Xia Hanping and Ao Huixiu
(South China Institute of Botany, Academia Sinica, Guangzhou 510650)
Abstract Vetiveria zizanioides, an excellent hedgerow for soil and moisture conservation, has being widely distributed and applied in the tropics and sub-tropics. China's domesticated vetiver was introduced from abroad in the 1950's, but undomesticated vetiver has been found in Guangdong and Hainan. Particularly in Wuchuan County of Guangdong a total area of about 6,700 ha natural vetiver community was found in 1957. This tropical grassland, however, has since then been severely destroyed and its area has dwindled over the past 40 years due to effects of human activities, land use change and utilization for commercial purposes. A proposal is put forward in this paper for protecting the wetland and its precious plant resources. Since the present systematic taxonomy of the Vetiveria genus is still not fully understood, it is not clear which species exactly the wild vetiver in China is, V. zizanioides, V. nigritana, or even V. Festucoides. We think it is probably V. Zizanioides.
Key words: Vetiveria zizanioides; V nigritana; V festucoides; community; China
Introduction: Vetiver grass (Vetiveria zizanioides), a perennial, is being widely cultivated and applied in the tropics and subtropics for its excellent capabilities for controlling soil erosion, protecting the environment, and many other uses. Vetiver is native to India, but there are natural distributions found in Southeast Asia and Africa. It is generally believed that China's vetiver was introduced from India and Indonesia in the middle 1950's. The Vetiver Network has never reported the existence of any wild vetiver distributions in China, nor have the pertinent monographs on vetiver. Our investigations, however, indicate that there are indeed natural distributions of vetiver communities in Guangdong and Hainan of China. A detailed review of Vetiver's distribution and utilization in China would be useful for future introduction, research, dissemination, and application to South China locations.
1 UNDOMESTICATED VETIVER DISTRIBUTED IN CHINA
1.1 Vetiver Specimen Sampled from Hainan
We still neither know when and where vetiver was first found in China, nor who first sampled it. However, there is a specimen in the herbarium of the South China Institute of Botany (SCIB) collected in the 1930's from Hainan. Mr. Liu Xinqi collected this specimen on September 5th 1936 near Daisha village, Gan'en County. The collection site characteristics were described as: "sandy wilderness near a road, unshaded and dry". In the 1950's Liang (1957) also reported: "Undomesticated vetiver has been found recently in Hainan, whose characteristics have no distinct differences to the domesticated". However, some roots from the undomesticated were aromatic and some not, likely due as a result of their different habitat situations and age, as they were found in low-lying areas and had grown their for many years. In 1960 ecologists from SCIB, whilst making a survey of Hainan vegetation also found wild distributions of the plant nearby in such habitats as lagoons. Later, Huang et al. (1964) pointed out that there were small scale distributions of vetiver along Duowen, Wenchang, and Huangliu in Lingao County, Hainan Island. Thus it is clear that natural vetiver indeed exists in Hainan, and furthermore it is found at different sites and habitats.
1.2 A Large Area of Natural Vetiver Community Found in Guangdong
A natural vetiver community with a total area of about 100,000 mu (15 mu = 1 hectare) was found in Wuchuan County, Guangdong by the same scientists from SCIB in 1957 while they were surveying the provincial vegetation. The community is located in an alluvial plain lying at the junction of 3 counties: Wuchuan, Maoming, and Dianbai, all associated with the lower reaches of Jianjiang River. It was first found in May 1957 when the plant was in a non flowering stage of growth, and the species could not be identified. In November of the same year an expert team, including Prof. He Daoquan, also from SCIB, went there to make a detail investigation of the community, and sampled plant and soil specimens. Later, they found the dominant species in the community was a famous aromatic plant, which was also good for fuel and for paper making. SCIB dispatched a another special team again to the location to survey, from the aspect of plant resources, the distribution and amount of vetiver, and conducted experiments on refining essential oil and paper making with the assistance of local factories. The results indicated that the wild species of vetiver could be used to produce quality essential oil and high-grade paper.
