Tap cW Khoa hoc DHQGHN, Khoa hoc Ty nhien va Cong nghe, T|p 30. So 1 (2014) 26-3o
Dac tnmg co ban ciia thuc vat rung nhiet doi gio mua Viet Nam
N g u y in D ang H oi*, K uznetsov A .N . Tnmg tdm Nhiet <}&i Viet-N ga. Bq Quocphdng
Nh§n ngay 05 thSng 9 nam 2013
Chinh sua ngay 19 thing 9 nam 2013; chip n h ^ ding ngay 07 thing 3 nam 2014
Tom tit: Tren co so tiip c|n sinh that hpc quin xa. da nghien cihi thanh phin loai thuc vat rung, cau true khong gian, cac khi'a c^nh sinh hpc caj^ go rung, dpng thai cay rung, hlnh that - thuy van cua dit rCmg va vi khi' hau rirag Theo dd. da thing ke dupe ting trSn chng dupe hinh thanh rir 330 lolu cay. ling gitta - 2.460 loai vi ting dual - 320 loai.
Bk nghien cuu dac diem ciu true dung ciia rimg, chiing toi su dung phuong phSp bieu do mat cit. Sir bien d6i trong thinh phin cic Ic^ cay tao rtmg diln ra chii yen o bic ho. trong khi d cac phan ting ben duoi. noi dieu kien mfii truemg thuc \’3t phat irien phu ihupc vio cic phan tang phi'a tren thi phin Ion d b& loai hoje cht thupc nhOng hp d6. Hp sinh thai rCmg nhiet ddi la die tnmg cho diiu kipn epe dinh ve khi hau v& c6 su can bang dpng thai trong chiic nang cua cac hS sinh thai rung.
Sp xuit hipn vung dit erdng vdi viec thieu tham thuc v§t rung la ket qua ciia sp thay doi che dp vi khi h|u, chi dp thuy van. tinh chit ciia dit va su phdt trien ciia qud tnnh x<5i mdn. Cly go rimg va cly tien phong khong the phat trien va thich nghi irSn nen dit mdi - nen nhieu yeu to da bi thay ddi m^nh me bdi con ngudi. Dieu nay gay n6n sp gian d o ^ trong chuoi dien the cua thuc vat.
Su giau cd thanh phan loai va phitc tap ciia rimg nhipt ddi gid miia dl throe thay the bdi quan xa thuc vli cd cau true don gian vdi uu the Ih cac lohi hc^ thao.
Keywords: Cau true, cay gd, dong bing, gid mila, loai, nhipi dot, mli, quin xa, phSn ting, rung, thpc vaL
Viet Nam ndl rieng, ban dao Dong Duong ndi chung !a mpt trong s6 cic ming tim da dpng sinh hoc. ining tarn phat sinh loii thuc vat tien the gidi. Tnroc day, nghign cuu thpc vat a Viet Nam chti yeu tap tnmg vao cac npi dung ve phan loai v l nhung tong quan ve he thpc vat
' T4c ^ lien h|. DT' 84-913346759 E-mail, danghoil 10@yahoo com
dia phuong [1, 2], Trong kha nhieu cong trinh con c6 nhung diem chua chmh xic, mpt so thong tin ve thanh phan loai con bj nbam Ian Hon niya, van chira xic lap dupe co sd khoa hpc mot each day du ve to chuc cau true - chiic nang cua he sinh thdi rimg nhiet ddi khu vpc Dong Duong.
Nhung nghiSn ctiu vd d ie diem hmh thanh va chiic nang ciia rimg nhift ddi gid miia cho phep g i^ quyet duoc mpt so nhipm vp trong
N.D Hoi, Kuziietsoi' AN /Tap chi Khoa hoc DHQGHN, KIwa hoc Tie nhiln va Cong nghe, Tap 30, So 1 (2014) 26-35 27
thuc tien nhir phuc hoi, khai thic, su dung hop ly va bao v6 nguon ti i nguyen rung. Tuy vay, a Viet Nam v& Dong Duong, nhung nghifin cuu n iy c6n rat han che. Nh&ng th§p ky vira qua, viec d ly manh khai thac ngudn tM nguygn rimg da Itet gia tang su roi loan nguon gen, l&m m§t di mot phan rimg nhiet doi ca a vimg dong bSng, trung du vli mien nui, cao nguyen.
6 khu vuc dong bang mi€n Nam ViSt Nam cung nhu cic dong bang, binh nguyen khSc ciia
Dong Duong, rimg cay hp Dau
Dipterocarpaceae thubng chiem uu the. Truoc nhung nam 50 ciia the ky 20, rimg cay hp Dau chiem dien rich rpng Ion a V ifl Nam tren cdc dai dp cao duoi 700m [3, 4]. Chiing 1^ tarn tham che cho cac khu vuc dong bang trgn phii sa cd, ngn phien s6t v^ cao nguygn bazan. V a d6 cung Hi ly do de Viet Nam tro thanh mo hlnh d?i dien de nghigo cuu quy luat ph^t trien ciia thuc vat rimg Ddng Duong.
Tir k it qua nghien cuu hon 20 nSm qua, bM b^o tap trung ban luan m6t so van de co ban v i dSc diim to chuc cau true - churc nSng, su phd huy nhSn sinh cung nhu cfic vSn d i ve phSn loai v^ dieu kien sinh cua cSy rimg nhiet doi gid m ua Viet Nam.
