VAI T R O CUA CAC QUAN XA THU'C V A T VEN BCS SONG H U O N G T R O N G VIEC BAO VE C A N H QUAN M O I TRlTOtNG
NG UYEN KHOA LAN - HUYNH THJ HOANG LAN Tnrdng Dgi hgc Suphgm ~ Dgi hgc Hue
TRUONG THJ PHUONG LAN Trudng Dgi hgc Y Dugc - Dai hoc Hue
Tom (it: Nhihig biln dong v^ chS dp thiiy vSn va tac ddng moi tnrcmg da gop ph^n tao ra su da dang cac quSn xa thuc vSt ven bo song Huong. CSn cu vao ciu tnic dia hinh, quan xS thirc vSt ven bo song Huong dugc chia thanh:
Quin xa thuc v^t bai b6i, quin xa thuc vat hb ke va quin xa thirc vat vimg sat lo. Bai viet thong bao ket qua nghifin cmi cau tnic ciia cac quan xa thuc vat dac tnrag nay va gioi thieu 03 mo hinh tr^ng cay de bao ve moi trucmg va xay dirag canh quan ven bcf song Huong, thanh pho Hue.
Thuc vat dong m6t vai tro quan trgng doi voi canh quan, moi trucmg. Thirc vgt ven bo song Huong khong chi co y nghia ve mat sinh thai ma con mang nhieu gia tri van hoa va lich sir ciia vung dat co do. Bai vilt gioi thi?u ket qua nghien ciiu cSu tnic mgt so quin xa thuc vat ven bo s6ng Huong, thanh ph6 Hue. Tir do, dk xuit mpt $6 mo hinh tr6ng cay dk bac v6 moi truang va xay dung canh quan ncri day.
2. DOI TLTONG VA PHUONG PHAP NGHIEN CLTU 2.L Boi tuffng nghien ciju
Cac quan xa thuc vat dac tnmg o ven ba song Huong thugc pham vi thanh pho Hue 2.2. Phmmg phdp nghiSn cuu
Phuong phap nghien ciiu quin xS: LSp 6 tiSu chuin, thu mlu, dinh lo?i [3], xac dinh cac chi tieu sinh thai: do nhilu, dp thuang gap, su phan b6... [5] dua theo phuong phap nghien ciiu cua Klein (1979), Nguyin Nghia Thin [8] va Hoang Chung [1].
Cac dia dilm nghien ciiu: Bai b6i Kim Long, ba ke Thien Mu va C6n Hin.
3. KET QUA NGHIEN CUU
3.1. C3u true mpt so qu4n x3 thyc vat dac trung ven hif sdng Hirong
Nhiing bien dpng ve che dg thiiy vSn va tac dgng m6i truong da gop phin tgo ra sir da dgng cac quin xa thuc vat ven bo song Huong [4]. Can cii vao ciu tnic dia hinh, quin xa th\rc vSt ven bo song hucrag dugc chia thanh: Quin xa ttiuc vat bai bdi, quin xa thirc v^t bo ke va quan xS thuc v$t vimg sat Id.
T^p chi Khoa hoc va Giao due, Truong Dai hoc Su pham Hui ISSN 1859-1612, S6 01(21) 2012: tr. 34-42
VAI TRO CUA CAC QUAN XA THUC VAT VEK BCJ SONG HUONG...
3.1.1. Quan xa thuc vat & bdi bdi ven song
Cac b5i boi a ven song Huong tuy khong co sir dong nhat ve mat khoang each, tinh chat dat, nhung co ciing dgc diem dp d6c ciia dat nho hem 30**. Vi vay, co the chia thanh: khu vuc ngap thuong xuyen, khu virc ngap dinh ky va khu vuc it nggp nuac.
3.1.1.1. Thdnh phdn lodi
Thanh phan Ioai thirc vat a day gom 63 loai thupc 22 hp khac nhau. Trong do, cac Ioai a hp Poaceae, Cyperaceae chiSm uu the. Day la nhung loai c6 siic song manh, kha nang chong chiu t6t va siic sinh san cao [3].
