Vi^n sinh hpc nhi$t at»\ KY Y £ U Hpi NGHj KH-CN 67
THAM THirC VAT DAT NGAP NU^6C BU HA LAM, HUYEN SONG HINH, TINH PHU YEN
Vii Ngoc Long, Ly Ngoc Sam
Phdng nghien cuu Tdi nguyen sinh vdt, Vien Sinh hoc Nhiet dai
MOfDAU
Ha Lam Bau thudc xa viing sau Ea Lam, huyen Sdng Hinh, tinh Phii Yen, cd tga do dja ly tir 13°05'04.3" N - 108°48'24.3"E din 13°05'35.6" N - 108°47'17.6"E. Day dugc xem la noi duy nhat d nude ta loai Ca Sau nude nggt (Crocodylus siamensis) cd the cdn hien dien trong ty nhien (ITB, 2005). Dien tich mat nude ty nhien cua Bau vao mua khd khoang 30ha, trai dai tren 4km theo hudng tir Ddng sang Tay. Chilu rgng cua Bau bien ddi tir vai met den 100- 200m d trung tam ciia Bau. Do sau trung binh tir 1- 2m vao mua khd va cao hom rat nhieu khi Bau thdng vdi sdng Ba vao miia mua. Theo ngudi E De, bau Ha Lam gdm 3 Bau nhd: bau Blaonao (bau Sen), bau Lam va bau Chao.
Hien nay, bau Ha Lam bi xam hai manh bdi cac hoat ddng ciia ngudi dan dja phuomg nhu: danh bat ca, chat pha rimg ban ngap, chuyen ddi viing ban ngap thanh dat canh tac lam thay ddi mdi trudng sinh thai, canh quan trong khi nhirng gia tri da dang sinh hgc d day vdn chua dugc hieu biet rd rang dang cd nguy co bien mat, nhat la khi thiiy dien sdng Ba Ha hoat ddng.
Nghien cim nay cung cap nhirng thdng tin ban dau ve thanh phan thyc vat, cac quan xa va hdi doan thyc vat, thyc vat ngoai lai nham giup hieu rd hon vai trd, cac gia tri ciia thdm thyc vat trong he sinh thai dat ngap nude d day.
VAT LIEU VA PHUONG PHAP
• Tham thyc vat than thao tren vimg dat ngap nude: cac d mau nhd (quadrat) cd kich thudc Im X Im (Im^) da dugc dat ngau nhien vdi sd lugng tiiy theo timg hdi doan thiirc vat. Tit ca cac loai thyc vat cd mach hien dien trong d mau se dugc ghi nhan va thu thap dl xac dinh loai. Miic do uu the ciia loai dugc xac dinh qua do che phii ciia loai trong d miu theo phuong phap Braun Blanquet (bang 1).
• Cac kilu rimg tren vimg dit ban ngap: d mau kich thudc 20m x 20m (400m^) dugc thilt lap. Miic do uu thi ciia loai dugc xac dinh dya vao viec do cap kinh dl .3m, sd lugng ca thi, sd lin xuit hien cac loai hien dien trong d mau.
• Thyc vat dugc dinh danh theo bd sach Cay cd Viet Nam (P.H. Hd, 2000) va tham khao cac tieu ban d B^o tang Thyc vat Qudc gia (85 Tran Qudc Toan Q.3, TPHCM).
• Nghien ciiu dugc thyc hien trong 2 dgt tu thang 10/2006 den 3/2007 trong dy an
"Dieu tra bd sung thdng tin ve loai ca Sau nude nggt (Crocodylus siamensis) d Sdng Hinh" do td chirc lUCN tai Viet Nam ho trg kinh phi.
68 m nghi KHOA HOC vA CPNG NGHE 2007 Bang 1: Thang xac djnh dp uu t h i ciia loai thiPC v | t trong mpt quadrat 1 m x 1 m (1m )
cap P9 bao phu (% dign tich 6 m§u) 5
4 3 2 1
76-100 51-75 2 6 - 5 0 6 - 2 5
<5
KET QUA
1. Thanh phan thuc vat
H
2%
Ket qua khao sat da ghi nhan dugc 186 loai thyc vat bac cao, phan bd trong 60 ho thyc vat. Cac hg cd nhieu dai dien la: hg Dau (Fabaceae, 22 loai), hg Hda thao (Poaceae, 20 loai), Hg Cdi (Cyperaceae,16 loai), hg Ba manh vd (Euphorbiaceae, 9 loai), hg Ciic (Asteraceae, 8 loai) va Ca phe (Rubiaceae, 7 loai). Trong 186 loai thyc vat da ghi nhan cd 4 loai Khuyet thyc vat, 1 loai Khoa tii, 116 loai Song tii diep va 65 loai Don tir diep
Dang sdng ciia cac loai dugc phan chia thanh (i) cay go, (ii) cay byi, (iii) than thao, (iv) tiiiiy sinh, (v) day leo, (vi) rang, (vii) phu smh (Hmh 1). Ba dang sdng chiem ty le cao nhat la than thao, thuy sinh va than go (80%); day la ba dang sdng dien hinh cua tham thyc vat dat ngap nude bau Ha Lim. Hai loai dai mdc tieu bieu cho dat ngap nude d day la Gao (Nauclea orientalis) va Chiec (Barringtonia acutangula subsp. spicata).
