Tap chi Khoa hgc DHQGHN: CSc Khoa hpc Trai dit va Moi trucmg. T^p 30, S6 4 (2014) 41-48
/ Tham thuc vat rung ngap man khu vuc mui Ca Mau
Pham H^nh Nguyen', Truong Quang Hai^*, Le K^ San'
Tdng c^c Moi trudng. Bd Tdi nguyen vd Mdi tnrdng
-Vien Viet Nam hgc vd Khoa hpc phdt triin, DHQGHN, 334 Nguyin Trdi. Hd Ngi. Vift Nam Nhan ngay 06 thang 10 nam 2014
Chinh sua ngSy 16 thang 1! nam 2014; Chap nhan dang ngay 8 thang 12 nSm 2014
Tom tSt: Khu vite Mui CS Mau g6m 04 xa: D5t Mui, Vien An, Dit Moi va U m Hai, thuoc ban dao C^ Mau, c6 vi tri dja ly vk diSu kien tu nhien die thii, thi'eh hgp eho phat tri^n rimg ngip mgn.
Hf sinh thai rimg ngap mSn 6 diy co dien tich phan b6 rpng va phong phii vh sd lugng lo3i. Cong trinh nghien cuu nJiy tap trung lam ro dac diem tham thue vat rung ngap man theo tifip e^n sinh Uiii canh quan, dac bi^t quy luat phan hoa tham thue vat gdn voi dac di^m hai vSn vh nim tieh ddy d khu vuc Mui Ca Mau.
Tirkhoa: Miii Ca Mau, rimg ngap man, thara thuc vat.
l.Oat v4n d e
Khu vuc M u i C a Mau d u g e nghidn c u u g o m 0 4 xa: Dat Mui, ViSn An, 0 a l Moi va Lam Hai vdi tong dien tich l u nhign 11 37.753,70 ha.
Day la khu vuc c o cae dieu kien sinh thai thieh h g p cho phat trien rutig ngap m^n: nen dat thap, bai trieu rgng, he thong kenh r^ch day dac, nong dO mu6i trong n u d c biSn tuong d 6 i eao va khd on djnh ngay trong miia mua, khi hau nhiet doi am gio miia. Vj tri khu vuc nay nam gan vdi cac khu vuc R N M khae cua Malaysia va Indonesia, nhimg trung tam hinh thanh cay ngap man tren the gioi [ I , 2], tir cac trung tam nSy giong cay ngap man dugc van ehuyen vao Vi^t Nam cbii yeu nho nhihig dong chay dai ducmg va dong chay ven b o . Khu vuc Miii Ca
'Tic gia lien h i DT.. 84-913283922 Email, [email protected] vn
Mau la khu vuc co RNM p h i t trien khong nhiing cua ban dao Ca Mau n i m trong viing ven bien Nam Bg, ma con ciia khu vuc Chau A - Thai Binh D u o n g [2]. RNM khu vuc nay cd di^n tich, so lugng loai v^ kich thude phat trien manh nhSt so voi cac khu v\rc khac ciia Viet Nam. So lieu thong kS nSm 1943 cho thay ban dao Ck Mau co dien lich RNM la 140.000 ha tten tdng s6 408.500 ha RNM Viet Nam'<gan 35%) (Huynh Qu6c Tjnb, 2008, Vien D i l u tta Quy ho?eh rimg, 2001) [3, 4 ] , ki'eh thuoc cay cao tir 20 - 35m [2]. Viing ven bien Nam Bg c o 100 loai cay ngap man ttong khi ven bien T n m g bg chi CO 69 loai va ven bien Bac bp chi cd 52 loai [2].