Cac loai co nhu vi thao bo, san cap, co la gtmg co dp che phu cao nhat chiem 50 - 65%
dien lich a cac dja diem thu mlu. Trong khi, san cap la loai ua am, thuong co do phii Ion nhit a vi tri tCr 4-8m each mep nuac; thi c6 la giing la Ioai tnmg sinh co kha nang chju bong, c6 mgt dg Ion tihat a vimg tir 6-12m each mep nuoc.
Loai thuang gap nhat 6 quin xa nay la eac loai co ua am . Vi du: coi gui tho, mom m&, nghe long da^, rSm nuac, thai lai trang, rau muang thon, co long tay va san cap. Thanh phin loai quan xa thuc v^t bSi bdi khong co loai dac tnmg, dong chay da giiip cac loai thyc vSt mo rgng khu phan bo o cae vi tri ven song [6]. Tuy nhien, quin xa co nhom loai dac tnmg. Nh6m loai dgc tnrag phu thupe vao moi truang song eua thirc vat.
Nh6m loai d^c trung cho vimg dit nggp nuoc thuong xuyen la nhom loai co tinh ua am, chju nggp nhu coi giiii tho-eo long tay. Cae loai nggp thuang xuyen nay c6 vai tro ling dpng, tich luy tram tich, nen Iam dien tich bai b6i dugc mo rpng.
Nhom loai dac tnmg cho viing nggp dinh ky vai dilu kien dp am eao la loai san cSp-vi thao bo. Sir eo mat ciia cac tham co ua am, thich nghi voi ngap dinh ky giiip CO dinh nen dat, tao dieu kien cho cac loai khac co mat.
Nhom loai dSc tnmg cho vimg bo cao la co la gung-diec bo. Day la cac loai co kha nang chiu ban, dang than thao bo, vi vay chiing che phu va giii im cho dat.
3.1.1.2. Suphan bd
Cac loai thyc vgt ven s6ng co su phan bo khae nhau va tao thanh cac dai sinh thai. Bao g6m:
CJ vimg ngap thuang xuyen, cac Ioai ngap va niia ngap nhu coi giui tho, mom md, co long tay, ram nude... va san nuac chiem uu the, mpc thanh nhirng dam ldn (tir 3-5m chilu rpng). Chiing sinh trudng kem vao miia kho. Day la nhung tim chin giiip ling dpng cac trim tieh, han che cac tac dgng ciia song va md rpng dien ti'ch bai boi ven song [2]. Nghl long day phan bo d vi tri cao hem, c6 djnh nen dat bun nhao, tgo dieu kien eho cac loai thuc vat khac den sdng. Khu vire nggp nude thudng xuyen ciing la manh dit man md eho cac loai ua am, chiu ngap khae nhu ram nude, thai lai trang va vi thao bo.
Mie du dien tieh khu vuc nay hep, rpng 0.5-2m tu mep nude, nhung anh huang ldn den ciu tnic quin xa bai bdi ven song.
NGUYEN KHOA LAN v i cs.
Vimg ngap dinh ky co thdi gian ngap dai trong miia lu tir 10-30 ngay. Thanh phan loai chu ylu ia nhimg Ioai than thao. Cac loai co gidi han sinh thai rgng vdi nhan td nude nhu CO chi, san cap phan bd dong dlu.Cac loai ua i m nhu thai lai tring, ram nude phan bd d vimg chuyin tiep giua hai khu vuc nggp nude thudng xuyen va ngSp nude dinh ky.
Cic loai cd siic sdng cao, he r l lan rpng nhu cac Ioai eo la tre, mai duong sinh trudng ehu ylu d khu vuc chuyen tilp giua vung ngap dinh kj- va ngap khong djnh ky.
Viing bo cao
Hinh 3.1. Ldi cat sinh thai viing bai bdi Kim Long
Dya vao phan tich tren, chiing tdi gpi ten quan xS thyc vSt bai bdi la "Qudn xd cdi giiii thd-cd ldng tdy & bai boi sdng Huong ".
3.1.2. Qudn xa thirc vgt b& ke
Bd ke TTiien Mu keo dai 32m, dd ddc bd ke khoang 45", dp rdng than kd 5m.