2. Tai lieu va phutmg phap nghien cihi
My su dung trong chien tranh D6ng Duong Ian 2 o K o n Turn, Quang Tri, Tay N inh,... [5, 6].
T rin co so quan diem tiep c ^ sinh hpc q uin xa [7], da tiin hanh nghien ciru: thinh phan loai, cau true tang tan, cau true khdng gian, cau true thinh phan loM quan xa thtre vat rung, d |c diem sinh hpc thuc vat ciing cic yeu t6 sinh thai, dia ly ph it sinh nhu dja hlnh, thuy vSn va vi khi h |u va dat rimg.
De xlc djnh thupc tinh loai, ngoli sir dung Bp cay co Viet Nam cua Pham Hoang Hp [8], da m o rpng bp cic dau hieu nhan b iit, trong dd bao gdm cic dau hieu hinh thai chung ciia than cay; mau sac, m |t cat cua vo v l than cay; mui, m lu sac va dp d |m die cua nhua cay. Da xay dimg quy trinh x lc dinh hinh d^ng, Wch thude cua II, cac die tnm g phign II, g in la, mui cua II (khi v6 nhau) va ir4t dp II qua so lieu ciia 60 loai cSy gd v l day leo pho bien.
Vi& phin chia rimg thinh cic tang dua tren CO so he thdng phSn loai co diln cac dsuig song CO ban cua thuc vat. Theo dd, rimg nhift dcri gid miia dupe phan thanh 2 tin g co' ban: tang cay go v l ting than thao. T ing cay go dupe chung tdi phSn thanh m$t so phSn ting dac trung cho cau Auc dung cua cay go rimg. C iu true dung cua rimg dupe uinh bly duoi dang cIc bieu do mat cit, dupe coi nhu chin dung ciia rimg.
Su dung chuoi so lieu nghifen cim tit 1989 den 2012 t?ti tram nghiSn cuu tu nhiSn Ma DI.
tinh Dong Nai trong cac kieu rimg cay hp Dau thin cao; rimg ddng bang khu vuc Vudn qude gia (VQG) Cat Tien va rimg tren day nui cao Hoang Lien Son thupc VQG Hoang Lien v l Khu bao tdn Van B ln, tinh Lao Cai. B in c ^ dd la c ic nghidn cuu t?u nhung vitng chju tic ddng ciia boat ddng n h in sinh, trong dd cd tic dpng ciia ch it d i|t cd, bom napan do quin dpi
3. Ket qua va thao lu |n 3.1. Cau true dimg ciia rimg
Trong q u i trinh hinh thinh he thuc vat va ciu tnic nguyen sinh, c ic cinh rimg nhiet doi gid mua II nhOiig h# thong sinh hpc phuc t|ip cd cau true dung dac thu. Trong mot dai dd cao cu thd, mot so loll cly gd hinh thanh nen cic phan tang nhat dmh. Trong khdng gian rimg, khoang biln thien ve do cao ciia cic cay tao nen mdi
28 RD. m . AR / r , cU H™ / « DHBGHN,» , « 7 . » C5«« «8W, Tj, 30, S3IC20H) 26-35
phan ling duoi phu thupc vao miic do p h ^ trien cua cdc phan ting tren, cung nhir phu thuoc vao do khep tan, ducmg ki'nh v i hinh dang tan^ la.
Thong thuong, phSn ting tren ding (phan tang 1) khong khep tan; phSn ting 2 phdt trien t6t va khep lan; phan tang 3 c6 ti'nh phan manh va phan tang dircri cung (phan tang 4) lai phat trien t6l. Theo s6 beu cua chdng toi, phin tren cimg cua rimg Vi?t Nam c6 k h o ^ g 330 lo ^ cly go, phin giua 14 2.460 loai va phin duoi 320 loai [9,10].
Theo muc do don gian - phurc tap. chiing toi da chia ra 3 dang ciu tnic diing ciia rimg ddng bing hinh thanh trong dieu kien liigng giang thuy trong mua mira c6 the dat tdi 2.000 mm.
c i u true duoc xdc dinh chii yeu thong qua dac diem dat v4 kha nang rich luy do am ciia dat rimg. Rimg c6 cau true don gian ( 1 - 2 phan tang cSy dimg, cao tir 4 - 12 m) phat trien chu yiu tren dat cat. set - gley va phien (dang cau tnic nay cung dung voi rimg o g|p mSn ven biin). Rimg c6 c iu tnic trung binh (c6 3 phSn ting, cao tir 10 - 35 m) hinh thanh chii ylu tren dat c6 thanh jrfian co gioi nhe, dat tren nen da phien sdt v4 d it than biin - gley. Rimg c6 cau tnic phirc tgp (4 - 5 phan ting, cao 40 - 55 m), phat trien tren dat feralite tang d4y, thoat nude tdt. cung nhu trSn d it phii sa doc thung lung song. Nhu vgy, tuy thupc vao muc do tham thau hoi am, mire do hinh thanh cac tang chua nude mua trong dat, dien ra qua uinh hinh thanh cau tnic dung phuc tap ciia rimg cay go.
