KHOA HOC CONG NGHE
iTiiXIH D A DAIXIG LOAI VA DAC DIEIVI CAU TRUC RUIVG PHdlVG HO VUr\lG HO CHUA IVUOC CUA DAT,
HUYEI\l THUOiXIG XUAIXI, TilXIH THAIVH HOA
Dd Anh T u i n \ Nguydn Hihi Tin^
TOMTAT
Rimg phong ho dau ngu6n hd chiia nudc Cira Dal co chirc nang sinh thai quan trong trong viec duy tri, nuoi duong nguon nuoc va han che xoi mdn dat. Tuy nhien, hien nay rimg d khu vuc chii yeu la rimg thii sinh ngheo do bi suy thoai, chua duoc danh gia v^ tinh da dang va dac diem cau tnic de lam cc sd xac dinh mpt cau tnic rimg hgp Iy theo chiic nang ciia rimg phong hp dau nguon. Ket qua nghien cmi tinh da dang va dac diem CEiu tnic ciia cac trang thai tham thuc vat rimg tai khu vuc thong qua viec didu tra dmh ky 2 nam/lan tir 12 6 tieu chuan cho thay rimg phong hp Cira Dat kha da dang ve thanh phan loai vol 23 - 48 loai cay g6/6 Ueu chuan (2000 m^. Cac chi sd da dang Ioai iuong doi cao (2,649 - 3,431), mirc do phong phii loai kha cao (2,277 - 3,863) va bien dpng ldn giua cac trang thai. O mot so trang thai rimg trung binh va giau da xuat hien quan xa vdi loai cay mi the thupc nhom cay gd co gia tn chiu bong (Thi rimg, Tau mat, Dinh huong, Gidi, Rang rang, Gioi gimg, Tnrong sang, De gai, Tram). Mat do cay tai sinh rimg dudi trang thai rimg co tni luong nhin chung la kha loo (> 3000 cay/ha) voi ti le cay sd cay co pham chat tot dat tren 55% va co xu hudng tang dan theo ihoi gian. Chi s6 dien tich tan (C^,) dat gia tri tuong ddi cao, 150-300%, nhung do che phu chi d miic dd trung binh (khoang 40%) va cac chi so nay c6 xu hudng tang dan theo thoi gian. Tdc dp tang trucmg binh quan nam cua chi sd dien tich tan Z (Cai) cua cac trang thai tham thuc vat tai khu vuc nghien cuu co the udc tinh thong qua chi sd C^ hien tai voi he so tuong quan !a 0,877 theo phuong trinh Z(C „) = 6,237 - 0,035*C, + 6,537E-^* C,,^ de du tinh vd chi so C„
Tir khda: Cau tnic ning, chi sd dien tich tan, Ciia Dat, da dang loai, tai smh, rimg pbong ho dau nguon, Thudng Xuan-Tlmnh Hoa.
LDATVAIUDE
Rimg phdng hd diu nguon co chirc nang sinh thai quan trong trong vide duy fri, nudi dudng ngudn nudc va han che xdi mon dat, vi thd no ddng vai trd quan trong viec han che lu lut, han hin, giam thieu bdi lap ldng hd. gop phan quan frong dam bao an sinh phat trien kinh te - xa hgi ciia cac cong ddng dan cu ti-ong luu \uc. Rung phdng hg dau ngudn hd chua nuoc Cua Dat thudc dia gioi hanh chinh huyen Thuong Xuan co tdng dien tich 105.508,88 ha, trong dd cd 66.638,3 ha la rimg tu nhien, chu yeu la rimg thu sinh ngheo.
Chiic nang phdng ho cua mdt he sinh thai limg phu thudc vao dac diem can tinic cua he smh thai do (Vo Dai Hai, 1996; Pham Van Dien, 2006). Bai bao nay phan lich dac diem, su bien dong ve cau tnic va t;ii sinh ciia he smh thai rimg phdng ho Cua Dat Iam CO sd cho viec xac dmh cau hiic rimg dinh hudng de ]:>liat huy hieu qua phong ho - kmh te cao va dn dmh tai lull v\ic ho thiiy lm - thiiy dien Cua Dat
Tririms: Dai hoc L:im nghiep
" Tnranj: Dai hpc Hong Diic
2 . DO! TUONG VA PHUDNG PHAP NGHIEN CUU 2.1. Ddi tuong v i nOi dung nghidn cuu Ddi tugng nghien cim la cac tham thuc vit rimg d cac trang thai IIIB, IIIA^, IIIA^, IIIAi, IIB va IIA thudc khu vuc rimg phdng ho dau ngudn ho chiia nudc Cira Dat tai 2 xa Yen Nhan va Luong Son, huyen Thudng Xuan, tinh Thanh Hda. Cac ndi dung nghien cim bao gdm:
i) Tinh da dang loai: chi sd da dang Ioai, chi so Simpson, miic dd phong phii va sd loai cay xuat hidn trong cac d didu fra.
n) Die diem cau tnic' cdng thuc td thanh, mat do, ty Id hdn Ioai ciia tang cay cao, dac diem ldp cay tai sinh, mdt sd chi sd lien quan den hieu nang phong hd (dien tich tan ciia ting cay cao, dp che phii cay bui, tham tuoi va vat roi rung).