Khu vyc M u i Ca Mau hien ed V u o n quoc gia (VQG) Mui Ca Mau dugc thanh lap ngay 14 thdng 7 nam 2003 theo QuySt dinh s6 142/2003/QD-TTg ciia Thu luong Chinh p h u
42 PH Nguyen va nnk. /Tap chiKhoa hgc DHQGHN: Cdc Khoa hgc Trdi ddi vd Mdt tnrdng. Tap 30. So 4 (2014) 41^8
tten ca so Khu Bao ton Thien nhidn Dat Mui truoc day. VQG Mui Ca Mau da dugc To chiic Van hda, Khoa hgc va Giao due Lien Hgp Qu6c (UNESCO) e6ng nhan la khu du tru sinh quyln the gioi vao ngay 26 thang 5 nam 2009, dugc Ban thu ky Cong uoc Ramsar c6ng nhan la Khu Ramsar thir 5 ciia Viet Nam va la khu Ramsar thu 2.088 tren th8 gioi vao ngay 27 thang 11 nam 2012.
Khu vuc Miii Ca Mau da dugc nhieu nha khoa hgc nghien euu ve he sinh thai RNM, tt'nh da dang sinh hgc, xdi 16- bdi tu. Trong khuon kho bai viet n&y, cac tac gia t|p trung lam ro d^c diSm tham thyc vat rimg ng^p m§n theo each tiep c^n sinh thai canh quan hgc, d§c biet linh quy Iuat ph^ln hoa tbam thuc vat gan voi dac diem hai vSn va trim tich ddy a khu vye Mui Ca Mau.
2. Cff sff dir lifU va phmmg ph^p ngbi€n cuu 2.1.Casddiiii^u
Cong trinh nghien cuu dugc thyc hien dua tren ca so dO: b?u bao gom:
i) Ban d6 dia hinh ty le 1:25.000 do Vifn Nghien cuu Do d^ic ban do, Bg T&i nguySn v^
Moi trucmg hieu chinh nam 2003; Ban do hien trgng Vuon quoc gia Miii Ca Mau ty le 1:25.000 do Trung lam Nghien cuu rimg va Dat ngap nuac thanh l^p nam 2011; Ban do hien tt^ng su dung ddt ty Ie 1:25.000 do Sa Tai nguyen va Mfli truong tinh Ca Mau thanh lap nam 2011.
ii) Anh v$ tinh Spot chup thang 7 ndm 2011, dp phan giai 2,5m.
iii) Kel qua dieu tra, khao sdt. kiem chung thuc dia ve tham thye vat khu vuc nghien cuu eua nh6m tdc gia; ke Uiira ket qua nghien ciru eiia Trung tam NghiSn cuu rimg va Ddt ngap
nuoc (FORWET) nam 2011 (kel qua nghien curu vS tham thuc v|it va da dgng sinh hgc tai VQG Mui Ca Mau thang 8 nam 2011 vi kSt qua r& soat pham vi, ranh gioi, dien tfch vao thang 10/2011) [5].
2.2.Phircmg phdp nghien ciru
i) Phuang phdp ban d6, viSn tham: Ap dyng phuang phdp viin thdm de nhan biet eac dSu hieu ttong viec giai dodn anh ve tinh, hieu chinh hinh hge, thu thap cdc s6 lieu vung mdu, phan dnh ede dieu kiSn va trang thai ty nhien tten bS mdt. Dong thai ung dung cdc phdn mSm GIS nhu Arcgis vd Mapinfo de phan loai thara thye vat, hieu chinh vd thanh lap ban d6 tham thyc vgt.
ii) Phucmg phdp dieu tra, khao sdt thue dia:
thu thap cde sfl Ueu nham ho trg va kiem chung ket qua giai dodn anh v? tinh ve phan loai tham thye vat. Tren ca sa nhflng kel qua thu th|p duge ngodi thye dia, tien hanh bfl sung va chinh hgp ban do tham thyc v|it. Cdc dgt khao sdt thye dia ciia nhom tae gia duge thuc hien vdo cae thai diem tucmg irng vai miia mua va miia khfl tai khu vyc nghien ciiu: tbdng 5/2012, tiidng 11/2012 va thdng 3/2013.