Doi vdi re cay go tao rimg, dieu quan trong bac nhat la muc do tiep nhan dp am trong dat sudt thdi ky ca nam. Su khde nhau ciia c4c loai dat la do s4u ciia tang khong tham nude, toe do tham thau am tir khi quyen, tinh chat phan pbdi I91 am cua chat khoang trong dat va kha nang rich nude cua dSt. Su khong tham nude 14 do Idp phien set (tir dat set den dsmg set ket tinh), bazan (xdp ho4c chat), da granit dang ph4n
manh hoac tru, canxit (chat hoac toi xdp). C4c lop nay phan bd d d6 sau khSc nhau, b it dau tir b i mat, dong thdi bien ddi tir su dan xen cho d in h iu nhu ddng n h it (d dang tim ho4c phiin). Kha nang ridu thodl nude theo dd sau ciia d it dam bao cho su phan ting he re ciia c4y thude c4c phan tin g cay go khde nhau. Ben canh viec tiSu thoat nude con do kha nang chenh l|c h cot dp cao.
Rimg cd ciu tnic phuc tap nhat gdm 5 phan tin g dupe hinh th4nh trong diiu kien khi hau gid miia dien hinh, thong thuong 14 phdl trien trdn loai d it feralite dd - vang lin g day (den 4m). 6 day, mot lupng Idn nude rniia mua (lupng mua 1.100 - 1.500 mm) dupe rich tu trong c4c ting dat v4 dd am theo rinh chat trpng luc va mao mach giup c ic loai cay gd rimg su dung trong sudt thdi gian ciia nam.
6 diiu kien dja hinh niii cung cho thay muc dd phuc tap khac nhau trong cac cau true dimg cua c4y rimg. C iu tnic don gian dupe dpc trung bdi cac loai Thong b a 3 la (Pimis kesiya) v4 Thdog hai 14 (Pinus latreri), cao den 20m, ph4t trien tren dai do cao 1.200 - 1.600m, dSc diem n4y cung dung vdi rimg rSu may mu va rimg lun (cay cao 2 - 6 m) tren cac dinh va gidng ni3i cd dp cao tdi 2.000 m vdi tang dat mong, nhieu sdi da. Rimg cay go vdi cau true don gian dupe b it gap tren dinh cua c4c day nili da vdi (dja hinh karst) o dai dd cao 400 - 600 m. Rimg cSy gd c6 cau tnic trung binh, cao 10 - 24 m, dupe hinh thanh tren sudn niii, tren c4c dinh cao nguyen, tren viing trung va doc c4c thung lung sdng d dd cao ddn 2.400 m. phat trien tren c4c lopi dat cd thanh phan co gidi v4 ngudn gdc kh4c nhau. tham chi la dat lln nhieu d4 nhimg dupe cung cap dii nude. Rimg co cau tnic phuc lap vdi chieu cao cay den 30 m bat gap tai c4c viing mii thap (din 800m) tren sudn thoai, trdn bac them rdng. noi dd sau cua tang dudng re khong dudi 1 m 15,11],
N.D. Hoi, Kuznetsov A.N ITap chi Khoa hoc DHQGHN, KJioa hoc Tit nhtfti va Cong nghe. TSp 30, SS’l (2014) 26-35 29
Nhu v |y , doi voi cac kieu nrag vung niii, nh&ng yeu to quyet dinh su phuc tap cua clu tnic dimg ciia rung la do cao (USn quan che do nhift), dp doc, huong don gio miia, tang day dSt (xdc dinh d§ sau ciia tSng duong re). Khi s3p dac tfnb cua dat rung theo c h i ^ giam kha nang tiSu thoAt nu6c, sir suy giam dp an sSu v^o dat cua h? re se cho thay su don gian hoa ciia cau true rimg theo chieu thang dung v6i viec giam so c&c phSn tang cay go.
Trong rimg nhipt doi gio miia, cung voi c5c loM cay g6 tao rung, luon c6 ede loai “thii yeu”, cac loai nky khi g |p dieu kien thuan Ipi c6 the tro thanh ede lodi chii yeu hoac Id cac loai quan trong (chia khoa). l i y vi dy nhu lodi Tung (Jetrameles nudiflora) thupc hp Dang (Datyscaceae) vd Bang lang {Lagerstroemia calyculata) t h u ^ hp Bdng lang (Lythraceae).
Ket qua nghien ciiu cho thay, day Id cac lodi nSn a ia rimg trong thung lung ciia VQG Cdt TiSn [10] hay loai Cdm {Parimri annamensis) thupc hp Cdm (Chrysobalanaceae) pho biSn tai khu vuc rimg dong bdng a ia dao Phd Qu6c, nhung chung lai Id loai thu yeu d rimg M a Dd.
Su ket hop phiic tap, doi khi doc ddo giua khi hau dja phuxrag, tho nhuong, thuy van vd ede ydu to mdi truong da d in den su xuac hien bat ngd ciia he thuc vat va doi khi lai Id nhung loai dac him. Vi du, cac canh rimg voi lodi uu the la Du sam niii dat (Kereleeria evelyniana) thupc hp Thong (Pinaceae) vd Thong la det (Pirns krempfU) phat trien tren nui mien Nam Viet Nam: Loai thu nhat Keteleena evelyniana chi phan bd a khdi niii Bidoup, trdn cac nhanh tir phfa Tay huong ve dinh ciia khoi niii; loai thii hai Pinus krempfii cung phan bo t£u khoi niii ndy (d$ cao 1.450 - 1.900 m) vd d khoi niii H6n Bd lien ke thuoc tinh Khdnh Hod (do cao 1.200 - 1.300m); trong ca hai mrdng hpp nay, cac loai deu phat trien tren n h m g i ^ u vuc cd kha nang thoat nude tot, tren dia hinh nhd len
dyng doi cua cac khoi niii dd voi dp cao tuong d d i l 0 - 7 0 m.
