cajuput refiners, (3) cajuput traders, (4) processing and packaging factories, (5) cajuput oil distributors, and (6) cajuput oil retailers (or pharmacies) [116]. The Minister of Industry issued a Road Map for the Essential Oil Industry Cluster Development in 2009, in order to strengthen the economic contribution of cajuput. Through this policy, Indonesia is projected to become one of the five leading producers of cajuput essential oil globally, and each province in Indonesia should develop at least one essential cajuput oil production center.
Agarwood is traded in sapwood or essential oil form, which is produced by the agarwood distillation process. The quality of agarwood highly depends on the resin matter and the agarwood sapwood dye [75]. Harvesting natural agarwood trees in the forest without sufficient replacement threatens the presence of natural agarwood. In addition, agarwood can also be obtained through the extraction of agarwood buried due to natural processes (i.e., decaying logs), which is mostly carried out in the Papua region [117].
Natural agarwood production has continued to decline since 2010, due to overharvesting and forest conversion to other uses [73]. At present, many groups of farmers are interested in agarwood cultivation to increase production through inoculation techniques. However, the production of cultivated agarwood is still hampered by the regulation on the export quota of agarwood, which is similar to that of natural agarwood. Agarwood is listed in the Conservation on International Trade in Endangered Species (CITES) of Wild Fauna and Flora, setting the associated exchange quotas. The government and farmers need to build cooperation to respond to these challenges. The formation of the ASGARIN (Indonesian agarwood exported association) may bridge the interests of those stakeholders, in order to set up better agarwood governance.
Indonesia's agarwood export markets include Middle Eastern countries and China. Agarwood is usually exported in the form of sapwood, which is used for its aroma. A report from the Ministry of Environment and Forestry in 2019 stated that Indonesia's agarwood production only reached 76.05 tonnes [1]. Thus, efforts are needed to increase national agarwood production through the reformation of regulations and policies.
Benzoin resin demand originates from domestic and international markets, resulting in high economic value and contributing significantly to the household economy of the farmers. The marketing chain involves traders at the village, sub-district, regency, and exporter levels [38,65,77]. Related to the marketing system, the farmers lack price information and price distortions are relatively high in the middle-man marketing chain at the village, sub-district, and exporter levels [38]. Farmers do not have a strong bargaining position against the selling price in all marketing chains. Farmers, therefore, are price-takers and do not have direct access to the exporter, which is generally located in the capital of North Sumatra Province [65,77]. The local government has not yet supported styrax development, either in regulation or market intervention.
The quality of cajuput oil traded in Indonesia must comply with Indonesian National Standards (SNI) 3954:2014 for Cajuput Oil. Indonesia imported 2000 tonnes of cajuput oil in 2019 to fulfill the 4500-tonnes cajuput oil demand. Domestic production has not met the demand for cajuput oil, so eucalyptus oil was also imported as a complement [79]. Cajuput oil has been widely used to relieve breathing and reduce inflammation. The results of a study stated that chemical compounds present in cajuput, such as cineole, terpineol, guaiol, inalool, β-Selinenol, α-Eudesmol, and γ-Eudesmol, have potential for anticoronavirus activities [43].
The Central Bureau of Statistics of Indonesia has reported fluctuations in cajuput leaves production. The lowest production in the 2011-2021 period was in 2012, which was 17,309,982 kg. In contrast, the highest production was in 2019, which was 40,514,739 kg [80]. The supply of cajuput oil in Indonesia comes from two business scales categories; namely small-and large-scale industries or cajuput oil factories. Perhutani (the Indonesian state forestry company) and KPH (Forest Management Unity) Yogyakarta are the largest producers of cajuput oil in Indonesia. Perhutani processed 41,649 tonnes of cajuput leaves and sold 322 tonnes of cajuput oil, worth IDR 85 billion in 2019 [81]. Perhutani has eight cajuput oil factories located in Banten, Central Java, East Java, and West Java. KPH Yogyakarta has two cajuput oil factories, Sendang Mole and Jadian, and produced 34,725 L of cajuput oil in 2017 [82]. Maluku province was once a large producer of cajuput oil. In 2017, the province produced 105,130 L of cajuput oil, which increased to 161,870 L in 2018 [112,113]. In Maluku province, there are more than 100 refinery units spread over four districts [204].
