CC BY
38
СООБЩЕНИЯ
УДК 582.42/47(597)
L. Averyanov Nguyen Tien Hiep
Л.В. Аверьянов Нгуен Тьен Хьеп Фан Ке Лок Фам Ван Те
Phan Ke Loc Pham Van The
DISTRIBUTION, ECOLOGY AND HABITATS OF CALOCEDRUS RUPESTRIS (CUPRESSACEAE) IN VIETNAM РАСПРОСТРАНЕНИЕ, ЭКОЛОГИЯ И ХАРАКТЕРИСТИКА МЕСТ ОБИТАНИЯ CALOCEDRUS RUPESTRIS (CUPRESSACEAE) НА ТЕРРИТОРИИ ВЬЕТНАМА
A newly discovered conifer species, Calocedrus rupestris, is described from rocky limestone mountains of northern Vietnam. It is distinguished by its obtuse to broadly obtuse leaf apex; small, subsessile, 4-scaled, broadly ovate seed cones 4-5(6) x 2.5-3(3.5) mm with very short stalk 0.5-1(1.5) mm long, having 6-8(12) obtuse scales, and fertile seed scales with incurved rounded apex having rough, more or less flat surface without any mucro. The trees were found as a co-dominant in relictual coniferous forests on rocky hills and ridges composed of highly eroded limestone. Distribution, ecology and natural conditions of habitats of this species are provided in details. Relictual primary woods with C. rupestris as well as their floristic complex represent a unique plant diversity center of global significance. Urgent and effective protection of this area should be of highest priority for conservation.
Calocedrus Kurz is a small genus of the cypress family with trans-oceanic distribution typical of many relict taxa of the Tertiary floras. Before recent floristic investigations in Vietnam it comprised 3 extant species (Li Hui-Lin, Keng Hsuan, 1994; Nguyen Tien Hiep, Vidal, 1996; Fu Li-Guo, Yu Yong-Fu, Farjon, 1999; Farjon, 2001), namely - Calocedrus formosana (Florin) Florin (distributed in Taiwan), C. macrolepis Kurz (occurring in southern part of China, north eastern Myanmar, Thailand, Laos, southern Vietnam) and - C. decurrens (Torr.) Florin (found in Mexico and southwestern part of the U.S., in California and Oregon). One more species of this relictual genus -
Calocedrus rupestris Aver., H.T. Nguyen et L.K. Phan was recently discovered in northern Vietnam (Averyanov et al., 2004). This species is an important addition to our knowledge on Cupressaceae missed out in modern treatment of this family (Farjon, 2004, pers. comm.).
The only species of Calocedrus reported before for mainland Asia including Vietnam is C. macrolepis. In Vietnam this rare plant is observed in the wild only in the territory of South Annamese floristic province (Dac Lac, Phu Khanh, Ninh Thuan and Lam Dong provinces in southern Vietnam) in mountains composed of acidic silicate rocks at elevations 1000-2000 m. (N.T. Hiep, Vidal, 1996). Collections of this species from other parts of Vietnam were presumably made from cultivated plants. There are no yet really reliable reports of wild populations of C. macrolepis in northern Vietnam.
Morphological analysis of collected materials on Calocedrus rupestris reveals distinct and significant differences of this plant and all hitherto known extant species of the genus. Without any doubt, this recently discovered conifer represents well-defined obligate calcium dependent species. It represents the terminal link in one of evolutionary lines of successive reduction of scale number in the seed cones of Cupressaceae. Meanwhile, this outstanding novelty was formally described with insignificant diagnosis in local conference proceedings (Averyanov et al., 2004), which did not got wide distribution. Appropriate description of this plant, as well as key for determination of Calocedrus species in the flora of Vietnam are presented below.
KEY TO THE SPECIES OF CALOCEDRUS IN VIETNAM
Calocedrus Kurz, J. Bot. 11 : 196, 1873.
1 Leaf apex acute to apiculate, adult canopy leaves with distinct or indistinct white
stomatal bands abaxially; seed cones with 6 scales, cylindrical to broadly cylindrical, 7-8(12) mm long, 3.5(5) mm wide, distinctly stalked, pendulous or sub-pendulous; stalk commonly recurved, 3-5 mm long, with 16-20 imbricate scales, acute at apex; fertile seed
scale distinctly recurved, with apiculate apex, with a short distinct mucro.......
....................................................................1. C. macrolepis
+ Leaf apex obtuse to broadly obtuse, adult canopy leaves uniform green or with indistinct
whitish green stomatal bands abaxially; seed cones commonly with 4 scales (very rarely with additional basal pair of small rudimentary scales), broadly ovate, 4-6(7) mm long, 2.5-4 mm wide, subsessile, erect or suberect; stalk very short, straight, 0.5-1(1.5) mm long, with 6-8(12) imbricate scales, obtuse-rounded to broadly obtuse at apex; fertile seed scale incurved, rounded at apex, sometimes with indistinct slightly flattened plate with rough surface bearing rarely a very small central umbo.........2. C. rupestris