Ddc biet, chiiog tdi da chiing minh dupe idng, sy thay doi hoan loan ede loai cSy g§ tao rung xay ra khi cd su thay doi kilu sinh thdi tho nhudng. Su biSn doi trong thanh phan cac loai edy tao rimg dien ra chii yeu a bac hp, trong khi 6 cac phan tang ben dudi, noi dieu kien mdi truong thuc v$t phat trien phu thupc vdo ede phan tang phia trdn th'i phan Ion 1^ a bac lodi hoac chi thude nhiing hp dd. Tai khu vuc dong bang vd binh nguyen mien Nam Viet Nam, tren dat feralite vdng-dd, ting ddy thudng hinh thdnh cSc kieu rimg vdi uu the d phan tang trSn cimg thupc v l dai dien a ia hp Dau (Dipterocarpaceae); c6n trdn khu vuc ngap nude theo miia, dat cd mau xlm , thuc vat chiem uu the lai thupc hp Tu vi (Lythraceae) Trong ca hai truong hpp, cSy go d cac phdn ting ben dudi hinh thanh vdi ede dai dien nhu Polyathia thupc hp Na (Annonaceae), Antidesma thupc hp Thau ddu (Euphorbiaceae), Lasianthus va Psychotria thupc hp Ca phS (Rubiaceae), hp Cam chanh (Rutaceae). Mdi quan he rd ret nhu the giua quan xa thuc vat rimg vdi dac diem kieu sinh thai tho nhuong Id he qua cua he thuc vpt nguyen sinh va cau true phuc tap a ia quan xa thuc v^t cd ngudn gdc lau ddi.
3.2. Cac van d i v i phan loai rimg nh iit d&i gio iniia
Phan loai rimg nhiet ddi Id mot trong nhung van de quan trpng. Sir phuc tap ciia viec phdn lo d ndy chinh Id tinh da dang ve cau true, da d?ing thdnh phan loai cSy tao rung va tmh da trpi cua chiing. Trude het, phai ke den he th ing phdn loai da dupe thira nhan a ia Thai Van Trimg [4]. 6ng phan thdnh ede nhdm khu vyc, khi hau theo vT dd va dai cao ciia cac kieu tham thyc vat rimg ciing vdi sy phan chia kieu phu thd nhuong vd cac don vi nhd hon. Da su dung
30 N D. HS, Ku-.mlsov AN /T,p chi K m hoc DHQGHN, Khoo hoc T,c ohiio l i CSog nglii. Tip 30, M 1 (20MJ 26-35
dSu hieu ho v i lo4i d l mo ta dac diem 6 cap do thSp hon.
Tuy nhiea, khi ap dung doi vcri rimg da troi thi each tiep c|in nay con thieu do tin cay. Don cii, khi chung toi nghien cun so sanh cac kieu rimg CO cung mot gidi h ^ do cao o ca mien Bac, mien Trung va mien Nam cho thay, chiing rSi gin gui nhau v'e thanh phan cac hp t?o rimg, nhimg lai khac nhau ve t h ^ phan lo&i. doi khi din chi. Mol dieu quan trpng doi v6i viec phSn loai la mo ta d5c dilm ih ^ h phan lo ^ cSy go theo cic phSn ling, dong thoi chi ra ede dang s6ng khac (day leo, than thao, bi sinh va ban bi sinh).
Them vao dd, viec sit dung ede thult ngu da ducfc thira nhan nhu: mira, am, kho, rung ia - nira rung la, thuemg xanh cho cac quan xa rung dupe nghien cun chua nhieu. V( du, cac canh rimg phat trien tren d6ng bang va cao nguySn nili thap vci uu the cita loM Dau dong (Dipterocarpus tuberculatus) ( 1 - 2 phan tang, cay g§ cao 4 - 12m, ting c6 p h ^ tridn tot) trong tai lieu khoa hqc, ke ca gido trinh, gpi la rung
“khpp" v& doi khi c6n ducrc goi Id rimg thua cdy hp Dau. 0 day chung toi mudn nhan manh ring, trong suol mua kho, khong cd mua. dat 6 vao trang ihai kho, phan Ion cac loai cdy bi rung la trong khoang thdi gian tu vdi tuan cho den vdi thdng, con tham co thi bi khd di. Tuy nhidn, trong thdi gian dd, cung cd thdi diem thi'ch hop dat dupe tudi am, tham chi' tudi Im nhieu den muc xuat hien Idp nuerc tren b l mat.
Do dd, thich hop nhat, theo chung toi la sii dung thuat ngu "rimg sang". Thuat ng& nay c6n chi ra day du sir phan bo “thua thdt” ciia rimg cay hp Dau.
Co so khoa hoc de de xu3t phan loai rimg Viet Nam cua chung toi dupe dira trSn cac dac diem sau: dia mao khu vuc (rung dong bang vd tren nui), vi tn dia ly tren tom qude (B§c,
Trung, Nam), dia chat, kieu sinh thdi tho nhuong, diu hipu canh quan (than cao, than thip, thua thdt hay day sit), dang ciu true dung (don gian, trung binh, phiic tap), cd lini y din thanh phSn phSn loai cac loai chiem uu thi/ddng uu th i d phan tiing cao nhit. Doi vdi rimg tren nui, con chi ra dai dp cao vd dac diem dia hlnh.
3.3. Dac diim chu nam c m rirng nhiet dai gio niiia
T iln hanh nghien cuu nhieu ndm va tat ca ede miia trong nam da cho phep chiing toi phdt hien ra chu ky nam ciia rimg nhiet ddi gio mua - mpt hien tupng con ft dupe nghiSn cuu.