The problem with small-scale cajuput oil agroindustry is that the farmers tend to be price-takers, and the price they receive is much lower than the price at the retailer level [84]. Moreover, essential oil products from Indonesia lack uniqueness [61]. Increasing economic value for cajuput oil-producing areas can be achieved through legal protection, using a Geographical Indication scheme [62,205].

Cultivation System
Indonesia has a high diversity of agarwood-producing trees species. The major cultivated agarwood species are Aquilaria malaccensis Lam., A. microcarpa, and Gyrinops versteegii. The population of agarwood in Indonesia has reached 3.4 million trees. The highest population is located in Central Kalimantan (24.7%), followed by North Sumatra (17.9%) [34]. The success of agarwood cultivation is determined by proper inoculation methods. Inoculation methods can divided into two groups: physical wounding methods (e.g., by drilling, nailing, or pruning) and biological methods (e.g., by introducing a microbial culture into the tree). Biological methods are more productive than the physical wounding methods [85,94]. However, this technology is not yet widely implemented. Until now, agarwood cultivation has been carried out by the community without significant support from the government.
Different from agarwood, sandalwood has been designated as s strategic NTFPs species, and has received sufficient support from the local government of the Nusa Tenggara Timur (NTT) Province, a province in the eastern part of Indonesia. Although sandalwood has been exported since 1436 from NTT [59], sandalwood production from Indonesia is relatively small, especially in terms of the market share in the international market.
From 1910-1916, sandalwood production from NTT reached 917,125 Kg [59], for a total production of 2,458,594 Kg in that period [206]. The share of sandalwood in the economy of NTT was 38.26% on average during 1989/1990-1993/1994 and 12.17% during 1995/1996-1999/2000 [76]. At present, the contribution of sandalwood is smaller, due to the scarcity of natural sandalwood populations. Various replanting efforts have not shown results, due to difficulty of the associated propagation techniques, such that the development of new populations is limited. Furthermore, policy transformation in sandalwood management through various replanting programs has not produced significant results, due to the long production cycle of sandalwood.
A better scheme has been applied for Styrax cultivation management. As an endemic species in the Tapanuli highlands of North Sumatra Province [37,65,121], the plantation area in North Tapanuli Regency covers 22.670 Ha and produces 321.3 kg/ha/yr resin on average (or 4.247 tonnes/yr [121]. The influence of local customs and culture also supports the sustainability of this NTFPs species. Stand and land management are similar to other land-use systems in traditional Batak customary rights. Benzoin forest is acquired and then inherited, based on Batak customary law occupying a patrilineal system [38]. The current tenurial status of styrax forest is private, clan, customary, or leased [37,65]. There is no unique management setting for privately owned or leased styrax forest.
An explicit arrangement is applied to the customary styrax forest. This forest has been cultivated for more than 3-4 generations [65]. Some studies have stated that the cultivation has been carried out for more than 13 generations [37,60], and it still exists to this day. The farmers cultivate styrax in groups. The membership of the group can only be inherited by the oldest son of each family. If the first son dies or does not live in the village, the membership is passed down to the second son, and so on. Harvesting of styrax resin is decided through a meeting of the members. The original members of the group can utilize customary land that is currently fallow. The land that the individuals manage can be owned privately, as long as they can manage it by themselves without the help of other members and do not use machine tools. If the land is sold, the person is prohibited from opening up a new area in that customary land. Challenges related to the land tenure system of styrax forests include conflict with the forest plantation industry that operates in some of the styrax forests in North Sumatra [37].
Farmers have also adopted local wisdom to support sustainability. Some sustainable cultivation techniques include limiting the harvesting period and the number of bark wounds. Resin harvesting is carried out periodically-only twice a year-with the number of tapping points adjusted to the size of the tree. For small to medium-sized trees, tapping points are only carried out on one pollang (about 1.5 m) with four tapping holes; while, for large trees, the tapping points are carried out on two pollang with eight scattered tapping points. Moreover, local farmers also only take care of the best young trees that grow around trees with high productivity as a long-term investment.