1. Calocedrus macrolepis Kurz, 1873, J. Bot. 11 : 196, Tab. 133.
Type: CHINA, Yunnan, Hotha, Anderson s.n. (holotype - CAL?; isotype - K). Calocedrus macrolepis is widely distributed in southern China (Guangdong, Hainan, Guangxi, Guizhou, southeastern Yunnan), northeastern Myanmar, Thailand, Laos and southern Vietnam (Li Hui-Lin, Keng Hsuan, 1994; Nguyen Tien Hiep, Vidal, 1996; Fu Li-Guo, Yu Yong-Fu, A.Farjon, 1999; Farjon, 2001). However, across its
distribution this species is very rare. Natural populations of C. macrolepis are disjunct and relictual, often standing on the verge of extinction in their native habitats. In southern Vietnam this species is recorded from the provinces of Dac Lac (between Buon Tria and Buon Trian Cao), Phu Khanh (Hon Ba mountains), Lam Dong (Da Lat, Camly, Prenh) and Ninh Thuan in Bi Doup mountains (Nguyen Tien Hiep, Vidal, 1996). Few available records of C. macrolepis from northern Vietnam (Tan Vien Mountain, Ba Vi district, Ha Tay province) probably came from cultivated samples (fig. 1). In Vietnam this tree grows in primary forests with closed canopy, which are evergreen tropical, humid, broad-leaved submontane and montane forests at elevations of 1000-2000 m on soils developed primarily from silicate rocks. Across Vietnam C. macrolepis is represented by single or rarely scattered trees. The trees are widely logged for its valuable timber and therefore the species deserves in the country a conservation status of endangered species (EN) according to RED list Categories and Criteria (EN, A-C, E): Version 3.1 of IUCN (2001).
Specimens examined: VIETNAM. Ha Tay Prov.: Ba Vi, 1200 m, Ban 6888 (LE); sine coll. 3670 (HN) all probably cultivated or naturalized. Dac Lac Prov.: between Buon Tria and Buon Trian Cao, 1000-1200 m, Poilane 32620 (P). Khanh Hoa Prov.: Nha Trang, Hon Ba mountain, Krempf1598 (P). Lam Dong Prov.: near Dalat city, Evrard 1355 (P); Hayata 176; Soviet-Vietnamese expedition LX-VN1455 (HN, LE); Nguyen Duy Chinh sine n. (HN); Schmid 860, id., Apr. 1954, sine n., id., June 1960, sine n. (P); Vu Van Cuong 1151 (P) all probably cultivated or naturalized; Camly, Evrard 249 (P); Prenn, Evrard 1458, 2202 (P). Border of Lam Dong and Ninh Thuan Prov.: Bi Doup mountains, Poilane s.n. October 1940 (P).
2. Calocedrus rupestris Aver., H.T. Nguyen et L.K. Phan, 2004, in Aver., Nguyen Tien Hiep, Pham Van The, Phan Ke Loc, Proc. Nat. Conf. Life Sci. Thai Nguyen Univ. Sept. 2004 : 41.
Type: VIETNAM. Prov. Bac Kan: Na Ri Distr., Liem Thuy Mun., Na Bo, 21°56’44'’N, 106°05’09'’E, 650-700 m, 3 June 2004 L. Averyanov, NT Hiep, P.V The, N.T. Vinh HAL 5441 (holotype - HN; isotypes - LE, MO).
Arbor 25 m.; folia decussata, dimorpha: folia dorsi-ventralia adpressa, (1)2-6(7) mm longa, (1.5)2-2.5 mm lata; folia lateralia, conduplicata, (1.5)2-6(7) mm longa, (0.3)0.5-0.75(1) mm lata, apice obtuso (non acuto); strobili feminei ovate, (4)5-6(7) mm longa, (2.5)3-4 mm lata; squamae 2 paribus, oppositae, decussatae, squamae inferiore subpeltato, apice incurvo, obtuse-rotundato (non acuminato); pare superioro connato, sterilis.
Tree up to 25 m tall, trunk to 1 m dbh, evergreen, monoecious, with broadly rounded crown; bark 8-12 mm thick, grayish-brown to brown, fissured, fibrous and exfoliating in longitudinal stripes, with numerous large resin ducts, resin abundant, bright yellow-orange, with pine-like fragrance; timber light yellow, odorless; branchlets arranged in a plane, spreading and ascending, flattened, prominently jointed. Leaves decussate, in whorls of 4, scale-like, broadly obtuse to obtuse at apex, base decurrent, dimorphic along branchlet, facial pair flattened (1)2-6(7) mm long, (1.5)2-2.5 mm wide, lateral pairs conduplicate, boat shaped (1.5)2-6(7) mm long, (0.3)0.5-0.75(1) mm wide,
in overlapping facial pairs, without glands, uniform green or with very indistinct stomatal whitened bands abaxially. Pollen cones terminal, solitary, cylindrical, terete, (4.5)5-6 mm long, 1.5-2(2.2) mm broad, with (8)9-11 pairs of scales, (the lowest 2-4 pairs sterile), each with 2-6 pendulous pollen sacs; microsporophylls (pollen cone scales)
0.8-1(1.2) mm long, 1-1.2 mm wide, obtuse-rounded to broadly obtuse, with finely erose margin, obtuse to broadly obtuse at apex, light green turning to light brown; microsporangia (pollen sacs) broadly-ovate to subspherical, 0.3-0.4 mm broad. Seed cone-bearing branchlets (stalks) terete or 4-angled, 0.5-1(1.5) mm long, with 6-8(12) imbricate scales, obtuse to broadly obtuse at apex. Seed cones greenish brown, terminal, solitary or paired at apex of lateral branchlets, ovate, (4)5-6(7) mm long, (2.5)3-4 mm wide, dehiscent when mature in first year, with 4 decussate, flat scales (very rarely with 1 additional basal pairs of scale rudiments); seed cone scales flattened, woody or somewhat leathery, broadly ovate, 4-6x2.5-4 mm; basal 2 scales fertile, dehiscent when ripe, normally 2-seeded (rarely 1), at apex incurved, rounded, sometime with an indistinct, slightly flattened or concave plate with rough surface, rarely with very small insignificant central umbo; apical pair sterile, connate. Seeds ovate or subovoid, acute at apex, slightly flattened, with 2 large subapical, unequal wings, 4-5 mm long. Fig. 2, tables 1, 2.
Phenology. Pollination occurs in December - January, with seeds maturing probably in September to October.
