6-. V«n KHLNVN - VAFS
ISSN: 1859 - 0373 Bgng tai tgi: www.vafs.gov.VD
NGHIEN CLCU MOT S6 DAC BI^M CAU TRUC VA TJNH DA DANG SINH HOC Kliu RCKNG KIN THU-ONG XANH H 6 N GIAO CAY LA RONG,
CAY LA KIM TAI VU-QN QU6C GIA BIDOUP - NUI BA
Nguyen Trong Binh
Khoa Ldm hoc - Truang Dai hoc Lam nghiep Viet Nam
T O M T A T
Tir khda: Da dang sinh hpc, Vudn Quoc gia Bidoup - Nui Bd
Vu£m Quoc gia Bidoup - Niii B i la mpt trong 4 trung tam da dang sinh hpc cua Viet Nam va la noi chiia dimg nhi^u gia tri khoa hpc. T6 thanh loai cay go CO so lupng loai cay xuat hien dao dpng ti!r 36 - 50 loai va co nhiiu hon 4 loii tham gia vao cong thiic to thanh tao thanh cac uu hpp khac nhau theo dai dp cao. Voi mat do trung binh s6 ciy trong 6 tieu chuin l i 203 cay, phan bo so cay theo duong kinh (N/D| 3) tuan theo quy luat phan bo khoang cich, con phan bo N/Hyn khong tuin theo cic quy luat phan bo dupc khio sat.
Mijc dp da dang sinh hpc 6 khu vyc dupc danh gia la cao v6i tong so 61 loai dupc ghi nhan trong 1.833 c i the cay than go thupc 27 ho voi nhieu dang song khac nhau. Lop cay tii sinh voi mot s6 loii tham gia chii yiu vao cong thiic to thinh nhu: Kha thu gai q u i {Castanopsis echidnocarpa); Dung {Symplocos racemosa); Do quyen {Rhododendron klossii); Son tra {Erioboirya anguslissima) va Cap mpc viet nam {Craibiodemdron heryt).
Mat dp cay tai sinh trung binh 20.516 cay/ha va phan thanh 4 cap chieu cao voi ty le gan 40% 6 cap chieu cao 1 - 2m. Tai sinh ty nhien chju anh huong ro ret cua cac nhan to cay bui va tham tuoi c6n cic nhan to dia hinh; dp tan che CO tic dpng khong ding ke.
Research on forest structure characteristics and biodiversity of closed evergreen mixed broad and needle leaf forest type in Bidoup - Nui Ba National P a r k
Bidoup - Nui Ba National Park is one of the four national biodiversity centers of Vietnam and the place contenting significantly scientific value.
Tree species composition ranged from 36 - 50 species and there were more than 4 species that participated in composition formula to creat many different dominances following height belt. With having the average density Key words: Bidoup - of 203 trees per plot, the distribution of tree number and diameter (N/D, 3) Nui Ba National Park. conformed to decreased distribution rule; meanwhile, the distribution of biodiversity N/H„, did not conform any researched rules. Biodiversity in the region was considered high with 61 species were recorded in the total of 1,833 individual trees belonging to 27 families and many different life forms.
Regeneration trees had some primarily species engaged in compostion formula such as: Castanopsis echidnocarpa, Symplocos racemosa.
Rhododendron klossii, Erioboirya anguslissima and Craibiodemdron heryi.
Average density of tree regeneration was 20.516 trees perha and divided into 4 height classes with the largest proportion (accounting for nearly 40%) at the height class of 1 - 2m. Natural regeneration was influenced sigfinicantly by the group factors of shrubs, vegetation, and terrian while the cover rale had negligible impact.