2.2. Phuang phip nghidn cuu 2.2.1. Phuong phap bd tii thi nghiem 12 d tieu chuan (OTC) vdi dien tich mdi (")TC la 2000 m" (40 m X 50 m) duoc lap b cic trang thai rung ( Bang 1) de dieu tra cac chi tieu ciia ting ciy cao.
Viec nghien ciiu ldp cay tai smh duac thuc hidn dcac d dang ban (ODB) vdi dien tich 25 m- (5 m x 5
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 8/2014
KHOA HOC CdHG HGH|
m)/ODB, dupc Up trong dc OTC (10 O D B / 0 1 OTC) d m ^ b6 lii theo 3 hang song song voi duong ddng miic, 2 hang trta duoi cich c?nh OTC 5 m, cac d cich nhau 7 m (8 6 D B ) , hang giua each canh trtn O r e 20 m mil 6 each canh bin 15 m (2 ODB) voi di^n tich 25 m 7 6 DB (kieh thuoc 5 x 5 m).
BillKl.Thdiigkes6hnirngvavitricic6flunghi$m TT
1 2 3 4 5 6
Tlrang thai
m.
inA, mA, niA, II,
n,
Sd 6 tidu c h u ^ va kyhieu
1(01) 3 (02, 03. 04)
2 (05,06) 1(09) 2 (07,08) 3(010, O n , 012)
Vitri lap 6 didu tra Sudn Chaa, sudn, dinh
Sutm, £nh Sudn Chin,sudn Chan, sudn, dinh 2.2.2. Phuong phap diiu tra thu thap sdtieu Sir dung sd lidu kiem kd rung ciia Sd NN&PTOT tmh Thanh Hda kdt hgp vdi vide td chiic dieu tra xic mmh dd dinh gii hidn frang vi phin Ioai frang thii rung.
Trong cac O T C , cic chi tidu vd die diem tham thyc vit dugc tidn hinh theo cic phuang phip di^u tra Iim hoc. Sd lidu vd tang ciy cao v i ldp ciy tii sinh dugc thu thip dinh ky 2 nim/Iin (tir nim 2008 ddn nim 2012) dd xic dinh sir bidn dOng ciia cic nhin td didu fra.
Cic chi tidu vd do che phii ciy bui, tham tuoi vi thim myc a cic trang thii rimg dirge xic dinb thdng qua viOc didu fra theo tuydn (lip 09 tuydn song song vdi dudng cheo d dang ban).
2.2.3. Tinh toin vixulysdhgu
Sd Udu thu thip dtrge chinh ly, tinh toin cic die trung miu vd cic chi tidu didu tia vdi su hd fra bing miy tinh cua cic phin mdm thdng kd chuydn dung.
Cic chi sd da dang v i can tnic dtrge xic dinh theo cic cdng thtic sau:
i) Muc dp phong phu (W^ Miic dO phong phii cua loii dtrge Itrgng hda qua cdng thiic:
yiN (2-1) Trong do: N Ii sd ci thd cua tat ca cac loii; m Ii
sd loii frong quin xi.
ii) Cic chi sd bidu thf mux: do da dang loii:
+ Tyl$h6n loii (HI) Ii ti sd giiia sd loii frdn tdng sd c i thd frong 6 tidu chuan
HI, - S/ N (2-2) HIj - S (5%)/ N (2-3)
Trong dd: S - tdng sd loii cd trong 6 tidu chuan;
S (5%) - sd loii cd do nhidu tuong ddi > 59fc N - Sd Iuong c i the ciy rimg tiong d tidu chuan.
+Him sdtien ket Shannon - Wiener.
^ ^-'EP, log P^
'=' (2-4) Trong do: m Ii sd loii frong OTC; n, Ii sd lugng
ca thd cua loii i frong quin xi; N sd c i the frong OTC; Pi Ii ty Id ci the ciia loii i: p, = n / N .
H =—{NlogN-yn,\ogn)
Hoac: " (2-5) Trong dd: C Ii hing sd: C = 2,302585.
H = 0 khi quin xa chi cd mdt loii duy nhat, vi khi dd A a o g A ^ = ^ " ' ^ ° ^ " ' . H^- ClogN khi quin xa cd sd loai cao nhat v i mdi loii chi cd mdt c i the. H cing ldn thi tinh da dang cing cao.