K it qua nghien cuu cho thay, sir thay la ciia cay go va day leo than go o khu vuc rimg dong bdng va niii thdp dien ra hang nam vao ddu mha kho. Cay go va day leo a phan phi'a tr8n tdn rimg cd thdi gian thay Id c6 dinh vd chii yeu diln ra trong khoang thdi gian ngan (vdi ngay).
Do vay, cd y kiln cho rdng chiing cd mdu xanh quanh nam. Sau khi xuat hien mpt the he Id mdi, dong thdi vdi su phdt trien ciia phien Id Id giai doan rahoa.
Mot so loai cay go rimg ra hoa trong tinh trang khong cd la. Su ra hoa diln ra hang nam d phan Idn cac lodi cay go vd day leo. Chi quan sat dupe a mpt so loai chu ky ra hoa keo ddi den 4 nam. Su no hoa thudng xay ra vao mua khd (hoac miia ft mua). Cdy gd o' phdn tang trSn cung no hoa tpi phan chdi, cay go d nhung phdn tang phia dudi vd day leo no hoa d phan chdi, nhanh hope thSn. Thuc v |t r t a g ra qua ca trong thdi ky mua khd vd mua mua.
Theo chiing toi, quy lupt chung cua rimg Vipt Nam dupe bieu hien o thdi gian vSt hau hoc cua cac phan tin g c3y gd: tir phdn ting trSn cung xudng ede phan tin g duoi, khoang thdi gian ra hoa tang len, trong khi mire dd thay Id
N.D. Hoi, Kuznetsov A.N ITgpchi KhoahocDHQGHN, KJionhocTie nhien va Congnghe, T^30, Sol (2014) 26-35 31
hoan t o ^ lai g i m di. 0 phan phia tren tdn rung. Id cay rung hodn toan, c6 the a trong tiang thai trui Id tir 5 - 9 ngay cho den 3 - 4 thdng. Cay a nhung phSn tang duai chu yiu rung la mot phSn. Thoi gian ra hoa o phan ting tren ciing Id 5 - 20 ngay, va thong thuong, chung ta quan sdt d u o c su ra hoa dong loat cua chilng. Cac loai 6 ph2n tang ben duoi ra hoa vd k6t qua trong thbi gian 3 - 5 thdng, th |n i chi' keo ddi gan suot nam vdi thoi gian gidn doan chi 1 - 2 thdng. Rimg duoc hinh thdnh don loai vd c6 Cling noi phan bo thi phan Ion no hoa dong then, ngoai trir cd mot so trubng hop su no hoa dien ra som hoac mu6n hon. Ngodi ra, cung bdt gdp mpt so cd the ra hoa trong thbi gian tao qua, c6 nghia la chung lai no hoa Idn thu 2. Co the gia thiet ring, nhung trubng hpp ngoai 1? ndy dam bao thdnh cong cho su tai tao cua mot loai trong dieu kien diay doi cac yeu to khi hau hang nam, cung nhu s^r bien dong so luong cua cac lodi c6n trung an Id, thu nho vd chim - nhung sinh vSt tieu thu trdi cdy va hat giong.
C5 rCrag tren nui (tren d§ cao 1.000 - 1.100 m), miia rung la di kem vbi hi?n tupng giam nhiet d§ ib ret theo miia va cung nhu 6 vimg dong bimg, la su sut giam ddng ke ve luong mua. Nhung kbdc vdi 6 dong bang, miia ryng la b rung tr§n nui bdt dau trong dieu kien cd suong mb va do am ciia khdng kW thubng xuyen cao (80 - 100%). Phan Ion ede cay tao nbn phdn trSn ciia tdn rung rung Id dan ddn trong 2 - 3 thdng (thay mdi hoan toan Id khi cac choi cay phdl trien trb lai). Chi cd mot so loai sau khi rung Id thi 6 tinh trang trui la trong thbi gian keo ddi den 1 thdng.
Ld non mdi thubng Id thuc an cho nhieu lodi con trung khde nhau, d |c bidt la sdu. Trong khu vuc rimg dong b ^ g vd tren niii, chung tbi da ghi nhan trubng hop 80 - 100% phien la cdy go ihuoc phdn tdng trdn ciing (Dipierocarpus dyeri, D. turbimtus, Hopea odorala, Shorea
roxburghii) thuoc hp Dau (Dipterocarpaceae) vd Betula alnoides thupc hp Cang 16 (Betulaceae) bi gdm vd sau do chung lai duoc tm tao mot Ian nba.
Trong rimg gid mua, hang nam tren be mat dat hinh thdnh mot Idp tham rung thuc vat, trong dd chii yen la la cua ede loai cay g§, day leo, bi sinh vd bdn bi sinh. Trong rung cay go than cao vdi cau true phiic tap, tren 1 m^ mat dat bat gap trong thdnh phan tham rung la cay ciia 8 - 44 lodi thpe v^t. ttong dd chiem uu thd la Id ciia 1 - 3 lodi cSy gd vd d ly leo. Trung binh, lop tham r\mg dat khdi luong 600g/m^
(khoi luong khd) (KysHeuoa, 2003). Dieu nay khd giong vdi tru luong ciia lupng roi trong lOTg cay la rpng d cac vung 6n ddi. Ldp tham nmg o rung nhiet ddi dong bang vd ndi thap khdng dupe hinh thdnh va hoan toan trdi nguoc lai so vdi rung vbng 6n ddi.