cay go; 36 20%
Khuyet ttnrcv$t;3;caybyi;
13; 7% DSyleo;
18; 10%
Thuy sinh;
37; 20%
TMnthao;
76; 41%
B Kismet
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• Caybvn D Day leo DTliaiitfaao SThuy siih B cay go
Hinh 1. Dang sdng cua cac loai thyc vat ghi nhan d u p ^ o bau Ha L3m
2. Tham thyc vat tren dat ngap niroc bau Ha Lam
Ket qua khao sat cho thay tham thyc bau Ha Lam dugc ciu tnic bdi cac kilu: Rimg hanh lang, rimg ban ngap nude, cac hdi doan thyc vat ngap nude va thuc vat ty nhien tren dat canh tac ndng nghiep dugc the hien tren ban do tham thuc vat dit ngap nude dudi day (hinh 2).
Kieu rimg hanh lang ven sdng sudi: phan bd theo sudn ddc hay tren khu vuc dit bang phang phia Ddng - Ddng Nam Bau Ha Lim. Cac loai uu thi la: Mudng (Cassia siamea), Tre gai (Babusa blumeana) va mdt so loai cay go khac nhu: Mallotus philippensis, Vitex canescens), Binh linh (Vitex sumati-ana var urceolatas), Dimg dinh (Caryota sympetala). Sung (Ficus variegata Bl var. variegata), Thilt dinh (Markhamia stipulata var. pierrei), Quao (Stereospermum cylindricum),... .
Do tac ddng cua con ngudi, kilu thyc vat nay dugc thay thi bdi kilu Each (Saccharum spontaneum) va Sung (Ficus esquiroliana) doc hai ben bd tren dia hinh bang phang cua dat canh tac nai bau ndi vdi Sdng Ba.
Vi^n sinh h(?c nhi^t a&\ KY Y £ U H Q I NGHj KH-CN 69 Hai loai Dau rai (Dipterocarus alatus) va Sao den (Hopea odorata) ciing dugc ghi nhan rai rac trong kilu rimg nay nhung da bi ngudi dan dia phuong khai thac diu va go. Sy hien dien va hien trang phan bd ciia cay hg Diu (Dipterocapceae) cho thiy kilu rirng ven sdng sudi cua khu vuc dim liy Ha Lim la kilu rimg im thudng xanh thii sinh nhan tac dugc hinh thanh sau khi rirng im thudng xanh tren niii thip vdi uu the cay hg Dau rat phd bien trong khu vyc trudc day. Theo danh gia miic do de dga cay hg Diu cua lUCN (1994, 2001), hai loai cua hg Diu ghi nhan dang d muc do "gan bi de dga (NT)".
Kilu rimg ban ngap nude - rimg Gao (Nauclea orientalis): Tren cac viing chuyin tilp giiia dit canh tac va dat ngap nude d trung tam bau Ha Lim vdi thdi gian ngap trung binh khoang 3-4 thang trong nam, Gao (Nauclea orientalis) la loai chilm uu the phat trien thanh rirng cay go thuin loai, rit diu, chilu cao trung binh 12m, dudng kinh trung binh 30cm. Ngoai ra cdn cd Chile (Barringtonia acutangula subsp. spicata), Tre (Babusa blumeana). Sung (Ficus racemosa). Ting tham cd la tai sinh cua Chiec, Gao, va cac loai than thao nhu: Pseudoechinolaena polystachya, Paspalum paspaloide, Pseudoraphis brunoniana, Panicum repens, Brachiaria mutica... Kieu rimg nay hien cdn rat it d dgc luu vyc Sdng Ba ma hilm noi nao cd the ghi nhan dugc, nhung se bi bien mat trong tuong lai gan ma nguyen nhan chinh la do nhu cau dat canh tac ndng nghiep, khai thac go cho xay dyng va dung cu gia dinh cua ngudi dan dia phuong, nhat la khi thiiy dien sdng Ba Ha ngan ddng.
