NAT. NAT. HIST. BUL L. SIAM S配 .43: 131-170 ， 1995 VEGETATION AND VASCULAR FLORA OF THE BAN SANEH PAWNG AREA ，LAI WO SUBDISTRICT ，SANGKLABURI DISTRICT ，KANCHANABURI PROVINCE ，THAILAND J.F. J.F. Maxwell* ABSTRACT Ban Ban Saneh Pawng 紅白 is located in rugged ，lowlan d， limestone t町制n. Th ere 訂 e two basic basic forest types ，viz. primary evergreen + deciduous and a degraded kind composed of deciduous deciduous species + b出 nboo. Calciphytes are abundant during the rainy season. Th e vascular flora flora includes 118 fam i1i es and 559 species ，etc. One new record the for flora of Th ail 組 d and two two new species were found. INTRODUCTION Ban (village) Saneh Pawng is a Karen (tribe) village located c. 12 km NE of Sangklaburi town at approximatly 15 0 N latitude ，98 0 5' ， east longitude and is in the southernmost p紅 t of of Toong (百lU ng) Yai Naresuan Wildlife Sanctuary. 百le village is situated in a valley between limestone cI iffs at 200 m elevation and is bisected by a shallow ， perennial stream ， Huay Rokee ，which flows 泊 a basically SW direction. Apart from shale of Kow My Dang ， a hill over which the main dirt road leading to the village passes ， the entire area consists of of weathered ， often steep ，rugged limestone terrain. 百le cI iffs and underlying bedrock belong belong to the Ratburi Formation which was originally formed as a coral reef during the Carboniferous-Permian Carboniferous-Permian periods of geological history ，some 225-345 million ye 釘 s ago (JAVANAPHET ，1969) ，姐 d was more recently uplifted and exposed to terres 凶 al we 抽出ng. 百le elevation of the village is 200 m and the highest ridge in the area is 525 m. 百le village village has been settled for several generations ， thus much of the vegetation of the lowlands and flatter areas in the limestone hills has been disturbed. 百le study period for 白is project was from March 1993 to April 1994. Climate There 訂 e three distinct seasons in the area which are sirnilar to those in northem Th ailand ， viz. 1. 1. Hot ，wet season from May to October ， 2. 2. Cooler ， dry period from November to Janu 訂 y，and 3. 3. A hot ， dry season from February to Apri l. Temperatures Temperatures vary with the seasons ，forest type ，姐 d time of day.τbe average rninin lU m * Herbarium ，Department of Biology ，Chiang M 剖 University ，Chiang M 泊 50200 ，Th a i1 and. 131 131 132 132 J.F. MAXWELL and maximum daily tempera 旬 res r叩 ge 企om 20 0 C to 35 0 C in the hot ，wet season; 10 0 C to to 29 0 C 加 the cool season ，and 15 0 C to 35 0 C in the hot ， dry se 踊 on. Daytime tempera 加re rises rises quickly ，especi a1 1y in open and disturbed areas ，佃 d can reach 40 0 C in Apri l. Over 80% of the rain in 白e 紅白 is brought by the SW monsoon from the Andaman Sea ， creating high levels of rainf a1 1 and frequently flooding the region ，especially in September September and October. Although the amount of rainf a1 1 is variable ，20 0-4 00 cmlyear is typic a1. VEGETATION Lowland and other Di sturbed Places The vi1l agers at Saneh Pawng are a1 1 farmers and rely on their crops for susten 阻 ce and cash. Fer a1 anim a1 s， charcoal making ， and house ，etc. construction materi a1 s have resulted resulted in the destruction of much of the origin a1 forest ，however much of the esc 紅 pment ， cliffs ， and summit areas 紅 e undisturbed. Since the entire region of N and NW Th ailand is is seasonal ， i. e. monsoon a1， there is a 批y season from November to about June ， during which many of the woody plants and perennial herbs drop their leaves. 百世 s is also the time time when frres are started to burn agriculωr a1 wastes ， enlarge fields ，etc. which has had disastrous a disastrous effect on forested areas ，many of which 紅 e repeatedly burned. Agricultur a1 fields 叩 d residental 紅 'eas have ubiquitous weeds such as Eupatorium odoratum L.， Tridax procumbens L.， Bl umea balsam 俳ra 仏.) DC. (all Compositae); Euphorbia Euphorbia hirta L.組 d Phyllanthus urinaria L.但 uphorbiaceae); various Cyperaceae such as as Cyperus halpan L. var. halpan ， C. iria L.