3.1.2.1. Thdnh phdn lodi
So vdi quin xa thuc vat d bai bdi, thuc vat d bd ke Thien Mu kem da dgng hon vl sd loai va hp (18 hp). Ci day tap trung cic loai than thao vdi 29 loii, cSy bui va ciy gd chiem sd lugng nho gdm 8 loai. Da s6 la cac thuc vat ua sang, ehiu hgn, tap tnmg vao cie hp nhu Poaceae, Asteraceae. Ngoai ra, cdn co cic loai thudc cic hg nhu Sclanaceae, Rubiaceae.
Thyc vat bd ke song trong dieu kien khdng thuin lgi, thilu nude, thilu chit dinh dudng.
Chiing phan bd thanh nhom d cac khe hd. Cic loai cay bui, than bo ed ehilu eao luui ehl, tang cudng phan nhinh, lan rgng. H§ rl ciia cay lan rOng vira cd tic dung bam, vira hut nude bl mit. Nhiing cay co rl egc nhu cam thao dit, din gai, rim niii re thudng dam sau vao cac khe hd, ting eudng hut nude eho cay.
3.1.2.2. Sif phdn bo
Sy phan bd cic loii d bd ke phu thudc vao ciu true eiia ke. Thuc vgt phan bd d tren than ke, mat ke va dudi chan ke. Tuy nhien, thyc vat dudi chin ke rit luin chi v l sd lugng
VAI TRO CI;A C A C QUAN XA THUC VAT VEN Bd SONG HUONG...
loai v i c i the. Thyc vat tren than ke chia lam cic nhdm chinh: Nhdm cay trung sinh, ua am vi nhdm eiy chiu hgn,
Nhom ua i m phin bd tii mep nude din 2m nhu sam (6.43%), rau mucmg thon, coi bdng cich, man man tim (3.51%), Khie vdi thue vat bai bdi, dday iteo loai ngap thudng xuyen. Do ket eau vi su ran chac cua chan ke lira cho thyc vat kem da dang.
Nhdm ciy chiu han phin bd d vi tri tir 2-5m tren than ke, tap trung thinh timg nhdm chu ylu d eac khe hd cua ke. Cie loai niy ed kich thudc hgn chi, he rl an sau ndn khong cd Ipi cho ke, vi du ciic hdi (2.53%), den gai (3.8%), rim niii (8,93%).
Nhdm ciy trung sinh phan bd rdng d than ke nhu cd la gimg (3.51%), tinh thao manh (18.13%).
Cic loii mgc d cie khe hd ciia than ke lan tda, md rdng dien tich bing than rl. Cie cay cd h$ rl Sn ndng, lan rpng nhu co l i gimg, tinh thio minh giiip phii xanh bd ke, ^ a m su xdi mdn, chdng nong cho ke. Can ehii y rang, mgt sd loai co he re Icin, an sau xudng kb, len ldi trong cic khe niit, tao ra cic khoang trdng ldn buy hogi ke (vi dy din gai), Than ke khdng phii li mdi trudng thuin lgi cho thyc vat sinh sdng, tuy nhien dg da dgng thyc vat cao hon so vdi mgt ke.
Viing chan ke Vimg mat k^
Hinh 3.2. Ldi cdt sinh thdi qudn xa thuc vdt d bd ke .rov Thien Mu Mat ke c6 sd lugng loii it. Cac loai than cd chu ylu la ed la gimg (25.31%), cd chi (17.28%), cd chan gi (19.14%) tao thanh tham phii bl mat ke. Day la nhirng loii cd he rl lan r^ng. Ngoai ra, cic cay go nhu phugng vy, bang, tning ca giiip che bdng va giu:
im. Thyc vat thin gd cd h? re an sau, pha vd ket cau ke gay ra hien tupng dpi ke.
NGUYEN KHOA LAN v
(5 eac dai sinh thai khu vyc bd ke, chiing tdi nhgn tiiay sy ed phan bd rpng cua cae loii chiu hgn. Chiing tie ddng din ciu tnic ke va quan x i thuc vit. Quan xa bd ke d diy c6 thi ggi la "Qudn xa thuc vgt ram mii - din gai b& ke sdng Huong".