Cajuput (Melaleuca cajuputi subsp cajuputi) initially grew in Ambon, Buru, Seram, and Timor Island [78]. Formerly, this plant was known as Melaleuca leucadendron (L.) L., and its oil is often equated with eucalyptus oil. Oil concentration and 1.8-cineole are the crucial determinants of the economic value of cajuput oil [122]. In contrast to other types, eucalyptus cultivation has been carried out on large-scale plantations for the production of essential oils.
In general, the silviculture system of NTFPs species in Indonesia is still underdeveloped. Agarwood, benzoin, and sandalwood cultivation follow a traditional silvicultural system with minimal applications of technology, while a relatively advanced silvicultural system has been applied to cajuput commodities. The supporting factor is that the cajuput commodity has been managed on a company scale and involves the cooperation of local governments and the private sector. In summary, innovation in cultivation technology is urgent for all NTFP species, in order to increase their productivity and sustainability.

Harvesting
Agarwood-producing trees can be harvested after one year of inoculation, although waiting three-year harvest produces the best quality. Harvesting is done by manually, cutting down every 2-3 m of the stems using a machete or axe. The use of mechanical appliances degrades the yield quality. All items are transported to the scraping site, as the processing stage is not carried out in the forest or garden. According to the government regulations complying with CITES, official papers must accompany the transportation of agarwood stems, in order to avoid illegal vindication. The scraping should be done by skilled persons, in order to obtain a high quality product without white wood residue. The proper scraping process using standardized tools will increase the price of agarwood up to 100% of the highest-grade value as a pre-requisite by industrial means [86].
Unlike the process of agarwood inoculation, benzoin is produced by the styrax plants themselves inside the epithelial tissue of their wounded bark [87]. Therefore, bark wounding is the pre-eminent method for the plants to produce the resin. Traditionally, the harvesting process is done using manual gears, including a guris for cleaning the bark, a tuhil for tapping, a peeler-scraper, climbing ropes, baskets, and drying mats [88]. The tapping process is started by scrubbing the bark and trunk surface. Then, eight to twelve tapping holes on each tree are created by penetrating the bark surface, resulting in a space between the bark and cambium. The wound size is five to ten cm in width. Then, the bark is re-sealed by hitting the bark surface gently. The gaps created in the inner bark will be full of liquid resin, which hardens in three to four months. The farmers then collect all of the resins, mixed with the bark pieces [88]. The average resin productivity is 1.291 kg/tree.
The conventional method to produce resin yields approximately 1.526 kg/tree [88,89]. A modified conventional method, by creating a larger wound to accommodate resin, can result in higher yields, up to 1.728 kg/tree (13.2%). Considering that farmers can harvest around ten trees per day, there is a significant increase in production, accounting for 1.92 kg of raw resin daily. Therefore, this alternative method is more practical and feasible to be applied in benzoin harvesting on a widespread scale.
The parts of the sandalwood tree that are utilized are the trunk and roots [123]. Harvesting sandalwood begins with extracting the roots, clearing branches and twigs, bucking the trunk, and transporting logs. This harvesting technique is similar to that performed by the local community in the NTT Province [184]. The technique of harvesting sandalwood trees is done manually, which is different from other commercial tree-harvesting mechanical techniques such as that used for harvesting trees of the Dipterocarpaceae family [185]. The sandalwood-collecting technique conducted by the Mukim community is similar to the tree-length logging method in natural forest harvesting [90]. It has a limiting factor; namely, the minimum diameter and the process of removing tree roots. The main part producing the fragrant santalol compound is the heartwood. On the other hand, root extraction in sandalwood harvesting reduces tree regeneration potential, whereas seed regeneration results in low growth potential [63]. The efficiency of sandalwood harvesting is only 66.46%, lower than the efficiency of harvesting trees in natural forests, which can reach 74%-75% [185]. Sandalwood tree harvesting refers to the diameter and ratio of the wood core. The sandalwood traded should have a minimum diameter of 2.5 cm, length of 100 cm, proportional heartwood, and no cracked or rotten parts of the wood [64].
Cajuput leaves will be ready for harvest at the age of 3 years, when the oil content is maximum. Pruning cajuput leaves should be done at the age of 9-12 months, in order to increase the yield. To facilitate the harvesting of leaves, cajuput trees are cut at 1.5 m height. Cajuput leaf harvesting is carried out periodically, every 9-12 months. The best time for harvesting is in the dry season [78], and harvesting is generally stopped during the rainy season, due to the high water content in leaves.
