KHOA HQC CONG NGHE
IMGHIEIV C U U L U g i V G CAC BOIM T I C H L U Y C U A R U I V G IMGAP M A I M T A I VUOIXI Q U O C G I A X U A I V T H U Y ,
IMAM D f l V H
NguyIn Thi Hdng Hanh^, Nguyen Hoang Tung^, Pham Hdng TinhS Le Ddc TruongS NguySn Khac Thdnh^
T6MTAT
Nghien cihi dinh lugng cac bon ciia rimg ngap man tai Vuon Qudc gia (VQG) Xuan Thuy dupe thue hien vao nam 2018, thong qua 3 be chiia cac bon (be chira cac bon trong sinh khoi thuc vat it Uen mat ddt, b^
chiia cac bon trong sinh khoi tbuc vat o duoi mat dat va be chiia cac bon trong dat). Ket qua ngbien ciiu cbo thdy, luong cac bon trong dat (159,96 -163,33 tan/ha) cao hon khoang 3,11 - 9,40 Idn be chiia cac bon trong sinb khoi thuc vat duoi mat dat (24,37 - 25,72 tan/ha) va 1.01 -1,20 lan so voi be chiia cac bon trong sinh khdi thirc vat tren mat dat (28,37 - 30,81 tan/ha). Kha nang tich luy cac bon ciia rimg dat gia tri trung binh la 14.32+4,54 tan/ha/nam (tuong ling voi luong CO2 la 52,55+11,56 tan/ha/nam). Vol kha nang tich luy cac bon cao trong cay va dac biet la trong dat rimg, la co so khoa hpc de thuc bi^n trCng rimg ngap man ket hgp voi cac bien phap bao t6n va quan ly ben vQng nhdm tang cuung trir luong cac bon bap thu, giam phat thai khi CO^ o cac vimg ven bien Viet Nam.
TCrldida: Cac bon, rung ng^p mSn, sinh khdi, VQG Xuan Thuy.
I.DATVANDE
Viet Nam da ti-o thanh thanh vi6n cua nhieu to chiic quoc te ve bao ve va phat trien rimg trong do chuong trinh REDD va REDD"^ Id mpt trong nhimg chuang tiinh co nhi^u dong gop heh cue trong cong tac xay dung cae chinh sach, hoat dong nhdm nang cao hieu qua quan ly rimg mot cdch phii hop voi dieu kien cua Viet Nam. Tuy nhien, de tham gia va thue hien cdc chuong trinh nay, Viet Nam can phai tinh toan duoc trir luong ede bon cua rimg hay uoe tinh sinh khdi, trir lugng eac bon rimg luu giO vd luong CO2 hap thu hoac phdt thai ti-ong qua trinh quan ly rimg. Vl vay, vdn de dmh lupng eac bon cua rimg hay uoe tinh duge sinh khoi, trir luong cac bon rimg lim giii va luOTig CO2 hap thu hoac phdt thai trong qud hinh quan ly rimg de tham gia chuong trinh REDD*
o Viet Nam la mpt nhu cdu cap thiet, nhdm eung cap thong tin du Ueu phdt thai COg tir quan ly rimg ddng tin cay.
Vuon Quoc gia (VQG) Xuan Thiiy, tinh Nam Dinh duoc coi Id mot trong nhtmg vimg dat ngap nuoc dien hinh ciia cd nuoe noi chung vd cac tinh ven bi^n mien Bde noi rieng. De gop phdn ddnh gid kha nang tich iQy cac bon cua rimg, da thuc hien nghien
cuu dinh lupng eac bon cua rimg ngap man tai VQG Xuan Thuy. Ket qua nghien cim phue vu quan ly nha nuoc ve giam phat thai khi nhd kinh, cung cap co so cho viee ddm phdn quoc te trong eac chuong trinh thuc hien cat giam khi nhd kinh.
2 . DOI TUONG VA PHUONG P H A P NGHBII CUU 2.1. D6i tuong nghiSn cihi
Lugng cdc bon tich liiy trong sinh khoi tren mat ddt (than, cdnh, la), dudi mat dat (re) cua cay ngap man thuc thu than g6 cua rimg va lupng cac bon tich lay trong dat eua rimg ngap man theo huong ddn eua IPCC (2006) tai VQG Xuan Thuy thuoe dia phan xa Giao Thien, huyen Giao Thuy, tinh Nam Dinh. Cac lodi dae trung thuc thu than go khu vuc nghien euu ehu yeu gom trang (Kandeha obovata), su {Aegiceras comieulatuni).
