Nghien cOu - Trao doi
Nghien cuHu xay duiig ctf so diir lieu pho phan xa riihg ngap man phuc vu quan ly va giam sat tai nguyen riAig
O N G U Y I N v u GIANG, NGUYEN TH| QUYNH TRANG, LE QUANG TOAN, VO H O U LONG TONG THj HUYEN AI, N G U Y I N AN BINH, NGUYEN MINH HIEU, PHAM VIET HOA, LEON HAUSER,
PHAM VIET HONG, LE VU HONG HAI Vien Cdng nghe vu tru, Vien Han lam KHCN Viet Nam
PHAM VIET HOA
Vien Dja ly Tai nguyen TP. Ho Chi Minh, Vien Han lam KHCN Viet Nam LEON HAUSER
Leiden University, The Netherlands PHAM VIET HONG
Vien Dia chat va Dia vat ly Bien, Vien Han lam KHCN Viet Nam LE VU HONG HAI
Hoc vien Ky thuat quan sU
ve tinh v i l n tham. Trong nghien cUu nay, mpt so IUdng Idn mau pho phan xa ciJa ryng ngap man da dUde thu thap, ehuan hda, phan tfch va xac dinh dUde dac trUng phan xa cua mdt so loai cay ngap man pho bien 6 Viet Nam.
Khu vUc nghien cyu va phUdng phap thUc hien
Khu vyc dUde lya chpn nghien cyu la he sinh thai ngap Gidi thieu
NhUng nam gan day, cdng tac dieu tra, giam sat, danh gia chat lupng rUng dang nhan dUdc su quan tam dac biet cua cac qud'c gia ndi chung va Viet Nam ndi rieng. NhOng tiep can dieu tra theo phUdng phap truyen tho'ng cdn gap nhieu khd khan, trong khi phUdng phap tiep can mdi sii dung tu lieu anh ve tinh cho thay nhOng Uu viet cao tuy each tiep can v i n cdn thd sd, khdng quy ehuan, thieu dO lieu bo trp. Viec dieu tra, xay dUng dUdc mpt cd s6 dO lieu pho phan xa cac doi tuong mat dat se rat cd y nghTa cho cac nghien cUu quan ly tai nguyen, do dac, giam sat rUng bang cdng nghe v i i n tham.
TU thuc te do, viec dieu tra, xay dung bp co sd dO lieu phd' phan xa cho cac nhdm doi tupng idp phu ndi Chung va rUng ngap man ndi rieng rat cd y nghTa lam Cd sd tham chieu khoa hpc cho viec do dem, giam sat, quan ly chat IUdng rQng bang tu lieu anh
3 4 Tdi nguyen vd Mdi tru'ong I Ky 2-Thang 12/2016
man ven bien huyen Ngpc Hien, tinh Ca Mau, noi cd dien tfeh riing ngap man cdn lai Idn nhat Viet Nam.
Trong khu vyc nghien cilu, cac loai ngap man Uu the la Mam, Dude, Vet, Da vdi va DUa nudc.
M i u pho phan xa cua 6 loai eay ngap man dUdc thu thap dya tren myc dp pho bien, sy phu hdp va kha nang lay m i u , bao gom:
Mam trang, M i m den (Avicennia Hinh 1. Khu vUc nghien cUu, huyen Ngoc Hien, tinh Ca Mau
officinalis). Dude (Rhizophora api- eulata), Vet (Bmguiera parviflora).
Da vdi (Ceriops tagal) va DUa nude (Nypa frutieans). Ben canh do, m i u pho p h i n xa cua mdt sd nhdm doi tUdng khac nhu dat, nude cung dUde thu thap trong qua trinh khao sat thyc dia de phan tich, so sanh, doi chieu.
