Haolun HUANG,Fangshu LI,Huide HUANG*

1.Institute of Scientific and Technical Information,Chinese Academy of Tropical Agricultural Sciences,Danzhou 571737,China；2.Danzhou Tiejiang Village Huanghuali Cooperation,Danzhou 571700,China

Hainan Huanghuali(Dalbergia odoriferaT.Chen)is also known as Hainan Huanghuali wood,and is a rare tree species.Hainan Huanghuali wood is one of the five famous trees all the time due to slow growth,hard quality and beautiful pattern,and it is a national secondclass protective plant.The essential oil extracted from Huanghuali wood can stimulate cytothesis and metabolism and is beneficial to nourishment of dry skin;and it has excellent anti-wrinkle function on skin and is capable of promoting skin tissue regeneration and strengthening skin elasticity.With continuous development of Hainan InternationalTourism Island,Hainan Huanghualiisverywellaccepted,bringing Hainan Huanghuali products and artwares good demand prospect.For this reason,this paper discusses the development of Hainan Huanghuali on the basis of its growth,timber formation characteristicand utility value.

Characteristics of Huanghuali

Morphologicalcharacteristics of Huanghuali

Hainan Huanghuali is a deciduous tree with a height of 10-25 m and a diameter at breast height(DBH)up to 0.8 m.The tree has a crown in wide umbrella form,and branches at a low level,forming many branches among which the lateral branches were thick and strong,and its bark is brown or hazel in color,and has coarse surface with longitudinally-split grooved lines.The branchlet has little and dense lenticels,and the older branch has nearly-spherical lateral buds.

There are odd pinnately compound leaves with a length of 12-25 cm;the petiole has a length of 1.5-3 cm;the stipule falls early;there are(3-)4-(-6)pairs of leaflets,which are nearly leathery,entire at margin and in a shape of ovoid or ellipse,and have a length of 3.5-8 cm and a width of 1.5-4.0 cm,the one at the top of compound leaves is the largest,the rest leaflets get smaller downwards,the last pair has a length of 1/3 of the top leaflet,the apex is acuminate or acute and has a blunt end,and the base is round or broad cuneate,and the pinnate vein is not obvious;and the petiolule has a length of 3-5 cm.

The flower,bisexual and axillary,shows panicle pattern consisting of multiple cymes with a length of 5-10 cm and a diameter of 6-7 cm,and has branches in a shape of corymb;the peduncle has a length of 3-5 cm;the bracteole growing from the base is near to triangle in shape with a length of 0.5 mm,and the calyculus-like bracteole is broad obovate with a length of 1 mm;the flowers having a length of 5 mm concentrate at the top of inflorescence branches initially and become alienated afterwards;the pedicel is of 1 mm;the calyx is about 2 mm in length,it has one lower calyx tooth which is longer and of lanceolate shape,and other calyx teeth are of broad obovate shape and acute;and the corolla is milk white or faint yellow,and has nearly-equilong petals,each of which has a petiole length of 1 mm,the vexil is obcordate with a length including petiole of about 5 mm and an upper width of about 3 mm,and has truncate slightly-concave apex,the ala is of long circle,and the keel is of half moon shape and had arch back.There are 9 stamens,which are monadelphous;and the ovary is of narrow oval shape,and has a long petiole of 2.5 mm and 1-2 ovules.

The flowering phase is from April to June;the pod is linguiform,long elliptical and flat,the mature period of seeds is from October to next January,the pod has a length of 4.5-8 cm and a width of 1.5-1.8 cm,its base is slightly hairy,its tip is blunt or acute,and the base narrows suddenly to joint with the fruit neck having a length of 5-10 mm;the carpel is leathery,and protrudes at the part of seed,like chess piece,with a thickness up to 5 mm,and there are one seed,or occasionally two seeds;and the seed is reniform,flat,with a length of 0.9-1.1 cm and a width of 0.5-0.65 cm,and it is tawny,glossy,with no endosperm but thick cotyledon.

Growth environment and quality of Huanghuali

Hainan Huanghuali is distributed in tropic zone with an annual average temperature of 22-25℃and a extreme minimum temperature of-1-4℃,an annual average amount of precipitation of 1 000-1 500 cm and an annual air humidity of about 70%.It is of defoliation phenomenon in dry season,and the trees growing at piedmont in rainforest with good soil and moisture conditions could keep evergreen,and only change leaves for a short period of 3-5 d during March and April.Hainan Huanghuali likes high temperature,but also could resist light frost and a short period of extreme low temperature at about-1℃.