3.1.3. Quan xd thtrc vgt viing sgt l&
Theo Chi cue Phong chdng lut bao va quan ly de dilu Thira Thien Hue, song Hucrag chiy qua thanh phd Hui cd 6 doan sat Id, bao gdm: Doan Thuy Bieu, doan Kim Long, dudi chin eiu Bgch Ho, doan Phii Hi6p, dogn Phii Hau va Cdn Hen. Trong do, khu vyc Cdn Hen li viing sgt Id nghiem trpng nhit, gan 3km.
3.1.3.1. Thdnh phdn lodi
Qua nghien eiiu da xae djnh dugc 39 loii, 17 hg thue vgt. Thanh phan loii phan bd tap trung vao eic hp chinh nhu Cyperaceae, Poaceae, Asteraceae. Thanh phin loai d quin xi vimg sat Id kem da dang ban so vdi quin xa bai bdi (63 loai), nhung da dang hon quan xa bd ke (37 loii). So sanh vdi hai quan xa cdn lgi, thanh phan cac loii cay than bui va cay than gd d day da dgng hon. Dg dde ldn han chi nhung loii cd cd hd rl lan rOng nhu vi thao bd, san cap. Thay vio do la eac ciy cd he rl an siu. Quin x i diuc vit vung sgt Id kem da dang cic loii thyc vat niia ngap. Vi vgy d day it ed su bdi tu lugng trim tich do dong chiy mang den va cing lim gia tang tinh trang sat Id ven bd.
3.1.3.2. Suphdn bd
Cau tnic quin x5 va dia hinh vung sat Id d Cdn Hdn li phirc tgp, Vdi dQ dde cao, ddng thdi ehiu sy tac dpng ciia ddng chay va nan khai thac cit sgn, nen tinh trgng sgt Id cd phan nghiem trpng hon. Vdi chilu dai khoang 3km cd thi ehia thanh 2 eiu mic chmh;
Viing cd dp ddc tii 60-90" va viing cd do ddc tii 30-60".
Vimg sat Id co do doc Ion hem 60°
Hinh 3.3. Lat cdt sinh thai qudn xa thirc vdt vitng sal Id Cdn Hin Vung CO dp ddc tir 60-90 : la viing sat Id nghiem trpng nhit [7], Chilu rgng tir mep nuoc ddn dudng khoang 0.5-3m. Thuc v§t kem da dang vl thinh phin loii (20 loai) chu yeu la tre, sung, tra v i cd rat it cac loii thin bui va than thao. Say rit phat triln day
VAI TRO CUA CAC QUAN XA THUC VAT \EN BCJ SONG HUONG...
la loai cd he rl nhd chin chit, an sau; tuy nhien do nen vi kit ciu giu dit ylu, Cic loai than thao bd, ed hd rl an ndng nhu cd lio, cam thio dit, ciic ving bd lam cho dit dl bj riia trdi, xdi mdn [5]. De hgn che qua trinh nay, nen xay dyng ke dat hay be tdng va trdng eac loai thye vat chju nggp de ting cudng su bdi tu va giii dit.
Trong ca hai khu vuc vdi dd ddc khac nhau, say va mdm md chilm uu thi nhu nigt tim chan d dgc bd sdng. Ddng thdi day la eac loii cd sd lugng ci the nhieu vi ehiem dien tich rgng. Vi viy, quin xa viing sgt Id dugc gpi la "Qudn xa say -mdm mo viing sgt Id b&sdng".
3.2. DS xuat mo hinh trdng cSy bao ve moi tnrdiig va xay dung canh quan ven bd song Huffng
Qua nghien eiiu, chiing tdi nhan thiy cd sy phirc tgp trong ciu tnic dia hinh sdng Huong tuong ung vdi ciu tnic ciia cie quin xa thuc vit ven bd. Tir kit qua nghien ciiu v l eiu tnic ciia cie quin xa dae trung, chiing toi dl xuit mdt sd md hinh trdng cay ven bd, bio ve va xiy dyng canh quan mdi trudng ncri day.