2 THE VETIVER COMMUNITY IN WUCHUAN, GUANGDONG
2.1 Habitat and Distribution
2.1.1 Locality and amount. The community lies in the alluvial plain near where the Jianjiang River enters the sea, at about 21° 28' - 21° 35' N, 110° 45' - 110° 55'. In the 1950's the total area of the community was estimated at 6,700 ha (100,000 mu). The local people call the community "Cao Lang", meaning "Grass Corridor", and call vetiver in the community "white cogon" , "oil cogon" or "cogon born". The results from plot surveys indicated that the total amount of vetiver roots in the whole community was about 191,000 tons, which could be refined to 406 - 503 tons essential oil (assuming 2.13% oil extraction rate). Shoots and oil-refined root residues were approximately 119,000 tons, which could make 42,800 tons high-quality paper (Huang, et al., 1964).
2.1.2 Climate The area belongs to the transition zone from subtropics to tropics, and has high temperatures and abundant rainfall. The average annual temperature is 22.8° C with a mean minimum of 15.4° C in January and a mean maximum of 28.3° C in July. The highest temperature measured is 37.4° C and the lowest 2.7° C. The average annual sunshine duration is 2,015 hours. The annual rainfall averages 1,691 mm, over a rainy season from April to September, and a dry season from October through March. There are some tropical cyclones in rainy seasons, particularly in August and September, which usually result in wind disasters and floods. The mean annual relative humidity and evaporation in the vetiver community were 82 - 85% and 1,351-1,989 mm, respectively, according to the original survey records in the 1950's.
2.1.3 Physiognomy and soil As above mentioned, this is a river-alluvial plain, flat and broad. There are lots of rivers forming a "river network". According to the original survey reports, the whole community was usually inundated during the periods of rainy season, and the ground water level sometimes might go down to at most round 200 cm deep in dry seasons. The soils, developed from river alluvial deposits, were over 1 -1.5 m deep and are divided into 4 layers, layer A, AB, B and C. The surface horizon was gray-brown middle-loamy soil with an organic matter content of up to 4.80%. and pH4.58. The underlying horizons were brown-yellow clayed soil with a block or large block structure and a tight and poor aeration status; organic matter in these horizons averaged 1.67% and pH4.48. No trees could grow here owning to seasonal floods and droughts each year. But vetiver and some other grasses that could resist drought and inundation gradually occurred and formed a special community, which is defined as the Hygrophytic-Mesophytic Tropical Grassland in vegetation type (SCIB, 1976).
2.2 Structure and Composition of the Community
On the basis of the original survey records, the community's appearance, at the time of investigation November 1957), presented a view of broad, dense and high grassland, and yellow-green color, dotted with white or yellow flower and seed heads. The composition of the community was simple, overwhelmingly dominated by vetiver and Hemarthria altissima. At that time, vetiver was in the stage of panicle falling, and H. Altissima just started heading. The total coverage of the community was generally more than 85-95%, even to 100%. It could be basically divided into 2 layers; the upper layer was mainly composed of erective vetiver, accompanied by (only in some areas having slightly high position) small blocks of Saccharum spontaneum or Saccharum narenga, Capillipedim parviflorum, and Sorghum propinquum, and so forth. Vetiver grew up to 210 cm and its leaf layer to 140 cm, whose coverage was about 30-40%, to the most 60%. There were 3-4 clumps of vetiver on the average in an area of 1 m2, and 14-20 tillers, to the most 28, per clump. However, the number of tillers per clump went up to 60 - 100 near low and wet ditches. It is thus clear that this plant prefers to wet surroundings. Vetiver had a multitude of fibrous roots, reaching 100-150 cm deep. The lower layer of the community was mainly creeping and slender grasses, which were about 70 cm height and 50 - 70% coverage. H. altissima, also a hydrophyte, was the dominant species in this layer, whose coverage and height were some 50% and 100 cm or so, respectively. In addition, there were a few Ischaemum aristatum, Hymenachne assamica, Paspalum orbiculare, Helminthostachys zeylanica, Ophiopogon sp., and Tylophora sp. with a feature of entangling stems (Table 1). There were no trees growing in the community (SCIB,1976).