+ Chi sd Simpson:
m 2
A ^ I - Z A
I (2-6) Trong dd: m Ii sd loii
P, =
«
^ Ii td thinh ciia loii i nio dd.
Vdi N khdng qui Idn so vdi n, thi dung cdng
A = l - «, f «, - I
N[N'l (2-7)
iii) Congthuc to thanh theo so cay co dang: kiAj + kjA2+--- + k A
Trong do: A, la ten loai; ki la h^ sd duoc tinh theo cong thirc:
k, =-i-.100 ' N iv) Mat d0 lam phan:
Nlha = -^.\0000 2000
(2-8)
(2-9) Trong dd: N/ha l i mit dp ciy frdn 1 ha rimg; N Ii sd ciy frong d didu tra; 2{K)0 li didn tich d tidu chuan vi 10.000 li 1 ha quy ra m^.
v) Chi sd dien tich tan:
TC C „ = — ^ * 1 0 0 %
^bTc (2-10) Trong dd. Cai chi sd didn tich tin li (%); ZSti
tdng didn tich tin ting ciy cao frong O T C ; S O T C diOn tich O T C .
NdNG NGHllP VA PHAT TRIEN NONG T H 6 N - KY 2 • THANG 8/2014 95
KHOA HOC C6He NOHi
Vl) Do che phu cay bui, tham tuoi.
€/>% = - . 100
L (2-U)
Trong do: 1 la tong chieu dai cac tuy^n diSu tra duoc che phu; L la tong chiiu dai cac tuyen dieu tra.
3 . KET QIH NGHra CIJU V« I K M lUMI
3.1. Tinh da dang loai ciia rimg phong ho Oia Dat
Ket qua tinh toan cac chi s6 da dang loai Simpson, chi sd da dang loai (S.W.H) va do phong phii thong qua cac cong thuc (2-1) den (2-6) o nam 2008, 2010 va 2012 duoc bieu thio hinh 1.
da dang loai (S.W.H) va muc dp phong phii a cit trang thai rimg IIA, IIB, ULA, co su tSng len theo thoi gian. Dieu nay cho thay he thdng rimg khu vut nghien cuu co chi^u huong phuc hoi tdt die bi&t U ddi voi cac trang thai niA,. IIB va IIA. Ddi vdi trang thai IIIA, va IIA sd luong loai cay gd tang 2-5 loji trong 4 nam (2008-2012). Trong khi dd d cac trang thai rung IIIB, IIIA;, va IIIA, sd loai cay gd gan ihii dn dinh (xem hinh 2).
rV>vA^
• r^»rwi!inB"''RB!'
Hinh 1. Chi sd Simpson, chi sd da dang loai vi miic do phong phii d cic OTC
Ty sd da dang loai cao nhat (3,431) dat duoc thuoc ti-ang thai rimg 11B va thap nhat (2,649) thuoc trang thai rimg 11^. Miic do phong phii d cic trang thii rung dao ddng 2,277 - 3,863 va ciing dat gia tn cao nhit b frang thai rimg IIB. Chi sd Simpson khdng CO su khic biet rd ret giira cac trang thai va gdn nhu on dinh qua cac nam. Tuy nhien, cac chi so
Bang 2. Ty sd hdn loai ciia cac
D So I o a i / 6 namlH 2008
• So loai/O nam | 2010 D So loai/0 nanil
2012
Trang thai n
Hmh 2: Bien ddng sd loii ciy xuat hidn ti-ong d (fite' fra tai cac frang thii rimg Neu xet theo chi sd vd ti le hdn loai, ket qua tinh toan chi sd ty le hdn loai cua cac trang thai rimg a khu vuc nghien ciru (bang 2) cho thiy ty sd hdn loai Hl| (ty sd giCra sd loai/s6 cic the) dao ddng tir 1/4,3 den 1/3,2 b cac trang thai. Cac gia tri k h i cao nay cho thiy mirc do kha phong phu ve thanh phan loai.
Hon niia ty sd hdn loai HI, ciia cac trang thai deu 16n hon it nhat 3 lin ty so hon loai ciia cac loai cd do nhidu £ 5% ( H y , dieu nay ndi ldn rimg tu nhien khu vuc nghien cim da xuat hien mot sd loii uu the.
tiang thii rimg qua cac nam Nam
Nam 2008 Nam 2010 Nam 2012
Ty so hon loai
HI, HI.
HI, HI, HI, HI,
III,, 1/3,2 1/14.3 1/3,2 1/14,3 1/3,1 1/14.3
IIIA, 1/3,6 1/20.0 1/3,6 1/20,0 1/3,6 1/20.0
IIIA, 1/3,7 1/11,1
1/3.7 1/14,3 1/3,7 1/14.3
IIIA, 1/3,8 1/25.0 1/3.8 1/25,0 1/3,8 1/25.0
IIIA.