2.2. Phirong phdp nghien cuu 2.2.1. Phuong phap bd tri thi nghiem Bo tri 3 tuyen dieu ti-a thi nghiem chay vuong goc de bien, mfii tuyen each nhau khoang 200 m.
Tren mdi tuyen dieu tra lap 3 6 tieu chuan, cae 6 tieu chuan dupe lap dira theo phuong phdp nghien cuu cua Nguyen Thi Hong Hanh vd cong su, 2017 [3], m6i 6 CO kich thuoc 10 m x 10 m = 100 m^ Khoang each giira eac 6 khoang 100 m. Vi tri ede 6 tieu chuan ' Truong Dai hpc Tai nguySn va Moi trucmg Ha Npi
^ Cong ty Co phan ETC
KHOA HOC C O N G N G H E
thuc hien nghien oiu duoc the hien qua bang 1 va hinh 1.
Thoi gian nghitn cuu duoc thuc hien tir thang 1 den thang 12 nam 2018. Trong thoi gian nghi6n ciiu,
tien hanh 2 dot thuc dia do chieu cao, duong kinh than cay va lay dat tai dia diem nghien ciiu: dgt 1 vao thang 4 nSm 2018, dot 2 vao thang 11/2018.
B a n E l . V Tuyen di6u tra
1
2
3
tri cac 6 ti^u chuan 0 tieu chuan
X T l . l XT 1.2 XT 1.3 XT 2.1 XT 2.2 XT 2.3 XT 3.1 XT 3.2 XT 3.3
trong rimg ng^P mgn t ^ VQG Xuan Tliuy Toa do 20" 13 58.8' N 20'' 13' 59.7' N 20°14'00.rN 2 0 ° 1 4 0 5 . r N 20° 14'06.1" N 20°14'06.7'N 20° 15'03.5" N 20° 15' 02.6" N 20° 15' 01.2" N
106° 33'56.5" E 106° 33' 57.0" E 106° 33' 57.3" E 106° 34'48.7" E 106° 34 49.4" E 106° 34' 50.3" E 106° 34' 17.1" E 106° 34' 19.5" E 106° 34' 19.9" E Ghi ehu:XT 1.1, XT 1.2, XT 1.3la eac d tidu chuan eua tiiydh dieu tia 1;XT2.1, XT2.2, XT2.3la cac d tieu chuan cua tuydn diiu tia 2;XT3.1, XT3.2, XT3.3 la cac d tieu chuan cua tuyen dieu tia 3.
X 10 m). Dua trfin sd lupng eay trung binh co trong mot 6 tieu chuan de tinh mat dp cay cua m6i tuyen dieu tra.
2.2.3. Phuong phap xac dinh sinh khdi Tir ket qua do duong kinh than ciia cay, xdc dinh sinh khoi trSn mat dat va duoi mat dat cua cay bing cdch quy doi tir ducmg kinh than eay theo cdc cong thuc sinh khoi cua Nguyfin Thi H6ng Hanh va cong su (2017) [3] doi vdi loai trang (Kandeha obovata) vk cua Komiyama va cong su (2008) [7] doi voi nhung loai eon lai.
Sinh khoi tren mat ddt va duoi mat dat cua o tieu chuan duoc tinh bdng tong sinh khdi tren mat dat va dudi mat dat cua tat ca cac cay trong 6 tieu chuan do.
2.2.4. Phirong phap xac dinh eac bon tich luy tiong sinh khdi cay
Tir sinh khdi eua cay vd rimg xac dmh luong cdc bon tich luy trong sinh khoi bdng cdch nhan sinh khdi cay hay sinh khdi ciia rimg voi he sd chuyen doi sinh khdi sang cdc bon. He sd chuyen ddi dupe xac dinh nhu sau:
- Ddi vol lodi hang (Kandeha abovata) dp dung he sd chuydn doi cua Nguyen Thi Hong Hanh va c6ng su (2017) [3] Id 0,4955.
- Ddi voi cac loai khde dp dung he sd ehuyen doi theo IPCC (2006) [5] Id 0,47.
2.2.5. Xac dinh luong CO2 hap thu tao ra sinh khdi eua eay
Hinh 1. VQG Xuan Thiiy - khu vuc nghien cim 2.2.2. Phuang phap xac dinh mat dp, chieu cao, dudng kinh than cua cay ngap man thuc thu thangd
Xae dmh duong kinh than cay bdng thud'c day do duong kinh (Forestry Suppliers Metric Fabric Diameter Tape Model 283d/5 m) tai vi tri 30 cm phia tren banh gdc ddi voi lodi trang (Kandeha obovata) vd tai vi tri 30 cm tren mat dat ddi vdi lodi su (Aegiceras comiculatuni).
