Tap chi KHLN 3/2014 (3408 - 3415:
© Vien KHLNVN - VAFS
ISSN: 1859-0373 Bang tai tgi: www vafs.gov.vn
NGHIEN Cl>U MOT S6 0AC OI^M CAU TRUC RUNG TU NHIEN LA RQNG THUaNG XANH TAI VU'ON QU6C GIA VU QUANG - HA TTNH
Nguyin Thi Thu Hien*, Tran Thi Thu Ha Truang Bgi hoc Nong Ldm - Dgi hoc Thdi Nguyen
Tir khoa: Cdu triic rimg, chisd da dgng, phdn bo khodng cdch. rifng tu nhien Id rpng ihuang xanh, yuan Quoc gia Vii Quang.
T O M TAT
Nghien ctru nay dugc ti^n hanh tai Vucrn qu6c gia Vu Quang, H^ Tinh trSn 6 6 tieu chuSn djnh vi (OTCDV). Kk qua cho thdy, khu vuc nghien cda co 14 loai uu thi, di6n hinh nhtJ-ng loai co he s6 t6 thanh cao nhit (vdri IV
> 10%) g6m: De an (Castanopsis indica), Buoi bung it Id gan (Macclurodendron oligophlebia), Nang (Alangium ridleyi), S k (Dracontomelon duperreanum). Chi s6 da dang loai theo Shannon - Wiener (H') va Simpson (D) ihn lugt dat 3,586 va 0,952, Nghien ciru cung da xac dmh dugc ham phan b6 khoang each la ham mo phong tot cho phan b6 s6 cay theo co kinh khu vuc nghien ciiu. K6t qua nghien cim nay sg gop ph^n lam CO so khoa hoc cho quan ly rirng tu nhien theo huong b6n virng, da chirc nang noi chung va lam co so cho nghien ciru dong thai cdu triic rirng 6 cac giai doan tiep theo noi rieng.
Keywords: Biodiversity index, distance distribution, evergreen broad- leaved natural forests, forest structure,
Vu Quang National Park.
Research on characteristics of evergreen b r o a d - leaved natural forests in the Vu Quang National Park, Ha Tinh province
This research about structural characteristics of evergreen broad - leaved natural forest was examined on the six permanent sample plots in the Vu Quang National Park, Ha Tinh province. The result shown that there were 14 dominant species in the study areas (with IV >10%), in which some species with Ihe highest composition coefficients as Castanopsis indica, Macclurodendron oligophlebia, Alangium ridleyi, Dracontomelon duperreanum. The Shannon - Wiener diversity index (H') and Simpson index (D) were calculated at 3.586 and 0.952, respectively. The distance distribution showed the best to fit N - D distribution of the forest stands in the study areas. This study resuhs have significantly contributed to the scientific basis for the management of natural forests in a sustainable manner in general and provided a basis for studying the dynamics of forest structures in the next stage.
Nguyen Thj Thu Hien ef al., 2014(3) Tgp chi KHLN 2014
I. DAT VAN DE
Rimg ty nhign noi chung va rirng ty nhien phan bo d vimg nhiet ddi ndi rieng la mgt he sinh thai co cdu tnic rdt phiic tap do sy da dang vg thanh phan loai va su sap xep cua cac loai theo khong gian va thdi gian, do \ d}' no trd thanh mot dg tai thu hiit su quan tam nghign cuu cua rdt nhieu nha khoa hpc trong nhieu thdp ky qua. Viec nghign ciiu cau tnic rimg CO mpt y nghia quan trpng cd ve ly Iudn va thuc tien. Ve mat ly ludn, rimg la mgt he sinh thai do vdy trong digu kien nhdt dinh nd CO khd nang tu phuc hoi, trao doi cao hoac luon luon co su can bang stnh thai. Tuy nhign, xa hpi ngay cang phat trien thi nhu cau cua con ngudi doi vdi cac sdn phdm tir rimg ngay cang ldn hon, con ngudi da khai thac rimg mpt each can kiet lam pha vd kha nang ty cdn bang cua rimg hay ndi mot each khac rimg dang dan dien the theo chieu hudng di xuong.