3. Tiep cgn sinh thai canb quan trong nghien cuu tbam tbirc v|lt khu vuc Miii Ca Mau
Sinh thdi canh quan (STC<2) Id khoa hgc nghien ctru quan he giua clu tnic eanh quan va cdc qud ttinh sinh thai trong pham vi canh quan.
Khdi nifm ddu tien tten till gidi vl STCQ Id cOa C.TroII, 1939: "STCQ Id khoa hpc nghien cuu quan he he thflng phuc lap giu'a cdc quin xa sinh vat voi dieu kien moi trudng dugc the hifn ttong mpt cau trUc canh quan dac tiiii ho|c la mpt he thflng phan loai khflng gian tiJ nhien c6 tiiu bac" [6]. Forman (1986) cho ring "STCQ Id
P.H. Nguyin vd nnk. /Tgp ch! Klioa hoc DHQGHN. Cdc Khoa hgc Trdi ddi vd MSi tnrcmg. Tdp 30. Sd 4 (2014) 41-48 4 3
khoa hpc nghien ciiru quan he khong gian giira cdc hgp phan ednh quan, bode cac hf sinh thdi, dong ndng lugng, dinh duang khodng, thanh phan lodi ttong cac hgp phin, vd dgng lyc sinh thai ciia canh quan theo thai gian" [7]. Naveh vd Lieberman (1992) cho rdng "STCQ la mgt chuyen ngdnh moi eiia sinh thdi hpc hien dai nghiSn curu moi quan he giira eon nguoi vdi cac
ednh quan tu nhien vd canh quan ky thuat" [8].
Cho din nay, do co nhieu cdch tiep cdn khdc nhau nen khdi niem ey the vl STCQ chua thye su thong nhat tten IhS gidi, dflng thai tfln lai nhieu truong phdi nghien curu, nhung nhin chung vin chfl trpng nhieu den cdc dae trtmg sinh thdi hpc va nhan vdn ciia canh quan.
Hinh 1. Ban dfl tham thyc vat MQi Ci Mau nam 2012.
(Thu nho tir ij'le 1:25.000)
4 4 PH. Nguyen vd nnk. /Tgp chi Khoa hgc DHQGHN: Cdc Khoa hgc Trdi ddt vd Mdi irudng. Tdp 30. Sd 4 (2014) 41 -48
.856,03 h a 6 %
11.273.82 h.a 29,86 %
• D i f n tich rimg t\f nhien D i ^ tieh rung tr6ng
• Dien tich cay trdng khac
Hinh 2. Bieu do co cau tham thuc vat khu vuc Mui Ca Mau.
Tham thyc vat Id nhdn to quan trpng trong mfli he sinh thdi, dugc coi la nhdn to ehi thi ttong canh quan ciia mgt lanh thfl. Tham thuc vdt c6 moi lien quan cb$t ch€ vdi cac nhan to khdc ciia canh quan: mau chat - nhan to thanh tao nen rdn trong cdnh quan; dja hinh - nhan to phan bo ndng lugng vd vat chat ttong ednh quan; khi hau - nhdn tfl thdnh tao nen nhift am ttong canh quan; thuy vdn - nhan tfl thanh lao nen am ttong canh quan; tho nhuang - nhan tfl thdnh tgo nen dinh du&ng ttong canh quan vd con nguoi vdi cdc boat dpng khat thdc tdi nguySn - nhSn to thanh tgo cae canh quan vdn hda. Vdi moi lanh iho e6 d^c thiJ ve nen rdn va nhift am khdc nhau sS phCi hpp voi su sinh injflrng vd phdt trien ciia cdc tham thuc vat khde nhau. Sy tde dgng cua con ngucri co the Iam thay doi eau trdc, difn tfch vd chat lugng cua tham thyc vgt.