1/3,6 1/16.7 1/3,6 1/16,7 1/3,6 1/16.7
IIIA, 1/3,3 1/16,7 1/3,3 1/16,7 1/3,3 1/16.7
Il«
1/3,4 1/33,3
1/3.3 1/33.3 1/3,4 1/33.3
II»
1/3,7 1/33.3 1/3.6 1/33.3
1/3.6 1/25.0
IIW, 1/3,3 1/20.0
1/3,3 1/20.0 1/3.2 1/20.0
Il»
1/4,3 1/14,3
1/4.2 1/16.7 1 / 4 2 1/16,7
III 1/3,7 1/12,5
l/3,.l 1/14,3
1/34 1/16,7
ll» 1/3.3 1/14.3 1/3,1 1/16,7
1/3,2 1/16,7 3,2. Mdt sd dac diem cau tnic rung phong ho Kdt qua didu tra khu vuc n,i,r|iieii ciiu qua cac Cua Dat OTC cho thay cd tir 7 ddn 15 loai llumi gia vao cong 3.2.1. Mat sd chi lieu cau Inic ting cay cao *tiuc td Ihanh cua tdng cay cao du„v thdng ke qua
To thaiih v:! mat do bang 3.
96 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THA- 8/2014
KHOA HOC CdHG HGHf
B i n g 3. i M i i g k t cang flaictdfliilnh tfaeo d J s d ITO trong nam 2008
m B I 13,48 Thr + 1 2 3 6 Tmu + 7,87 Gi + 6,74 Mr -i- 5,62 Nh + 4,49 Rr -i- 4,49 Gg + 4,49 Bh + 40,46 CLK MA, 1 3 T h r - i - 1 3 T m u - f 9 M r t 7 B h + 7Gi-i-5Mx-l-4Nh-i-4Rr-f4Snn-34.0CLK
m/W
17,35 Thr +13.27 Mr + 10,20 Tmu -> 9.18 Rrx + 5,10 Bh -i- 5,10 Rr -f 4,08 Gix -i- 4,08 B U 31,64 CLKmA,
20 Thr+14,74 Tmu -i-13,68 Mr -i- 8,42 Rm -f 4,21 Gfa; -i- 4,21 Mx -i- 4,21 Sr <- 4^1 Bl -i- 26,32 CLK IHAz 13,08 Thr + 13,08 Srx -i- 7,48 Tmu + 5,61 BI -i- 5,61 Gix -i- 4,67 Rr + 4,67 Gi -i- 3,74 Rnh + 3,74 Trs +38,32 CLK
IlIAj 12,84 Thr -i-10,09 Bl -i- 6,42 Tmu -)• 6,42 Rrx + 6,42 Mr -i- 4,59 Gi -i- 4,59 Trs -i- 4,59 Rr -i- 3,67 Enh H 40,37 CLK
inAi 7,43 Hd -1- 7,43 Ng -i- 6,42 Thmm + 6,42 Sr + 6,42 St -i- 5,50 Rrx -i- 4,59 Thml -i- 3,67 Gc + 3,67 Gg +3,67 Tr + 3j67Ttnu + 3,67 Ln -i- 37,44 CLK
17,93 Mvth H-11,03 Tmu -i- 6,90 Trtr -i- 5,52 Hd -i- 4,14 Tr -i- 3,45 Bs -i- 3,45 BI + 3,45 Cot + 2,76 Gix + 2,76 G-I-38,61 CLK
1060 Tmu -1- 9,27 Mvth -1-8,61 Trtr + 7,45 Tr -i- 5,96 Bl -i- 5,96 Khv -i- 5,30 Ch -i- 3,97 R -i- 3,31 Tr -i- 3,31 C6t -1- 3,31 Rrx -1- 2,65 Vh- + 2,65 Gg -i- 2,65 Gix -i- 2,65 G -i- 25,66 CLK
27,45 Mr -i- 9,80 Bb -i- 9,80 Mkh + 7,84 Lm -i- 6,86 Tr -i- 6,86 Xg -i- 5,88 Hd -i- 2L9 CLK
8,57 Mkh -1^ 7,62 BI -i- 7,62 Lm -i- 7,62 Tr -i- 6,67 Mr -i- 6,67 Bb -i- 6,67 Xg -i- 5,71 Khv + 4,76 Ch -i- 4,76 Hd -1- 3,81 R -1- 3,81 Rr -1- 3,81 Bs -I- 21,9 CLK
IIA 9,52 Bl -1 CLK
J,57 Mkh -1- 8,57 Tr -i- 7,62 Ch + 6,67 Khv + 6,67 Lm + 5,71 Hd + 4,76 Gg -i- 3,81 Rr + 38,1
(SbuM: Bb - Biim bup: Bl - Bai ldi nhat; Bs - Ba soi; Ch - Cheo; Cot - Com tang; Bh - Bmh huang; G - Gdi; GC' Giecau; Gg- Giegai; Gi- Gioi; Gix - Gioi xanh; Hd - Hu day; Khv - Khao vang, Lm - Long mang; In- IA nSn; Mkh - Mic khen; Mr - Mo roi; Mx - Moi xanh; Mvth - Mo vol thuoc; Nh - Nhoc; Ng - Ngat; Sr - Sung rimg; St - Sdi tia; Rnh -Re nhoi; Rr- Rang rang; Rrx - Rang rang xanh; R - Re; Thr - Thi rimg; Thmm - Thimg macmd; Thml- Thiing m^c long; Tmu- Tau mudi; Tr- Trau; Trs- Truong sang; Trtr- Tram trang; Jig-Xen gai; Vtr- Vang tning; CLK-cic lo^khic).