Phuong phap xdc dmh chieu cao cay: duge do bdng thuoe met, bdt dau tinh tir vi tri do dudng kinh than den ngpn eao nhdt cua cay. Xac dmh chieu cao cua tat cd cae cay ngap man thuc thu than gd trong 6 tieu chuan.
Phuong phdp xac dmh mat dp cua cay: Tien hdnh dem sd luong eay trong mdi 6 tieu chuan (10 m
240 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 +2 - THANG 2/2019
KHOA HOC CdNG NGHE Tu lugng ede bon tich luy, xae dinh lugng CO2
bdng cdch chuyen doi tir eac bon tich luy, eu the:
Tdng lupng CO2 (tan/ha) = Tong cae bon tich luy (tan/ha) x 3,67 (hang sd chuydn doi dp dung cho tat cd cac lotii rimg).
2.2.6. Phuang phap xac dinh ham lupng cae bon tiong dat
Lay mdu dat: Su dung khoan lay mdu dat cua My vdi Modem HUNIwilde, ed chieu dai 120 em, lay mdu lan lupt tir tang ddt sau xudng 100 cm, dimg thuoe do vd lay dat ph^n tich 6 cac do sau 0-20 cm, 2040 cm, 40-60 cm, 60-80 cm. Sau do dem mdu dat ve Phdng thi nghiem mdi tiirdng, Trudng Dai hgc Tdi nguyen va Moi trudng Ha Npi de xu ly va phan tich.
Sd lupng mdu dat phan tich cae bon: Khuon dat/d tieu ehudn x 9 6 tieu chuan/rimg x 5 khoang dat/khu6n mdu (0 - 20 em, 20 - 40 em, 40 - 60 cm, 60 - 80 cm, 80 -100 em) x 2 dot lay mdu = 90 mdu.
Xac dmh ham lugng cae bon him eo (%) trong dat: theo phuong phap Chiurin (Le Van Khoa vd cong su, 2000) [8].
Xdc dinh tirii lupng ede bon trong dat dua theo nguyfen tde: ddt cd dung trgng rieng (specific bulk denify) dugc tinh bdng khdi lupng dat kho khong khi/the tich dat. Vi vay, lupng cac bon o dp sau nhat dinh tai mot khu vuc dupe tinh theo cong thiie eua Nguyen Thanh Ha, 2004 [1] va Kauffrnan & Donate, 2012 [61.
A(H) - Y^ a(h) X dh; a(h) = c(h) x ^
0
C(H)=A(H)xlO^
Trong do: dh [cm] Id dp sau cua mdt mdu dat; H [cm] la dp sau eua phdu dien dat thi nghiem; e(h) [%]
Id ham lugng cac bon o' dp sau h; T(h) [g/cm^] la dung trgng cua dat hay khdi lupng dat kho khong khi tren the tich dat d- dp sau h; a(h) [g/cm^j Id su tich luy ede bon trong dat d- dP sau h; A(H) [g/em^]
Id su tich luy cac bon ti-ong ddt o dp sau H; CCH) [tan/ha] la su tich luy cdc bon trong ddt cua rimg d- dp sau H,
2.2.7. Phuang phap danh gia kha nang tao be chua cac hon cua rimg ngap man
Ddnh gia khd nang tao be ehua cdc bon trong ddt cita rimg ngdp man (RNM) theo IPCC (2006) [5], dua vao cdc lan dieu tra xac dinh txu lupng cac bon a cdc be chica, tinh todn dp tang, giam binh quan eua lugng cac bon theo cong thiic:
AU - 4 t . AB = ^ i
Trong do: AB: Tin ehi ede bon trong mot khoang thdi gian; Atj: Trii luong cdc bon nghien ciiu tai thdi diem nghifen ciiu ti; Atg: Trir lupng cdc bon nghien ciiu tai thoi diem nghiSn eiiu tg.