Bdng lilp cgn STCQ nghien euu tham thuc v|t khu vyc Mui Cd Mau. nhom tac gia phan tt'ch d^c diem tham thye vat ciia rimg ngap man, Idm ro quy Iuat phan hod tham Ihyc vgt gan vdi d$e diem hai vdn va trim lich ddy 6 khu vye Mui Ca Mau.
4. Kit qua nghign clhi va tbao lugn 4.1. Dgc diim di$n tich phdn bd rimg ngdp mdn
Theo so tifu tt'nh todn dya trfn ban dfl tham tiiyc vat Mui Cd Mau ti If 1:25.000 (hinh 1), dien tich dat cd rimg 6 Miii Ca Mau la
18.129,85 ha, chiSm 48,02% tflng difn tich khu vyc (37.753,70 ha - khong tinh phan dat ngap nudc bien ven ba), bao gom: rimg ty nhien la 6.856,03 ha, chiem 18.16%; rimg trflng la 11.273,82 ha, chiem 29,86%. Dien U'ch cdc tiiam thuc vat khde la 19.623,85 ha chilm 51,98
% (hinh 2).
Thdm thyc vgt ty nhien cua khu vyc gflm eo rimg Mdm (Avicennia spp.) ly nhien, rimg Duoc (Rhizophora spp) ty nhien, rimg Mdm (Avicennia spp) - Buac (Rhizophora spp) hfln giao vd eay byi-cfl.
Tham thye vgt trflng trong khu vyc gflm cd rimg Mdm (Avicennia spp) ttong, rimg Duoc (Rhizophora spp) trflng, cay trflng ttong khu dan cu va cdy ttflng hdng ndm, ttong do rimg Dude ttflng cd difn lich Ion nhat (bang I).
Thdm thyc vat lu nhien e6 difn ticb 25.544,55 ha, ehilm 67,66% tong dien tich khu vyc (bang I). Trong dd rimg Mdm (Avicennia spp) ty nhien c6 2.667,38 ha, chilm 7,07% tflng dien tfch khu vyc, rimg Mam (Avicennia spp) - Duac (Rhizophora spp) hfln giao 3.637,23 ha, chiem 9,63% long dien ti'ch khu vuc, cdy bui - CO 18.688,52 ha, chilm 49,50 % tdng dien tich khu vyc. Tham thue vgt trflng ed dien tich 12.209,15 ha, chilm 32,34% tflng dien tich khu vuc nghiSn cuu. Trong dd, rimg Duoc (Rhizophoza spp) ttflng cd dien ti'ch Idn nhit 10.699,87 ha, chilm 28,34% tflng difn ti'ch nghien cuu. Cdc loai tham thyc vat khdc cd difn ti'ch nhd nhu: rimg Mdm (Avicennia spp) trflng, cay trflng hang ndm va cay trdng trong khu dan eu.