In general, the processing of raw materials depends on the end-product to be obtained and the characteristics of the original material. Considering that the four NTFPs are aromatic products, two extraction methods are generally applied: (a) extraction with solvents and (b) steam distillation [88,124]. Simple processing, including sorting or cleaning the woody part of the resin, can be applied-especially to produce higher quality agarwood incense. The production of fragrant oils of agarwood, sandalwood and cajuput typically uses steam distillation [91,92]. This technique has also been applied in a limited manner to produce essential oils from benzoin resins [88].

Benefit and Uses
Historically, traditional rituals-especially those related to the world of spirits-use agarwood [95], sandalwood [186], and benzoin [96] through various methods such as burning, powdering, or in the form of incense. Cajuput is used for aromatherapy [140]. Agarwood is used as a qi-regulating drug and carminative medicine to lessen gastric problems, rheumatism, asthma, coughs, and high fever in traditional Chinese medicine [141]. Arabian medicine also uses essential agarwood oil for aromatherapy. In other countries, including Indonesia, agarwood has also been widely used as an incense in religious rituals for centuries [142].
Aromadendrene compounds can act as an effective chemical determinants for agarwood. These chemical compounds characterize agarwood: the higher the aromadendrene content, the better the quality of agarwood oil [125]. In its various forms, such as oil, wood, powder, and plant (Figure 1), agarwood has been used to improve health and treat various illnesses, including for the treatment of mothers after giving birth and diseases of the female genital organs. It is also applied to alleviate spasms in the gastrointestinal and respiratory systems. In addition, it has been applied to cure asthma, abdominal pain, chest congestion, diarrhea, hiccups, nausea, nerves, colic, mental disorder, and cancer, and for the treatment of regurgitation and malnutrition [97][98][99][100]143,146].
Malaysians, Indians, and Chinese use agarwood oil mixed with coconut oil as a lotion for treating various skin diseases. Furthermore, agarwood oil can be used in a decoction to cure rheumatism, lung disease, stomach tumors, carminative diuretic, and other body pain [99,100]. Traditional Chinese and Japanese medicine utilizes high-grade agarwood as a sedative, analgesic, and digestive agent [101,148]. It is also applied in pharmaceutical tincture production [102,103]. The properties of agarwood have been utilized for antiasthmatic, tonic, stimulant, aphrodisiac, carminative, and astringent purposes in India, Bangladesh, and Egypt [143].
Sandalwood oil is employed largely as an astringent, sedative, coolant, and disinfectant in the bronchial and genitourinary tracts, as well as an expectorant, stimulant, and diuretic [147]. Malaysians, Indians, and Chinese use agarwood oil mixed with coconut oil as for treating various skin diseases. Furthermore, agarwood oil can be used in a d to cure rheumatism, lung disease, stomach tumors, carminative diuretic, and oth pain [99,100]. Traditional Chinese and Japanese medicine utilizes high-grade ag as a sedative, analgesic, and digestive agent [101,148]. It is also applied in pharma tincture production [102,103]. The properties of agarwood have been utilized asthmatic, tonic, stimulant, aphrodisiac, carminative, and astringent purposes Bangladesh, and Egypt [143].
Sandalwood oil has been widely used in the cologne manufacturing indust Sandalwood oil has shown various activities in animal laboratory tests. A santa tract has displayed a spasmolytic role in digestive motility, anti-bacterial, anti-bio inflammatory, anti-oxidant and stress-modulatory activities; and prohibited hear [150][151][152][153]. Sandalwood oil is also effective for curing psoriasis, eczema, commo Sandalwood oil has been widely used in the cologne manufacturing industry [149]. Sandalwood oil has shown various activities in animal laboratory tests. A santalum extract has displayed a spasmolytic role in digestive motility, anti-bacterial, anti-biotic, anti-inflammatory, anti-oxidant and stress-modulatory activities; and prohibited heart muscle [150][151][152][153]. Sandalwood oil is also effective for curing psoriasis, eczema, common warts, and molluscum contagiosum, as well as an anti-acne agent [154]. It is also applied in aromatherapy to ease anxiety, stress, and depression [155,156]. B-santalol has been found to be successful in inhibiting the replication of influenza virus A/HK (H3N2) and preventing tumor growth [156,157]. Sandalwood oil has been reported to have anti-inflammatory activity [158]. α-Santalol (10-40 µm) has been found to be an effective inhibitor of angiogenesis by acting on vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR2), which further inhibited the growth of prostate cancer [160]. At present, research on the anti-cancer potential of sandalwood has increased considerably [128,160,161,163,181]. It also been proven effective for treating skin papilloma and carcinoma [127,163].