Etymology. From the Latin word “rupestris” meaning rock-dwelling, growing on rocky slopes or cliffs.
Paratypes: VIETNAM. Prov. Bac Kan: Na Ri Distr., Liem Thuy Mun., Na Bo, 21°56’44'’N, 106°05’09'’E, 27 May 2004 L. Averyanov, N.T. Hiep, P.V The, N.T. Vinh HAL 4919 (HN), 3 June 2004 L. Averyanov, N.T. Hiep, P.V. The, N.T. Vinh HAL 5439 (HN), L. Averyanov, N.T. Hiep, P.V. The, N.T. Vinh HAL 5440 (HN).
Specimens examined: VIETNAM. Prov. Cao Bang, Bao Lac Distr., Yen Lac Municipality, vicinities of Yen Lac village, 22°44' N, 105°50' E, 1450-1500 m, 16 April 1999, P.K. Loc, P.H. Hoang, L. Averyanov CBL 1462 (HN), sterile; Bao Lac Distr., Dinh Phung Municipality, Man Lung ridge, 22°47' N, 105°49' E, 1550-1600 m, 18 April 1999, P.K. Loc, P.H. Hoang, L. Averyanov CBL 1515 (HN), sterile. - Prov. Ha Giang, Yen Minh Distr., Lao Va Chai Municipality, vicinities of Ngan Chai village, 6 km to W of Yen Minh town, 23°07' N, 105°08' E, cultivated treelet introduced from wild at 1600-1700 m, 1 May 1999, P.K. Loc, P.H. Hoang, L. Averyanov CBL 1977 (HN), sterile.; Quan Ba Distr., Bat Dai Son Municipaliry, Bat Dai Son Nature Reserve, around point 22°59’50'’ N, 105°05’46'’ E, about 1600 m, 10 May 2002, P.K. Loc, L. Averyanov, N. T. Vinh HAL (HN), sterile; Quan Ba District, Can Ty Municipality, at Sin Suoi Ho village and river, 23°06’57" N, 105°01’48" E, 514-900 m, 1 April 2000,
D.K. Harder, N.T. Hiep, L. Averyanov DKH 4854 (HN), sterile; Quan Ba Distr., Can Ty Municipality, in the vicinity of Lung Vai village at left side of Mien River, 23°05’09'’ N, 105°03’23'’ E, 1440 m, 8 May 2002, P.K. Loc, L. Averyanov, N.T. Vinh HAL 1457 (HN), sterile; Quan Ba Distr., Can Ty Municipality, Ha Tung Sung Valley, Bat Dai Son Natural Reserve around point 23°05'46’’ N, 105°01’05’’E, 1230 m, 18
: 7 ' ' i f
January 2003, T.V. Thao, N.S. Khang VT 021 (HN), sterile.- Quan Ba Distr.,
Thanh Van Municipality, cultivated tree taken from the wild in the vicinity of Lung Cung village at right side of Mien River, around point 23°07’12'’ N, 105°00’52'’
E, 980 m, 8 May 2002, P.K. Loc, L. Averyanov, N.T. Vinh HAL 1471 (HN), sterile; Quan Ba Distr., Thanh Van Municipality, in the vicinity of Lung Cung village, around 1 km to the E from point 23°05’32'’ N, 105°00’10'’ E, 1100-1200 m,
9 May 2002, P.K. Loc, L. Averyanov,
N.T. Vinh HAL 1493 (HN), sterile; Quan Ba Distr., Thai An Municipality, in the vicinity of Lo Thang village, 22°59’50'’
N, 105°05’46'’ E, 1600 m, 10 May 2002,
P.K. Loc, L. Averyanov, N.T. Vinh HAL 1513 (HN), sterile; Quan Ba District,
Thai An Municipality, December 1999,
N. Tap 2B (HN), sterile. - Prov. Son La,
Yen Chau Distr., Muong Lum municipality, Lum village, 21°00’47'’ N,
104°29’30'’ E, 1200-1350 m, 2 March
2001, D. Harder, P.K. Loc, N.T. Hiep,
L. Averyanov DKH 7066 (HN), young female cones; Moc Chau Distr., Van Ho Municipality, Hua Tat village, 20°46’18'’
N, 104°47’45'’ E, 1200-1350 m, 6 October 2000, D. Harder et al. DKH
5763 (HN), sterile. - Prov. Hoa Binh, Da Bac Distr., to the SW of Doan Ket village, 20°54’01'’ N, 105°04’19'’ E, 900-1000 m, 29 March 2001, N.T. Hiep, L. Averyanov, N. T. Vinh, D. T. Doan HAL 367 (HN), sterile.; Mai Chau Distr., Hang Kia Municipality, near Thung Ang village, mountain Tao Xinh, 20°43 ’43'’ N, 104°51 ’21'’ E, 1000-1100 m, 6 April 2001, N.T. Hiep, L. Averyanov, N.T. Vinh, D.T. Doan HAL 629 (HN), sterile. -Prov. Nghe An, Con Cuong Distr., Binh Chuan Municipality, Phu Pha Cau mt., 19°18’13'’ N, 104°53’50'’ E, 1100-1250 m, 26 February 2004, VM. Son, N.T. Vinh
HLF 3136 (HN), sterile. - Prov. Quang Binh, Bo Trach Distr., Tan Trach Municipality, vicinities ofA Rem village, 17°23’32'’ N, 106°12’46'’ E, 650-750 m, 24 January 2005, L. Averyanov, P.K. Loc, P.V. The, A. Averyanova, N.T. Vinh, N.Q. Vinh, N.T. Binh HAL 6109 (HN, d-EXSICCATE OF VIETNAMESE FLORA 0001/HAL6109), male and young female cones, 25 January 2005, HAL 6164 (HN), male and young female cones, 26 January 2005, HAL 6200 (HN), male and young female cones.