Do vdy, viec nghien ciiu rimg la de tim higu cac quy luat kgt cdu ciia rung tir do bang cac bien phap ky thudt tac dgng tich cyc nham ndng cao kha nang cung cdp tir ning hay noi each khac la tiing budc giiip rimg dign thg theo chigu hudng di Ign.
Viet Nara la mgt nudc thugc khu vyc nhiet ddi, ndng dm mua nhieu do vdy tinh da dang ve thanh phan loai va kgt cdu ciia rimg la rat phiic tap. Viec nghien ciiu dugc cdc quy ludt ket cdu nay la rat kho khan va doi hoi phai co sy hieu biet sdu sac vg he sinh thai rimg mua nhiet ddi. Trong nhirng nam qua, rimg ty nliien d nudc ta dang bj tan pha va suy giam nang ng ca ve sd lugng va chdt lucmg (trgn 50% dien tich rimg ty nhign la rimg thii sinh ngheo, ngheo ca ve thdnh phdn loai cdy muc dich Idn kha nang cung cap). Do vdy, viec nghign ciiu cdc quy luat cdu tnic lam co sd de xudt bien phap tac dgng phuc hdi nhiing doi tuprng rimg nay la van de het siic cdn thigt dat ra cho cac nha Idm nghiep.
Xudt phat tir nhirng van de trgn tac gia da tien hanh nghien ciiu chuyen de: "Nghien ctiu mgt so dac digm cau tnic rimg tu nhien la rgng ihudng xanh d VQG Vii Quang - Ha TTiih".
Ddy se la ca sd cho nghign ciiu dgng thai cdu tnic rung tai VQG Vu Quang d cac giai doan tiep theo.
II. MUC TIEU VA PHU'OfNG PHAP NGHIEN Ctru
2.1. Muc tieu nghien ciru
Xac dinh duac mpt so dac digm cdu tnic ca bdn cua rimg ty nhien la rpng thudng xanh tai Vudn quoc gia Vii Quang dg gop phan cung cdp CO sd khoa hpc cho qudn Iy rimg tu nhign theo hudng ben vtmg va da chiic nang.
2.2. Phvong phap nghien cihi a. Ke thua tai lieu
Nghign ciiu da kg thira 6 6 tigu chudn dinh vi (OTCDV) da duac thigt lap nam 2007 trgn dja ban Vudn Quoc gia (VQG) Vii Quang thugc dg tai ciia PGS.TS Trdn Van Con (2007).
b. Thu thgp so lieu tren 6 tieu chuan - OTCDV de thu thdp sd lieu la mot hinh vuong CO kich thudc 100m x 100m (dien tich lO.OOOm^). Do toan bg cac cdy co dudng kinh Dl 3 >10cm. Xac dinh tgn cho timg cdy, ngu cay nao khdng bigt tgn Idy mau hoac chup anh de giam dinh. Cac chi tieu dieu tra dugc do dem nam 2012, bao gdm: tgn cdy, D13, Hvn, Hdc, D| va pham chdt cdy.
t. Xu ly so lieu
Cac so lieu thu thdp dugc xii ly trgn cac phdn mem thong kg toan hpc Excel 5.0 (Nguyen Hai Tult, Ngo Kim Khoi, 2009) va SPSS (Vu Tign Hinh et al, 2006).
Tap chi KHLN 2014 Nguyen Thi Thu Hi4n ef at.. 2014{3j^
* Cong thiec to thdnh lodi
- Cong thirc t6 thanh dugc tinh bdng: tri so IV% (chi s6 quan trgng: Important Value) cua Daniel Marmillod nhu sau:
IV,% = N , % + G i % (2.1) Trong do- IV%, Ni%, Gi% la ty le to thanh, %
theo so cay cua loai i va ty le theo t6ng tigt dien ngang ciia Ioai i trong QXTV rimg.
* Tinh da dang loai
- He s6 hon loai: H L l ^ S/N; ty le hon loai dugc bigu thi dudi dang l/n (trong do n la mgt so nguyen) co nghia la cir n cay ca the thi co 1 loai. Do do, ta co n = N/S (va chi Idy tron so nguygn). Trong do: S la so loai trong OTC va N la tong so cdy trong OTC.