P.H. Nguyen vd nnk. /Tap chi Khoa hgc DHQGHN: Cdc Khoa hgc Trdi ddt vd Moi Intdng. Tdp 30. Sd 4 (2014) 41^8 4 5
Bang 1. Dien tich cac tham thyc vgt khu vuc Ca Mau TT
I 1 2 3 4 II 5 6 7 8
Tham thirc vat TItam Ihfrc v^t lu nhiin Rimg MSm (Avicennia spp) tir nhien
Rimg Mam (Avicennia spp) - Diroc (Rhizophora spp) hSn giao
Rimg Duac (Rhizophora spp) tu nhi€n Cay byi - co
Thdm thiic vdt trong Rimg Mam (Avicennia spp) trong Rimg Dude (Rhizophora spp) tr6ng Cay trong trong khu dan eu C2y trong h&ng nam T6ng (I + n )
Dien U'ch (ha) 25.544,55 2.667.38 3.637,23 551,42 18.688,52
;2.20!l,;5 573,95 10.699,87 908,35 26,98 37.753,70
%
S7M 7,07 9,63 1,46 49,50 32.34 1,52 28,34 2,41 0,07 100
Sfl lifu tten cho thay, dien tt'ch rimg ty nhien tgi khu vyc nay it ban nhieu so vdi dien lieh cdc tbam thyc vat khdc. Difn tt'ch rimg ty nhien chi con 6.856,03 ha, chiem 16,08 % tflng difn U'ch khu vuc so vdi rimg ttong 11.273,82 ha, chiem 29,86% tflng difn tt'ch khu vyc vd cay byi - cfl 18.688,52 ha, ehilm 49,50 % tdng dien tt'ch khu vyc. Trong khi dd mgt sd nghien ciiu trudc day da ehi ra rang RNM Mui Ca Mau e6 dien tt'ch, sd lugng loai vd kich thudc phdt triln mgnh nhdt so vai cdc khu vyc khac ciia Vift Nam vd Id noi RNM phat trien ciia khu vyc Chdu A Thdi Binh Duong. DiSu nay phan anh sy suy giam difn tfch rimg ty nhien ciia khu vyc. Nguyen nhan suy giam dien tfch rimg chii yeu Id do sir dyng chat diet cd Irong thdi gian chiln tranh, khai thac qud miic, phd RNM Iam dim nudi torn quang canh, phd RNM lay dat san xuat nflng nghiep, do thi hod, 6 nhiSm mfli inrdng vd mgt sd nguyfn nhan khac do nhan thurc vd ehinh sdeh khdng dung dfli vdi bao vf RNM vd da dgng sinh hpc [2]. Theo Huynh Qudc Tjnb va nnk (2008), dien tfch RNM tai ban ddo Cd Mau tir 140.000 ha vdo nam 1943
giam xuflng chi c6n 51.000 ha vao nam 1995, giai dogn difn tfch rimg bj gidm mgnh nhat Id 1992 - 1995 [4]. Din ndm 1996, Thu nrdng Chinb phu vd chinh quyen dia phuang da ban hanh chinh sdch vl phuc hdi RNM, ttdng rimg tgi nhimg khu vye bj tan phd va tdi sinh rimg ty nhien tren cac bai bfli mdi tgi khu vyc Mui Ca Mau. Nbd do RNM tgi khu vyc nay dupe phue bfli [4].
4.2. Cdc khu phdn bd rimg ngdp man Cdn cLT vdo dde diem phan bd cdc logi tham thye vat ttong mfli lien quan vdi eac yeu tfl sinb thdi phdt sinh nhu nSn dinh duong, qua tnnh bfli ly-xdi 16, mure dg ngap trieu... tham thyc vdt d Miii Ca Mau phan hda thdnh 3 khu vuc khdc nhau.
- Khu vyc bd bien phia Tay: viing dat bai bdi mdi, dja hinh triing vd bang phdng, do sdu ngap trieu tten 80 cm. Tren ban dd tham thyc vat (hinh I), phan Idn difn tich khu vyc bd biln phia Tay phan bo cde tham thue vat ty nhien nhu rung Mdm, rimg Dude vd rimg Mdm - Dude hfln giao. Tham thue vat ciia khu vyc
4 6 P-H. Nguyen \d nnk. /Tap chiKhoa hgc DHQGHN: Cdc Khoa hgc K i ddt vd .Vdi tnrdng. Tdp 30.Sd4 (2014) 41-48
phan bd cd U'nh quy Iuat: fir ngoai bien vao dit ben, til bai trieu thap den bai trien cao tucmg ung vdi muc dp nggp trieu giam, nen dat ran chdc hon, miJC dp tac ddng ciia sdng va thuy trieu gidm dan [^an bd cae tham rijng Mdm ty nhien, tiep theo la rimg Mam - Dude hon giao rdi den rimg Dude ty nhien. Sy phan bfl ndy phii hgp vdi dien the sinh thdi ty nhien ciia rirng nggp tndn d khu vyc Nam Bg da dupc mot so nbd khoa hgc nghien ciru tmdc day (I^ian Nguyen Hdng, 1991, Le Dien Dye va nnk, 20I2)[3, 9].