Table 1 Statistics of 5 plots (each 1 m2) from the natural vetiver community in Wuchuan County (November 1957)
Mean height (cm)
Mean height (cm)
Hemarthria compressIshaemum aristatum. 5221375 1 25
3365++ 140 200
60 / 1001002080
2.3 Evolution of the Community over the Past 40 Years
After 40 years, in May 1997, the authors revisited the site to resurvey the community. They found that the natural community had changed radically. It had broken into pieces, and its total area had dwindled. It had a green appearnce, dotted with a few grey-green panicles, and its coverage was at most 70-80%. The community was still 2 layers; the upper layer was chiefly vetiver with a coverage of round 10-15%, even less, and a height of 150-160 cm; the lower layer was mainly composed of H. altissima with an average coverage of 40-60% and an average height of 50-70 cm. Due to severe effects from human activities and differences of topography and habitat conditions, the whole flood plain has formed lots of phytobiocenoses whose species, composition and structure all have pretty evident discrepancies, resulting in distinctly different ecological series. River courses consist mainly of emerged plants, such as Nymphaea stellata, and sparse Nymphoides indica. Nearby river courses are chiefly dominated by H.assamica, Paspalum conyugatum, Polygonum hydopiper. In low waterlogged land, there are quite long waterlogged periods; as a result, vetiver, H.altissima communities gradually forms, in which P. conyugatum, P. orbiculare, H assamica emerge occasionally. On the flat and high grounds the period of wet season waterlogging is much shorter, and these communities are mainly composed of mesophytes, including: C parviflorum, the dominant species, and Imperata cylindrica var.major, Setaria geniculata, Ischaemum aristatum, and S spontaneum, including some small shrubs, such as Antidesma ghaesembilla, Mimosa pudica, and Lespedeza cuneata. At the time of the investigation, it happened to be the flood season, and the whole grassland was inundated with water to some 40 cm depth, so the roots and soil could not be observed.
2.4 Utilization of Vetiver by the Local and Its Effects on the Community
The original survey reports wrote: "The vetiver community occurred hundreds of years ago, and is too old to identify its origin or evolution". Since there were several months' floods at that time, this large grassland could neither be used as natural grazing grounds, nor be reclaimed as farmland. But local villagers cut grasses in the community once in October of each year in the 1950's; the harvests were used as fuels for baking pottery and for thatching. Villagers said that "cutting once a year did not negatively effect the Grass corridor"; on the contrary, if not cut, vetiver would not germinate in next spring, and might even die. At that time, Jiangmen Paper-Making Factory was successful in making paper with it.
Since the 1960's, however, this tract of highly valuable wetland began to be gradually destroyed. In the beginning of the sixties, the local government motivated the masses to uproot vetiver for refining oil. We all know that vetiver is multiplied by division of roots, whose multiplication rate is relatively slow compared to those through seeds. Therefore, digging up on the large scale not only diminished the area and amount of vetiver, but also fragmented this huge grassland. Since the seventies, because of the increasingly large population, and the human activities such as expanding villages and communities, digging canals, and building up dams, it has been impacted more and more severely. Especially since the eighties, large stretches have been developed into fishponds. The result is that the original 7,000 ha natural vetiver community has been reduced to only several hundred hectares, and the amount of vetiver per unit area has decreased significantly. Despite sustaining such great damage, this tropical grassland is still an ideal habitat for Emberiza aureoba, a migratory bird, during winter months; this natural phenomenon has been lasting dozens of years. This precious wetland is most likely to be completely obliterated in the near future, unless protective measures are taken, to restrict the excessive activities and developments relating to population growth.
3.1 A Proposal about Protection of the Natural Vetiver Community
Since vetiver is an excellent biological measure for moisture and soil conservation and environment protection, it has, in the last few years, been disseminated rapidly all round the subtropics and tropics. Apart from its great success for erosion control, vetiver has lots of other uses. For example, it can ameliorate extreme soil, reclaim mining areas, regulate micro-climates and can also be used to extract oil and used as fuel, forage and raw materials for making paper (National Research Council, 1993; Xia, et al., 1997). Currently, Vetiver's application in the above-mentioned aspects is called "Vetiver Grass Bioengineering or Vetiver Grass Technique". Since vetiver has difficulty in producing viable seeds, and the general propagation method is via division of roots, which is relatively slow. Therefore to spread and apply the bio-engineering on a large scale it is necessary to propagate as many seedlings as possible.