Since ancient times, benzoin has been used as a medicine or perfume [130]. The valuable biological activities of Styrax officinalis L. extracts have been promoted as featuring hemolytic, anti-tumor, anti-complement, anti-leukemic, anti-fungal, anti-bacterial, antioxidant, and tyrosinase inhibitory activities. Benzoin can also be directly applied to cure the throat and breathing passages of inflammation. In skincare, it kills germs, reduces swelling, and stops bleeding from minor cuts, skin ulcers, bedsores, and cracked skin. A combination of benzoin with other herbs, such as aloe, storax, and tolu balsam, is used as a skin protectant. Benzoin has also been used to treat many diseases caused by gastric acidity, chest infections, pneumonia, asthma, noisy breathing, obstructive sleep apnea, aspiration, heart failure, and cirrhosis [130,164,165].
Volatile compounds in cajuput oil, such as 1,8-cineole and γ-terpinene, are associated with its cooling aftertaste, while 1,8-cineole and caryophyllene have been linked with its sweet taste [166]. The volatile compounds of 4-terpineol, linalool, α-terpineol, and 1,8-cineole identified in mouse blood plasma after inhalation of the cajuput oils might correlate with the content of cajuput essential oil [167]. Cajuput oil consists of menthol, which is used as an herbal treatment for abdominal pain [168]. α-terpineol from cajuput oil showed favorable responses as an antidepressant agent [169]. Cajuput oil has displayed relatively high anti-bacterial and anti-fungal property [166,171,172].

Value Chain and Product Diversification
Processing phases change the form of the NTFPs, from the farmer to the end-user. The raw materials produced by the farmers are very diverse in form and quality. The process results in multiple value chains, involving rural labor and generating economic benefits from the farmer level to the end-user (Table 2). Generally, agarwood is transformed in various product derivatives [97]. The wood is sometimes chopped into sticks or splinters without any further processing, to be used as a fragrance in incense that is a high-valued perfumery raw material, surpassing the value of gold [197]. Sandalwood oil is also used in stick incense products, incense cones, soaps, and creams/lotions. Other products made from sandalwood are statues/carvings and sandalwood bracelets/prayer beads. Sandalwood oil is the most common product. Sandalwood oil packaged in glass bottles costs around IDR 150,000/15 mL to IDR 850,000/3 mL.
One of the most well-known sandalwood derivative products is incense (i.e., stick and cone incense). In Indonesia, cone-shaped sandalwood incense is sold at a minimum of IDR 22,500/jar (70 cones) or IDR 15,000/pack (8 sticks). Deodorant cream created from a mixture of aluminum sulfate and sandalwood essential oil is non-irritating and provides comfort [173]. Sandalwood cream/lotion is sold at around IDR 3000/150 mL. Sandalwood oil can be used as a soap additive [104]. In Indonesia, sandalwood soap is sold for around IDR 5000/81 g to IDR 13,000/125 g.
