Hiện trạng thảm thực vật ngập mặn ở vùng đất ngập nước tam giang cầu hai, tỉnh thừa thiên huế

88 Tap chi Nghien cffu va Phat trien, sd 1 (78) 2010 HIEN TRANG THAM THlJC VAT NGAP MAN 6 VUNG DAT NGAP Nl/dc TAM GIANG CAU HAI, TINH THl/A THIEN HUE Hoang Cong Tin, Mai Van Pho, Ton That Phap'''' I Dat[.]

Trong dd, Ru Cha la mdt mdng rii^g ngap m a n duy n h a t edn lai d pha cd vai trd ldn trong viec ehe chdn gid bao eho vung Hffffng Phong eung nhff gdp phan duy tri ngudn lgi va da dang sinh hge eua vung dam phd Tuy nhien, hien eac hoat ddng canh tae ndng nghiep, xay ddp de ngan man, phat trien nuoi trdng thuy san va tai bie'n thien nhien da va dang la eac tae nhan de dga de'n t h a m thffc vat ngap man (TVNM) nay

Vi vay, viec danh gia mgt each toan dien ve eau true eua tham thffc vat ngap man, xae dinh dac diem phan bo lam ca sd cho viec dinh hffdng ehien Iffgc quan ly vd quy hoach t h a m TVNM, n h a m bao tdn va tang kha nang bdo ve cua vung trffdc cae tac ddng eua bie'n ddi khi hau la mgt van

de cap thie't dang dffge quan tam ldn hien nay

II Phtfcfng p h a p n g h i e n cii'u

2.1 Ddi tiiOng vd dia diem nghien ciHu

Tham thffc vat ngap man d vung DNN xa Hffang Phong, huyen Hffffng Tra, thudc he thong dam phd ven bien tinh Thffa Thien Hue' (TTH) (Hinh 1)

2.2 Ddc diem khu viic nghien cdtu

Hffffng Phong la mdt xa ddng bang ven dam pha thude huyen Hffang Tra, each t h a n h phd" Hue khoang 12km

Dia gidi h a n h ehinh cua xa dffgc bao quanh bdi hai con sdng la sdng Hffffng, song Kim Ddi va mgt m a t giap phd Tam Giang Dia ban xa Hffdng Phong nam trong tga do tff 16°32'41,04"-16°35'6,27" vT do bac va 107°34'30,06"-107°37'45,52" kinh do ddng vdi tdng dien tich da't tff nhien 15,7km2, vdi gan 10,34km ehieu dai dffdng bd ven pha thudc dia ban hai thdn Thuan Hda va

Van Quat Ddng Day la hai thdn ndm phia bdc cua xa, tie'p giap vdi pha Tam

Giang doan ddi dien vdi cda bien Thuan An

Xa Hffang Phong, huyen Hffang Tra thude tieu vung khi hau la trong

phan vung khi hau tinh Thffa Thien Hue Vung nay ed nhiet dd'trung binh nam tff 24-25,2°C, tong nhiet dp tff 8.700-9.200°C, tong so gid ndng tren 1.900 gid/nam, nhiet do t h a p n h a t ed the xud'ng dffdi 10°C, eao nha't ed the len tdi 41°C Tdng lffgng mffa tha'p nha't tinh, tff 2.600-2.800mm, tff thang

1 den thdng 8 dffdi 800mm Dp am trung binh cung tha'p nha't tinh, tff

• Trffdng Dai hpc Khoa hpc Hue

Tap chi Nghien cffu va Phat trien, sd 1 (78) 2010 89

Hinh 1 Ban do dja ban nghien cffu

83-84% va thieu am trong 6 thdng, tff thang 3 de'n thang 8 Day la vung nhay cam thffdng chiu dnh hffdng manh cua gid bao, lu lut, han han va gid tay kho ndng