Tgp chi KHLN 2014 Nguyen Trpng Binh. 2014(2)
I. DAT VAN DE
Vudn Qudc gia (VQG) Bidoup - Niii Ba vdi dien tich 70.038ha la mot trong nam VQG cd dien tich ldn nhat Vi^t Nam. Nam tren cao nguyen Lang Biang, dugfc cac nha khoa hoc danh gia la mot trong bdn trung tam da dang sinh hoc cua Viet Nam (Nguyen Dang Hdi, Kuznetsov A.N., 2011). Trong cac kieu tham thuc vat riJmg thi kieu rung kin thudng xanh mua am a nhiet ddi niii thap vdi dien tich 21.577ha la kieu rung cd dien tich ldn nhat. Ngoai ra kieu rirng hdn giao la rdng, la kim ciang chiem dien tich kha ldn vdi 16.258ha tai VQG Bidoup - Niii Ba (Vudn qudc gia Bidoup - Nui Ba, 2011). Dac trung ndi bat nhat ciia kieu riing nay la cd cau true rat da dang. Hien tai, cac nghien cuu ve cau tnic riJmg d VQG Bidoup - Niii Ba van cdn it va han che. Xuat phat tir yeu cau thuc tiln ve cdng tac bao tdn va phat trien he sinh thai rilrng cua VQG, Nghien cuu dgc diem cdu true va tinh da dang sinh hoc kieu rieng kin thudng xanh hon giao la rong vd cdy la kim tai Vudn Quoc gia Bidoup - Niii Bd nhSm gdp phan bd sung nhiing hieu biet ve c4u tnic quan xa thuc vat rirng, tinh da dang sinh hoc va hudng phat trien ben viing, bao tdn cac he sinh thai rung tai VQG Bidoup - Niii Ba va trong vung khi hau a nhiet ddi, niii cao d Viet Nam.
n . NOI DUNG VA PHUONG PHAP NGHIEN c u t )
2.1. No! dung nghien cihi
Nghien ciiu tap trung vao viec xac dinh mot sd dac diem ve cau triic quan xa thirc vat (QXTV) rirng kin thudng xanh hdn giao cay la rdng va la kim; dac diem tham thuc vat rirng, td thanh, mat dp; tang thii; phan bd cay theo chieu cao viit ngon, theo ca dudng kinh;
do tan che va mdi quan he loai. Ngoai ra, nghien ciru cdn tidn hanh xac dinh mot sd dac dilm tai sinh cua cac loai cay gd trong giai doan cay ma: td thanh, m$t dp, chat lugng, ngudn gdc, ty le cay trien vong, phan bd cay tai sinh theo chieu cao. Nghien cuu anh hudng cua dp tan che den tai sinh tir nhien dudi tan rimg.
2.2. Phirong phap thu thSp sh lieu Tac gia da ke thira mdt sd tai lieu nghien cuu nhu dieu kien tu nhien, kinh te xa hdi ciia dia phuong nghien ciiii; cimg vdi cac tai lieu tham khao cd lien quan den van de nghien ciiu cua cac tac gia trong va ngoai nudc.
Bd tri 9 d tieu chuan (OTC) dien hinh tam thdi vdi dien tich 2.000m^ (40m x 50m), dinh vi cac OTC bang may GPS. Cac OTC duac phan bd deu tren cac dai cao cd quan xa thyc vat rung kin thudng xanh hdn giao cay la rong va la kim.
Trong OTC, cac nhan td didu tra ciia tang cay cao, tai sinh, cay bui tham tuoi va mot sd cac yeu td khac nhu: dp che phu, tan che, dat, cac dang sdng... dugc do dem theo quy trinh dieu tra rirng va lam hoc nham dam bao miic dp tin cay cua cac sd lieu thu thap dugc.
2.3. Phuong phap xu- Iy so liSu
Sd lieu thu thap dugc tidn hanh lpc bd so lieu ngoai lai de loai bd gia tri gay sai lech trong qua trinh xac dinh dang phan bd N/D].3, N/Hvn va xac dinh cac chi tieu dac trung khac.
Phmmg phdp xie ly sd lieu doi vdi tang cay cao To thdnh dugc tinh theo phuang phap cua Daniel Marmillod va Vu Dinh Hu6 (1984), Dao Cdng Khanh (1996):
3256
Nguygn Trpng Binh, 2014(2) Tgp chi KHLN 2014
IV% = N% + G%
Trong do: IV% la ty le td thanh (dp quan trpng) cua loai i;
N % la % theo sd cay cua loai i trong iam phan;
G% la % theo tdng tiet dien ngang cua loai i trong lam phan.
Chi so da dang ve lodi: Ap dung 2 chi sd Simpson va Shannon - Wiener de xac dinh miic dp da dang loai trong khu vuc nghien cuu:
Chi so Simpson
D , = l - | ; F , ^ = l - | ; ( n i / N ) ^ P,: ty le cua loai thii i tren tdng sd cac ca thd trong quan xa;
S: tdng sd loai dem dugc.