Trong rimg tren nui doc theo dai cao 1.000 - 1 200 m, ldp tham rung cung dupe hinh thdnh.
Trong dd. ldp tham rung ddy nhat den 30 cm dupe ghi nhan dudi tdn cay hat trln ciia cac lodi: Thong Id det (Pinus krempfii), Thong nam la Pinus dalatensis thuoc ho Thong (Pinaceae), Po mu (Fokienia hodginsii) thuoc ho Hodng dan (Cupressaceae).
Ldp tham rung trong rimg Id noi cung cap cac chat dinh dubng chinh cho ede he sinh .thai.
Trong dieu kien vi khi hau dac trung ciia rimg (nhiet dp trong ede ldp khdng khi trung binh nam 20 - 32‘’C, dp chiSu sang 2(X) - 8(K)lux, dp am khdng dudi 70%) ldp tham rung dupe dong vat dat, mdi va nam su diing gan nhu toan bp (90 - 100%) trong vbng 7 - 8 thdng vao thbi ky mua mua va chuyen mua. Thubng xuyin quan sdt dupe mdi lam to trong khoang thbi gian 3 - 4 thdng ddu miia mua. Ddy Id net dac trung cua rimg phdt trien d dp cao 900 - 1.100 m d mien Nam vd dp cao 600 - 800 m d mien Trung va
32 N.D. Hoi. Kuznetsov A N /Tap chi K?«w hoc DHQGHN. Khoa hoc Tie irki^n va Cong nghe. Tap 30. So 1 (2014) 26-35
niien B3c. Sinh vat tieu thu chu yeu luang rcri (la, c ^ h , than cSy) trong rirag dong bang nmg nui thip la cic lo a moi thuoc giong Macrotemes, Odontotermes v l Clobitennes.
Chung thuong xuy&i xay dimg cic to hinh mai v6m 1cm tren dat (cao rir 1 - 2,5 m, dirong kinh mdi v6m 0,7 - 3 m). Theo sir ting dan ciia do cao (lit 800 - 1 -2{K) m), vai tr6 chu dao trong vi$c su dung tham rung dan chuyen sang cac nh6m dpng v$t dat khac cung nhu cic loai nim.
Lop tham rung c6 vai tr6 nhir mpt tam tham bao ve dac biet. Khi mot luQmg mira Ion do xuong, tim tham nay sS bao ve cho b§ mat dat khoi su xoi mon, ngoai ra n6 cdn giup duy tii cau true ciia lop dat b i m$t, tao dieu kien cho nuoc mira khi quyen di chuyen theo chieu phiu difn, ngan chw su xuat hlen vH do thira quS muc ciia niroc theo c3c ySu to tieu va trung dja hlnh khi cd mira rao. Chi trong giai doan dau v i cuoi miia mua, khi luong mua dSn 60 mm trong khoang 1/3 gio, lop tham rung c6 kha nSng phSn bo M luong nude trdn be mat va tich tril nude trong khoang thdi gian ng5n d dang dja hinh trung.
Tin rung cung gidp bao ve m |t ddt khoi bj xdi mdn do mua. Khi rung bi mat di se din den hau qua l i m it dat bi bao mdn, chiu anh hudng true tiep ciia buc xa m it trdi v i mua. Clu true ciia Idp dat tren bd mat dudi tie dong cua mua Idn se bj p h i huy va bio mdn do ddng chay trong suot mua mua. Khi mua mua kSt thiic, dit d d§y se truong ra va rin lai, edn vdi nhiet do cao ciia mCia kho lam thieu dot dir ddi bS mat dit. Ket qua la tao nen Idp v6 feralite dac trung day 3 - 7 cm vdi dac tinh khong thira nude. Sir ton tai cua Idp vd nay ngSn khong cho nude tham theo chieu doc, lam tin g tdc do ddng chay be m |t vd do do 1^ cho d it bj xdi mdn.
Ddi vdi dat cd kha n§ng thodt nude tdt dudi rung nhiet ddi gid mua khu vuc ddng bang, theo quan diem kinh didn thi ting mun khong
cd kha nang phat trien. Ngoai le. d vfing trung luon dong nude, tang miin d day (than bun - miln) phat tndn tdt. C ln luu y rang, luong mdn tfch luy trong didu ki?n luong m ua cao (2.000 mm/nam) keo d ^ trong thdi gian 5 - 6 thing ciia mua m ua Id nguyen nhan phat trien qui tiinh gley hda, dieu dd dan den thay doi dac tfnh tieu thoat nude ciia dat va che dp thiiy van chung cua rung. Ngupc Im, ddi vdi dat rung trSn niii tht ting mun lai duoc hinh thanh [12]
v l theo quan sat ciia chiing tdi, hien tupng nSy c6 o rung tu dp cao 1.000 - 1.2(X) m.
3.4. Dac diem tdi sinh tir nhien cua rimg nhiet ddi mua mua
Ngay nay, khai niem “bien ddi khoang trong” (‘‘cua so” rimg) da duoc thira nh§n trong CO so khoa hoc co ban sir tIi sinh tu nhidn ciia rimg. Tuy nhien, ddi vdi rimg nhidt ded gid miia, khai niem nay khong phan anh sir bien ddng thirc te q u i trinh phuc hoi ciia tan rung.