2.3 Phiicfng phdp nghien cvCu

Cac tff lieu va phffffng phap nghien cffu thffc dia truyen tho'ng cung nhff cdng nghe mdi (vien tham va GIS) da dffgc ket hgp sd dung trong nghien cffu tham TVNM ven bien nhff sau:

i Khdo sdt dieu tra, thu mdu phuc vu ddnh gid hien trgng thdm TVNM

theo he thd'ng tuye'n va d tieu chuan (OTC) lOxlOm theo Thdi Van Trffng (1978), Nguyen NghTa Thin (1997, 2007) va Phan Nguyen Hdng (2003) Xac dinh vi tri, so loai va sd lffffng cay trong mdi OTC Do dffdng kinh tdn cay, dffdng kinh than ngang ngffe (1,3m), do do cao vut nggn bdng thffdc va may

do ehieu cao

ii Phdn tich ddnh gid thdm thUc vgt: Dinh loai theo phffffng phdp

so sanh hinh thai bdng cae tai lieu ehinh: Pham Hoang Hg (2001), Phan Nguyen Hdng (2003), FAQ (2007) vd phan tich danh gia thdm thffc vat theo Mabinay & Magrita (2003), Huy (2005), Kathiresan (2007) gdm cae chi tieu: Mat do trung binh, dd thffdng gap (tan sd' xua't hien), do ffu the' tffang ddi

va dien tich tiet dien than

Hffffng Phong, phdng van ban eau true (Semi-structure interviews), lap ban

dd tai nguyen (Resources mapping), dieu tra theo tuyen (Transect line) va

hgp tde vdi chinh quyen dia phffang de tim hieu eac dac diem ba't thffdng va

sff tde ddng ciia bie'n ddi khi hau len t h a m TVNM eung nhff dinh hffdng sd

dung va phdt trien kinh te cae vung sinh thai quan trgng d xa Hffang Phong

III Ket qua n g h i e n ciJu

3.1 Cau true thdnh phdn lodi TVNM '

Qua ke't qua nghien cufu da xac dinh dffge 16 loai TVNM thugc 16 chi va

14 hg d vung DNN xa Hffang Phong Trong dd, da bd sung them'10 loai cho

danh luc he TVNM d vung dam phd ven bien tinh Thffa Thien Hue (Bang 1)

Thanh phan loai TVNM dffge chia lam 2 nhdm: Nhdm TVNM chinh thffc

ed 6 lodi (chiem 37,50% tdng so' loai) va nhdm thffc vat gia n h a p rffng ngap

man ed 10 loai (ehie'm 62,50% tdng so' loai)

Mae dau t h a n h phan loai khdng phong phu nhffng vai trd eiia thdm

TVNM nay khong nhffng cd y nghia ve m a t sinh thai ma cdn cd gia tri dd'i

vdi cdng ddng eff dan thdn Thuan Hda trong viee phdng t r a n h thien tai

hang nam

Bdng 1 Danh luc thffc vat ngap man d vung DNN xa Hffang Phong (Sdp

xep theo Brummit, 1992) ,, , ; ••

TT

(1)

1

1

2

2

3

Ten khoa hoc (2) POLYPODIOPHYTA

PTERIDACEAE

Arcostichum aureum L

MAGNOLIOPHYTA

MAGNOLIOPSIDA

ACANTHACEAE

Acanthus ilicifolius L

BIGNONIACEAE

Ten Vi^t Nam

(3)

Nganh Dffdng xi

Hp Cd seo ga Rang bien, Rau mop

Nganh Ngpc lan Ldp 2 la mam ,

Hp 6 ro

0 ro gai

Hp Quao ' •

Dang song (4)

C

Bu

Nhom TVC) (5)

MS

MS

Nguon anh vien tham ALOS-AVNIR (10m) sff dung de giai doan do che phu cua TVNM

dffpc cung cap bdi dff an "Quan trac cac he sinh thii ven bien Viet Nam" do Cd quan tham

hiem vu tru Nhat Ban (JAXA) tai trd thong qua Vien Hai dffPng hpc Nha Trang Tap the

tac gia xin ehan thanh cam Pn sff ho trp ngudn tff lieu gia trj nay

Tap chi Nghien cffu va Phat trien, sd 1 (78) 2010 91

3

4

4

5

5

6

6

7

7

8

8

9

9

10

10

11

11

12

13

12

14

13

15

14

16

Dolichandrone spathacea (L.f.)