Chi s6 Shannon - Wiener
H = Yji(nilN).Lg(nilN)\
N: la tdng sd ca the dieu tra;
P,: ty le ciia 1 loai tren toan bp quan xa, Pi = Ui/N vdi nj la sd ca the cua loai thii i (i chay tir 1 den S);
S la tdng sd loai.
Mpt sd dac diem ve cau tnic cua khu vuc nghien ciiu nhu cac dac trung mau dugc chia td ghep nhdm cac tri sd quan sat theo cdng thiic kinh nghiem ciia Brooks va Carruthere (1953); can cii vao phan bd thuc nghiem de tien h^mh md hinh hoa quy luat cau tnic tan sd
ly thuyet khac nhau (Weibull, khoang each va phan bd giam).
Pbmmgpbap xtr Iy so Ueu doi vdi cay taisinlt Nghien ciiu danh gia mdt sd chi tieu cho ldp cay tai sinh nhu:
Ty le td thanh:
K, - - <10 Trong do: Ki: he sd td thanh loai thii i;
nj! Sd lugng ca the loai i;
m: Tdng sd ca the dieu tra.
Chat luong cay tai sinh: N% == — x 100 Trong do: N % : ty le phan tram cay tdt, trung
binh, xau;
n: tdng sd cay tdt, tnmg binh, xau;
N: tdng sd cay tai sinh.
Phan cap cay tai sinh theo cap chieu cao theo 4 cdp: 1 (H < 0,5m); II (0,5m < H < Im); III (Im < H < 2m) va IV (H > 2m).
Ben canh cac chi tieu tren, tac gia cung xac dinh su anh hudng den qua trinh tai sinh cua mdt sd yeu td nhu: dp tan che, cay bui tham tuoi va yeu td dja hinh (xac dinh sd lugng cSy tai sinh, chat lugng cay tai sinh theo sir khac nhau ciia cac yeu td).
Phan mem xir ly so lieu
Tac gia sii dung mdt sd phan mem thdng ke thdng dung hien dang dugc sir dung cho tinh toan cac sd lieu thdng ke sinh hpc nhu SPSS 15.0, Excel 7.0 (Nguyln Hai Tudt et a/., 2006).
Tap chl KHLN 2014 Nguyen Trong Binh. 2014(2)
III. KET QUA VA THAO LUAN 3.1. Mot so dac diem ve cau true rung hon giao la rong va la kim tai khu vu-c nghien cuu Chi si quan trong (IV%) va ciu true to thanh loai
Ket qua tai bang 1 cho thay; tuy co cung trang thai rimg IIIA nhimg cong thilc t6 thanh o cac dai cao Ichac nhau co sir sai Idiac idia ro ret.
Cu thS, tai dai cao 1.500m co 36 loai cay xuSt hien, trong do c6 6 loai tham gia vao cong thuc t6 thanh va hinh thanh nen iru hgp thirc vat "Thong 2 Id det, Thong 5 Id, Trdm vo do,
Bang 1. To thanh quSn xa thuc vat rung tai 3 dai cao cua khu vuc nghien ciru Cdp moc bidoup, Trdm trdng vd Cdp mdc viet nam"; a dai cao 1.700m co s6 luong loai cao nhlt (50 loai), cong thurc t6 thanh dai dien 5 loai tham gia; s6 luong loai trong OTC giam xu6ng con 48 loai 6 dai cao 1.900m. 0 2 dai cao 1.500m va 1.700m, Thong 2 la det co chi s6 IV% cao nhat, con a dai cao 1.900m thi chi s6 IV% ciia Po mu la ion nhat. O cac dai cao nay xuit hien mot s6 loai quy hiSm va dac tnmg cua trang thai rimg kin thuang xanh hon giao cay la rong va cay la kim, day la net dac tnmg cua kiSu rimg nay voi nhimg loai dien hinh ciia viing nui cao, lanh va am.
STT
1 2 3 4 5 6 7
Oai cao 1500m Loai Thong 2 la dat Thong 5 la Tram vo do Cap mpc bidoup Tram tring C^p mpc Viet nam 24 loai con lai
Tong Cong N 33 25 46 47 48 60 369 628
IV%
12,8 11.55 6,82 6,61 6,17 6,13 49,92
100
Dai cao 1700m Loai Thong 2 la dat Thong 5 la Tram trang Kha thy gal qua Cap mgc bidoup
45 loai khac Tong cpng
N 29 19 45 41 45
455 634
IV%
13,3 7,44 6,57 6,2 5,9
60,59 100
Dai cao 1900m Loai P o m u Chap tay 05 quyen Cap mpc bidoup
43 loai khac Tong cpng
N 27 28 40 35
441 571
IV% 11,84 5,75 5,45 5,11
71,85 100 Chii thich: N: so cay (cay/tong so OTC dieu tra); 1V%: Chi so quan trpng (%).