Cac hdi doan thyc vat ngap nude: 37 loai thyc vat thuy sinh va cac loai thyc vat thich nghi vdi mdi trudng am quanh nam da hinh thanh nen cac hdi doan thyc vat dat ngap nude bau Ha Lam. Cac hdi doan thyc vat tieu bieu la:
•' ^ • JKi ioka Lac Lic hAr. {Scitptu jrwrric) - S^hnnbo mtc^fa^ (S«a) '/":'•'• ' H ^ d^iu *>MX (S-tinmbc mtci^jrel — Lvc }xah {Ijclth^tue rrssziycz) wH»ii: £>at e^uth rac oooff n^u%>
H$i StoxA C« Oof i^ani-cum rtp^ns) — Co L«sf tiy rSrachiarie muricti) - BSet dwoE rim$l (Soiecfolipti vfyoua-oUUi) - Luc Smh (Escifhonua ctxijsgfcc*
I K:cu S U B ; \^ict*i *jqw;/wKma) — Lic'i (jSaccharum jponran^ioR i
ti
Ba River n * ^ E
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Hinli 2: Ban do tliaiu tliirc vat dat ngap n u o c bau Ha Lam
70 HQi nghi KHOA HOC VA CONfi NGHE 2007
(a). Hdi doan Sen (Nelumbo nucifera) - Lyc binh (Eichhomia crassipes): hien dien chii ylu d khu vyc triing sau giiia ldng bau Lam, bau Blanao. Nelumbo nucifera va Eichhomia crassipes tao thanh hdi doan bao phii toan bd dien tich mat nude cua Bau. Cac loai thyc vat thiiy sinh nhu: Sacciolepis myosuroides (Bit dudi chudt), Brachiaria mutica, Panicum repens, Ceratopteris thalicti-oides, Ludwidgia adscendens, Ludwidgia octovalvis, Polygonum lanigerum. Polygonum hydropiper, Sagittaria sagittaefolia, Commelina diffusa, Wolffia arrhiza, Limnocharis flaya, Pistia stratiotes... cung dugc ghi nhan trong hdi doan nay. Day la noi tni ngu, kiem an ciia cac loai chim nude, thii nhd, Ich nhai, ca va la noi cung cap thiic an, noi tni ngu an toan cho ca Siu nhd dien tich mat nude rgng va du sau vao mua khd.
(b). Hdi doan Lac hin (Scirpus grossus) - Sen (T^elumbo nucifera): phan bd chu yeu d bau Blanao va dien tich nhd d bau Chao. Scirpus grossus phat trien thanh dam day cao trung binh 1,2m. Mdt sd loai thyc vat thiiy sinh khac dugc ghi nhan d day nhu: Eichhomia crassipes, Ceratopteris thalictroides, Ludwidgia adscendens, Ludwidgia octovalvis. Polygonum lanigerum. Polygonum hydropiper, Commelina diffusa,.... Kieu thyc vat nay dang bi thu hep dan do nhu cau canh tac ndng nghiep ciia ngudi dan.
A. ^ r
(c). Hdi doan Cd Ong (Panicum repens) - Cd Ldng tay (Brachiaria mutica) - Bat dudi chudt (Sacciolepis myosuroides) - Luc binh (Eichhomia crassipes): Hien dien noi cd myc nude thap vao miia khd (0,5 m) d long bau Lam, bau Chao. Chiing phat trien rat manh tao thanh "trap cd" ndi rat day ma chiing ta cd the di chuyen tren dd. Cac loai than thao va thiiy sinh hien dien trong trap nhu: Ceratopteris thalictroides, Ludwidgia adscendens, Ludwidgia octovalvis. Polygonum lanigemm. Polygonum hydropiper, Commelina diffusa, Ludwidgia epilobioides Maxim, var. epilopioides, Ludwidgia prostrate, Altemanthera sessilis, Eclipta prostrate, Merremia hirta, Ipomoea alba, Fimbristylis miliacea, Fimbristylis griffithii, Clitoria Marianna, Phramites vallatori ...
tao sy da dang cho kieu thyc vat dac trung nay.
Sy phat trien ciia trap cd mdt vai trd quan trgng cho he sinh thai dit ngap nude, neu phat trien vira phai thi trap la ncri tni ngu va kiem an ciia nhilu loai chim nude va mdt sd ddng vat khac, cdn neu phat trien qua miic thi se anh hudng rit Idn vi trip gay can trd ddng chay, xam chiem mdi trudng sdng cua cac kilu thyc vat ngap nude khac. Cac trap cd rat de chay vao miia khd do hoat ddng ciia ngudi dan dia phuong de dga den ddi sdng ciia nhieu loai ddng thyc vat trong bau nhat la kha nang kilm an va tni ngu ciia ca Sau.