Pho phan xa eiia 6 loai cay ngap man dupe thu thap su dung thilt bi do pho ASD FieldSpec
Pro, vdi dai bUde sdng 325 nm - 1075 nm, trudng nhin 7.5= Cac tri do dude tien hanh khoang tu 9 den 11 gid sang, va 14 den 17 gid chieu dudi dieu kien thdi tiet va anh sang on dinh. Thiet bj thu sieu pho vdi dp phan giai pho I n m . Dau thu dupe dat chech phia tren.
each tan 1,5 m de bao dam m i u pho thu dupe cua moi loai cay la dong nhat. Moi dd'i tupng dupe do 10 Ian de cd the han che va loai bd nhung sai so phat sinh. Thiet bi do pho dupe do ehuan dong tdi trudc mdi dot do va ehuan phan xa (white reference) ngay trudc mdi Ian do de loai bo sy thay doi ve dieu kien chieu sang do may va eac yeu td mdi trudng khac.
Ben canh dd. ban than thiet bi do pho cung dUpc cai dat de ty dpng lUu tru gia tri do dong buc xa tu 10 gia tri cho moi ian do cua cung mpt doi tUdng. Moi dd'i tUdng do cung dupe ghi chu md ta chi tiet ve loai, cap tuoi. trang thai sinh trudng. tpa dp vj tri. dieu kien do.
Phan tich, xii ly so lieu do DO lieu phd sau khi thu thap ngoai thyc dja dupe trut vao may thong qua phan mem xu ly chuyen dung RS3 Spectral Acquisition.
Trudc tien. phep ipc Savitzky- Golay dupe ap dung tren toan bp tap m i u de loai bo nhOng tri do khac thudng do anh hudng cua moi trudng hoae nguyen nhan bat thudng nay sinh trong qua trinh ghi nhan du iieu pho phan xa. Sau do.
B i n g 1 . Sd luang diem mau thu thap cho sau loai ngap man Uu the d huyen Ngoc Hien va so luang dc sai so thd dUOc nhan dien va loai bo
Loai cay ngap man Ten tieng Viet
M i m tring M i m den Dya nu'dc Dude Da vdi Vet
Ten Latin Avicennia Alba Avicennia Officialis Nypa frutieans Rhizophora Apiculata GeriopsTagal
Bruguiera Parviflora Tong sd
Sd lieorng sal sd tiid
bl loai ftd 15
4 12 32 11 8 82
Tong so Itfong
miu 147 115 48 225 49 25 609 Bang 2. Cac dai song to'i Uu cho phan biet cac loai cay ngap man
dua tren phan tich SDA s6
Iwmg
Cac dai song phu hop (nm) Dai nhin thay
•7 ^396, 404. ^ 0 454. 528,
; 568, 600, 634, 648, 678
Ria do - Red edge 690, 730
Can hdng ngoai 754, 890, 968,
974, 1056
Wilk's
0,007
phep phan tich don bien de loai bo cae gia trj bat thudng da dupe ap dung cho tap du lieu nay de ioai bd cac gia trj ngoai bien, 6 day ap dung cho nhung dd'i tupng vupt qua 3 ian dp lech ehuan. Khdi lupng thong tin thu dupe trong du lieu sieu pho la rat Idn. cac gia tri 6 nhOng dai sdng hep lien ke nhau cd the chua cac thdng tin cd tinh tuong quan va dp tuong dong cao.
Do vay. phep ipc da bien su dung khoang each Mahaianobis cung dUdc ap dyng de loai bd cac trj do bat thudng tu mpt lupng Idn m i u pho. Gia trj trung binh (mean spectra) chi dupe tinh sau khi da loai bd cac trj do khdng on dinh, de dam bao m i u phd thu duoc la tuong ddi dong nhat cho mdi ddi tupng do.