3.KErQUAniGHBICUU
3.1. Mat do, dudng kinh than vd chi^u cao cua eay ngdp m ^ t^ii VQG Xuan Thuy - Co s& xdc dinh sinh khdi va lupng cdc bon cija sinh khdi rimg
Tai cac tuyen dieu tra xuat hien 2 lodi cay ngap man thue thu than gh do la loai su (Aegiceras comiculatunii va loai trang (Kandeha obovata), trong dd su xuat hien chii yeu va chidm uu the tai tuyen didu ha 1 vd 2, edn tuyen dieu tra 3 thi lodi hang chiem ira the. Do dd, mat dp cay trong 6 tiSu ehudn CO su khac nhau theo ttiyen dieu tra. Ket qua nghifen cuu ve mat dp, dudng kinh than vd ehieu eao cay the hien d bang 2.
Tuyen dieu tra Tuyen 1 Tuy^n 2 Tuyen 3
B4ng 2. Mat dO, dudng kinh, chi Loai
cay Sii Trang Sii Trang Sii Trang
Mat d6 (cay/ha) 4/2018 3800±4,28 1766+2,17 4133±4,42 2233+2,52 760+1,28 2800+3,25
11/2018 3800±4,28 1766+2,17 4133+4,42 2233+2,52 760±1,28 2800+3,25
^u cao cay ngap man tai "VQG Xuan Thiiy Duong kinh than (cm)
4/2018 6,71±0,33 6,89+0,59 6,46+0,78 7,27 +0,97 6,26+0,91 6,37+1,09
11/2018 6,91±0,53 7,12+0,82 6,69+1,01 7,54±1,24 6,42+1,07 6,58+1,30
Chieu cao cay (cm) 4/2018
197,3±19,8 204,2±25,2 188,6+15,1 212,8+19,4 147,4±13,3 233,8+31,6
11/2018 207,5+ 30,00 217,8±38,8 201,3±27,8 227,9+ 34,5 156,9±22,8 245,6±43,4 Ket qua o bang 2 cho thay, mat do cua loai su va
hang cd su khde nhau tai mdi tiiyen dieu tra. Trong hiydn dieu ti-a 1, loai sii chidm uu the vdi 3.800
eay/ha, edn loai trang ehi ed 1.766 cay/ha. Tuong tu trong tuyen dieu tra 2, lodi sit cung chiem 4133 cay/ha, cdn trang la 2.233 eay/ha. Mat khae tai tuyen
KHOA HOC C O N G NGHl
dieu tra 3, loai ti-ang chiem uu the hon vdi 2.800 cay/ha va loai su ehi co 760 cay/ha.
Duong kinh than cay va chieu eao eay cd su khac nhau giiia cdc lodi vd cdc tuyen dieu tra. Ngay ca khi cimg loai, dudng kinh than cay va chieu cao eay eung cd su khde nhau. Tai ede tuyen dieu tra, dudng kinh than eiia eay su (A corniculatum) la thap nhat. Dudng kinh than eua eay, ed anh hudng nhieu den sinh khoi cay va luong cae bon ti-ong sinh
khdi tren mat dat vd dudi mat dat cua cay (Nguyen Thi Hdng Hanh va cgng su, 2017) [3].
3.2. Lugng cac bon tich luy trong sinh khdi tren nUit ddt cua rung ngap man tgi VQG Xuan Thuy
Lugng eac bon tich luy tren mat ddt cua rimg ngap man tai VQG Xuan Thuy dupe Ihd hien trong bang 3.
Dpt didu ti-a
Thang 4/2018
Thang 11/2018
Tuyen dieu tra
Tuyen 1 Tuyen 2 Tuydn 3 Trung binh Tuyen 1 Tuyen 2 Tuydn 3 Trung binh
Luong cae bon trong sinh khdi tren mat dat cua
loai su 21,15+4,34 21,46+4,21 4,19+0,68 15,60+3,08 22,91+6,10 23,49+6,24 4,78+1,27 17,06+4,54
Luong cdc bon trong sinh khdi tren mkt dat
cua lodi trang 9,98+2,15 13,22±1,92 15,11+3,78 12,77+2,62 10,59+2,76 14,32+3,02 16,35+3,16 13,75±2,98
Tdng lugng cdc bon tich liiy trong sinh khdi tren mat dat cua
rimg 31,13+6,09 34,68+6,13 19,30+4,46 28,37+5,70 33,50+8,86 37,81+9,26 21,13+4,43 30,81+7,52 Ket qua nghien ciiu trong bang 3 cho thay,
lugng cac bon tich luy trong sinh khdi tren mat dat cua cay ty le thuan vdi sinh khdi tren mat dat cua eay. Tai dpt khao sat 1 (thdng 4/2018) loai su e6 lugng cdc bon tich liiy eao hon lodi trang, dat 15,60+3,08 tan/ha, edn loai ti-ang dat 12,77+2,62 tan/ha. Lugng cdc bon tich liiy tren mat ddt cua eac lodi cung cd su khac nhau giua eac tuydn. Ddi vdi lodi su, tuyen 2 co mat do eao nhat nen lugng eac bon tich liiy tren mat ddt tai tuyen ndy cao hon 2 tuydn eon lai, dat 21,46±4,21 tan/ha, tiep theo la tuyen 1 voi 21,15+4,34 tan/ha con thap nhdt la tuyen 3 vdi 4,19+0,68 tan/ha. Mat khac, ddi vdi loai trang cd mat do cao tai tuydn 3 nen lugng eac bon tich luy ti-en mat dat tai tijyen nay dat cao nhat voi 15,11+3,78 tan/ha, tiep theo la tuyen 2 vdi 13,22+1,92 tan/ha vd thap nhat Id tuyen 1 vdi 9,98+ 2,15 tan/ha.