Thong qua mot sd loai cSy khac nhau, chiing tdi da x lc djnh dupe cac thdng sd dac tnm g ciia su phuc hoi hoac tai sinh ciia cic loai cay go. Cay gd ciia rimg nhidt ddi gid mua than cao vdi cau triic diing phuc tap, tIi sinh thd hd sau theo d|c tinh man rimg - cua sd. Trong qua trinh niy, mot phan cac loM cay tao rimg va nhung loai cay thuoc phan ting ben dudi dupe tai sinh trong “cua sd” rimg v l d nhung noi dudi bong rpp ciia cay rimg. Trong khi dd, nhung loli khic, bao gdm ca cic loli trong rimg cay hp DSu than cao (Dipierocarpus dyeri, D. retusus, D. turbinatus) cung chi tIi sinh dudi tan rimg, dieu nay cd nghia la chiing chi tai sinh trong pham vi hep.
Hat giong ciia c ic loli cay gd chi phat trien tdt trong gidi hpn nhipt dd khong khf trung binh n3m 24 - 32“'C, nhidt dp d It den dp sdu 20 cm lit 25 - 27‘’C, dp am tuong ddi 85 - 95% v3 do chieu sang 0,04 - 1,0%. Trong dieu kien Inh
N.D. Hoi, Kuznetsov A.N /Tap chi Khoa hoc DHQGHN, KJioa hoc Tu nhien t« Cong nghe, Tip 30, So'I (20ii) 26-35 33
sing yeu v i nhieu ap lire nhir vay, cho phep Chung tranh dirge sg ermh tranh tir cac hat giong cua c ic loii c6 v i day leo. Theo trinh tu, a khu vuc "cua so” hat giong ciia cac load cSy go chii yeu ciia rung deu bi chet, eSy nho yeu ert, IS bi thieu dot boi anh sing m il croi. Tiep tgc di sau lam r5 cac thong so a ia 6 tii sinh cic loai cSy go tao nm g khic nhau giup dg b io dugc nhung hau qua doi voi quin xa rung dudi sg tic dgng cua con nguoi cung nhu tim kiern each tiep can phuc hoi lai nhung rung cSy go da bi mit.
Sg hinh thanh “ciia so” crong rung nhiet doi gi6 miia la hau qua ciia cay do, tin do, gay cinh va nhinh ciy. Quan sat sg suy yeu v i chet kho cua c iy g§ trong cic kieu rung khic nhau cho phep xac djnh rang, doi voi cic loai ciy g6 Ion gong so cac loai tao rung dac diem niy khdng ro ret. Dieu nay phii hop voi sg suy giam tiep theo cua cay go theo “hifu ling domind”, tuc la t^o ra “cua so” Ion hon hoac se khong xay ra o cac khoang trong gong tin rung. Phan Idn cic cay bi yeu di va chet gong q u i trinh cic canh, nhinh ciia tin cay lien tuc bi chat v i do la k it qua lim cho than c iy bi p h i hiiy din din sau nhieu nam. Than c iy thudng bj g iy v i d6 l i do chung thudng bi chat, tia lam thua dan tang tin v i d iy la ket qua cua boat dong khai thac gd ciia con nguoi. Cl rimg trin nui (dac biet la gen d it tin g mong v i d i) c iy bi do l i hien tugng pho bien v i mang troh tg nhien. Tpy nhiin,
“ciia so” Ion d d iy khdng dugc hinh thinh [6].
3.5. Hgu qua cua chat sinh that vc dp l\ec cua hoqt dong nhdn sinh ten rimg mua nhiet doi
Viec danh gia hau qua sinh thai do chien ganh hoa hoc ciia quin doi M J gay ra chi c6 the thuc hifn sau khi xiy dgng dugc co so khoa hgc dga gen c ic y iu to thgc tien va he thong tn thiic v i cac quin xa thgc vat rimg nhiet doi cung nhu hinh thai rung noi chung. C ic nghiSn cuu he sinh th ii rimg nhiet doi gi6 miia nguyin
sinh v i nhung canh rimg d i bi thay doi do bin tay con nguoi o 3 mien Bac, Trung, Nam cung nhu 6 Nam L io v i D6ng Kalimanta (dao Borneo) cho thay phan ung cua quan xa rung ddi voi sg p h i hiiy do hoit dgng nhin sinh mang tinh chat dac thii v i dugc xic dinh bing to hop cic yeu t6, trong d6 vai g6 quan ggng hang dau la thinh phin lo ii thgc vat, cau true khdng gian ciia quan xa rung, sg c6 mat ciia cic loii chu dao hoic cac loai lap quan, nhimg d ie diem sinh hgc cua ciy rimg, die diem vi khi hau rung, cau true va die diem thiiy van dat [9].
Dga gen ket qua nghien cmi cua chung toi va c ic tii lieu da cong bo, c6 th i khang djnh rang, cac quan xa xavan v i tuong tu xavan li thii sinh doi voi Viet Nam v i noi chung cho ca D6ng Duong. Su xuat hien quin xa thgc vat voi uu the ciia cac loai h o i thao la do tic dgng cua con nguoi nhim p h i rung de canh tie nong nghiep hoic phuc vu quan su. Sau tham hga do con nguoi gay ra, tham thgc vSt tg nhiin bj bien doi, hinh thinh nen cic quan xa dgng xavan voi c ic loii hoa thao. Day la kieu tham thgc vat phi dia doi dugc hinh thanh gen dat voi sg bien doi ve U'nh chat ly - hoa hgc v i che dg thuy van.