3.2.1. Md hinh trong cdy bao ve vd cdi tao bai boi song Hirang
Hinh 3.6. Md hinh trdng d bdi bdi sdng Huang
(1) Vimg ngap thudng xuyin trdng cdc lodi nira nggp nhu cdc lodi trong hg coi, hg hda ihdo nhu cdi giiii thd. mdm ma...
(2) Viing nggp dinh kj vd viing nggp khdng dinh kj' trdng cdc lodi ua dm, than thdo bd vd dung xen kenhu vi thdo bd. san nude, thdi lai trdng...
(3) Viing bd cao rgng, trdng cdc lodi cd he re lan rdng chii yeu Id cdy thdn thao nhu cd Id gimg. san c^p, diec bd. Trdng them cdc cdy than go cd khd ndng giir ddi, chiu nggp nhu gao vdng, sung, vd cdc lodi hoa. cm cdnh.
NGUYEN KHOA LAN va cs
3.2.2. Md hinh trdng cay bdo ve vd cdi tgo b& ke song Huffng
Hinh 3.7. Md hinh trdng d bd ke sdng Huang
(1) Chdn ke trdng cdc lodi nua nggp, cd sire sdng cao nhu cdc lodi trong ho cdi: cdi giiii thd, mdm md.
(2) Thdn ke trdng cac lodi thdn thdo bd d vi tri khe hd, cd khd ndng lan rgng, sue sdng cao nhu vi thdo bo. san cap. tinh thdo mdnh... Ogiira vung (2) vd (3) trdng cdc cdy bui tgo Id chdn bdo v^ nhir lodi dam btit,
(3) Mdt ke trdng cdc lodi cd he ri lan rdng, sue sdng cao chii yeu Id cd Id gimg, san trdn vd cdc cdy thdn gd tgo cdnh quan nhu phuang vT, bdng.
3.2.3. Mo Mnh trong cay bdo vi va cai tgo vitng sgic Id ven bd song Hirffng
(1) (2) (3) Hinh 3.8. Mo hinh irdng viing sac Id ven bd sdng Huong
VAI TRO CUA CAC Q U A N XA THUC VAT VEN B O SONG HUONG...
(1) Chdn ke ddt trdng cdc lodi nira nggp. cd sue song cao nhu cdc lodi trong hp cdi: cdi giiii tho, mdm mo.
(2) Thdn ke ddt trong cdc loai thdn thao bd, cdy bui cd he re dn sdu, bdm chdt, lan rdng...
Trong xen cdc lodi ire, sung tang cudng khd nang chdng sgt Id. He thdng coy bui giup giir da! d bd cao, trdnh xdi mdn.
(3) Mat ke ddt trdng da dgng cdc lodi cd vd cdc cdy thdn gd nhir sung, tra, gdo vdng. tdng cudng su rdn chdt ciia bd ddt.
4, KET LUAN
Qua ngiiien ciiu ciu tnic quan xa thuc vat ven bd sdng Huong, chiing tdi nit ra mgt sd kit luin sau:
1. Cd 3 quan xa thuc vgt dac trung ven bd sdng Huong: Quin xa cdi giiii thd-cd ldng tiy d bai bdi, quan xa say-mdm md 6 vimg sgt Id v i quin xa ram niii-din gai d bd ke xay.
+ Quan xa thue vat d bai bdi cd sy chuyen tiep giOa cie vimg phan bd. Cac loii eiy gd ehi cd mat d vung dit bd cao, Cic loai cay bui, xuat hien d vimg dat bd eao va viing ngip khong dinh ky. Cie loii ciy thio phan bd rdng khap quan xa. Quan xa thyc vat d bai bdi ed dd da dang cao nhat, khdng chi ve thanh phin loai ma cdn c i ve sd hp v i dgng sdng ciia ciy.
+ Quin x3 vimg sat Id khdng co sy phan ehia rd rang. Vdi dp ddc ldn, eic loai ngap ed diSn tich han che, thim cd kem phat trien, tuy nhien nhdm eiy byi da dang.
Cac cay gd, bui mpc sit mep nude lam giam hiSn tugng nia trdi, xdi mdn nhu sung, tra, tre la nhiing hang rao chin bio vd dit.