Figure 1. Map of distribution Calo-cedrus macrolepis (round marks) and C. ru-pestris (quadrate marks) in Vietnam. Location of presumably cultivated or naturalized specimens are marked with question mark.
Figure 2. Calocedrus rupestris Aver., H.T. Nguyen et L.K. Phan a - portion of young adult canopy branch; b - portion of old adult canopy branch; c -decussate leaves of young adult canopy branch (adaxial side); d - decussate leaves of young adult canopy branch (abaxial side); e - young pollen cone on portion of adult canopy young branch; f - mature pollen cone on portion of adult canopy young branch; g - microsporophylls with pollen sacs; h - open pollen sac; i - portion of young adult canopy branch with seed cone; j, k - seed cones (front and lateral views) with rudimentary additional pair of sterile scales; l -seed cone, with removed fertile cone-scale, front view; m - seed. (all drawn from the holotype L. Averyanov, N. T. Hiep, P. V. The, N. T. Vinh HAL 5441 by L. Averyanov).
Most significant morphological differences between Calocedrus macrolepis and C. rupestris are summarized in table 1.
Calocedrus rupestris along with other endemic and sub-endemic conifers like Keteleeria davidiana (Bertrand) Beissn., Pinus kwangtungensis Chun ex Tsiang, Pseudotsuga sinensis Dode, Tsuga chinensis (Franch.) Diels, Xanthocyparis vietnamensis Farjon et Hiep, as well as other gymnosperm trees such as Amentotaxus argotaenia Pilger, A. hatuyenensis N.T. Hiep, A. yunnanensis Li, Cephalotaxus mannii Hook. f., Dacrycarpus imbricatus (Blume) de Laub., Dacrydium elatum Wall., Nageiafleuryi (Hickel) de Laub., Podocarpus neriifolius D. Don, P. pilgeri Foxworthy and Taxus chinensis Roxb. represents formative element of primary mixed and coniferous forests in rocky limestone areas of northern Vietnam. These woods form here floristic nucleus of highly endemic limestone floras and support specific very sensitive ecosystems of outstanding high level of biodiversity. A great number of strict endemics of high taxonomic rank are associated with woods of this kind. Among them are recently discovered endemic and sub-endemic genera such as Caobangia A. R. Smith et X.C. Zhang (Polypodiaceae), Grushvitskya Skvorts. et Aver. (Araliaceae), Vietorchis Aver. et Averyanova and Zeuxinella Aver. (Orchidaceae), Xanthocyparis (Cupressaceae), and some others (Skvortsova, Averyanov, 1994; Farjon et al., 2002; Averyanov et al., 2002; Smith, Zhang, 2002; Averyanov, Averyanova, 2003).
In the past Calocedrus rupestris was undoubtedly widely distributed in northern Vietnam. This tree was one of the most important species-edificator of woody communities and indicator of intact pristine primary climax aboriginal zonal relictual woods typical for ancient highly eroded remnant rocky limestone ridges in northern part of eastern Indochina. During modern explorations it was commonly found as a
Table 1
Morphological differences between Calocedrus macrolepis and C. rupestris
Morphological feature C. macrolepis C. rupestris
Apex of canopy leaves acute obtuse to broadly obtuse
Seed cone position distinctly stalked, stalk usually recurved, cone commonly pendulous, or sub-pendulous subsessile (cone erect or sub erect)
Seed cone form, dimensions broadly cylindrical to elongate 7-8(12) x 3.5-4(5) mm broadly ovate, 4-6(7) x 2.5-4 mm
Seed cone stalk & scales 3-5 mm long, with 16-20 imbricate scales, each acute at apex 0.5-1(1.5) mm long, with 6-8(12) imbricate scales, each obtuse to broadly obtuse at apex
Number of scales in seed cone 6 4 (very rarely 6)
Apex of fertile scale in seed cone distinctly recurved, apiculate, with short distinct mucro incurved, rounded, sometimes with indistinct slightly flattened plate with rough surface, rarely with very small insignificant central umbo
Number of seeds (ovules) on fertile scale 1 or 2 2 (rarely 1)
more or less usual co-dominant of the first forest stratum in last remains of primary mixed and coniferous forests associated regularly with Dacrycarpus imbricatus, Dacrydium elatum, Keteleeria davidiana, Pinus kwangtungensis and Pseudotsuga sinensis. Presently this tree forms majestic mono-dominant pure stand in a few places of the country (Table 1a). Forests with C. rupestris commonly cover the rocky tops of ridges and hills composed with highly eroded solid crystalline white and gray marblelike limestone. The coniferous canopy stratum in these forests commonly does not exceed 15-20 m tall on more or less open isolated rocky tops of limestone remnant mountain formations. However, on steep slopes near the tops, conifers (particularly Keteleeria davidiana) often reach 30 m tall with trunks to 1.5 m dbh. The largest observed samples of C. rupestris were about 25 m tall and about 1.2 m dbh. Preliminary observation of timber rings indicates that these trees are probably more than 600-800 years old. Maturity of micro sporangia and pollination of this species come in December -January, while seed dispersing falls probably on September - October.
In our days distribution of Calocedrus rupestris in northern Vietnam due to deforestation is very limited and comprises miserable isolated disjunctive rocky limestone hilly and mountain systems with predominant elevations 600-1000 (1600) m. Available data on distribution of this species are presented on the map of distribution (fig. 1). This cypress tree probably may be also found in many other isolated rocky limestone mountains of northern Vietnam, which still keep primary woody vegetation. However, in most observed localities this tree definitely becomes rare due to many factors and exactly moves to its coming extinction. Some discovered localities of C. rupestris were found very near to Chinese and Laotian borders (fig. 1). This fact indicates that species may be also found in limestone regions of both mentioned countries allied to the territory of Vietnam.