， Fimbris ηl お dichotoma (L.) Vahl ssp. dichotoma; dichotoma; and Gramineae (grasses) including Chloris barbata Sw. ，Digitaria setigera Roth ex ex Roem. & Schult. var. setigera ， Eleusine indica (L.) Gaertn. ， Imperata cylindrica (L.) P. Beauv. Beauv. var. major (Nees) C.E. Hubb. ex Hubb. & Vaugh. ， Pennisetum pedicellatum Trin. ， and Sacciolepis indica (L.) Chase. Ar eas 也at have been less disturbed and abandoned slashed and burned places have developed developed secondary grow 出 which consists of soft-wooded ，rapidly growing ， mostly short- lived lived evergreen and deciduous trees up to c. 10 m tall. Some of these are Fl acourtia indica (Burm. 五) Merr. (日 acourtiaceae) ， Microcos paniculata L. (Tiliaceae) Or o. 砂 lum indicum (L.) (L.) Kurz (Bignoniaceae ， Fig. 5) ，Gmelina arborea Roxb. (Verbenaceae) ，Macaranga gigantea gigantea (Rchb. f. & Zoll.) M.- A. (Euphorbiaceae) ，組 d Ficus hispida L. f. var. hispida (Moraceae). 百1e ground flora in these secondary areas is typically weedy and often includes includes some ta1 1 vigorous grasses ，e.g. Thysanolaena latifolia (Roxb. ex Hom.) Honda 佃 d Saccharum arundinaceum Retz. (Gramineae); some shrubs and other perenni a1 herbs which are typic a1 of regenerating 訂 eas. Some woody ex 創 nples 紅 e Helicteres hirsuta Lour. (Sterculiaceae) ，Le ea indica (Burm. f.) Merr. 仏eeaceae) ，Allophyllus cobbe (L.) Raeusch. (Sapindaceae) ，and Debregeasia longifolia 但urm. f.) Wedd. (U 凶 caceae). Tin o. 司pora crispa (L.)肱.王&百 1. and T. sinensis (Lo 町.) Merr. (Menispermaceae) ， both deciduous ，and Cayratia Cayratia tenuifolia (W ight & Arn.) Gagnep. var. tenuifolia (Vitaceae) are some vines which are are commonly found in secondary grow 也 Some other herbs found in 血is habitat 紅 'e: Alpinia Alpinia malaccensis (Burm. f.) Rosc. (Zingiberaceae) ，Dioscorea bulbifera L. (Dioscoreaceae ，a vine) ，加 d Lygodiumflexuosum (L.) Sw. (Schizeaceae ，a climbing fem). VEGETAT ION AN D VASCULAR FLORA OF s AN SANE l-I PAWNG A R EA 133 Fig llr e 卜 Di !! elli a p 引 /I agyna R oxb . (Di ll 巴nia - Figllr e 2. Ta!aullla hodgso llii Hk. f. & Th. (Mag C 巴ae) ，a dec idlloll S lre e in dec idll oll S + no li ac巴ae) ，an lln co mm on lI nderstorey bamboo for es t，p rodll ces inflor esce n ces tr ee ，is fOllncl in shad巴dpla c巴s In m o re and infrll ctesce n ces on leafl ess bran ch巴5 巴ve rgJ 巴en fo res ted areas，es p巴ciall y durin g th e hot (flo we rs) and ea rl y rain y alo ng Rok 巴巴 St ream. Ph o to: Mario (fruit s) s巴aso ns. Th 巴 trunk of th e lr ee is A mbr os in o，1 2A pril 1994 (Maxwe ll 94- in in th 巴 bac kgrollnd. Ph oto: Pat Co rri gan ， 500) 15 Jun 巴 1993 (Maxwe ll 93- 610 ) Fig llr e 3. Cappa 川 s assa mi ca H k. r. & Th (Ca ppara c巴a巴) ，di stin g lli shed by it s narro w ，lax ，re fl exe d intl oresce n ces an d in frll cte scenc es ，thi s s lend er clim ber- hrllb shrllb is fO llnd in shade d，primar y，m ore eve rgr ee n for es tecl place s. Phot o : Pat Corr iga n， 11 Apr il 1994 (Ma xw ell 94 487) 487) 134 J.F. MAXWELL Figure 4. Dischidia hirsur a (Bl.) Decne. (Asclepiadaceae), found on tree branches a lo ng Rokee Stream, is a s le nd e r, epiphytic, succulent vine. The Karen name fo r this plant is " poo gwaiy gee thay" . Photo: Pat Corri gan, 19 March 1993 (Maxwell 93-293). Figure 5. O roxylum indicum (L.) Kurz (B igno11iaceae), a common treelet or tree of secondary g rowth , has la rge, nocturnal, bat-pollinated flowers, from whi ch th e coroll as fa ll off after sunri se. The immature fru its (capsules) are edible. Photo: Mario Ambrosino, 12 April 1994. V EGE T A TI ONAN D V ASCU L A R FLOR A OF 8AN SANE I-I P A W NG A R EA 135 FigUl 巴 6. C lI rclI lII CI s p. (Z in g ib eraceae) is a dec idu o us，p ere nnial he rb fo und in dec idu ous + bamb oo ，f il 巴守 pron 巴 areas . Th e 4-a ngled infl oresce n ces w ith red- orange brac ts are di stin cl. Ph o to: Ma ri o A mb rosi no，7 O ctob巴r1 993 (M axwe ll 93- 11 53) Figllr es 7-8. A lll olph opl w llu s IIIlf ell er; 8 1. (A racea 巴) ，th 巴 m os t co m mo n spec i es in thi s g巴nu s in th 巴 stu cI y area ， is a cI ec icI uoll s，p 巴rennial he rb fo un cI in cI ec icIlI oll s + bamb oo areas . Th e infl oresc 巴nces an cI leaves 1' 0 1' in cI ivicIlI al pl ant s are neve r pr ocIlI ce cI toge th er in a grow in g seaso n.