Chiing toi da x ic djnh dugc rang, khi mSt tan cay, chieu hudng dien bi€n tiep theo la sg xim Ian rat nhanh chdng cua cic loai than thao khic nhau doi voi loii ban dia. Tren khu vgc dong bang, hinh thanh cic quan xa voi cac loai c6 cong Ion (tu cac chi Imperata, Pennisetum, Themeda), g e nua (tir cic chi Bambusa, Dendrocalamus), Co lio {Eupatorium odoratum), a vung nui quan xa chiSm iru the l i Duong xi {Dicranopteris, Diplopterygium, Gleichenia, Pteridium) hoac tre n^a [6].
Tren thgc te, dieu ege ky quan ggng can biSt la su sinh ton ciia cic quan xa hoa thao mdi nay tren lanh tho Viet Nam se con tiep tgc ton tai khong biet den bao gib. Dieu n iy l i do thieu vang cac yeu to (Ion hon yeu t6 do con nguoi)
34 N.D. Hoi, KuznetsovA N /Tap chi Khoa hoc DHQGHN, Khoa hoc Tie nhien i« Cong nghe, Tap 30. S o l <2014} 26-35
CO ihi lam lhay d6i xu ih i phat triSn cua chung.
Nhin vao su ton tai ben vflng nhieu nam qua ciia cac q u ^ xa hoa thao, chiing toi c6 ccr so nhan dinh v i so c6 mat ciia Men tuong gian doan trong chu6i dien the. D |c diem sinh hoc dac tnmg cua cSy rung U khdng c6 kha nang tai sinh Cling voi cdc loai hoa thao, ke ca khi c<5 chS do cuong buc va trong cay. Do v|ly, tai cdc khu vuc bi mat rung, xuat hien ranh gioi ro rft giGa cac qu4n xa xavan, nrong tir xavan va cay go rimg. De phpc hoi rimg nMet doi, con ngirbi cSn phai tao ra nh&ng dieu kien nhu de hoi sinh cac lo^i cay chii dao trong rung - d5c trung cho moi viing lanh iho, cung nhu tao ra nhung rung c5y da loai bing cdch kien tri trong c§y duoi tan rimg thuoc pham vi cua doi chuySn tiep.
4. K e t l u |n
Dong Duong noi chung, Viet Nam ndi rieng mot trong so khdng nhieu trung t§m da dang thuc vat tren the gioi voi sy phong phu cao cdc don vi ph w lorn.
TrSn CO so quan diem sinh hoc quin xa, da tien hinh nghien cuu va lam ro thanh phan loai, cau trdc, dac diem sinh hoc thuc vat rung; sir bien d6i cua tham rung, die diem d it v i vi khi hau rimg. Da ghi nhan tren 7.050 loii thuc vat tham gia hinh thanh rung, trong do c6 khoang 53 loii thuoc 34 chi cua 19 ho la nhung loai chii yeu thinh tao rung nhiet doi gio miia Viit Nam.
Muc do phuc tap ciia rung phu t h u ^ vao dac diem chung va kha nang giu am ciia dat rimg. Trong cau true diing ciia rimg, tir phin tang tren cung xuong cac phan ting duoi, khoang then gian ra hoa ting ISn, trong khi muc do thay la lai giam di. d rimg tren niii tir do cao 1.000 - 1.200 m. hang nim tren be mat dat Mnh thanh mot lop tham rung thyc vat. Da xac djnh duoc die trung cic thong s6 ciia 6 tii sinh hoac
phuc h6i cac loai cay g6 rimg. Duoi nhung tic dong cua con nguoi, thanh p hin loii va sy giiu c6 ciia rung nhi?t doi gi6 miia duoc thay th i boi quin xa thyc vat c6 cau true don gian voi iru thS la cac loai hoa thao.
DS phuc hoi rimg nhiet doi, con nguoi can phai tao ra nhihig dieu ki?n phuc hoi cac loii cay chii dao trong rimg theo dSc trung cho moi vung lanh th6, cung nhu tao ra nhung rimg cay da loii bing edeh kien tii trSng cay duoi tan rung thuoc pham vi ciia ddi chuyen tiep.
T a i U |u U iam k h a o
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Basic Characteristics of Vietnam Monsoon Tropical Forest
Nguyen Dang Hoi, Kuznetsov A.N.
Vietnam ■ Russia Tropical Center, Ministry ofViePiam Nation Defence
A bstract: On a base of uniform biogeocoenosis approach the forest plant species composition, vertical and horizontal structure, the biological aspects some forest trees, the forest plant litter dynamic, the morphology and hydrology o f forest soils and forest microclimate were studied. The top of forests is formed by app. 330 tree species, the canopy - 2460 species and less than 320 species - the understorey.
For representation of vertical structure of forests, we use a method of the profile diagrams. The changes in spectrum of environment forming trees in different forests occur mainly at a level o f a rank o f family, whereas in subordinated layers - in the greater degree at a level of species and genus inside family. Native tropical forest ecosystems represent a climatic climax. There is a dynamic balance in functioning of these ecosystems.
The occurrence not forest open territories has resulted in change of a microclimate, hydrological regime, properties of soils and development o f erosive processes. Forest trees and the ecoton trees, are not evolutionary adapted to development on new, changed by the human, territories. This effected in the interruption o f the series of successional changes of the vegetation. Complex, species-rich and evolutionary formed forest commumties are substituted by simple in structure and species composition new or evolutionary alien communities with grass domination.
Keywords: Structure, forest tree, plain, monsoon, species, tropical, mountain, com m um ties, layer, forest, vegetation.