Mpt sd ddc diem ve da dang sink hpc tgi khu v^c nghien ciru
Chi so da dang lodi: Ket qua cho thay chi sd Simpson D = 0,097 = 0, cd nghia la miic da dang sinh hpc (DDSH) la kha cao, vdi tdng sd 61 loai dugc ghi nhan trong 1.833 ca the cay gd dugc dieu tra. Trong khi dd, chi sd Shannon Wiener H = 3,62, cho thay sd lugng giua cac loai cay gd tai khu vuc nghien ciiu cd khac biet tuong ddi ldn; qua do cdn the hien tinh ddng deu hay sd lugng ca the trong mdi loai tai kieu rimg kin thudng xanh hdn giao cay la rdng va cay la kim la cao. Tuy nhien, 02 chi sd nay chi cd the danh
gia dugc miic do da dang sinh hgc cua tang cay gd.
Da dang ve dang song: Ket qua cho thay tai khu vuc cd su da dang cao ve thanh phan loai cay gd vdi 61 loai cay gd thudc 27 hp. 0 mdi dai dp cao tuy cd sir khac biet ve sir xuat hien cua cac loai va hg nhung la khdng dang ke. Trong dd, hp cd sd loai ldn nhat la hp De (Fagaceae) vdi 8 loai xuat hien; hp Long nao (Lauraceae) va hp Com (Elaeocarpaceae) vdi 5 loai; cd 5 hp cd 4 loai la hp Bua (Clusiaceae), hp Mdc lan (Magnoliaceae), hp Thdng (Pinaceae), ho Che (Theaceace) va hp Dd quyen (Ericaceae); cd 4 hp cd 2 loai 3258
NguySn Trpng Binh, 2014(2) Tgp chi KHLN 2014
xuat hien la hp Dung (Symplocaceae), ho Sau sau (Hamameliaceae), hp Sim (Myrtaceae) va hp Hoa hdng (Rosaceae); 14 hp cdn lai cd duy nhat 1 loai xuat hien.
Da dang ve cay bui thdm tuoi: Day leo dac trung Embelia pulchella (Myrsiimaceae), Melinila hp Mua (Melastomaceae) va Piper sp hp Tieu (Piperaceae). Tang cay bui kha phat trien, cd ty le che phu khoang 15% hh mat. 6 day xuat hien nhieu loai cay than thao nhu:
Chirita cf. annamensis, Slackia tonkinensis, Pentaphragma gamopetalum; Cac loai Quyen ba (Selaginella sp.); Mang tang (Litsea cubeba);
Chan chim langbiang (Schefflera dongnaiensis var. langbianensis); Xa thao
japonicum) va cac loai thudc hp Tnic dao (Apocynaceae); Vien chi (Apocynaceae)...
Da dang ve nhom thuc vdt ngoai tdng. Tai khu vuc xuat hien nhieu loai thuc vat ngoai tang nhu: cac loai day leo: Kim cang (Smilax bracteata); Thien ly (Telosma cordata); thuc vat phu sinh/ky sinh: cac loai thupc hp Lan (Orchidaceae), hp Dd quyen (Ericaceae), hp Td dieu (Aspleniaceae); nganh Reu (Bryophyte).
Phan bo cua cdc lodi thuc vat theo cdc dai cao Su chenh lech ve dp cao da anh hudng den sir.
phan bd cua mdt sd loai thuc vat than gd. Ket qua xac dinh sd lugng loai d ca 3 dai cao dugc tdng hgp tai bang 2.
Bang 2. Phan bd loai theo dai cao tai khu vuc nghien ciiu
D|ic diem Chi c6a3a\^ .500 m Chi CO o (Jai 1 700 m
ChicoffiJai 1.900 m
C6adaM,500mvS 1 700m
C6 ff dai 1 700m va 1.900m
c a f f dai 1500m va 1900m C6 & ca 3 dai
Ten loai 1 loai' Chan chim {Schefflera heptaphylla)
7 loai: Bgch tung {Dacrycarpus imbricatus). Com d6ng nai {Elaeocarpus tectorius), De cau {Lithocarpus cerebina). Go dong bidoup {Gordonia bidoupensis), Que rirng (Cinnamomum iners), Th] {Diospyms decandra), Thich la que (Acer launnum).