Huanghuali is a precious species specific to Hainan,and distributed at hilly area with low altitude or plain and tableland of Hainan island,mainly in the Li ethnic region,and the Hannan Huanghuali at Wangxia of Changjiang is especially precious,which generally grows on the slopes with an altitude below 350 m.Huanghuali grows fast in Eastern Hainan with open view,abundant rainwater and sunshine,resulting in sparse texture,large pattern and coarse lenticels,while Huanghuali in western mountain region with high altitude grows slowly due to dense forest fighting for nutrient,resulting in fine texture most of which would sink in water and plentiful and fine pattern;and by comparison,relatively,western Huanghualiis betterthan eastern Huanghuali,avocado is better than Huangli,and head of tree is better than tree trunk.

The distribution region of Hainan Huanghuali has an annual average temperature of 23-25℃,an annual amount of precipitation of 1 200-1 600 mm,and an evaporation amount of 1 600-2 300 mm which is higher than the precipitation amount.The precipitation concentrates in the six months from May till October with a monthly amount of precipitation above 213.3 mm,accounting for 80% of the annual amount of precipitation,meanwhile,the average temperature from March till November is higher than 22℃,and the season with high temperature and abundant water is good for growth of Huanghuali including sprouting and flowering.However,dry season begins from November to next April,with a monthly amount of precipitation of 16-29 mm,lasting half a year,showing obvious alternation of dry and damp seasons.During the period with enough rain and heat,flowers and leaves appeared simultaneously,promoting growth of Huanghuali,while in the dry and cool season,Huanghuali has flowers and leaves fallen off,and stops growth to live through unfavorable growth environment.

The unique tropical oceanic monsoon climate of Hainan Island provides suitable growth environment for Huanghuali,the annual rings of which are fine and clear,and have two or more alternated colors caused by the influence of the unique climate on Huanghuali growth.During hot rainy growth season,the formed texture part is wider and has lighter color,while during dry cool rainless period,Huanghuali stops growth,resulting in slightly deeper or very deep color.The pattern of vertical section of Huanghualilikes jumping stream,moving dune and gentle slope,and the tangentialsection shows swinging patterns such as speckles on leopard cat,grimace and umbrella-type pattern.

Rarity of Huanghuali

Hainan Huanghuali is previous due to the fact that growing into useful timber is very hard for it,and the bigger,the better.Hainan Huanghuali is previous in the smooth texture,elegant,fine and plentiful patterns and incomparable intense fluorescence.Owing to over exploration year by year,it is difficult to find wild forest in Hainan Island,and there is only Huanghuali cultivated artificially in a small region and regenerated forest.

The main factor for the rarity of Huanghuali is its slow growth,especially the heartwood for fabricating furniture has very slow conversion speed.According to investigation,in natural regenerated forest,the 32-year-old trees have a height of 16.50 m and a DBH of 22 cm.The DBH has an annual average increase of 0.6875 cm only,the 20-year-old artifical forest planted in tropical arboretum has an average tree height of 15.60 m and a DBH of 16.8 cm,and though such growth speed is faster than that of natural regenerated forest,it is very slow compared with other broad-leaved forest.The useful timber of Huanghuali is the heartwood converted from sapwood continously,while the heartwood is formed later generally and has low convension speed,for example,the newly cut Huanghuali with a diameter of 12.70 cm has the heartwood part of 2.60 cm only.

Characteristics and Value ofHainanHuanghualiWood

Characteristics of Huanghuali wood

Huanghuali is honoured as the first of“the three kinds of tribute wood for Ming and Qing dynasties”[1].Hainan Huanghuali was praised highly in Ming and Qing dynasties for its beautiful pattern,gentle color and luster and fragrance;it has hard texture suitable for inlay and graving,as well as the advantages of good processability,moderate hardness and weight and hard deformation,thus it is especially suitable for fabricating classical hardwood furniture. The heartwood of Huanghuali is red brown or purplish brown turning to dark red after a long time,and often has dark brown stripes,with luster and fragrance.The timber has cross-section texture naturally formed,and beautiful pattern.The furniture made of Hainan Huanghuali is lucid,lively,gorgeous,glossy,elegant and durable,and would not rot in hundreds years.Huanghuali furniture also emits quiet and beautiful wood fragrance permanently,and it is said that it could refresh mind and avoid evil spirits[2].

Huanghualifurniture could be handed down completely through several centuries,which is related to its performances of resisting corrosion,dampness and bite by termites.ADalbergia odoriferamore important fact is that the aromaticDalbergia odoriferae oil has infiltrated into the timber itself through long humidification process,and the timber emits fragrance when being sawed;under natural sunshine,old furniture fabricated hundreds years ago could glitter as before after being wiped and coated with colorless transparent beewax.Huanghuli has an airdry density of 0.82-0.94 g/cm3in the case of a water content of 12%.Some western avocado has an air-dry density above 1.0,and would sink in water.