- Chi so da dang Ioai: Nghien ciiu sir dung mgt so phuang phap xac dinh chi so da dang loai sau:
+ Chi so da dang Shannon - Wiener (H') dugc tinh bang cong thirc:
• UP- '"Z'' (2.2)
Trong do: p, = n,/N: la ty le ca the loai i so vdi tong sd cdy trong OTC.
Cong thirc nay the hien hai nhan t6 do la s6 loai - tire la dp phong phii cua sinh vdt trong qudn xa va tinh dong dgu theo miic do phdn phoi cac ca the trong loai. So loai cang nhigu thi mirc do phiic tap cang cao, nghia la H' cang ldn thi luong thong tin trong qudn xa cang ldn va tinh da dang cang cao.
+ Chi so da dang loai Simpson (1949) dugc tinh bang cong thiic:
D | = 1 - I P ? (2.3)
1=1
Trong do. p, la dp nhiSu hrong d6i cua loai i.
+ Chi s6 Renyi: Chi so Renyi dugc tinh bSng cong thirc nhu sau:
H„
itf]
\-a (2.4)
Trong do: s la tdng so loai, pi la do nhi^u tuong doi Ioai thii i trong OTC, a la mgt tham so quy mo c6 bi^n thien tir 0 den co.
Trong nghign cim nay, tac gid da sii dung phan tich su bien thign cua gia tri Ha trong cac trudng hop a = 0,1; 0,25; 0,5; 1; 2; 3; 4;
5; 6; 7; 8 va co dg ve do thi mo td tinh da djing loai cua khu vyc nghign ctiu.
* Mo phong cdc quy ludi phdn bo so cdy theo duang kinh (N/D/ 3)
Tinh cac dac trung thong kg mo ta phan bfl N/Di 3. Do so Iupng cdy trong OTC ldn, so cdy d cac co dudng kinh Idn khong nhieu, ngn ta tien hanh chia td ghep nhom, xac dinh gia trj Idn nhat, nho nhat. Sau do chpn mac dinh cu ly to K, thudng la gia tri chdn cho phil hop vdi ddi tugfng nghien ciiu. Do doi tuong nghign ciiu la rimg ty nhien, nen cir Iy to K dugc chpn cho dudng kinh ngang nguc D] 3 = 5 cm/cd.
Tiep dgn, nhiing phdn bo thuc nghiem diroc Iam phil hop vdi phdn b6 ly thuygt. Nhihig dang ham phan bo ly thuygt dupc chgn tren CO sd mo ta tdt cdc kigu phdn b6 ciia d6i tupng nghien ciiu. Theo dd, s6 lieu thirc nghiem se duac Iam phii hgp vdi 3 dang ham phan bo ly thuygt thudng gap: Phan b6 Khoang each, phdn bd Meyer va phdn b6 Weibull. Su phii hgp cua sd lieu thuc nghiem vdi nhirng phdn b6 ly thuygt dugc danh gia theo kigm dinh x^- Qua do da xac dinh duoc hdm phan bo khoang each la ham phii hgp hon ca de mo ta quy ludt tuong quan N/Di,3.
Nguyen Thj Thu Hien etat.. 2014(3) Tgp chi KHLN 2014
Ham phdn bo khoang each: La phdn bd xac sudt cua bien ngdu nhien diit quang, ham toan hgc co
F(x) =
[ ( l - r ) ( l - a ) . a "
(2.5)
Kiem tra gia thuygt ve luat phdn bo: bang tigu chudn phil hop y^. Neu 2,^ ^ Zo5 ha bang vdi bdc t u d o k ^ m - r - l t h i phdn bo ly thuygt Idiong phil hgp vdi phan bo thyc nghiem.
HI. KET QUA NGHIEN ClTU
3.1. Dac diem cau true t6 thanh va tinh da dang loai thirc vait rung tir nhien la rong thudng xanh tai Virdn Quoc gia Vu Quang - Ha Tinh
3.1.1. Bac diem cau triic to thanh loai thuc vgt
Cdu tnic to thanh dg cap den sy to hgp va miic dp tham gia cua cac thanh phan thuc vat trong quan xa, doi tuong la loai cay. To thdnh la mpt trong nhimg chi tieu cdu tnic quan trgng, nd cho biet sd loai cay va ty Ie cua moi loai hay nhom loai cdy nao do trong lam phdn. To thanh Ioai con la chi tigu dimg dg ddnh gia tinh da dang loai, tinh dn dinh va bgn virng cua he sinh thai rimg. Cdu tnic to thanh cua ldm phdn ndi Ign todn bp gid tri cua Idm phdn.