8 loai: Cong tia {Calophyllum saigonense). Cong trang {Calophyllum soulatn), Oai bo (Achidendmn robinsonit), De xanh {Lithocarpus pseudosumdaicus), H^o duyen {Actephila anthelmintics), Mang tang {Litsea cubeba), Mgt sa (Meliosma lepidota), Son tram (Vaccinium sprenglii).
5 loai: C^p mgc Viet Nam {Craibiodemdron stellatum). Com la kem {Elaoecarpus balansae). Dung den (Symplosos poUanei), Th6ng 2 la d^t (Pinus krempfii). Thong 5 \i {Pinus dalatensis).
13 loai: Bdi loi (Litsea cambodiana). Chip tay (Symingtonia populne), C6m tang {Elaeocarpus dubius), De cpng manh (Lithocarpus stenopus). Po mu (Fokienia hodginsii), H6i nui {lllcium griffithii), Nhya ru6i (Ilex cochinchinensis), Mg su-a (Helicia niiaginca). Sang ma (Carallia brachiate). Sin niii {Madhuca alpinia), Thach ch§u (Pyrenaria jonqueriana). Thong 3 la (Pinuskesiya). Thong tre {Podocarpus neriifolius).
2 loai: Chua chat (Malus doumen); Gioi chevalier {t\/lagnolia chevalien).
25 loai
Ket qud tgi bang 2 cho thay: vdi tdng sd 61 loai d ca 3 dai cao thi sd lupng loai tap trung ldn nhat tai dai cao 1.700m (50 loai), sau dd d^n dp cao 1.900m (47 loai) va 1.500m (33 loai). Trong dd, sd loai cd bien dp sinh thai rpng (xuat hien d ca 3 dai dp cao) la 25 loai, sd lugng loai xuat hien d 2
dai giam dan theo dp cao (1.700m va 1.900m la 13 loai, 1.700m va 1.500m la 5 loai, 1.500m va 1.900m la 2 loai), sd lupng loai chi xuat hien d 1 dai cao nhat dinh cung cd xu hudng giam dan tir dai 1.900m den dai 1500m ( 8 - 7 - 1 loai theo ihii tu).
Tap chl KHLN 2014
Quy lu^tphan bo so c&y Bang 3. KSt
STT
1 2 3
Phan bd
Khoang each l^ayer Weibull
Nauven Tronq Binh, 2014(2)
theo cap dw&ng kinh 1,3m (N/D1.3)
qua m o phong ve luat phan bo N / D i j tai k h u virc n g h i e n c i h i Cac tham so
a 0,541 515,2 1,00
B
0,04 r 0,36
X.
0,066 5ttinh
13,7 1280,6
60,5 X . . .
14,1 16,9 15,5
K i t i u | n
H.*
Ho"
Ho"
Ket qua bang 3 cho thay: vdi 3 dang phan bd xac dinh cho viec md hinh hda phan bd thuc nghiem N/Di 3 chi cd phan bd khoang each cd chi sd xiinh < Xbang (xac su4t bSng 0,05) hay ndi each khac phan bd sd cay theo dudng kinh tuan theo quy luat cua phan bd khoang each vdi tan suat phan bd tap trung vao cap kinh tir
8 - 16cm (cap kinh thu 1) va vao cap kinh 16 - 24cm (c^p kinh thii 2). Dieu nay hoan toan phu hgp vdi dac trung trang thai riing nay (trang thai IIIA), bdi trang thai rimg IIIA cd sd lugng cay tap trung nhieu d cac co kinh nhd va cd xu hudng giam dan d cac cd kinh ldn (khi rimg cd su phat trien dn djnh).