Value of Huanghuali

Huanghuili is one of the noble materials for domestic traditional furniture due to its bright color,beautiful pattern,fine texture and charming fragrance[3].It is not only suitable for fabricating furniture,but also serves as the carrier for inheriting the fabricating process of classic furniture culture in our country.The classic furniture of Ming and Qing dynasties has elegant,concise and simple configuration,precise structure and moderate decoration,and has been honored as the peak all along ancient furniture history in our country,and it is also unique in the furniture history of the world,having eminent status.As one of the materials mainly used in later period of ancient furniture,Huanghuali fully deserves the status of important carrier for inheriting ancient culture techniques.

Useful huanghuali timber forms at a very slow speed,while its medicinal and collection value is high,resulting in increasing price in recent years[4].Huanghuali wood,especially for large timber,could not be supplied normally in market currently,and is scarce to the extent of being sold in a unit of cun or inch[5].Huanghuali is the most expensive rosewood currently,has wide application and very high value,and is known as “Muhuangjin” or gold wood[6].Huali wood is one of the five special goods in Hainan,and it is a first-class material for fabricating highclass furniture,artware,musical instrumentand precious decorative product,and also could be used as precious traditional medicinal material.At present,high-quality timber including Hainan Huanghuali has been or would be out of stock,relatively-abundant Huali wood would be the important timber for inheriting contemporary rosewood furniture.One classic bed made of Hainan Huanghuali is worth 10 600 000 RMB yuan,and a pair of chairs is worth 8 000 000 RMB yuan[7].The price of Hainan Huanghuali varies according to its material quality,and superior Huanghuali raw material has a price up to 10 000 RMB yuan[8].

Development Ways for Hainan Huanghuali

Guiding farmers to plant Huanghuli

Precious native tree species in Hainan include Huali,agilawood and sandalwood,and by mixed plantation of different tree species,the effects of promoting the stability of biodiversity could be achieved,so as to protect ecology.Though native tree species grow slowly with long period,they have considerable economicvalue and great potential of market demand.Therefore,y guiding farmers to make full use of wasteland,slopes,scattered land,roadside and other resources,Huanghuali couldbe wellplanted,which increase rural economic resource by realizing plantation of rare trees with a price up to 10 000 RMB yuan per plant by roadside,increasing productivity effect of forestry production.

Developing Huanghuali garden economy

Huanghuali,belonging to rare tree species,could be planted in courtyard,by rural road,and around the houses of farmers.Hainan Huanghuili is sold at a price of several dozens RMB yuan per kg.By calculating according to 1 050 plantss per hectare,the yield would be 90 m3,480 000 kg after 20 years,and the economic value would reach 9 600 000 RMB yuan according to 40 RMB yuan per kg.Each family could plant Huanghuali by dividing space with roads,and then personalized scene could be created,forming a living environment which is more natural and harmonious.With nature as the main consideration,the landscaping greenbelt of the courtyard area and the residential area could be planned for planting Huanghualiamong which flowers could be planted.The multilayerplanting structure formed by Huanghuali,shrubs and flowers is a specific embodiment of highlighting green,which provides basic guarantee for increasing green quantity,creates a natural kindly living environment for the residents,and plays the best ecological,social and economic benefits.

Planting landscaping-type Huanhuali

Greening is an important part for urban gardening,which is crucial to improvement of living environment quality for residents and promotion of physical and psychological health of residents.Landscaping companies and landscaping specialized companies should provide landscape planning and design with urban characteristics, and planting precious Huanghuali could create Huanhuali landscaping greenbelt, Huanghuali street,including residentialgarden,small garden and children playground and other block-and belt-type public green spaces,form pretty residential environment with prominent local feature,and endow landscape of residential gardens with both ornamental value and practicability. Planting Huanghuali in landscaping could make full use of local environment and surrounding localresources,forming good transition between residential area and urban space,and good plant landscape serving as small garden ornament could create the living field in which human and nature get along with each other very well,and improve garden taste.

Conclusions

Hainan Huanghuali has high economic value and good commercial quality,and Hainan Huanghuali timber is in shortage,resulting in high price.Therefore, developing Hainan Huanghuali has good market prospect.

Hainan Huanghuali is precious commercial wood,and the furniture made of it is durable and artistic,and suitable for long-time use.Planting Hainan Huanghuali could green the island as well as attract tourists,facilitating the construction of Hainan International Tourism Island.

By planting Hainan Huanghuali in corners and landscaping regions,farmers and enterprises could create high-end greenbelts,obtaining considerable economic benefits.

With the continuous development of Hainan International Tourism,Hainan Huanghuali has presented its greater ecological,social and economic benefits.

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