Sumatran benzoin has mainly used for incense purposes [134] in the past. Recently, it has been expanded to be utilized in the fragrance industry ( Figure 2) as a fixative agent for anti-aging purposes, and as food flavoring [129]. Benzoin oil is also processed into a perfume base-note [89]. Furthermore, benzoin has also been employed as a hair growth and blackening agent. It also has medicinal properties to reduce fever, relieve itching on the skin, and can be used as a liniment or massage oil [105]. The highest price of raw resin at local traders reaches IDR 250,000-290,000/kg for the highest grade and IDR 50,000 to 75,000 for the lowest grades. The benzoin oil resulting from the distillation process has a higher economic value, ranging from IDR 5 to 7 million/liter. The value-added can reach four times higher than that of the raw resin [89]. Cajuput oil is the main product of cajuput, which is used in incense sticks, soaps creams/lotions, candies, and the middle layer of three-layer masks (Figure 3). Other prod ucts from cajuput leaves are herbal teas and sponge cakes. Cajuput oil is sold from IDR 5000/15 mL to IDR 40,000/120 mL in plastic bottles. In comparison, cajuput oil packaged in glass bottles costs around IDR 250,000/350 mL. Based on the 48th International Fra grance Association (IFRA) 2015, incense is a cajuput oil product that does not contact th skin directly. Incense with the cajuput oil aroma that can burn for 12 h is sold at IDR 25,000/pack (3 sticks) in online stores. Cajuput oil incense tends to have an oily surfac and is more difficult to burn. Cajuput oil is a scented aroma agent in soaps [130]. Cajupu soaps are sold for IDR 8500/160 g in the online market. Cajuput oil is the main product of cajuput, which is used in incense sticks, soaps, creams/lotions, candies, and the middle layer of three-layer masks (Figure 3). Other products from cajuput leaves are herbal teas and sponge cakes. Cajuput oil is sold from IDR 5000/15 mL to IDR 40,000/120 mL in plastic bottles. In comparison, cajuput oil packaged in glass bottles costs around IDR 250,000/350 mL. Based on the 48th International Fragrance Association (IFRA) 2015, incense is a cajuput oil product that does not contact the skin directly. Incense with the cajuput oil aroma that can burn for 12 h is sold at IDR 25,000/pack (3 sticks) in online stores. Cajuput oil incense tends to have an oily surface and is more difficult to burn. Cajuput oil is a scented aroma agent in soaps [130]. Cajuput soaps are sold for IDR 8500/160 g in the online market. 5000/15 mL to IDR 40,000/120 mL in plastic bottles. In comparison, cajuput oil packaged in glass bottles costs around IDR 250,000/350 mL. Based on the 48th International Fragrance Association (IFRA) 2015, incense is a cajuput oil product that does not contact the skin directly. Incense with the cajuput oil aroma that can burn for 12 h is sold at IDR 25,000/pack (3 sticks) in online stores. Cajuput oil incense tends to have an oily surface and is more difficult to burn. Cajuput oil is a scented aroma agent in soaps [130]. Cajuput soaps are sold for IDR 8500/160 g in the online market. One of the "ArthroSoothe" cream ingredients that can be used to moisturize the skin is cajuput oil. In Indonesia, cajuput cream is sold from IDR 9000-15,000 per pack. Cajuput oil has also been used in lotion products. Other product innovations are sucrose and nonsucrose cajuput candies, which have been produced since 1997 in Indonesia, to add the economic values of cajuput oil [180]. The candies are priced as much as IDR 70,000-125,000/kg. Cajuput candy inhibits Candida albicans and Streptococcus mutans during the development of dental caries [166].

Challenges and Prospects
In general, propagation materials for NTFPs species rely on natural regeneration, except for cajuput, which has been mass-propagated both generatively and vegetatively to One of the "ArthroSoothe" cream ingredients that can be used to moisturize the skin is cajuput oil. In Indonesia, cajuput cream is sold from IDR 9000-15,000 per pack. Cajuput oil has also been used in lotion products. Other product innovations are sucrose and non-sucrose cajuput candies, which have been produced since 1997 in Indonesia, to add the economic values of cajuput oil [180]. The candies are priced as much as IDR 70,000-125,000/kg. Cajuput candy inhibits Candida albicans and Streptococcus mutans during the development of dental caries [166].