Quy luat phan bo so cay theo cap chieu cao vut ngpn (TV/Hvn)
Bang 4. Ket qua md phdng ve luat phan bd N/Hvn tai khu vuc nghien ciiu
STT
1 2 3
Phan b6
Khoang each Mayer Weibull
Cac tham s6 a
0,709 1.2917
2,4 B
0,129 T 0,031
0,002
X x™
675,5 2 224,8
67,7 Xb^ng
15,5 15,5 15,5
Kdt lupn
Ho"
Ho"
Ho"
Ket qua bang 4 cho thay: ca 3 ham ly thuyet deu cd gia thuyet Ho bi bac bd. Phan ldn cac cay gd deu cd chieu cao tuong ddi dn dinh va hlnh thanh nen mpt tang rung chinh (phan tang 1). Hau het cay rung deu tap trung d cd chieu cao 15 - 18m, day la cap chieu cao quyet dinh tang chinh cua kieu rimg kin
thudng xanh hdn giao cay la rdng la kim.
Chinh su phan bd nay ciing vdi quy luat phan bd N/D] 3 da phan anh dugc tinh dac tnmg lam hpc cua kieu rimg kin thudng xanh la rdng la kim trong quy luat ket cau cua lam phan ciia kiiu rirng nay tai VQG Bidoup - Niii Ba.
Cau true mat do tang cay cao
Bang 5. Tdng hgp mat dp tang cay gd d kieu rirng hdn giao la rdng va la kir
Dai d9 cao (m) 1.500 1.700 1.900 Tnjng binh
S6 li/p-ng (cay/OTC) 209 211 190 203
M^t dp (cay/ha) 1.046 1.056 951 1.016
3260
Nguygn Trpng Binh, 2014(2) Tgp chi KHLN 2014
So sanh ve cac dai dp cao khac nhau, thi mat dp sd cay khdng cd su khac biet rd. Sd cay trung binh trong OTC la 203 cay va mat dp cua lam phan tai khu vuc nghien ciiu la 1.016 cay/ha. Voi mat dp nay, sir canh tranh ve khdng gian sinh trudng la khdng ldn, chii ydu la sir canh tranh khdng gian sinh tnrdng cua cac cay tAng cao vuon len chiem ting uu the.
Vdi mat dp nay, cho th4y kieu rimg nghien ciiu dang sinh trudng dn dinh. Tuy nhien, so sanh vdi mdt sd mat do cay rimg cua kieu rimg kin thudng xanh la rdng la kim vdi mdt sd noi khac d trang thai IIIA, thi d VQG Bidoup - Niii Ba la kha cao.
Bo tdn che cua rimg
Dp tan che tai cac dai do cao khdng cd su chenh lech nhieu, dp tan che trung binh la 0,69. Ket qua nay cho thay do mat dp d cac dai dp cao tuong ddi gan bang nhau, cay go ldn cd tan rdng nhimg khdng day dac, cac cay rimg da budc vao giai doan thanh thuc tu nhien. Dieu nay la mdt trong nhiing dau hieu cho thay nhimg thay ddi ve cau tnic ciia QXTV rimg d cac dai do cao trong tuong lai.
3.2. Dac diem tai sinh tir nhien tai khu virc nghien ciru
To thanh loai cay tdi sinh
Bang 6. Cdng thirc td thanh cho ldp cay tai sinh tai khu vuc nghien curu
STT 1 2 3 4 6 6
Loili Castanopsis echidnocarpa Symplocos racemosa Rhododendron WOSSH Erioboirya anguslissima Craibiodemdron heryi Cdc loai khac
Tong cOng
N (cay) 253 184 147 126 117 1.482 2.308
N%
11 7,97 6,37 5,42 5,07 64,2 100
K 1.1 0,8 0,64 0,54 0,51 6.42 10
Kit qu^ bang 6 cho thdy: Loai tham gia chu y^u vao cdng thiic td thanh la: Kha thu gai qua; Dung; Dd quyen; Son tra va Cap mdc vi?t nam. Q 3 dai cao khdng cd sir sai biet nhilu v^ sd lugng cay tham gia vao td thanh, dao dpng 5-6 loai. Mat dp sd cay tai sinh kha
ldn (2.308 cay/ha), sd lugng loai cay tai sinh d dai cao 1.700m la ldn nhat. Sd lugng cac loai cay la kim cd ty le tai sinh kem so vdi ty le td thanh tang cay cao.