Tong hgp vg dac diem, cdu tnic to thanh loai thuc vdt dac trung cho timg OTCDV ciia khu vuc nghien cuu dugc tong hgp d bang 1.
Bang 1. To thanh loai cay OTCDV
VQl
VQ2
VQ3
VQ4
VQ5
VQ6
Loai cay De an Cheo tia Giln trang Tong uu the Bt^oi bung it la gan De an Ha ny Tong uu th4 De an Nang Mau cho thau itinh Thirng muc la to Tong uu the Ca Id sp4 Tong uu the Chanh ranh Sau Calo Tong uu the Nang Sau Nho noi Chin tang Calo Tong uu the
t h a m gia t a n g tan c h i n h - V Q G V i i Q u a n g N (cay/ha)
20 19 22 61 60 29 20 109 33 23 22 16 94 17 16 33 27 9 23 59 44 15 43 18 21 141
G (m^/ha) 1.2 1,1 0,8 3,1 1,2 1.4 0.7 3,3 4,2 1,6 0,8 0,9 7,4 1,3 1,0 2,3 2,5 3,0 1,1 6,6 3,3 4,7 1,2 3,2 1,8 14,2
N (%) 6,8 6,5 7,5 20,8 24,0 11,6 8,0 43,6 13,3 9,2 8,8 6,4 37,7 5,8 5,5 11,3 7,1 2,4 6,0 15,5 14,1 4,8 13,8 6,8 6,7 45,2
G {%) 8,9 8,3 5,7 22,9 13,8 16,0 7,8 37,6 25,5 8,8 4,5 5,5 44,3 7,2 5,4 12,6 11,3 13,2 4,7 29,2 12,1 17,1 4,5 117 6,7 52,1
iV (%1 7,9 7,4 6,6 21,9 18,9 13,8 7,9 40,6 19,4 9,0 6,7 6,0 41,1
6,5 5,4 11,9 9,2 7,8 5,4 22,4 13,1 10,9 9,1 8,7 6,7 48,5
Tapchi KHLN 2014 Nguyen Thi Thu Hien et at., 2014^3[
Ket qua tinh toan cho thiy, tong giiS tri ve chi s6 quan trpng (IV%) ciia t6 hpp loai uu the o 6 OTCDV CO biSn dpng rit lon, tir 11,9%
(OTCDV VQ4) din 48,4% (OTCDV VQ6). S6 loai uu ths va chi s6 IV% cua loai uu the 6 khu vuc VQG Vu Quang dku thip hon so vol VQG Ba Bi, cu thi: s6 loai uu the cua khu vuc nay biin dpng tir 2 loai (OTCDV VQ4) din 5 loai (OTCDV VQ6). Chi si 1V% ciia cac loai uu thi chua cao va co mite biin dpng tit 5,4%
(loai Ca 16 6 OTCDV VQ5) din 19,4% (loai De in 6 OTCDV VQ3). T5 hpp loai cay uu thi 6 VQG Vu Quang gim 14 loai: Cheo tia (Engelhardtia roxburghiana), De an (Castanopsis indica), Giin tring (Xylopia pierrei), Buoi bung it la gan
(Macclurodendron oligophlebia). Ha nu (Ixonanthes reticulata), Nang (Alangium ridleyi), Mau cho thiu kinh (Knema lenta), Thimg muc la to (Wrightia macrocarpa), Ca 16 (Caryodaphnopsis tonkinensis), sp4, Chanh
ranh (Dodonaea viscosa), Sau (Dracontomelon duperreanum), Nhp nii (Diospyros apiculata), Chin ting (Diospyros pilosula).
3.1.2. Tinh da dang loai thtrc vat Di nghien cixa ve tinh da dang thuc vat, trong pham vi nghien ciiu nay sir dvmg he s6 hon loai, cht s6 da dang ciia Shannon - Wienerr, chi s6 da dang cua Simpson. He s6 hon loai cho biit mirc dp da dang ve loai cua quin xa.