Challenges and Prospects
In general, propagation materials for NTFPs species rely on natural regeneration, except for cajuput, which has been mass-propagated both generatively and vegetatively to meet the high demands of large-scale plantation to produce commercial essential oil [177,187]. Preparation for agarwood seeding is conducted by sowing abundant seeds from the mother trees, which bear fruit in two periods: May-June and January-February. However, seed collection requires special preparation for climbing the mother trees and precise information about the ripeness of the fruit. Therefore, farmers are more likely to collect several young wild seedlings (5-10 cm) which germinate around the mother trees, then transfer them to polybags and maintain them until they are ready to be planted in the field [34]. Relatively similar conditions also occur for the preparation of plant materials of benzoin and sandalwood tree species. Despite the selection conducted, the propagation of benzoin-producing trees in cultivation centers in North Sumatra still relies on natural regeneration [106]. Only the best-growing plants around the highest productivity mother trees are maintained and nurtured. To date, efforts to develop mother trees with the best phenotypes are still limited. Fortunately, despite the small and limited scale, several vegetative propagation attempts of mother trees from various provenances in North Sumatra have shown great potential and prospects for wide-scale development in the future [188]. Meanwhile, cajuput populations in natural distribution are becoming scarce due to unsustainable leaf-harvesting practices. The local people stimulate the growth new shoots and leaves growth by burning cajuput stands. Due to these repeated fires, the main stem is vulnerable to death [177,187].
Like most forest tree species, seed propagation has also become a standard for these four aromatic species. However, their populations have tended to dramatically decline, as worsened by some difficulties in propagating through conventional procedures. Several vegetative propagation techniques have also been adopted and, recently, in vitro techniques using various types of concentration ratios of growth regulators have been found to be more effective for mass reproduction [108,189].
As an example of a success story for the local community in sandalwood, cultivation has encouraged the local government to include sandalwood development through social forestry programs (Figure 4). This scheme is expected to increase sandalwood planting inside and outside the forest area in Eastern Indonesia. In addition, climate change and rainfall intensity is expected to affect the sandalwood phenology [190,191].
four aromatic species. However, their populations have tended to dramatically decline, as worsened by some difficulties in propagating through conventional procedures. Several vegetative propagation techniques have also been adopted and, recently, in vitro techniques using various types of concentration ratios of growth regulators have been found to be more effective for mass reproduction [108,189].
As an example of a success story for the local community in sandalwood, cultivation has encouraged the local government to include sandalwood development through social forestry programs (Figure 4). This scheme is expected to increase sandalwood planting inside and outside the forest area in Eastern Indonesia. In addition, climate change and rainfall intensity is expected to affect the sandalwood phenology [190,191]. Most agarwood comes from natural forests, but some valuable commodities are managed on private lands or community forests, in order to protect assets for security reasons in the long-term. Since the 2000s, around 3.5 million agarwood-producing trees, including Most agarwood comes from natural forests, but some valuable commodities are managed on private lands or community forests, in order to protect assets for security reasons in the long-term. Since the 2000s, around 3.5 million agarwood-producing trees, including Aquilaria and Gyrinops species, have been planted in community forests or gardens throughout Indonesia [34] (see Figure 5). Aquilaria and Gyrinops species, have been planted in community forests or gardens throughout Indonesia [34] (see Figure 5). As a cultivated plant, agarwood production faces some challenges, including the inoculation process, which requires an effective fungal species for agarwood formation [109][110][111]. In addition, the inoculum practice at a large scale requires high-quality agarwood-forming inoculants and skilled labor. Based on several inoculation tests, some candidate fungi have been identified, as shown in Table 3.  As a cultivated plant, agarwood production faces some challenges, including the inoculation process, which requires an effective fungal species for agarwood formation [109][110][111]. In addition, the inoculum practice at a large scale requires high-quality agarwood-forming inoculants and skilled labor. Based on several inoculation tests, some candidate fungi have been identified, as shown in Table 3. Aquilaria sp. moderate [216] Remark: Success rate is categorized as high (90%-100%), moderate (60%-89%), or low (<59%).
As a semi-tolerant species, agarwood-producing trees need shade at the beginning of their growth. In this case, an agroforestry system that combines agarwood with rubber trees can be developed. Further, the combination of agarwood, shade trees, and horticultural crops (e.g., vegetables) can result in complex agroforest systems on limited land [192]. The trees can also possibly be planted in the yard (home garden). Planting in the garden around the residences makes them easy to monitor for safety, inoculation, and harvesting [34].