Td thdnh ttang thai IIIB, IIIAj, IIIA2, IIB chu yen la c^c lodi ciy chiu bdng cd gia tri kinh te cao (nhu IThi ning, Tau mudi, Nhpc, Gioi, Dmh huong). Trong
khi dd d cdc trang thdi rimg IIIAi vd IIA td thanh chii y^u Id cdc lodi cay ua sdng mpc nhanh cd gid tri kinh t^ thdp, t^p trung chu yeu la cay go nhdm VI -VIII (nhu Mdc khen, Trau, Hu day, Ldng mang,...). Nhin chung, khong cd sir bidn dong ro ret ve td thdnh lodi cay ning trong giai doan 2008-2012 (xem hinh 3).
UO
»
UI
« »
A \
K
J 0^ oj oj 0^ oil 01 M D W A
.•^ ^A '
Cl OS 01 c
S i M l / O
V.M.ni«%M
o n PI 01 p^ W W 1^11
S i t H . t u m i i a C I t J Ihlnh
• * > N M 2 ( K I I - • - N ^ 2010
~ t - N M 2012
Vd mat dp, ket qui dieu fra cho thay khu vuc nghien ciiu cd mat dp ting ciy cao tuong ddi Idn, cao nhat thudc trang thii Ilg ( 725 -755 ciy/ha) vi tiiap nhit thudc tiang thii nig ( 445 - 450 ciy/ha). 6 eic trang tiiii IIIB, IILI^ v i IIIA2 mat do tuang ddi thap, tuong ddi dn dinh tiong giai doan 2008-2012, cic trang thii cdn Iai d i cd su bidn ddng nhung khdng lan.
Mdt sd quy luit phin bd
O cic trang thii rimg didu tra, phin bd sd eay theo chidu cao viit ngon (N/Hvn) ddu tuin theo luat phin bd Weibull mdt dinh ldch trii, vdi do ldch A dao ddng 0,00316 - 0,1089 v i dp nhpn a dao ddng 1,457 - 3,539.
Nhin chung, phin bd sd ciy theo cap dudng kinh ngang nguc (N/Dj 3) cr khu vuc nghien cuu tuin theo quy luit phan bd him Weibull mot dinh ldch frii, vdi do Idch A tir 0,0047 den 0.259 v i dp nhpn a tir 0,259 den 2,211. Ridng d frang thai rimg giiu thi phin bd niy tuin theo quy luit phan bd khoing cich vi Mayer.
Quan h^ giiia HVN v i D,3 cua cic tiang thii rimg tuin theo hai dang him chinh, him Cubic v i him S Hinh 3. Bidn ddng m i t dd. sd loii ciy v i sd loii tham
gia cdng thiic t& thinh
N O N G NGHIEP V A PHAT TRI^N NdNG THdN - KY 2 - THANG 8/2014 97
KHOA HOC CONG NGHE vdi miic dd tir hoi chat den rat chat vdi he sd tuang
quan 0,4303 - 0,9386 theo cac phuang trinh tuong quan dang Cubic vi dang ham S:
Phuang trinh tuong quan him Cubic cd dang:
HvN = b„ + b,Di.3 + b^D^ 3 + hj)^ 3 (3-1) Phuang trinh tuang quan ham S cd dang:
H^^^g(bo.b,/D^^) (3.2) 3.2.2. Ciu tnic Idp cay tai sinh
Td thinh va mat do
Ket qua dieu tra cay tai sinh d cac frang thai tham thuc vat rimg cho thay muc do da dang Ioai cay tai sinh da tang Ien rd ret. Ngoai mdt sd loai cay gd tidn phong dmh cu ua sang it gii tri kinh te, cdn cd mdt sd loai cay thugc nhdm cay gd chiu bdng cd gia tn kmh te cao nhu (Thi rimg, Re nhdt, Gidi, Tnrdng mat, Nanh chudt, Cheo, Tram tia,...).