As early as the 1950's, China introduced vetiver from abroad and cultivated it in Guangdong, Fujian and Zhejiang to extract essential oil from its roots. The local vetivers were not given much importance even though undomesticated varieties of the plant had been found in Hainan and Guangdong at that time or even earlier. Since then the tropical grassland has been severely destroyedand reduced in area, and the vetiver component has been severely reduced. In order to protect this highly valuable plant resource and the this precious wetland, we propose a reserve in situ should be demarcated and established in the largest vetiver growing area in China -- Wuchuan County, Guangdong. This would not only efficiently protect such bio-resources as vetiver, Helminthostachys zeylanica and Sorghum propinquum, but would also offer Emberiza aureoba a good winter habitat. The proposed reserve would provide an ideal basis for conducting research on wetland and biodiversity in South China.
3.2 Taxonomy and Nomenclature on Vetiver
The genus of Vetiveria has been described and at least 12 species identified since the genus was named in 1822. However, because very little is known about the genesis and genealogies of Vetiveria, and there are no remarkable differences between the species, the descriptions of the species are not strictly comparable, and the names of some species, even of the genus, are often changed. To late, there has been no reliable diagnostic key for the genus of Vetiveria (Greenfield, 1995). For example, Hack ever denominated V. Nigritana a variable of V zizanioides, or V zizanioides var. nigritana. In another example, the National Research Council (1993) pointed out "V.nigritana apparently also occurs in scattered locations in Sri Lanka, Thailand, Malaysia, and the Philippines", but Thai botanists have not found the species in their country (Office of The Development Projects Board, 1996). Netherlands botanist, Dr. J.F. Veldkamp, does not think there are any distributions of V. nigritana in Asia, either. He even holds "if Vetiveria is to be maintained the only two species would be V. festucoides, andV. zizanioides". It is thus clear that the systematic taxonomy of Vetiveria genus is far from complete. The Vetiver Network and experts on vetiver from USA, Holland, Australia, and New Zealand are conscious of the problem, and are dealing with it on a multi-discipline approach including the use of Random Amplified Polymorphic DNA Techniques to distinquish between vetiver types. This work has made encouraging progress.
In 1957, when the ecologists made a survey of the vetiver community in Wuchuan, the vetiver in the community was named V. zizanioides, which follows the species being widely planted in the subtropics and tropics. However, Huang et al (1964) called it V. nigritana in their paper entitled "A Preliminary Study On The Aromatic Plant V. nigritana". The monograph of "Guangdong Vegetation" also regarded the community as V. nigritana community, and called the vetiver V. Nigritana (SCIB, 1976). Of all 4 specimens, however, that were sampled from the community in the 1950's and have been preserved in the Herbarium of SCIB, one is labeled V. zizanioides, one V. zizanioides var. chryospogniodes, the other two are just written Vetiveria sp., and unexpectedly, none are regarded as V nigritana. However, according to our recent observation and comparison, we think that the vetiver from the community is probably V. zizanioides, and unlikely to beV. nigritana. In addition,V. festucoides exists in some areas of Asia according to Dr. Veldkanip's view; if it is the case, then we do not rule out the possibility of its being this species. Evidently, this problem remains to be further studied by scientists.
We are indebted to The Vetiver Network and Mr. Richard Grimshaw, the president of The Vetiver Network, for its financial support for this year's investigation, and also wish to thank Professor He Daoquan for providing the original survey records and instruction..
Greenfield J C. Vetiver Grass -. The Ideal Plant For Vegetation Soil And Moisture Conservation. In: Vetiver Grass For Soil And Water Conservation, Land Rehabilitation, And Embankment Stabilization (Grimshaw R G and Helfer L ed). The World Bank, Washington D C, 1995.3-38
Huang B H, et al. A Preliininary Study On The Aromatic Plant V Nigritana. Collected works of Guangdong Provincial Botany Association, 1964, 114-121. (in Chinese)
Liang S S. Vetiveria zizanioides. Tropical Crop, 1957(22): 29-31. (in Chinese)
National Research Coirncil. Vetiver grass: A Thin Green Line Against Erosion. National Academy Press, Washington D C, 1993.49-58, 113-127
Office of The Royal Development Projects Board. Vetiver Grass For Environment Protection And Other Usages. Office of The Royal Development Projects Board, Bangkok, 1996.28-31
Xia H P, et al. Vetiver Grass - An Excellent Plant For Soil And Moisture Conservation. Ecological Science, 1997, 16(1)114-121. (in Chinese)