K.Sehum

C H E N O P O D R A C E A E

Suaeda maritime (L.) Dum

CONVOLVULACEAE

Ipomoea pes-capre (L.) Sweet

EUPHORBIACEAE

Excoecaria agallocha L

FABACEAE

Derris trifolia (Benth) Barker

Canavalia maritima Thouars

MALVACEAE

Hibiscus tiliaceus L

MYRSINACEAE

Aegiceras corniculatum (L.) Blanco

VERBENACEAE

Clerodendrum inerme Gaertn

RHIZQPHORACEAE

Bruguiera gymnorrihza (L.) Lamk

Rhizophora stylosa Gritf

LILIOPSIDA

ARACEAE

Colocasia esculenta (L.) Schott

CYPERACEAE

Cyperus stoloniferus Retz

PANDANACEAE

Pandanus tectorius Sol

Quao

Hp Rau mudi Mudi bien, Rau mudi

Hp Bim bim Muong bien, Rau mudng bien

Hp Thau dau Gia, Cha

H p D a u Coc ken Dau bien

Hp Bong Tra (hoa vang)

Ho Dpn nem

Su

Hp Co roi npffa Ngpc nO bien

Hp Dffdc Vet du Dffdc vdi

Ldp 1 la mam

Hp Ray Mon nffde

H p C d i

Co gau bien

Hp Dffa dai Dffa gai

G

Cmn DL

G/GB

DL

DL

G Bu/GB

Bu

Gn

G

C

C

G

MAS

MAS MAS

MS MAS MAS MAS

MS MAS

MS

MS

MAS MAS MAS

* Chu thich:

MS (True Mangrove Species): Thffc vat ngap man chinh thffc; MAS (Mangrove Asssociated

Species): Thffc vat gia nhap rffng ngap man; Bu: Cay bui; G: Cay gd; Gn: Cay gd nhd; GB:

Cay gd dang bui; DL: Day leo; C: Cay than thao; Cmn: Cd mpng nUdc

3.2 Hien trang do tdn che vd mat do TVNM

3.2.1 Do tdn che cua TVNM

Dp tan ehe eiia thdm TVNM d vffng DNN xa Hffffng Phong dffge quye't

dinh ehu ye'u bdi 2 loai Gia (Excoecaria agallocha) va Quao (Dolichandrone spathacea) Trong dd, loai Gia chiem

91,57% dp tan ehe va Quao ehi chiem mdt ty le nhd 8,43% trong tang tao tan cua tham TVNM (Hinh 2)

3.2.2 Mat do cua TVNM

Ca'u true eua quan xa TVNM la rffng thff sinh kha thuan loai va dffge minh chffng bdi sd' lffgng ca the eiia cae eay

gd nhd (Gid, Quao) d tat cd cac ()TC nghien cffu Trung binh tren 1 ha cd

CGiS I Quao

Hinh 2 Ty le % dd tan che cua TVNM tai

cac OTC tren dja ban nghien cffu

cea) phan bd Trong dd, Gid la quan the ffu the d vung nay tao thanh riftig

tai sinh thudn loai mgc tren nen dat set eao trieu hoac dat bun ngap trieu

trung binh Hi) Vung thffdng xuyen ngap trieu gdm cae quan the eay bui nhff Dffdc vdi (Rhizophora stylosa), Gid (Excoecaria agallocha) va O rd (Acanthus ilicifolius) Ngoai ra edn ed ede qudn the eay bui phan bo' dffa bd ao, bd de