Dgc diem cdu true mgt dp, chat lirffng vd ty l^ cdy tdi sinh
Bang 7. Tdng hgp sd cay mat dp, pham chat cay tai sinh tai khu vuc nghien ciru
STT
1 2 3
Dai cao (ml
1500 1700 1900 T4ng
S i cSy/o
723 827 758 2.308
Phim c h i t T6t
Cay 160 249 226 635
Ty l# % 25,2 39,2 35,5 100
Trung binh Cay 297 345 315 957
Ty l# % 31,1 36,0 32,9 100
x i u Cay 266 233 217 716
T y l # % 37.2 32,5 30,3 100
M | t d 9 (cay/ha)
19.280 22.053 20.213 20.516
Tgp chi KHLN 2Q14 Nguyen Trong Binh, 2014(2)
Ket qua bang 7 cho thay; Kieu rung tai khu vuc cd mat dp cay tai sinh kha cao 20.516 cay/ha. Mat dp cay tai sinh giiia 3 dai dp cao khdng cd sir khac biet ldn; dai cao 1.500m la 19.280 cay/ha; dai cao 1.700m la 22.053 cay/ha; dai cao 1.900m la 20.213 cay/ha. Ci dai dp cao 1.700m, do cd sd lupng va thanh phan loai cay gd tang cao nhieu nen sd cay tai sinh va mat do cay tai sinh d dai nay cung ldn nhat. Ty le % trung binh cay tai sinh cd pham chat xau chiem tuong ddi cao, dao ddng tir 30,3% den 37,2%, dieu nay dan den kha nang ldp cay tai sinh tham gia vao tang cay thap.
Phdn bo cay tdi sinh theo chieu cao Bang 8. Tdng hgp sd cay tai sinh theo chieu cao
Cap chi^u cao H 1 II III IV
Sd cay tai sinh N (Cay) 527 912 656 213
Ket qua bang 8 cho thay: Giai doan cay tai sinh cd cap chieu cao 0,5 - Im la giai doan
cay tai sinh cd sir phat tridn manh, cd sd lugng ldn (chilm 39,5%), khi chiSu cao ldn hem Im giai doan nay b4t dau cd sir canh tranh va dau tranh sinh tdn lam giam ty le va sd lugng cay tai sinh (chidm 28,5%), den giai doan tren 2m sir canh tranh xay ra manh me, nhdm cay tai sinh d giai doan nay da giam sd lugng ro ret (chiem 9,2%). Day ciing la xu hudng phat trien chung cho ldp cay tai smh dudi tan rimg.
Anh hjr&ng ciia mpt so nhan to sinh thai din tdi sinh tw nhien
Anh huong cua do tdn che: dp tan che anh hirdng khdng ldn den mat dp va chat lugng cay tai sinh trong khu vuc nghien ciru, dieu nay dugc ly giai la do cay tai sinh cd kha nang chiu bdng ngang nhau, it cd sir phan hda va canh tranh, sir canh tranh va thich nghi anh sang the hien d mot sd loai cay tai sinh bi dao thai. Trong dieu kien cdn tan rimg, cac cay tai sinh mudn tdn tai thi can phai thich nghi t6t vdi dieu kien thieu hut ve anh sang. Day la thdi gian can thiet de cay rimg chudn bi tdt cho cac giai doan canh tranh khac nghiet hon trong tuong lai.
Bang 9. Anh hudng ciia do tan che d8n mat dp va chk lugng tai sinh tu nhien
Oai cao (m) 1.500 1 700 1.900 Trung binh
Dp tan che 0,66 0,69 0,74 0,69
S6 cay tai sinh theo c i p H (cay/ha)
< 0 , 5 m
527
0 , 5 - 1 m
912
1 - 2 m
656
> 2 m
213 N (cay/ha)
19.280 22 053 20 213 20.516
Pham c h i t (%) T6t 25,2 39,2 35,5 33,3
Xiu 37,2 32,5 30,3 33,2
Ngoai yeu td mat dp va dp tan ciia tdng cay gd anh hudng tdi tai sinh theo chidu thdng diing thi ldp cay bui va tham tuoi ciing anh hudng hudng den tai sinh theo chieu mat phdng ngang. Trong dieu kien tu nhien cua khu vuc nghien cuu cung xuat hien qua trinh tai sinh Id trdng. Lo trdng la khdng gian tdt dS cay tai sinh phat trien. Tuy nhien, tham tuoi va cay bui
vdi uu the sinh trudng nhanh da che phii nhung Id trdng tir dd lam anh hudng dM tai sinh. Ghi nhan tai d dieu tra, tai nhimg lo trdng thi sir che phii cua cay bui tham tuoi dat tir 40 - 60% dien tich, vi vay da han che qua trinh tai smh tu nhien ciia cay tai nhirng Id trdng nay.