(d). Kieu thyc vat tren dat canh tac: chu yeu hien dien tren vimg ban ngap cua bau Ha Lam. Thyc vat hoang dai chiem uu the trong kieu nay thudc cac hg Cyperaceae Poaceae va Fabaceae nhu: Aechynomene aspera, Aechynomene indica Sesbania sesban, Cyperus iria, Scirpus articulatu, Cyperus ohwii, Cyperus compactus Cyperus fulvo-albescens, Echinochloa crus-galli, Ludwidgia octovalvis Eleusine indica, Altemanthera sessilis... Sy hien dien ciia chiing chi lam tang tinh da dane cd y nghia phu xanh, chdng xdi mon, nia trdi tir ben tren xudng bau.
Thyc vat ngoai lai: Thyc vat ngoai lai ghi nhan dugc d bau Ha Lam la: Luc binh (Eichhomia crassipes), Rau dieu (Altemanthera sessilis), Co Lao (Eupatorium
Vien sinh hpc nhigt d6i KY Y £ U HQI NGHj KH-CN 71
odoratum), Nhan ldng (Passiflora foetida), Mac cd (Aechynomene indica), Cd dng (Cynodon dactylon), Beo cai (Pistia stratiotes), Trinh nu (Mimosa diplotricha)...
Ben canh y nghia lam tang tinh da dang sinh hgc thi cac loai ngoai lai cd thi gay hai cho mdi trudng ty nhien bau Ha Lam. Loai Mimosa diplotricha cd thi lam chit cay nhd kha nang leo cao triim len cac loai cay go Idn, lam chit tir tir. Sy phat triln qua nhanh va xac ciia Eichhomia crassipe, Pistia stratiotes khi chit se gay d nhilm nude, han chi anh sang di vao mdi trudng nude anh hudng din thiiy sinh vat, la noi in nip va sinh san cho mudi (Tran Triet, 2006).
KET LUAN
186 loai thyc vat cd mach dugc ghi nhan trong cac tham thyc vat dit ngap nude bau Ha Lam, trong do cd 2 loai cay hg Dau (Dipterocarpaceae) cd ten trong Sach Dd ciia thi gidi d miic do NT (lUCN, 1994, 2001) va mdt sd loai thyc vat ngoai lai c6 thi gay hai cho mdi trudng ty nhien cua bau. Hien nay he sinh thai nay dang bi de dga nghiem trgng do cac tac ddng cua con ngudi. Tren co sd nghien ciiu, chiing tdi CO mdt sd kien nghi:
• Can bao ve tham thyc vat dat ngap nude hien tai ciing nhu ngan chan cac hoat ddng xam hai cua ngudi dan dia phuong len rimg Gao (Nauclea orientalis).
• Nghien ciiu ddng thai hinh thanh trap cd de kiem soat viec tac ddng len cac hdi doan thyc vat ngap nude, noi sinh sdng, tni ngu va kiem an ciia nhieu loai sinh vat.
• Viec xay dyng thuy dien sdng Ba Ha can xem xet, danh gia mdt each than trgng ve nhumg tac ddng ciia nd len he sinh thai dat ngap nude bau Ha Lam d thdi diem hien tai va lau dai.
TAI LIEU THAM KHAO
1. Pham Hoang Hd (1999). Cay cd Viet Nam. NXB Tre. 3 tap.
2. Nguyen Xuan Vinh and et al., (2005). Technical report: Status of the freshwater crocodile (crocodylus siamensis) in Song Hinh district, Phu Yen province, VietNam. 50 pages.
3. Tran Triet and et al., (2001). The vegetation of U Minh Thugng National Park. Final reprot. 69 pages.
4. Vien Sinh hgc Nhiet ddi (2000). Khao sat mdi trudng phuc vu xay dyng dy an kha thi phuc hdi Ca Siu nude nggt tai Vudn Qudc gia Cat Tien. Bao cao giai doan 1.
22 H»i nghi KHOA H^C vA C 6 N G NGHg 2007
SUMMARY
The wetland vegetation of the Ha Lam lake, Song Hinh District, Phu Yen Province
Ly Ngoc Sam, Vu Ngoc Long Institute of Tropical Biology
Ha Lam Lake is located in Ea Lam commune, which is a remote commune of Song Hinh district, Phu Yen Province. This place is knew as a unique location which freshwater crocodile (Crocodylus siamensis) still exists in the wild. This survey recorded 186 vascular plant species which were present in the four types of the wetland vegetation of Ha Lam Lake: riparian forest, submerge forest, submerge vegetation and cultivated habitats of the wetland vegetation of Ha Lam Lake. This study recorded 2 plants ranked in the lUCN Red List including: Dipterocams alatus (NT), Hopea odorata (NT) and some invasive weeds which are possible damaged to natural environment of Ha Lam Lake, such as: Eichhomia crassipes, Pistia sfratiotes, and Mimosa diplotricha.
This wetland area is sfrongly impact because of human activities such as: cultivated, deforestation and especially hydroelecfronic building alone the Ba River which will be destroy this vegetation.