Largest intact stands of Calocedrus rupestris were recently found and studied in south-eastern part of Bac Kan Province (bordering with Thai Nguyen and Lang Son provinces in the center of northern Vietnam) and in Quang Binh Province (in limestone area of Phong Nha - Ke Bang national park). In these studied areas C. rupestris represents an integral element of primary coniferous forests with Keteleeria davidiana, Pinus kwangtungensis and Pseudotsuga sinensis (Bac Kan) and with Dacrycarpus imbricatus and Dacrydium elatum (in Quang Binh Province). Fragments of these forests cover isolated rocky tops and edges of ridges of highly eroded remnant limestone formations, which appear as a numerous hills, small mesae-like mountains or rocky ridges with very steep slopes and numerous vertical cliffs. Mountains in studied areas are composed of solid crystalline white to gray marble like limestone, which represents relictual geologic formation derived from marine deposits presumably of late Paleozoic age (Dovzikov et al., 1965a, b). Deep erosion of ancient highly metamorphosed marblelike limestone formed spectacular landscape in this area, which still keeps primary vegetation typical for rocky limestone areas of north-eastern Indochina.
Recent climatologic studies define climate in the area of Calocedrus rupestris distribution as monsoon tropical climate with cold winter and summer to summer-autumn rains (Nguyen Khanh Van et al., 2000). Summers here are wet, with rainfall
peaks coming to July - October. Annual rainfall commonly varies from 1200 to 3000 with mean annual rainfall for the region averaged at about 2200 mm. Temperature regimes have a strong seasonality and depend of elevation. Winter conditions with cool temperatures extend usually from November to April with normal lows in lowlands of 14-16°C. The mountain regions experience cooler temperatures and higher levels of mean annual rainfall with increasing elevation. At elevations above 900-1000 m night hoarfrost is sometimes observed in open places during winter months. Persistent cool drizzling rains are very typical from early February until the end of March. Summers are hot and humid, with maximum temperatures reaching to 35°. Common mean annual temperatures are about 23.5°C. Detailed description of climate conditions of the mentioned area was presented earlier (Averyanov et al., 2003a, b).
Canopy forest stratum in the area of Calocedrus rupestris distribution reaches on tops of limestone mountains 15-20 m tall, but is elevated up to 25-30 m on slopes protected from winds. Some broad-leaved trees, like Platycarya strobilacea Siebold et Zucc. (Juglandaceae) and several tropical oaks (Quercus spp.) occur sometimes in this stratum besides mentioned conifers. On mountain slopes broad-leaved trees become more common in the first forest stratum and often include such species as Anogeissus acuminata Wall., Bischofia javanica Blume, Dracontomelon duperreanum Pierre, Pometia pinnata J.R. et G. Forst., Radermachera sinica Hemsl., Streblus macro-phyllus Kurz, as well as species of Aglaia Lour., Lagerstroemia L., Paulownia Sieb. et Zucc., Sterculia L. and Toona M. Roem.
Second forest stratum includes many species of trees commonly 6-15 m tall. Among them most common are Acer tonkinense Lecomte (Aceraceae), Bonioden-dron parviflorum (Lecomte) Gagnep., Cinnamomum sp., Machilus sp. (Lauraceae), Garcinia sp. (Clusiaceae), Nephelium sp. (Sapindaceae), Carpinus sp. (Betulaceae), Celtis sp. (Ulmaceae), Ficus spp. (Moraceae), Knema sp. (Myristicaceae), Lysidice rhodostegia Hance (Fabaceae), Myrsine seguini Leveille (Myrsinaceae), Ormosia sp. (Fabaceae), Pistacia weinmannifolia Franch. (Anacardiaceae), Radermachera boniana Dop (Bignoniaceae), Reevesia sp. (Sterculiaceae), Schefflera pes-avis R. Vig. (Araliaceae), Sinosideroxylon racemosum (Dubard) Aubrev. and S. wightia-num (Hook. et Am.) Aubrev. (Sapotaceae). Some gymnosperm trees, such as Amento-taxus yunnanensis, Cephalotaxus mannii, Nageia fleuryi and Podocarpus nerii-folius are also regular component in this stratum.
Next stratum of the forest includes small trees and shrubs commonly (1.5)2-6 m tall. They are creating more or less dense cover composed with great number of species. Main co-dominants here are such species as Alstonia guangsiensis D. Fang et X.X. Chen (Apocynaceae), Anamitra sp. (Menispemaceae), Ardisia sp., Myrsine kwangsiensis (E. Walker) Pipoly et C. Chen (Myrsinaceae), Blastus sp., Memecylon edule Roxb. (Melastomataceae), Bischofia sp., Phyllanthus sp., Sauropus sp. (Euphorbiaceae), Callicarpa sp., Premna sp. (Verbenaceae), Campylotropis henryi Schindler (Fabaceae), Carallia sp. (Rhizophoraceae), Decaspermum parviflorum (Lam.) J. Scott, Rhodamnia trinervia Blume (Myrtaceae), Eurya sp. (Theaceae), Glycosmis sp. (Rutaceae), Illicium cambodianum Hance (Illiciaceae), Ixora sp.,
Psychotria sp. (Rubiaceae), Licuala sp., Rhapis divaricata Gagnep., R. subtilis Becc. (Arecaceae), Ligustrum sp. (Oleaceae), Mahonia nepalensis DC. (Berbe-ridaceae), Melientha suavis Pierre (Olacaceae), Pistacia cucphuongensis Dai et Yakovlev (Anacardiaceae), Polyalthia sp. (Annonaceae), Schefflera sp. (Araliaceae), Strobilanthes sp. (Acanthaceae), Tirpitzia sinensis (Hemsl.) Hallier f. (Linaceae), Viburnum cinnamomifolium Rehder, V. lutescens Blume, V. propinquum Hemsl., V. triplinerve Hand.-Mazz. (Caprifoliaceae). On steep more or less open slopes and cliffs may be observed short palm-like cycads - Cycas dolichophylla K.D.Hill, Hiep et P.K. Loc and C. chevalieri Leandri.