tren nen dat set kho hay am ffdt

Sff phan tang eua quan xa TVNM d vung DNN xa Hffang Phong phan

thanh 3 tdng chinh: i) Tdng eay gd cd ehieu eao trung binh tff 4-7m gdm ede lodi nhff Dffdc vdi (Rhizophora stylosa), Gia (Excoecaria agallocha) va Quao (Dolichandrone spathacea) tao tan ii) Tang eay bui chieu eao trung binh dffdi 2m gdm ede loai Su (Aegiceras corniculatum), 6 rd (Acanthus ilicifolius) va Ngge nff bien (Clerodendrum inerme) p h a n bo' dffdi tan cua tang cay go Hi) Tang eay thdo gdm cdc lodi Mud'i bien (Suaeda maritime),

Cd gau bien (Cyperus stoloniferus) va Rang bien (Arcostichum aureum) vdi

ehieu eao dffdi Im

3.4 Bdn do ldp phu thdm TVNM d vung DNN xd HUcfng Phong

Dffdi sff hd trg eua cdng nghe vidn t h a m va GIS ke't hgp vdi ke't qua nghien cffu thffc dia, chung tdi da xay dffng dffge ban dd ve hien trang sd dung dat d khu vffe nghien cffu cung vdi cac ldp phu t h a m TVNM d vung DNN xa Hffang Phong Ke't qud phan tich eho tha'y ldp phii t h a m TVNM cd tdng dien tich l l , 5 5 h a (Hinh 3)

Trong dd, p h a n ldn dien tich eay ngap m a n tap trung d Ru ehinh vdi dien tich 5,24ha ehie'm ty le 4 5 , 3 7 % tdng dien tich, sau dd la khu vffe

Ru t r e n vdi dien tich 3,64ha ehie'm ty le 31,52% va sau eung la khu vffe Ru dffdi chi

CO 2,68ha ehie'm ty le 23,20% tdng dien tich

rv Ket l u a n

1 Ve hien trang thdm TVNM, H/nh 3 Ban do hien trang phan bd tham TVNM da xac d i n h dffge 16 lodi

d xa Hupng Phong, tinh Thffa Thien Hue TVNM thude 16 ehi, 14 ho d

Tap chi Nghien cffu va Phat trien, sd 1 (78) 2010 93

;^iu^

l-linh 4 6 ro gai - Acanthus'ilicifolius L

a canh mang hoa; b cum hoa; c hinh thai la:

d quan the cay

Hinh 6 Gia (Cha) - Excoecaria agallocha L,

cay ; b canh mang hoa; c canh mang qua; sinh canh song

a

•*^'

hlinh 5 Duoc vol - Rhizophora stylosa Griff

Hinh 7 Tham thuc vat ngap man 6 viing DNN

Tam Giang - Cau Hai vung DNN thude xa Hffffng Phong, huyen Hffffng Tra, tinh TTH, trong dd nhdm TVNM chinh thffc cd 6 loai (chiem 37,50% tdng so loai) va nhdm eay gia nhap rffng ngap man 10 loai (chiem 62,50% tdng sd loai), bd sung 10 loai mdi cho danh luc he TVNM d xa Hffffng Phong

2 Da ffng dung edng nghe vien thdm va GIS trong xay dffng bdn dd ldp phu thdm TVNM de xae dinh dien tich phan bd' cua he sinh thai nay vdi dien tich l l , 5 5 h a Trong dd, Ru ehinh ed 5,24ha, Ru tren 3,64ha va Ru dffdi 2,68ha Day dffge xem la nhffng thong tin ed y nghia trong thffc tien qudn ly va dinh hffdng phdt trien ben vffng tai nguyen vung dat ngap nffdc

nay Hai loai'Gid (Excoecaria agallocha) va Quao (Dolichandrone spatliacea)

quyet dinh mat dp eay, trung binh ed 10.500 than Gid/ha va 422 than Quao/ha Tffang ffng dd tan che ciia Gia chiem 91,57% va Quao ehi chiem mpt ty le nhd (8,43%).' - •