Cac ket qua do sau khi duoc xu ly. ehuan hda da dupe s i p xep. to chuc thanh mpt bd co sd du lieu, phan theo cac cap. nhdm de tien tim kiem va tri'ch xuat nhu:
Loai hinh Idp phu, loai. chi. trang thai, tuoi. Thdng tin duoc trich xuat cho phep nguoi dung co the Ung dung, su dung cac ph&n
mem xu ly anh vien tham de nhan dien mau phd phan xa va phan loai ddi tupng. B i n canh dd, thdng tin tham chieu, md ta vj trf do, thu thap du lieu, anh chyp ddi tupng do cung dude lien ket trong CO sd dO lieu cac diem do, giup ngudi dung hieu va khai thac td't hon bd CO so du lieu.
Ket qua va thao luan Phd phan xa trung binh cua mdi loai da dupe thu nghiem phan tich tu tap du lieu sau khi ehuan hda. Duong cong phan xa phd cho thay cac loai cay nay cd phd phan xa tUdng ddng vdi dUdng cong phan xa phd dac trung cho nhdm thyc vat.
Mat ngudi nhan biet va phan biet cac ddi tudng khac nhau nhd anh sang nhin thay dUpc phan xa tu be mat cac vat the. Trong vung sdng anh sang kha kien. cac loai cay deu cd phan xa phd thap nhat trong dai sdng xanh iam 430-500 nm va song dd 650-670 nm, ddng thdi phan xa cao nhat trong dai song xanh luc 540-580 nm. Dieu nay giai thich vi sao chung ta quan
'Li-ar.g I Ky2-Thang 12/2016 3 5
sit thiy l i ciy cd mau xanh lyc, do chung phin x?i mgnh inh sang mau nay trong dii bUde sdng nhin thiy. Ngoai ra, d l thi phin xa cung cho thiy thyc t l trong toan dii phi do dUdc, cic loai thyc vat cd phan x? rat m^nh d vung sdng can hong ngo^ii 750-950 nm.
Cac y l u t l chinh khiln cd nhyng thay doi khac nhau v l do phin X9 ciia t i n la l i sac t l la - pigment, dac biat l i chlorophyll-a, chlorophyll-b va beta-carotene ben canh cac y l u t l ciu true tan va dd day tan. Do thj phi cho thi'y sy khic nhau ve phin xa phi do dUdc giya cic loai cay.
Mam trang va Mam den cd phin xa pho kha tydng ding 6 dii sdng nhin thi'y nhung v i n kha khic biet so vdi nhdm cac loai cdn lai diu thudc hp dude (Rhizophora- ceae) la V?t, Da vdi va DUdc.
Phan tich do thj phin xa phi ch? ra sy khac nhau ding k l (10%) v l phin x? pho giOa 2 nhdm loai pho biln d khu vyc nghien cyu la Mam (Avicennia) va DUdc (Rhizophoraceae) 6 dii sdng xanh luc va can hong ngoai, trong khi sy khic biet nay lai khdng q u i rd net trong d i i sdng xanh lam va sdng dd. Sy khac biet nay phu hdp vdi thyc t l la tan la cay mam cd mau xanh sang hdn so vdi tan la dude cd mau xanh tham trong mdi trudng ty nhien. Dilu nay gdi y cho eac chuySn gia nghien cUu, Ung dung viln tham cd thi phan loai, tach biet dUde 2 loai cay nlu cd inh phin giii pho tit va sii dung ky thuat phu hdp.
Trong nghifen ciiu nay, phUdng phap phan tich phan lap tuyIn tinh SDA (Stepwise linear Discri- minant Analysis) cung dUdc thCr nghiem de tim ra nhyng d i i bUde sdng ed khi nang phin biet loai td't nhat. Khi nang phan biet loii trong phin tich SDA ed t h i dUdc IUdng hda bang gia tri Wilks' X.
Wilks' X la dai IUdng dUde sCr dung
pho biln d l danh gia k h i ning tich bidt giya cac dd'i tUdng.
Trong trudng hdp nay, nd dUdc coi la mot ch? thj d l i vdi k h i nang phin biet loii tr§n mdt hoic nhieu budc sdng. G i i tri Wilks' X cang thi'p, khi nang phin bi§t giya cic loai cang cao.