Khu vuc Miii Ca Mau chiu anh budng eiia che dp ban nhat trieu kbong deu vdi bien dp Idioang 1,8 - 2,8m d khu vyc bd Dong va nhgt trilu khong deu vdi bien dp khoang 0,8 - l,0m a khu vuc bd Tay [10]. Sy chenh Ifch muc nudc giiia 2 bd tao dp lyc di ehuyen dong vat chat tir bd E)dng sang bd Tdy tbdng qua he thflng sdng, kenh, rgeh day dac. Chiu anh hudng ciia chl dg thiiy trifu dac thu nen khu vyc Mui Cd Mau cd xu hudng md rgng them dien tieh ve phia Tay nhd hang nam dugc boi tu them trim tieh v|n chuyin din tbeo ddng chdy ven bd va he thdng song. kenh. rach. Toe dp bfli tu trung binh tgi khu vye ndy trong khoang thdi gian tiJ ndm 1953 din nam 2011 la 40,65 m/nam [11], phu hgp vdi ket qua n ^ e n ciru ldc dp bdi tu lai khu vuc ndy tir 1904 din 2002 khoang 30 - 73 m/nSm [10]. Cac vhng ddt mdi bdi tu hang nam tai khu vyc bd Tay la mdi trudng thugn lgi eho loai Mim trdng (Avicennia alba) phit irien. Mam tring (Avicennia alba) Id loai cay tien phong, phat tan bat gidng nhd thuy trieu. Cay Mdm phdt trien tdt tren nhirng bai boi mdi ldn ra bien, trd thanh gid the giii tru mam cua cay Dude vd cdc loai cay khac. Sau do rimg Oudc phat trien xam ldn rimg Mdm, ttd thanh rung Mdm - Dude bon giao rfli thanh riing Dude ty nhien thuan loai.
- Khu \"uc bd bien phia Ddng Nam: Dia hon khu vote ven bien phi'a Ta\. do l u sau tir 30 den 80 cm. Tham thuc vat p tten dat phen. dp nen chat cua dai cao Ihiu xdi Id dudi tac dgng ciia dong chay l a sdng bien. Toe do xdi Id tnmg binh len Uong khoang ihdi gian tir nam 1953 1 2011 la 33.24 m/nam [11]. phti hgp
| u a nghien cim tdc do xdi Id tir 19(U '. khoang 23 - 43.8m/nam [10]. Tham thuc vat khu xirc nay chii yen la rimg Mdm - Dudc^Bi giao. rimg Dude ttong \a rimg Mam trflng i v i h I). Khdc \di khu \'yc bd bien phia Tay, tai khu vuc bd bien phfa Dong Nam. dien tt'chHH tu nhien cdn rat it vd khong cdn rimg Mdm ty nhien. loai rims tien phong lan bien.
Tai khu MJC nay. ba bien bi xdi Id ngay cang sau vao dat lien lam giam dien tich rimg tu nhien cd san. vi \a\ rimg .Mam ty nhien khong I bien gidng nhu khu \-yc bd phfa Tay.
liyen Hdng (1999) ghi nhan. quan xa 1 (Avicennia marina) tu nhien tai khu I Khai Long (xa Dat Mui) dang bi thu
•fch do bd bien bj xdi Id [2]. Tuy nhien leu nghien cim ciia nhom tac gia, hien nay khiM"uc nay chi con rimg Duac ttdng, rimg Mdm ^ v g va rimg Mdm - Dude hdn giao.
Dieu^B gop phan lam sdng td nhan djnh vl bienHlig xdi Id bd bien dnh hudng den su phan bd ciia tham thue \at tai khu \-ue bd biln phia Ddng Nam khu \-uc MiJi Ca Mau.