+ Quin xa vimg bd ke cd sy phan chia kha rd ring: Vung chin ke, than ke va mat ke. Vimg chin ke k6m da dang v l loii vi sd lugng ci thi. Thin ke vdi su da dang cic loii than thao, byi. Cac logi cd bd chu yeu mgc d cac khe hd cua ke xay. Phia tren ke l i khoing dat nhd vdi sy phan bd chii yeu ciia cac loai cd chiu bong, cac loai eiy gd cd tan rgng.
2. Cie nhdm loai thyc vat: ngip, nua ngip, ua im, trung sinh va chiu ban tdn tgi d e i ba quan xa. Tuy nhidn, d mdi quan xa cd cac nhdm loai dac trung cd vai trd quan trpng ddi vdi quin xa va sinh cinh. Thuc vgt ngap nhu cdi giiii thd-cd long tay, cd khi nang gift dit cd dinh nin bim nhao, ling dpng trim tich, md rOng dien tich bai bdi. Vimg sgt Id vdi nin dit co dp set cao, rdi rac. Vi viy, d day ehii yeu la eac loai co he rl an sau, cd vai trd la tam chin nhu say, mdm md. Hien tugng be tdng hda bd ke da tao ra mdi trudng bit lgi, ban ehl sd lugng loii v i ci the. Cac loai thye vat ua sang va chiu hgn cd he he re dam sau nhu ram niii, den gai chiem uu the.
3. Tir ket qua nghien eiiu vl ciu tnic eiia cic quin xa dac trung, chiing tdi da de xuat 03 md hinh trdng cay bao ve va xay dyng canh quan mdi trudng ven bd sdng Huong.
NGUYEN KHOA LAN va cs.
TA! LIEU THAM KHAO
[1] Hoang Chung (2002). Cdc phuang phdp nghien cuu qudn xd thuc vgt. NXB Giao due. Ha Ndi.
[2] Cronk Julie K., Feimessy M.Siobhan (2001). Wetland plants biology and ecology.
Lewis Publishers, USA.
[3] Pham Hoang Hp (1999, 2000). Cdy cd Viel Nam (tap /, //, IU). NXB Tre, TP H6 Chi Minh.
[4] Tran Thi Hue (2010). Hien trgng vd khd ndng thich nghi cua mdi sd lodi thuc vat sdng ven bd sdng Huang. Thdnh phd Hue. Luan van Thac sT Sinh hpc, Tnicrag Dai hpc Su pham Hue.
[5] Tran Kien, Phan Nguyen Hdng (1990). Sinh thdi hgc dgi cuong. NXB Giao due. Ha Npi.
[6] Theodore T. Kozlowski (2002). Physiological - ecological impacts of flooding on riparian forest ecosystems. Wetlands 22(3): 550-561 2002, University of California, Berkeley, Califoraia, USA.
[7] Do Quang Thien, Tran Hihi Tuyen (2002). Moi quan he giiia cau tnic dia chat vdi qua trinh boi xoi ha luu song Huong. Tgp chi khoa hgc Dai hgc Hui, 11, 2002.
[8] Nguyin Nghia Thm (2007). Cdc phuang phdp nghien cuu Thuc vol., NXB Dai hoc Quoc gia Ha Npi, Ha Noi,
Title: ROLE OF PLANT COMMUNITIES ALONG THE HUONG RIVER TO PROTECT LANDSCAPE AND ENVIRONMENT
Abstract: The changes in hydrological regimes and environmental impacts have conUibuted to the diversity of plant communities along the Huong River. Based on die strucUire of the terrain, vegetation communities along the river is divided into: alluvial vegetation communities, plant communities embankment and plant communities landslide area. Article reported the results of strucmral studies of the plant communities and introduce 03 models to plant trees for environmental protection and consuiiction of landscape along the Huong River, Hue City.
PGS. TS. NGUYEN KHOA LAN ThS. HUYNH THI HOANG LAN
Khoa Sinh hoc, Trucmg Dai hpc Su pham, Dai hpc Hui ThS. TRUONG TH! PHUONG LAN
Trucmg Dai hoc Y Dugc, Dgi hpc Hui