Ket qua didu fra ciing cho thay cd su khac biet ve td thanh ciy tii sinh d cac trang thai rimg khac nhau. (7 cac frang thai rimg IIR II^ va 111^1 td thanh cay til sinh co su khac biet rd ret so voi td thanh ting cay cao, bao gdm chii yeu cic loii tii sinh thugc nhdm loai ciy tien phong uu sang va mgt sd loai ciy chiu bdng. Tuy nhien, d cac trang thai IIIj^, 111^3 vi Illg td thanh ldp cay tai sinh kha tuong ddng vdi td thanh tang cay cao, vdi tm the ve sd luong cay ciia cac loai thudc nhdm cay chiu bdng.
Mat dd vi tyle cay tii sinh cd tndn vgng Hinh 4 bieu thi sir bidn ddng ve mat do cay tii sinh va mat dd cay lai sinh trien vong tir nam 2008 den nam 2012. Hinh 4 cho thiy, mat do ldp ciy tii sinh d cic trang thai rimg la kha cao, hau het ldn hon 2500 cay/ ha, trong dd ldn nhat 3200-3650 cay/ha thudc trang thai IIB. Mat do cay tai sinh nhin chung it bien ddng d cac frang thai IIIB, IIIA3 IIIA2; tuy nhien lai cd bien ddng dang ke d cic OTC thudc ti-ang thii IIIAi, IIIB, IIA (xem hinh 42.
Cay/ha
v.
• 5 = 5 5
m 20'3a im2010 niW12
Hinh 4. Bien ddng mat do cay tai sinh chung va cay tii sinh cd tridn vong
Ve ldp ciy tii smh cd trien von '-t Q^3 dio thay ty Id ldp cay niy li k h i cao, chu 1 55-78% tong sd cay tii suih. Khic vdi mat do ciy tai smh, ty Id cSy tai smh tnen vgng d tat c i cic frang thai cd xu hudu]
tang din. Didu nay cho phep nhin dmh ring khi nang phuc hdi cua ldp cay tai sinh la k h i tdt va cc tidm nang. Vi viy ip dung cic bien phip phuc hoi rimg bing khoanh nudi xuc tidn tai sinh tu nhien tk vdi cac frang thai rimg d khu w^c do cd sin ldp ca)' tii sinh trien vgng vdi sd lugng dam bao.
3.2.3. Dac diem tham thuc vit ve hieu nang phdng ho
Chi sd dien tich tin, do tan che, do che phfil cac chi sd cd y nghia quan trgng frong vide danhg chuc nang phdng hg cua rimg.
Chi sd dien tich tan (C^,. %)
Chi sd dien tich tin la mgt chi tieu quan trgri Uen quan den kha nang dieu tiet ddng chay m^
giam thieu he sd ddng chiy mat va xdi mdn hk mi ciia tham thuc vit. Ket qua tinh toan chi sd didn lid tan a cac nam 2008, 2010 va 2012 dupc bieu thii hinh 5.
iii||as<g"<7
Trang thai riing
Hinh 5. Bien ddng chi sd didn tich tin qua cic n ^ cic frang thii rimg
Hinh 5 cho thay, chi sd dien tich la tang dani cac trang thai HA, IIIA,, IIB, IIIA^, IIIA3, IIIB. Otrai rimg IIA, chi sd nay dao ddng khoang 150%; ti nhien d' ti-ang thii IIIB chi sd nay dat gin 300%, the thoi gian chi sd didn tich lan deu tang b cac trao thai (hinh 5); didu nay cho thiy ran ijr b khu vuc dai cd xu hudng phuc hdi tdt, kha i r..r phdng hp dW nang len do tang tin van duac -' -^^ p]^^]- trl^n.
Til' sd heu dieu tra ve chi sd ,, ^^^^ ^^i rimg da xay dung cac phucmg ^.^^g ^^^ gg luong tang trucmg C„ (ZCJ v(, ^^^ hidnt?!' duac tdng hgp tai bang 4.
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THAN
8/20J
KHOA HOC C d N G N G H |
B i n ^ 4: Fliuong trinh tuans quan giOa hioDg tSng hudng v i chi sd didn tich tin R
0,877
Sig.
0,001
Sigt 0,001
Sigt, 0,014 Z(CJ = 6,237 - 0,035*C=^ + 6.537E-5*C3.^ - 0*C3,'
0,877 1 0,001 1 0,001 1 0,014 Z ( C J = 6,237 - 0,035*C + 6,537E-5* C^i^
0,847 1 0,001 1 0,061 | 277,858
Z ( C J = 0,537-H ^'"
Sigt.