^ ^ H vyc ngi dja: Khu \-yc nay ndm ttong dat lien,jien ddi da dn dinh. Rime tu nhien cdn
\'eu la rimg Duoc (Rhizoplwza spp) Rimg .Mam (Avicennia sppi - Dude v sppi hdn giao phan bd dpc cac . con lai la rimg Dude (Rhizoplioza xen ke vdi eay bui - cd. Su phan b6 op vdi ddc thil ciJa khu vye ngi dia co nen dat n djnh. dp man giam so vdi vims sat
P.H. Nguyin vd nnk. /Tgp chi Khoa hoc DHQGHN: Cdc Khoa hoc Trdi ddt vd Moi tnrcmg, Tgp 30. So 4 (2014) 41-48 47
bien phii hgp vdi sir sinh Irudng vd phdt trien ciia rimg Dude (Rhizophoza spp).
4.3. Ddc diim sinh thai cdc logi thdm rimg ngdp man
* Tham thyc vat ty nhien
- Rimg Mam ly nhien phan bd lgi khu vue ven bien tir rach Hai Tbifn den cira sdng Bay Hdp phia Tay khu vuc Mui Cd Mau. Loai rimg nay gdm 2 ttang thai: 1, Rdng Mdm non phdt trien ttfn dat bdi bfli, dang dat bim long va 2.
Rimg Mdm tne&ng thdnh phat ttien tten ddt bai bdi, dang bun. Cdc quan xd cay nggp man ciia logi rimg nay chii yeu Id: quan xa mam bien thuan logi (Avicennia marina), quan xa mdm den thudn loai (Avicennia officinalis) va quan xd mdm ttSng (Avicennia alba).
- Rimg mdm, dude hdn giao phan bd xem kg vdi rimg Mdm tai khu vyc ven bien tir Rach Hai Tbifn den cua sdng Bay Hap phia Tay Nam khu vuc Mui Cd Mau, khu vuc Xdm Miii (kfnh Dao den kenh Hai Thien), Xdm Diy vd dpe cde sdng, kenh rgch tren dit bai bfli eao tai khu vyc Con Cdt, Trai Xeo, Xdc Cd, Cdi Xep vd mdt sfl noi khdc. Loai rimg nay gflm 03 ttang thdi: 1, Rimg Mdm - Dirdc hdn giao non phdt trien tten dat bdt dau 6n djnh, dang dat s6t mem, cdy mam Id loai chilm uu ihl, cay dude bat diu xuat hifn; 2, Rimg Duac - Mdm hdn giao phdt triln tten nSn dat da dn djnh, dang dat set mSm, cdy dude chiem uu the va dang ttong qua trinh thay the cay mdm; 3, Rimg hdn giao giira timg tv nhiin vd rimg trong nhung duge tiidng kf vdo dien tich rimg tu nhien do ty IS cay rimg ty nhien xam nhap vao rimg Dude ttong rdt cao lam thay ddi cdn ban cau tnic rimg cung nhu cdc dde diSm lam hpe eiia rimg ttdng tai Mui Ca Mau. Trong logi rimg ndy chu ySu phan bfl qudn xd Mdm ttdng (Avicennia alba) - Dude (Rhizophoza apicuiata).
- Rimg Dude ty nhien phan bd tgi Xdm Mui, Kenh Dao (kenh tt^en), Rach Tau (kenh 5, kenh 3 din rach Ca Bai, rgch Ba Khau) va Nflng trudng Trang Sdo. Logi riing ndy gflm 02 trang thdi: 1, Rimg Dude non ttr nhien phdt trien ttSn nSn dat da fln dinh, dgng dat s6t mem.