He s6 h6n loai duoc bieu thi duoi dang l/n (trong do n la mpt so nguyen) co nghia la citn cay ca thi thi co 1 loai. Chi so da dang cua Sharmon - Wiener (H) va chi s6 da dang loai Simpson (D) the hien muc dp phong phil cua cac loai trong quan xa, so loai cang nhieu thi mirc dp phirc tap ciing cao. Neu H' va D cang cao chiing to quin xa co lugng thong tin lon, tinh da dang cang cao.
Kit qua tinh toan cac chi so nay tai cac khu vuc nghien ciru dugc the hien qua bang sau:
Biing 2. Tinh da dang thuc vat tai khu vuc n
OTCDV VQl VQ2 VQ3 VQ4 VQ5 VQ6 TB
He S6 hdn loai 1/4 1/4 1/4 1/4 1/6 1/6 1/4
H 3,923 3,266 3,447 3,947 3,664 3,266 3,586
^hien ciru
D 0,971 0,913 0,949 0,975 0,967 0,938 0,962
Tir bang 2 ta thay, he s6 hon loai tai khu vuc nghien cuu biin dpng hi 1/4 (OTCDV VQl, VQ2, VQ3, VQ4) din 1/6 (OTCDV VQ5, VQ6).
Chi so da dang loai Shannon - Wiener trong khu vuc nghien ciiu biin dpng tir 3,266 (OTCDV VQ2, VQ6) din 3,947 (OTCDV VQ4); con chi so da dang loai Simpson biin
dpng tir 0,913 (OTCDV VQ2) din 0,975 (OTCDV VQ4).
Tir do cho thiy ring, OTCDV VQ4 la 6 co he so hon loai cao (ciing dat gia tri voi OTCDV VQl, VQ2,VQ3), tuy nhien tinh da dang loai thuc vat a OTCDV VQ4 (theo chi s6 da dang cua Shannon - Wiener (H) va chi s6 da dang
Nguyen Thi Thu Hidn ef al., 2014(3) Tgp chi KHLN 2014
Ioai Simpson (D)) la cao nhdt trong khu vyc nghien ciru, Diing thir 2 la OTCDV VQl, tigp d6 ldn lugt la OTCDV VQ5, OTCDV VQ3, OTCDV VQ6, va cu6i ciing la OTCDV VQ2.
Ngoai cac chi tigu danh gia mirc do phong phli ve thanh phdn loai, chi tieu ve do dong dgu cua cac Ioai trong qudn xa cung co y nghTa hgt siic quan trpng. Mpt s6 chi so t6ng hgp vira the hien tinh da dang Ioai va miic do dong dgu giira cdc loai trong cac qudn xa do la chi so Renyi (Ha). Ha co the la thudc do lien tuc tinh da dang cua thdm thyc vat. Ha co uu diem hon so vdi nhigu chi so da dang truyen thong. Mgt uu diem nira la chi so Renyi rdt
thich hgp cho viec dinh nghTa tinh da dang thong qua viec kgt hgp giira do nhieu vd dp dong dang (do deu). Vdi nhimg uu diem do, chi so Renyi da dugc nhieu tac gia sir dung trong phan tich tinh da dang cua tham thyc vat. Trong nghien ciiu nay, tac gia da sir dung he so nay dg phan tich su bien thien cua gia tri Ha trong cac trudng hop a ^ 0,1; 0,25; 0,5; 1;
2; 3; 4; 5; 6; 7; 8 va oo de ve do thi mo ta tinh da dang loai cua khu vuc nghien ciiu.
Tinh toan chi so Renyi cho rimg tu nhien la rpng thudng xanh d khu vuc nghien ctiu thu dupc kgt qua sau:
5
4,5
4 -
3,5
3 -
2,5 -
2
1.5-
1 •
0,5 •
0 •
R e n y i - -A- • VQl
—«—VQ2
^ < — V Q 4
""*'^^^'^^'=^^!^;5^^<^^ ^ V Q 5
^ ^ ^ ^
- — - VQ6" " ^
X
0 0,25 0,5 2 3 4 5 6 7 8 vc
Hinh 1. Bieu do chi so da dang Renyi cua khu vuc nghien cdu Kgt qua hinh 1 cho thdy, dudng cong cang
nam trgn cao thi miic do da dang cang cao.