Herbaceous species composition in habitats of Calocedrus rupestris is extraordinarily rich and includes a great number of terrestrial and lithophytic species among which most common are Aglaonema sp., Amorphophallus sp., Arisaema spp. and Typhonium sp. (Araceae), Alpinia spp. (Zingiberaceae), Amischotolype sp. and Pollia sp. (Commelinaceae), Ardisia maclurei Merr., Ardisia silvestris Hance and Ardisia spp. (Myrsinaceae), Carex spp. (Cyperaceae), Disporum cantoniense (Lour.) Merr., Ophiopogon peliosanthoides Wight et Am., Peliosanthes teta Andrews, Polygo-natumpunctatum Royle and Tupistra sp. (Convallariaceae), Elatostema spp. (Urtica-ceae), Impatiens spp. (Balsaminaceae), Lysimachia microcarpa C.Y. Wu and L. insignis Hemsl. (Primulaceae), Ophiorrhiza spp. (Rubiaceae), Pentaphragma sp. (Pentaphragmaceae) and Polygala sp. (Polygalaceae). On the shady forest floor are occasionally observed rare achlorophyllous mycotrophyc and parasitic species -Balanophora sp. (Balanophoracerae), Burmannia unguiculata Aver. (Burmannia-ceae), Didymoplexis pallens Griff, and Epipogium roseum (D. Don) Lindl. (Orchi-daceae) and Sciaphila clemensae Hemsl. (Triuridaceae). Shady vertical cliffs represent typical habitat of numerous obligate lithophytes, such as Aeschynanthus sp., Boea spp., Chirita spp. (Gesneriaceae), Begonia aptera Blume, B. cavaleriei H. Lev., Begonia spp. (Begoniaceae), Peperomia blanda (Jacq.) Kunth (Piperaceae) and numerous ferns. Among most common vines in habitats of C. rupestris were observed species of Aristolochia L. (Aristolochiaceae), Clematis L. (Ranunculaceae), Cynan-chum L. and Dischidia R.Br. (Asclepiadaceae).
Shady humid conditions of primary forests in studied mountains support great diversity of epiphytic, lithophytic and terrestrial ferns. Among most common species observed here are Adiantum caudatum L., A. gravesii Hance, Amphineuron tonki-nense (C. Chr.) Holltum., Antrophyum sp., Arthropteris repens (Brack.) C. Chr., Asplenium antrophyoides H. Christ, A. cardiophyllum (Hance) Baker, A. griffithianum Hook., Asplenium spp., Colysis bonii Ching, Colysis elliptica (Thunb.) Ching, Colysis pothifolia (D. Don) C.Presl, Colysis sp., Ctenitopsis austrosinensis (H. Christ) Tardieu, Cyclopeltis crenata (Fee) C. Chr., Cyclosorus sp., Cyrtomium fortunei J. Sm., Cyrtomium sp., Drymoglossum sp., Dryopteris sp., Lemmaphyllum microphyllum C.Presl, Neocheiropteris ensata (Thunb.) Ching, Hymenophyllum sp., Loxogramme sp., Microsorum sp., Phymatosorus sp., Polystichum spp., Pteridrys sp., Pteris spp., Pyrrosia porosa (C. Presl) Hovenkamp, Pyrrosia sp., Tectaria polymorpha (Hook.) Copel., T. stenomioides (Alderw) C. Chr., T. subpedata (Harr.) Ching, Tectaria spp.,
Trichomanes spp. and Vandenboschia auriculata (Blume) Copel. Fern allies include Huperzia phlegmaria (L.) Rothm., H. squarrosa (G Forst.) Trevis. (Lycopodiaceae) and Psilotum nudum (L.) Beauv. (Psilotaceae).
The orchids reach extraordinary high diversity in coniferous forests with Calocedrus rupestris. Most of them are rare obligate calcium dependent species growing commonly as lithophytes. Among species of this group most common in studied area are Acampe rigida (Sm.) P.F. Hunt, Bulbophyllum macraei (Lindl.) Reichenb. f., Calanthe alismifolia Lindl., C. triplicata (Willem.) Ames, Callostylis rigida Blume, Cheirostylis yunnanensis Rolfe, Cleisostoma rostratum (Lodd.) Seidenf., Collabium chinense (Rolfe) Tang et F.T. Wang, Coelogyne fimbriata Lindl., Corymborkis veratrifolia (Reinw.) Blume, Cymbidium aloifolium (L.) Sw., C. ensifolium (L.) Sw., C. lancifolium Hook. f., C. sinense (Jacks.) Willd., Dendrobium fimbriatum Hook., D. loddigesii Rolfe, Epigeneium labuanum (Lindl.) Summerh., Eria boniana (Gagnep.) Tang et F.T. Wang, E. corneri Reichenb. f., Flickingeria fimbriata (Blume) Hawkes, Goodyera hispida Lindl., G viridiflora (Blume) Dietrich, Hetaeria anomala (Lindl.) Hook. f., Hygrochilusparishii (Reichenb. f.) Pfitzer, Liparis cordifolia Hook. f., L. distans C.B.Clarke, L. latilabris Rolfe, L. mannii Reichenb. f., L. stricklan-diana Reichenb. f., L. viridiflora (Blume) Lindl., Ludisia discolor (Ker-Gawl.) A. Rich., Malaxis acuminata D. Don., Neuwiedia balansae Gagnep., Oberonia cavaleriei Finet, O. ensiformis (Sm.) Lindl., O. kwangsiensis Seidenf., Odontochilus elwesii Hook. f., Paphiopedilum concolor (Batem.) Pfitzer, Pelatantheria insectifera (Reichenb. f.) Ridl., Pholidota rubra Lindl., Podochilus khasianus Hook. f., Phaius flavus (Blume) Lindl., Sunipia scariosa Lindl., Tainia hongkongensis Rolfe, Tropidia angulosa (Lindl.) Blume and T. curculigoides Lindl.