0,031
SigtH 0,000 (^3)
1 0,031
(^)
0,001
(^5) Cic phuong trinh tuang quan (3-3), (34) vi (3-5)
cho thiy giua lirong tang trudng vd didn tich tin vdi chi sd didn tich tin hidn tai cd mdi quan hi chat (dd tin ciy 0,847 - 0,877). Tuy nhien phuang tiinh (3-5) cd xic suit t cua tham sd a (Sigt^) = 0,061 > 0,05 ndn tham sd a khdng tdn tai, mat khic Idii hd sd d ciia phuong trinh (3-3) = 0 thi phuong trinh (3-3) Iai chinh li phuang trinh (34). Vi viy, chiing ta chi cd thd sir dung phtrong trinh (34) dd suy doin lupng ting trudng di^n tich tin binh quin ciia cic frang thii thim tiiuc vit khu vyc nghidn ctiu thdng qua chi sd Cai hidn tai.
£>d che phu cua ciy bui, thim tuoi (CP, %) va dg che phu cua vit roi rung (VSR, %)
DO che phu ciy bui tham tuoi li mdt chi sd lidn quan ddn kha ning phdng chdng xdi mdn eua thim thuc vit rimg. Kdt qui xic dinh chi sd niy a cic frang thii rimg d' khu vuc rung phdng hO Cua Dit frong 3 Ihdi didm (2008, 2010 vi 2012) dupc tiie hidn b hinh 6.
Nhin chung dp che phu eua lop ciy bui tham tuoi bidn dong Idii rd rdt theo trang thii rimg, khi cao d frang thii HA, IIIAj vi giam dan 6 cic tr^g thii IIIA2, UB, IIIA3, thip nhit d cic ti:ang thii mB.
Vd miic dd bidn ddng, b cic trang thii rimg giiu vi trung binh, nai cd chi sd didn tich tin cao dd che phii ciia ciy bui, thim tuoi giim din theo thdi gian.
Tuy nhidn, ehi sd niy lai cd xu hudng tang, giim theo thdi gian or cic trang thai IIA vi mA].
Kdt qua didu fra ty Id che phii cua vit roi ryng (VRR, %) duac bidu tin tai hmh 7.
Nhin chung, dd che phii ciia vit roi rung d cic frang thii rimg Ii khi cao, 59,18 -78,34%, tiiap nhit or frgng thai IIA vi ddu cd xu huang tang din theo thdi gian, tuy nhidn miic dp ting ldn li khdng nhidu, chi duy nhit d trang thii UA muc dO hidn ding vd dd che phii ciia vit roi rung Ii rd rang.
- Nam 200s -Nam 2010
>^> 0 0 T J J -CV
Trang lliai TTV
Hinh & Bi^n dOng t^ 1$ che phil cAy bi4, thdm tuoi
Nam2(l()X - N a m 2010 - Nam2012
Tranti lliai TTV
Hinh 7: BiAi ddng t^ 1^ che phii v&t roi ryng qua cdc ndm
N O N G NGHlfP VA PHAT TRIIN NdNG THdN - KY 2 • THANG 8/2014 99
KHOA HOC CONG NGHE
4.K£TLUANVAKHUYHyNGII 4.1. Kdt luin
Rimg phdng hd Ciia Dat cd sd luong 23 - 48 Ioai cay gd/d tidu chuan (2000 m^ vdi sd loai tham gia vao cdng thiic td thanh 7 -15 loai. Chi sd da dang loii tuang ddi cao (2,649 - 3,431) va miic do phong phu kha cao (2.277 - 3,863). Tuy nhien muc dd bien ddng vd cac chi sd da dang Ioai giua cac frang thai la dang ke, cao nhat b trang thai rimg dang phuc hdi (IIB) va thap nhat b trang thai (IIA). Da xuat hien mdt sd quan xa ven loai cay uu the thuoc nhdm cay chiu bdng cd gii tri (Thi rimg, Tau mat, Dinh huong, Gidi, Ring rang, Gidi gimg, Tnrdng sang, De gai. Tram) b trang thai IIIB, IIIA,, IIIA2.
Phan bd N/HVN cua ting cay cao tuan theo luat phan bd Weibull mdt dinh lech trai, vdi dp lech A tir 0,00316 den 0,1089 va do nhon a tir 1,457 den 3,539.
Quan he giu'a HVN - D n theo cac dang ham tuong quan Cubic vi ham S voi muc dd tir hoi chat den rat chat vdl he sd tuang quan 0,4303 - 0,9386.
Mat do cay tai sinh dudi frang thai rimg cd trir lugng nhin chung li kha ldn (> 3000 cay/ha) voi ti le cay cd tridn vgng dat trdn 55%, nhung b trang thai (ILA) mit do cay tai sinh cd trien vong lai rat thap (<
1500 cay/ha). Mat dd cay tai sinh trien vong cd xu hu'dng tang theo Ihdi gian.
Vol cac chi sd lien quan den kha nang dieu tiet ddng chay mat va chirc nang chdng xdi mdn cua tham thuc vat rimg chi sd dien tich tan C^i dat gia fri tuong ddi cao 150-300%, nhtmg do che phu ciia cay bui, tham tuoi chi d muc do tmng binh (40-65%), co su bien ddng giira cac tiang thai va co xu huong tang dan theo thdi gian.