Mat khac, ngu dudng cong cang doc chiing to sy ddng dgu ve so lugng ca the ciia cac Ioai cua Idm phdn cang thdp (co su chgnh lech ldn vg s6 lugng ca the giira cac loai). Hinh 1 da thg hien mpt each tryc quan tinh da dang loai
va mirc do dong deu cua cac Ioai. Nhu vay, chi so Renyi la mgt chi sd tong hgp, co thg bieu thi tdt cho tinh da dang loai va miic do dong deu cua cac loai trong qudn xa. Qua hinh trgn ta thdy, OTCDV VQ4 c6 tinh da dang Ioai va do ddng deu ca the cua cac loai la cao nhdt; va thdp nhdt la OTCDV VQ2.
Tap chi KHLN 2014 Nguyen Thj Thu Hien etai,:
3.2. Dac diem cau triic N/D1.3 rimg tir nhien la rong thwdng xanh tai Vudn quoc gia Vu Quang - Ha Tinh
Phan b6 N/D 1.3 thg hien quy ludt sap xep cac thanh phdn cdu tao nen qudn thg cay rimg trong khong gian va thdi gian. Day la co sd quan trgng cho viec thong kg, dy doan trir lugng, san lugng rimg nen no la quy ludt quan trgng trong kgt cdu lam phan. Tir quy ludt cau triic nay, chiing ta co thg danh gia dugc kgt cdu ciia rimg, dg xudt cac bien phap ky thuat ldm sinh thich hgp de xdy dyng qudn xa thyc vdt CO nang sudt va tinh on dinh cao. Thong qua mat dp cua timg cdp kinh c6 thg bigt dugc
rimg dang d trang thai nao, xu hudng phat trign trong tuong lai.
Trong pham vi cua nghien ciiu nay da thii nghiem nan phan bd N/D ] .3 theo ba phan bd \j thuygt thudng gap: Phdn bo Khoang each, Phan b6 Meyer va Phan bo Weibull. Kgt qua cho thdy phdn bo khoang each la phii hop dS ndn phan bo nay theo quy ludt ty nhien (do s6 lugng cdy trong OTC ldn, so cdy d cac co dudng kinh ldn khong nhieu, vi vdy trong nghien cim nay Idy cy ly giiia cac cd duong kinh de nghien ciiu la 5cm).
Ket qud nan phan bo N/Di 3 cua ham da lira chgn dugc tong hgp dudi ddy:
Bang 3. Mo phong phdn bo N/Di„ I ham khoang each
OTCDV VQl VQ2 VQ3 VQ4 VQ6 VQ6
Gamma 0,34 0,46 0,37 0,37 0,45 0,31
Anpha 0,64 0,67 0,72 0,73 0,65 0,74
xl
5,30 6,54 15,98 18,72 11,39 12,78
Xm 12.6 9,49 14,1 14,1 11.4 18,3
K i t l u a n H*
H*
H- H"
H*
H'
Kgt qua cho thdy, tong so co 4 OTCDV dgu (Hinh 2). Kgt qud mo phong dudng cong CO gia tri z,,< xL (Trir OTCDV VQ3,
VQ4). Ket qua nay chiing to ham khoang each mo phong kha tot quy ludt phdn b6 s6 cay theo cap kinh ca khu vuc nghign ciiu
phdn bo so cdy theo cd dudng kinh cua cac OTCDV tai Vudn qu6c gia Vu Quang duac thg hien qua hinh 2.
120
100
J 60
0TCWV01
\
\ ^"
\
\ ^
' M . - - * . , , , ^ ^ ^
D i J (cm)
OTCmVQJ
100
30
1
,i60
40-
\
\
\ '\
\ ,
''*^--.,.__^
!5 20 25 30 35 40 45 50 55 80 65 TO a\3 (cm)
Nguyen Thi Thu Hiln ef al. 2014(3) Tap chi KHLN 2014
artuvvoi
.
V-
'~^^'*'—^
• • V ^ * - l ^ . v ^ . _
0 T C B V V Q 5
BD
4 0
2 0
\
\ 'V^
\ .
^ ' ^ ^ ^ ^ ' ^ ^ t - * - .
l i » f f i » S S « « i S 0 I B M S S 7 . , S » , l
=™v«
. k ' ~'
!? ' '\
^ \ .