Loai rimg ndy xuat hien ttSn nen dat mdi cd dinh, thay the cho cdc lodi Mdm. Dieu nay pht) hgp vdi quy luat diln the ty nhien tgi Miii Cd Mau; 2, Rimg Budc trudng thdnh phdt triSn tren nen ddt da fln dinh, dang dat set mem bode set Cling . Cdc quan xa cay nggp man ciia logi rimg nay chii ySu la: qudn xd Dude (Rhizophoza apicuiata), quan xd Dude (Rhizophoza apicuiata) - V?t tach (Bruguiera parviffora); quan xd Dung {Rhizophoza mucronata) - Dude (Rhizophoza apicuiata).
* Tham thuc vgt ttdng
Tham thuc vat ttdng lgi khu vyc gom cd rimg Mam trflng, rimg Dude trflng, cdy ttflng trong khu ddn eu vd eay ttflng hang ndm. Hau bet rimg dugc trflng tten nen dat da ed dinh, dgng set. Loai rung nay chu yeu bao gom quan xa Mdm ttang (Avicennia alba) va qudn xa Dude (Rhizophoza apicuiata). Cay trflng hang ndm ehii yeu Id hoa mau phan bfl tten ddt gidng eat ven bifn cd mgeh nudc nggt tteo. Cdy ttflng ttong khu dan cu chQ yeu la rau va cay dn qua, phan bd dgc cdc con song ldn vd kenh rgeh irSn dat bai bdi cao.
5. Ket lu^n
Tham thye vgt tu nhien eua khu vuc Mui Ca Mau gdm eo. rimg Mdm ty nhien, rimg Dude tu nhien, rimg Mdm, Dude hd giao vd cay bui - cd. Thdm thyc vat ttdng ciia khu vyc gdm cd:
rimg Mdm trong, rimg Dude ttflng, eay ttdng ttong khu dan cu, cdy ttflng hdng ndm. Dien tich ddt cd rimg d Mui Cd Mau Id 18.129,85 ha.
48 P» Nguyin ra nnL /Tap chiKhoa hgc DHQGHN: Cdc Khoa ligc Trdi dd! vd Moi inrdng. Tgp 30. S6 4 (2014) 41-48
ehilm 48,02 % tflng difn U'ch khu vuc, bao gdm: rimg ty nhien 6.856.03ha, chiem 18,16%;
riing ttflng 11.273,82 ba, chilm 29,86%. Dien ti'ch cde tiiam thye vat khac Id 19.623,85 ha, ehilm 51,98 % tdng difn tt'ch khu vuc
Sy phdn bd ciia cdc tham tiiuc vat khu vuc Miii Ca Mau cd mdi Uen quan ch^t che ddi vdi nin dinh dudng, dgc dilm bdi vdn va qua trinh bdi ty-xdi Id cua khu vyc. Khu vyc Mui Cd Mau vdn giii dugc qua trinh dien the ty nhiSn ciia hf sinh thdi RNM. Tuy nhien dien tieh rimg tu nhien lai khu vyc nay cdn khdng nhieu so vdi cdc thdm thyc vgt khae. Sy suy giam dien u'eh do nhieu nguySn rdian khde nhau, ttong dd ldc dgng eiia con ngudi la mpt ttong nhiing nguySn nhan chinh.
Tai lifu tham khao
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Mangrove Vegetation on Ca Mau Headland
Pham Hanh Nguyen', Truang Quang Har, L6 Ke Son
^Viemam Environment Administration. MONRE
'VNU Institute of Vietnameses Studies and Development Sciences, 334 Nguyin Trdi, Hanoi, Vietnam Abstract: Belonging lo Ca Mau headland, 4 communes of Dat Miii, An Vien, Dat Mdi and Lam Hdi lie on Cd Mau perunsula, where the geographic location and natural conditions are unique, suitable for the growth of mangroves. The mangrove ecosystem here is supposed to be fast-growing in size with tremendous numbers of species. This article, from landscape ecological perspective, focuses on characterizing the vegetation, especially the distribution of the vegetation associated with the corresponding oceanographie characteristics and bottom sediments in the area of Cd Mau headland.
Keywords: Ca Mau headland, mangrove, vegetation.