3 Ve phan bo, tham TVNM vung DNN xa Hffffng Phong cd sff phan bo theo chieu thdng dffng theo 3 tang chinh: tang eay gd nhd, tang eay bui va tang cay thao Sff phan bd theo khdng gian dffpc phan lam 3 vffng chinh:

nang dd'i phd va thich ffng vdi nhffng tae ddng cua bie'n ddi khi hau dang ngay mdt ro ret nhff hien nay

H C T - M V P - T T P TAI LIEU THAM KHAO

1 FAQ and Wetlands International (2007), Mangrove Guidebook for Southeast Asia Printed

by Dharmasarn Co., Ltd

2 Pham Hoang Hp (2001), Cay co Viet Nam, tap I, II, III, Nxb Tre, TP Hd Chi Minh

3 Phan Nguyen Hdng (chu bien) (1999), Rdng ngap man Viet Nam, Nxb Nong nghiep, Ha Npi

4 Ton That Phap (chu bien), Lffdng Quang Ddc, Mai Van Phd, Le Thi T r i , Phan Thj Thuy Hdng, Nguyen Van Hoang, Vd Van Dung, Hoang Cdng Tin, Trffdng Thi Hieu Thao (2009),

Da dang sinh hoc dphi Tam Giang-Cau Hai, tinh Thda Thien Hue, Nxb Dai hpc Hue

5 Sd Khoa hpc va Cdng nghe Thffa Thien Hue, Dac diem khi hau-thuy van tinh Thda Thien

Hue, Nxb Thuan Hda, Hue, 2004

6 McLeod, Elizabeth and Salm, Rodney V (2006), Managing Mangroves for Resilience to

Climate Change lUCN, Gland, Switzerland 64pp

7 Oilman, E.L., et al (2008), Threats to mangroves from climate change and adaptation

options, Aquat Bot., doi:10.1016/j.aquabot.2007.12.009

8 Tomlinson (1986), The Botany of Mangroves Printed in United of American

TOM TAT

Hien trang tham thffc vat ngap man d vung dat ngap nffdc Tam Giang-Cau Hai, tfnh Thffa Thien Hue dffpc xac djnh gdm 16 loai thffc vat ngap man thupc 16 chi, 14 hp Trong

dd, hai loai Gia (Excoecaria agallocha) va Quao (Dolichandrone spathacea) quyet dinh mat dd

d^day, vdi gia trj trung binh 10.500 than Gia/ha va 422 than Quao/ha Tffpng ffng dd tan che cua Gia chiem 91^57% va Quao ehie'm mdt ty le nhd (8,43%) Ben canh dd, nhd sff hd trd eua edng nghe vien tham va GIS trong xay dffng ban dd Idp phu tham TVNM da xac dinh dffpc dien tich phan bd la 11,55ha Cac ke't qua nghien cffu cau true, hien trang phan bd va thanh lap ban dd tham TVNM cd mdt y nghTa quan trpng trong viec quan ly, phan vung quy hoaeh eung nhff hoaeh djnh bao tdn va phat trien ben vffng he sinh thai nay

ABSTRACT

THE CURRENT SITUATION OF MANGROVES AT TAM GIANG-CAU HAI

COASTAL LAGOON, T H Q A THIEN HUE PROVINCE

_^ The results of study on mangroves at Tam Giang-Cau Hai coastal lagoon, Thffa Thien Hue province consists of 16 mangroves species belong to 16 genuses, 14 familiar are

presented Excoecaria agallocha and Dolichandrone spathacea are most densities, 10,500 trunks per hectare and 422 trunks per hectare in average value Correlative with Excoecaria

agallocha cover value 91.57% and Dolichandrone spathacea value 8.43% In other hands,

under supporting of remote sensing and GIS techniques on mapping mangroves cover which showed the area of mangroves cover with value 11.55 hectare Mangroves structure, distribution characteristics and cover map has been played a vital information/data tor management, zoning, and conservation planning and sustainable development the ecosystem