1 ""*''*~K .*,--K„.
D l 3 ( c m )
Hinh 2. Phan bo n/Q 3 theo ham khoang each 6 OTCDV tai khu viic nghien cifu Hinh 2 cho thdy, cac OTCDV co hinh phan bo
N/D 13 kha giong nhau, cac dudng phdn bo thyc nghiem co hinh dang gan tning vdi ham Iy thuyet. Dudng kinh tang va dat cyc dinh tai cd kinh Di3=10 - 15cm va giam ddn khi dudng kinh Di 3 tang. Cac cdy dugc tap trung chil ygu d cap kinh 10 - 25cm vd theo quy ludt phan b6 giam. Ca biet khu vyc nghign ciiu co OTCDV sd lugng cdy co D|.3>40cm chiem ty le cao (OTCDV VQ6 vdi 68 cdy/ha va OTCDV BB3 vdi 31 cdy/ha) dac tnmg cho loai rimg ty nhign da co thdi gian phuc hoi, it bi tac dpng cua con ngudi, cdu tnic tucmg doi on dinh.
IV. KET LUAN VA KHUYEN NGHI 4.1. Kit luan
* vi cau true td thanh loai cay t&ng cay cao:
- Ldm phdn d 6 OTCDV nghien cim co su khac biet ro ret ve to thanh Ioai va miic dp uu
thg Ioai. Cac Ioai uu thg d OTCDV VQ6, VQ3, VQ2 deu the hien uu the rdt ro rang vdi tong he so to thanh (tinh theo chi so IV%) kha cao va ldn lugt dat la: 48,5%, 41,1% vd 40,6%; thdp nhdt Id d OTCDV VQ4 vdi 11,9%.
- Tai 2 OTCDV VQ6 va OTCDV VQ3 co t6 thanh loai uu hgp phong phii hon han so vdi cac OTCDV con lai, Dieu nay the hien thong qua so loai trong to hgp loai uu the cua cac OTCDV, cu thg: OTCDV VQ6 co 6 Ioai uu thg; OTCDV VQ3 co 4 loai uu thg;
OTCDV VQl, VQ2, VQ5 dgu co 6 loai uu the; va cuoi cimg Id OTCDV VQ4 vdi 2 loai cdy uu thg.
* Ve tinh da dgng lodi:
Danh gia tinh da dang loai thyc vdt theo Shannon - Wiener (H), Simpson (D) va chi s6 Renyi dgu cho thdy tinh da dang loai d 6 OTCDV khu vyc nghien ciiu theo chigu giam
Tap chi KHLN 2014 Nguyen Thi Thu Hien et al, 20UB)
ddn nhu sau: OTCDV VQ 4 > VQl > VQ5 >
VQ3 > VQ6 > VQ2,
* Ve cdu true N/D/j:
Phan b6 s6 cay theo cd kinh khu vuc nghien ciiu tudn theo phan b6 khoang each. Dudng cong phdn hd s6 cay theo co dudng kinh c6 dang giam. So cdy dat gia tri cue dinh d cd dudng kinh thii nhdt (D| 3 =10 - 15cm) va giam dan khi dudng kinh tang cao.
4.2. Khuyen nghi
Nghien ciiu ndy mdi chi thuc hien tai VQG Vii Quang. Can co cdc nghign ciiu tigp theo tai cac khu vyc khac dg cd cai nhin toan dien hon vg dac digm cau triic cua timg doi tugng nghign cim.
TAI LIEU THAM KHAO
I Tran Van Con, 2007. Nghien ciJu cac dac dilm c^u true va dong thai cila mpt so kieu rirng chu y6u 6 Viet Nam, Vien Nghien cCru Lam sinh, Vien Khoa hpc Lam nghiep Viet Nam
2. Vu Tiin Hinh, Nguyin Hai Tuat va Ngo Kim Khoi, 2006. Giao trinh phan tich thong kg trong lam nghiep, Nxb. Nong nghiep.
3. Nguyin Hai Tuk va Ngo Kim Khoi, 2009, Giao trinh Thdng ke sinh hpc. Nxb. Nong Nghiep,
Ngu'61 tham dinh: PGS.TS. Trdn Van Con