Benzoin development has shown high potential, regarding its cultivation history, and is closely linked with the livelihood of communities. Nevertheless, benzoin tree cultivation is subsistence and sub-optimal, characterized by traditional, low processing techniques and limited product diversification with high economic value. There are no appropriate processing technologies that inhibit benzoin oil industry development or affect benzoin forest management in the long-term [88,217]. Sub-optimal conditions also refer to the management of stands that do not reflect the normality of growth and yield; for example, individual growth and resin productivity are still below average, due to still relying on natural regeneration and limited efforts to develop seeds from breeding. Therefore, appropriate strategies can be implemented by accelerating the development of superior seed sources and in situ/ex situ genetic conservation to reduce genetic depletion. Research on seed technology is needed to increase germination; a crucial aspect is the superiority of developing seeds through phenological [188] and ecological observations [106], as well as collection of genetic material from various provenances and the development of superior mother trees [218]. The development of provenance stands can be used as an initial breeding strategy to obtain superior benzoin seeds and genetic conservation [219].
The key to the sustainability of agarwood production is cultivation activities in the form of mass-scale plantings. Indonesia has various agarwood-producing tree species that have a comparative advantage. Efforts to collect various genotypes in seed or clonal orchards must be carried out for further breeding and tree improvement. Cultivation, especially in the private sector, practically does not exist in Indonesia. Private businesses are still focused on natural agarwood products. At present, there exist about 40 companies that collect and export natural agarwood to various countries. Cultivation that takes a long time from planting to harvesting-at least ten years-has been identified as the cause of the problem. However, other ASEAN countries, including Malaysia, Thailand, Myanmar, Cambodia, Lao PRD, and Vietnam, have planted many trees involving the business sector. In these countries, agarwood oil is the main product, while agarwood sapwood is processed for incense.
To sustain the global agarwood supply, Indonesia must begin increasing the number of cultivated agarwood plantations and products through mass-scale planting activities and the inoculation of agarwood. The world market requires low-grade agarwood products for medicinal purposes, accessories for many religions, and perfumes (Table 4). Furthermore, the sustainability of sandalwood management is determined by the collaboration of both the local governments, community, and the private sector, especially in planting development on owned-land and forest areas. Integrating sandalwood-based commodities in social forestry programs using agroforestry systems [99] provides an opportunity to increase community participation in the plantation in forest areas, especially in the 2308 villages both in and around the forest in the NTT Province [220]. The local government's campaign for sandalwood conservation requires increasing the tree population in the natural habitats and encourages the participation of multiple stakeholders, such as schools, offices, community leaders, religious institutions, NGOs, and public organizations. The government has funded the development of millions of sandalwood trees in recent years due to their commitment to restoring their population, production, and sustainability. Breakthroughs in sandalwood development by the local government need to be in balance with planned and measured maintenance [221], in order to improve the quality and quantity of sandalwood production. In addition, attention to seed sources and habitats that support the proper growth and development of sandalwood is needed [191], primarily to support the success of sandalwood cultivation.

Conclusions
In this study, we reviewed the challenges and prospects of four essential aromatic NTFPs species in Indonesia. The forest-dwellers utilizing NTFPs such as agarwood, benzoin, sandalwood, and cajuput, have lasted centuries across generations. However, NTFPs regulations have not yet been established for good governance implementation; that is, the value chain of NTFPs to the farmers (as producers) has not been sufficiently strengthened, adaptive management has not been properly implemented, farmer-economic institutions have not been facilitated, trade and market information has not been enhanced, floor prices have not been set, appropriate incentives are not yet provided, and cross-sectoral coordination remain to be improved. Regarding the marketing system, the middle-man wholesalers still dominate the current marketing information and pricing. Increasing international demand for NTFPs products has led to over-exploitation of the NTFPs, especially natural agarwood and sandalwood. Uncontrolled harvesting of NTFPs will result in the unsustainability of these resources. The cultivation systems for agarwood, benzoin, and sandalwood are still traditional, calling for the application of better silviculture technology. On the other hand, cajuput has been cultivated with a better system. Research and development into cultivation technology is necessary, in order to improve all NTFPs plantations. Harvesting and processing of the products still rely on traditional techniques and local knowledge, as some existing technological innovations do not significantly increase the yield or quality.
The government needs to improve the governance of NTFPs, starting from the system of cultivation, harvesting, processing, and marketing, such that the abundance of NTFPs in Indonesia can sustainably improve the welfare of communities.
Author Contributions: All authors made equal contributions to resources, conceptualization, methodology, analysis, validation, writing, review, and editing of the manuscript. All authors have read and agreed to the published version of the manuscript.