Anh hudng cua dia hinh tdi tdi sinh: Vdi 3 dai cao tuong img 1.500m; 1.700m va 1.900m 3262
NguySn Trpng Binh. 2014(2) Tgp chi KHLN 2014
mat dp va ty le chat lugng cay tai sinh khdng cd su bidn dpng Idn. Ci VQG Bidoup - Nui Ba, dja hinh cd anh hudng khdng dang k^ din mat dp va chat lugng tai sinh ciing nhu sd loai cay tai sinh.
IV. KET LUAN
Tai khu vuc nghien ciru, trong sd 36 - 50 loai dugc phat hien tai cac OTC chi cd 4 - 6 loai cd mat d cdng thiic td thanh. Hai loai Thdng 2 la det va Thdng 5 la cd chi sd IV% cao nhdt d 2 dai cao 1.500m va 1.700m va da tao thanh nhdm loai uu the ""Thong 2 Id del, Thong 5 Id, Trdm vo do, Cdp moc bidoup, Trdm trdng vd Cdp mpc viet nam" a dai dp cao 1.500m. Do cd sir khdng ddng nhat d cac OTC nen mat dp cd sir khac biet giua cac OTC, binh quan la 203 cay/OTC (trung binh cho lam phan la 1.016 cay/ha) cho thay kieu rimg nay dang sinh trudng kha dn dinh. Ve phan bd sd cay theo dudng kinh (N/D) tuan theo quy luat phan bd khoang each vdi sd cay tap trung chu yeu d cd dudng kinh 8 - 16cm va 16 - 24cm, cdn phan bd N/H khdng tuan theo cac quy luat phan bd ly thuyet.
Td thanh cay tai sinh: cd 5 loai chinh tham gia vao cdng thiic td thanh la: Kha thu gai qua;
Dung; Dd quyen; Son tra va Cap mdc viet nam. Ben canh do cdn cd mdt sd loai cay tdng cao tham gia vao cdng thiic td thanh chinh d cac dai cao 1.700m va 1.900m nhu Thdng 2 la det va Po mu, tuy nhien vdi sd lugng it. Mat dp cay tai sinh kha cao, loai cay tai sinh giiia cac dai khdng cd sir chenh lech ldn (trung binh 20.516 cay/ha) va chat lugng cay tai sinh ciing cd it su khac biet. Cap chieu cao cua ldp cay tai sinh chia lam 4 cap, trong dd sd cay tai sinh d cap chieu cao 1 - 2m chiem ty le ldn nhat (gan 40%) trong khi cap chieu cao tren 2m chi dat 9,2%. Mat dp va chdt lugng cua cay tai sinh trong khu vuc nghien ciiu chu yeu do nhan td cay bui va tham tuoi; cac nhan td cdn lai it anh hudng.
Mirc dp da dang sinh hpc tai khu vuc nghien ciiu ddi vdi ddi tugng rimg kin thudng xanh hon giao cay la rdng va cay la kim la rat cao.
Ket qua dieu tra vdi 1.833 ca the cho thay chiing gdm 61 loai thudc 27 hp. Chi sd Shannon - Wiener dat 3,62 ciing cho thdy su da dang cao ciia khu vuc nghien ciru. Dac biet, khu vuc cdn bao gdm rat nhieu kieu dang sdng dang sinh trudng va phat trien rdt tdt:
cay gd, cay bui, day leo, tham tuoi, thuc vat phu sinh, hoai sinh.
TAI LIEU THAM KHAO
I Nguyen Dang Hpi, Kuznetsov A.N., 2011. Da dang sinh hoc va dSc tru-ng sinh thai Vucm Qu6c gia Bidoup - Niii Ba, Nxb Khoa hpc tir nhien va Cong nghe.
2. Nguyen Hai Tuat, Vu Tien Hinh, Ngo Kim Khoi, 2006. Phan tich thong l^e trong lam nghiep, Nxb Nong nghiep, H^ Npi.
3. V i r ^ Quoc gia Bidoup - Nui Ba, 2011. Bao cao tong Icet nSm 2011 cua Vuon Quoc gia Bidoup - Nui Ba.
Ngudi tham dinh: PGS.TS. Nguyen Hoang NghTa