K i t q u i ciia phin tich SDA chpn ra dUdc 17 d i i sdng phu hdP CO k h i nang phin biit t i t giya 6 loii ciy ngap man tren tap mau da dUdc chuin hda sau khi khdng cdn sy c i i thi§n nao v l gia trj Wilk's X. Q u i trinh phan tich dCrng S gia trj Wilk's X la 0,007.
Trong c i c d i i sdng dUdc lya chpn, cd 7 bydc sdng ty 454 nm den 678 nm trong d i i k h i kiln, mdt trong vung ria dd 690nm v i mdt budc sdng 890 nm trong vung can hong ngoai l i cac budc sdng nam trong d i i thu cua cac ve tinh VNREDSat-1, LANDSAT 8, SPOT 6, 7. Dilu nay cho thay, ben canh vung sdng can hing ngoai, vung sdng nhin thay van cd y nghTa kha Idn trong viec phan biet cac loai cay ngap man khi Ung dyng cac lo^i i n h va tinh quang hoc pho biln nay trong khi chua cd inh v§ tinh sieu pho.
Ket luan
Mdt IUdng Idn dy liSu p h i phin xa cua cac cay ngap man pho biln 6 Ngpc Hiln, Ca Mau da dUdc thu thap, xii ly, cho phep phan tich, nhan dian dUdc sy khic biet v l loii sau khi da dUde xCr ly, ehuan hda d l lo^i bd nhyng sai so trong q u i trinh do. DU lieu pho phin xa thu dUdc, dUde chuin hda va to chUe thanh cd s6 dU lieu, bao gom c i eic thdng tin md t i dli tuyng do ri't cd y nghTa trong viec chia se va khai thic sau nay. Cd sd dy lieu pho niy cho phep ngUdi sCr dung cd thi khai thac nhU mpt dang thU vien phi de phin lo^i cac loai cay ngap man trdn nhilu loai inh viln tham.
DU nau phi thu thap thyc t l
cdn cd the dydc khai thac, ling dyng de hieu ch?nh phin x? inh viln tham thdng qua cac md hinh thuc nghiam va md hinh bile x^.
Ben C5inh dd, viae phin tich dO lldu va danh gia dUdc sy khac biit v i pho phin x^ cua cac loai cay S cac d i i bUdc sdng khac nhau rit cd y nghTa cho cac nghien cUu, phat triin c i m biln chyp i n h cung nhU thilt ke tinh nang cho cac v6 tinh vien tham quang hpc sau nay phuc vy nghien cifu, theo ddi ldp phu thyc vat.
Ldi c i m dn
Day la mdt phin kit q u i ciia du an dilu tra ed b i n ma so VAST.DTCB.02/14-15 Vien Han lam KHCN Viet Nam. D l tai chan thanh cam dn Sd NN&PTNT t?nh Ca Mau, cac can bd Vudn QuIc gia Mui Ca Mau, v i Ban quin ly RUng phdng hd Nhung Mien, huyen Ngoc Hien, tlnh Ca Mau da tao dilu kien thuin ldi, giup doan khio sat va thu thap dy lieu ngoai thyc dja.
Tai ii$u tham khio Dang Trung Tan (2005) H$
thi/c vit rUng ngip Ci Mau, Vien Khoa hpc Lim nghiep Viet Nam.
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Koedam (2015). Changes in man- grove vegetation area and charac- ter in a war and land use change affected region of Vietnam (Mui Ca Mau) over six decades. Acta oecologica, 63, 71 -81.
Jensen, J. R (2009), Remote sensing of the environment: An earth resource perspective 2/e.
Pearson Education India, 2009.
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Deeh, S. (2011). Remote sensing of mangrove ecosystems: A re- view. Remote Sensing, 3 (5), 878-928. •
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