Tdc dd tang truong binh quan nam ciia chi sd dien tich tan Z {CJ ciia cac trang thai tham thuc vat tai khu vuc nghien cim cd the udc tinh thong qua chi s6 C,^, hien lai voi he sd tuong quan la 0,877 theo phuong trinh'
Z(C J = 6,237 - 0,035*C,. + 6,537E '* Cj 4.2. Khuydn nghi
Cic tiiam thuc vit cua khu vuc nghidn cuu cfi tinh da dang kha cao v i dang d' frong giai doan phuc hdi tich cue the hien rd net d su gia tang ve mat d(
ting ciy cao, mat dp cay tii sinh trien vgng, chiaS dien tich tan. Do vay cin tidp tuc khoanh nudi baovt va xuc tien tai sinh tu nhidn nhim duy tri, phit huy hieu nang phdng hg, nang cao hieu qua kinh te ciia rimg thong qua viec nudi dudng rimg vi chat cai thidn td thanh cay cd gia tri.
Cd the ap dung phuang trinh Z(C^ de xac djnli luong tang trudng ve chi sd dien tich tin va du bao dien tich tin cua Iim phin frong tuong lai thdng qua \ chi sd dien tich tin hidn tai Iim ca sd xac dinh hi&i nang phdng hd toi uu cua rimg.
TAI UEU THAM KHAO
1. Vd Dai Hai, 1996. Nghien cuu cac dang da ^ tnic hgp ly cho rung phdng ho dau ngudn d Y\i\ \ Nam. Luan an phd tien si khoa hge ndng nghi^.
Vien Khoa hge Lam nghiep Viet Nam, Ha Ndi.
2. Vu Tidn Hinh, Pham Van Dien, 2006. NgM^\
cuu cac giai phip phuc hdi limg bing khoanh nudi tai cac tinh phia Bdc Viet Nam. Bao cao Khoa hoc de tai cap Bd. Dai hoc Lam nghidp.
3. Nguydn Ngoc Lung, 1991. Phuc hoi ning a Viet Nam. Thdng tin Khoa hge Ky thuat Lam nghidp, ( l ) , f r . 3 - l l .
4. Pham Thd Vinh (chii nhiem de tii), 2009. Bio cao tong hgp ket qua nghien cuu dc- tai khoa hoc W ban '^Einh gii anh hudng cua cin true tham thuc i^' anh hudng ddn lu lut, han hin h n-c sdng Chu, di xuit cac giai phap giam tiiidd'. p j ^ \^ . vifti Khoa hge va Cdng nghe Vidt Nam, ,5^ 2009.
100 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG V201t
KHOA HOC CGNG N G H |
THE SPECIES DIVERSnY AND SniUCTURE OFTHE WATERSHED FOREST AT CUA DAT RESERVOIR OF THUONG XUAN DISTRICT, THANH HOA PROVINCE
Do Anh T\ian. Nguyen Huu Tan Summary
The watershed forests at Cua Dat reservior have important ecological functions in water conseivation and soil erosion prevention. However, the forests in the area is mainly the degredaded secondary forest, and have not been eraluated in terms of species diversity and structure as the basis for determining an appropriate forest structure fiinctions of a watershed protection vegetation. This research results from 12 plots on speaes diversity and structural characteristics of flie forest types showed that the forests of Cua Dat reservior are rather diversify in terms of species richness with 23-48 frees species per 2000 m^ plots.
The species diversity index is relatively high ( 2.649 to 3.431), and abundance level vanes from 2.277 to 3.863), but there is a large degree of variation between the large states . In rich and medium forest, there have appeared a number of communities with dominant free species belonging to the group of shade tolerant valuable timber trees. Sapling density under conopies of stocked forest ypes are generally rather high ( > 3000 saplings / ha ) with the high percentage of good quality ones (over 55%). TTie leaf area index (Cai ) reaches relatively high values, from 150 to 300%, but flie ground cover is at moderate level (approximately 40%) and varies greafly among the forest types. In the last 5 years, these cover indicators is increasing by time. The inceament of Cai (Zcai) of the forest vegetation in the study area can be estimated by the following equation wifli high level of correlation coefficient (0.877): Z ( Cai ) = 6.237 - 0.035 x Cai + 6.537 * Cai E-^ * Cai^.
Keywords: Cua Dat reservior, forest structure, canopy area index, species diversity, saplings, headwater forests, Thuong Xuan district, Thanh Hoa province.
Ngudi phin bidn: PGS.TS. Vd Dai Hai Ngiy nhin bii: 2/6/2014
Ngiy thdng qua phin bidn: 2/1 mu Ngiy duydt ding: 9/7/2014
^ 6 N G NGHIEP vA PHATTRIIN NONG THON - KY 2 - THANG 8/2014 '0'