Epiphytic orchids in coniferous forests are also numerous and include many species, particularly Aerides crassifolia Burbridges, A. odorata Lour., A. rosea Lindl. et Paxt., Appendicula hexandra (Koenig) J.J.Smith, Ceratostylis himalaica Hook. f., C. subulata Blume, Cleisostoma birmanicum (Schltr.) Garay, C. paniculatum (Ker-Gawl.) Garay, C. rostratum (Lodd.) Seidenf., C. striatum (Reichenb. f.) Garay, C. wil-liamsonii (Reichenb. f.) Garay, Cymbidium dayanum Reichenb. f., Dendrobium hercoglossum Reichenb. f., D. nobile Lindl., D. parishii Reichenb. f., D. salaccense (Blume) Lindl., D. spatella Reichenb. f., D. terminale Par. et Reichenb. f., D. thyrsi-florum Reichenb. f., D. truncatum Lindl., Eria globulifera Seidenf., E. lasiopetala (Willd.) Ormerod, E. paniculata Lindl., E. pannea Lindl., E. pusilla (Griff.) Lindl.,
E. siamensis Schltr., Flickingeria angustifolia (Blume) Hawkes, Gastrochilus acuti-folius (Lindl.) Kuntze, Kingidium deliciosum (Reichenb. f.) Sweet, Liparis elliptica Wight, Luisia morsei Rolfe, Ornithochilus difformis (Lindl.) Schltr., Panisea tricallosa Rolfe, Parapteroceras elobe (Seidenf.) Aver., Pholidota articulata Lindl., P. chinensis Lindl., P. imbricata Hook., Renanthera coccinea Lour., Rhynchostylis giganthea (Lindl.) Ridl., Robiquetia spathulata (Blume) J.J. Smith, Schoenorchis gemmata (Lindl.) J.J. Smith, Thelasispygmaea (Griff.) Blume and Trichotosiapulvinata (Lindl.) Kraenzl.
The orchid flora in habitats of Calocedrus rupestris includes numerous rare orchids endemic for South Chinese and North Indochinese floristic provinces (Averyanov
et al., 2003a, b). Among them are Anoectochilus calcareus Aver., Biermannia calca-rata Aver., Bulbophyllum ambrosia (Hance) Schltr., B. longibrachiatum Tsi, Calanthe argenteo-striata C.Z. Tang et S.J. Cheng, Cleisostoma melanorachis Aver. et Averyanova, C. simondii (Gagnep.) Seidenf., Eria spirodela Aver., E. thao Gagnep., Habenaria ciliolaris Kraenzl., Liparis averyanoviana Szlach., L. petelotii Gagnep., L. petraea Aver. et Averyanova, L. pumila Aver., L. tixieri Guillaum., Luisia appres-sifolia Aver., Micropera poilanei (Guillaum.) Garay, Mischobulbum longiscapum Seidenf., Panisea albiflora (Ridl.) Seidenf., Paphiopedilum emersonii Koopowitz et Cribb, P. hangianum Perner et Gruss, P. helenae Aver., P. hirsutissimum (Lindl.) Stein. var. esquirolei (Schlechter) Karasawa et Saito, P. malipoense S.C. Chen et Tsi, Phalaenopsis gibbosa Sweet, Pholidota roseans Schltr., P yunnanensis Rolfe, Renanthera citrina Aver., Rhomboda petelotii (Gagnep.) Ormerod and Vanda fuscoviridis Lindl.
Some of them, particularly Paphiopedilum emersonii, P. hangianum, P. helenae, P. malipoense, Renanthera citrina, Phalaenopsis gibbosa and Vanda fusco-viridis have extraordinary significance in ornamental horticulture and breeding programs. All they vanish in most localities of their primary distribution in Vietnam due to commercial collecting and approach now to full extinction in the nature. Discovered primary coniferous forests with C. rupestris still support probably last intact populations of these very rare critically endangered species. Without any doubts, all discovered stands of C. rupestris represent highly endemic, unique plant diversity centers of global significance. Urgent and effective protection of nature in these areas should be regarded as a goal of highest priority in the World nature protection strategy.
Logging of Calocedrus rupestris, as well as other cypress trees (like Fokienia hodginsii (Dunn) A. Henry et H.H. Thomas., Calocedrus macrolepis Kurz., or Xanthocyparis vietnamensis) with fragrant valuable timber highly demanded on domestic and international market is serious factor of their fast extinction in most areas of their primary distribution in Vietnam.
Very few seedlings and saplings of Calocedrus rupestris were observed during field exploration in most studied localities. Definitely, general climate desertification connected with wide deforestation in northern Vietnam is the important limiting factor which damaged natural age-spectrum of population C. rupestris in their natural habitats. Certainly, in prehistoric ages coniferous limestone forests found acceptable conditions on relatively low elevations and spread widely in northern Vietnam. In our days these plant communities and populations of concrete coniferous species on low elevations rapidly degrade due to global decrease of humidity (even being not directly damaged by human activity). Climate desertification connected with very wide deforestation shift ecological optimum of most conifers to more high elevations. This process leads to slow invincible extinction of conifers in mountain systems where elevations do not exceed 700-800 m (table 1, e). Ecological optimum of most native coniferous species is now out of this mountain belt and their populations on low elevations are highly endangered and extremely sensitive to any damage. It is particularly true for C. rupestris. Obviously, this unique relict of the world flora desires status of endangered species
and should be reasonably included in Red Data Book of Vietnam as endangered species (EN) according to RED list Categories and Criteria EN, A2cd, C1, E (Version 3.1 of IUCN, 2001, Nguyen Tien Hiep et al., 2004). Certainly, all populations of this species need urgent effective protection that may prevent coming extinction of this significant endemic species in nature.
In our days largest stands of intact primary woods with C. rupestris in Vietnam were observed in rocky limestone areas of Phong Nha - Ke Bang national park (table
1, a). Relatively large pristine forest lands on this territory probably still support appropriate humidity, microclimate, soil, edaphic, watering regime and other natural conditions peculiar to indigenous intact plant zonal limestone communities of northern part of eastern Indochina. This is alone observed locality of C. rupestris with normal age spectrum of populations, which exhibit normal succession of natural species regeneration from seedlings and saplings to ripe trees up to 25 m tall and 1.2 m of bole diameter presumably 600-800 years old (table 1, b). Definitely, C. rupestris woods in this area represent unique intact model of primary zonal limestone vegetation typical for pristine indigenous nature of Indochinese peninsular. It is necessary underline, that coniferous forests on rocky limestone are most endangered type of vegetation in the world. Such forests were extinct completely in most areas of their natural distribution and their natural regeneration always very problematic. In this connection, absolute integrated protection of coniferous woods with C. rupestris on the territory of Phong Nha - Ke Bang national park are extraordinary important point of nature protection activity of high national, as well as global significance.
It was noticeably to observe that sometime many seed cones in populations of Calocedrus rupestris were damaged by very small unidentifiable insect larvae. All damaged cones became enlarged and were uniformly developed into spherical seedless formations with hemi-woody connate sub peltate scales, which superficially resemble cones of Fokienia hodginsii or some species of Chamaecyparis Spach (table 2, g). Formation of such unusual peculiar terats may give indirect evidence on certain relationship of mentioned genera. On the other hand, the observed occasional insect invasion and damage of female cones may be limiting factor for successful natural seed propagation of this species in some localities. Meanwhile, its introduction into cultivation may be an additional important effective action for protection of this relictual tree ex situ.
Acknowledgements. We cordially thank authorities of the Institute of Ecology and Biological Resources of the Academy of Science and Technology of Vietnam for comprehensive help in organizations of all our investigations. Field studies in Vietnam, the results of which are presented in this paper, were funded by grants from the U.S.A. National Geographic Society (grant 7577-04 “Exploration of rocky limestone flora and vegetation in Bac Kan province, northern Vietnam"), American Orchid Society (“Discovery of endemic orchid flora in remote limestone areas of Northern Vietnam”) and from jointed program of Fauna & Flora International and Counterpart International (Preliminary survey of orchids (Orchidaceae) in Phong Nha - Ke Bang national
park). We cordially thank Dr. Jacinto C. Regalado from Missouri Botanical Garden, U.S.A. for his kindest help in improving the English text of this paper and our reviewers (particularly Dr. Victoria C. Hallowell and Dr. Aljos Farjon) for careful and fruitful work with our manuscript.
LITERATURE
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Table 1. Habitats and habit of Calocedrus rupestris Aver., H.T. Nguyen et L.K. Phan a - Pure mono-dominant stand of C. rupestris on steep slopes of rocky limestone ridges in Phong Nha Ke Bang national park (Quang Binh Province); b - Typical canopy shape (same area); c - Base of middle aged tree bole (Bac Kan Province); d- Canopy branches (HAL 6109); e - Extinction of conifers (Calocedrus rupestris, Pinus kwangtungensis and Pseudotsuga sinensis) on south faced cliffs of low elevated limestone mountains in Bac Kan Province (photographs by L. Averyanov and Pham Van The).
Table 2. Morphology of Calocedrus rupestris Aver., H.T. Nguyen et L.K. Phan a, b - Bark of middle (a) and old aged tree (b) at the base of boles (HAL 4919); c - Bole cut to reveal resin ducts and resin drops (HAL 4919); d- Young and ripe pollen cones (HAL 6200); e - Young seed cones (HAL 6200); f-Ripening seed cones (HAL 5441); g - Seed cone formations (HAL 5441) damaged by invasion of insect larvae (photographs by L. Averyanov and Pham Van The).
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РЕЗЮМЕ
В статье описывается Calocedrus rupestris (Cupressaceae), растение, недавно открытое в горных известняковых районах северного Вьетнама. Вид характеризуется туповатыми, закругленными на верхушке листьями, широкояйцевидными семенными шишками, состоящими из 4 чешуй и сидящими на очень короткой ножке, покрытой 6-8 (12) чешуями, а также фертильными семенными чешуями с закругленными шероховатыми верхушками, не имеющими заострения. Новый вид является доминирующей породой первого яруса реликтовых хвойных лесов, покрывающих вершины скалистых останцовых гор, сложенных сильно эродированными древними мраморовидными известняками. Детально описывается распространение, экология и условия произрастания вновь открытого вида. Первичные реликтовые леса с участием C. rupestris, как и их флористический комплекс, уникальны по уровню биоразнообразия и эндемизма и представляют объект охраны наивысшего приоритета всемирного значения.
Komarov Botanical Institute of the Russian Academy of Sciences, Получено 24.07.2005 г.
St.-Petersburg,
Institute of Ecology and Biological Resources of the Vietnamese Academy of Science and Technology,
Hanoi