Tai dpt khao sat 2 (thang 11/2018), loai sii eo lugng eac bon tich luy cao hon lodi trang, dat 17,06+4,54 tan/ha, cdn loai ti-ang dat 13,75±2,98 tan/ha. Lugng cac bon tich luy ti-en mat dat cua cac Ioai cung cd sir khde nhau giiia eac tuyen. Vd dpt 2 cd su gia tang lugng ede bon so voi dpt khao sat 1 vao thang 4/2018, cu the lugng eac bon trong smh khdi tren mat dat cua lodi sii gia tang 0,79±1,21 tan/ha.
lodi trang tang 0,56+1,17 tan/ha. Tdng lugng ede bon gia tang la 1,35+1,19 tan/ha.
Ddi vdi timg tuyen didu tra cd the thay tdng luong cac bon tich liiy trong sinh khdi tren mat dat eua rimg theo thu tu tuyen 2 > tuyen 1 > tuyen 3, cu the: tong luong cdc bon tich luy trong sinh khdi tren mat ddt cao nhat la d tuyen 2 voi 34,68 + 6,13 tan/ha, tiep do la tuyen 1 voi 31,13 + 6,09 tan/ha, thap nhat la tuydn 3 voi 19,30 + 4,46 tan/ha. Nhu vay, trung binh cac bon tich liiy trong sinh khdi tren mat dat cua toan bg khu vue nghien cim dat 28,37 + 5,70 tan/ha nhung cd su khde biet giiia ede tuyen dieu tra va giira cdc lodi cay ngap man.
So sdnh voi ket qua nghien ciru eua rimg trdng thudn lodi trang 18, 17, 16 tuoi tai xa Da Loc, huyen Hau Loc, tinh Thanh Hoa (Nguydn Thi Hdng Hanh va Ddm Trgng Due, 2017 [4]) thay, luong cdc bon trong sinh khdi tren mat dat eua rimg trdng thudn loai trang cao hon rimg ngap man VQG Xuan Thuy, cu the: lupng cac bon trong smh khdi tren mat ddt cua rimg 16 tiidi Id 49,27+1,22 tan/ha, cua rimg trang 17 tudi la 54,41+1,46 tan/ha vd riing trang 18 tudi la 60,31+2,10 tan/ha. Su khac nhau nay la do rimg trang hdng eo mat dp cao hon nhieu so vdi mat do rimg ngap man VQG Xuan Thuy, rimg trang 16 tudi
242 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1+2 - THANG 2/2019
KHOA HOC CONG NGH|
CO mat dp la 16.700 cay/ha, rxmg trang 17 tudi co mat do la 17.400 cSy/ha va rimg trang 18 tuoi co mat do la 18.000 cay/ha. Ket qua nghien ciiu da chi ra rang, luong cac bon tich luy trong sinh khoi tren mat dat cua rung phu thuoc vao thanh phan, cau triic va mat dp cila cay rung.
3.3. Lirpng cac bon tich liiy trong sinh khdi dinM mat dat cua ciy ngjp mSn tai VQG Xuan Thuy
Luong cac bon tich luy trung binh trong sinh khdi dum mat dat ciia cay dupe the hi^n trong bang 4.
Bang4. Lupi^
Dot dieu tra
Thang 4/2018
Thang 11/2018
g cac bon tich luy trone sinh khdi (tan/ha) dlKri mat Mt nia nmir niran mfln tai VOOXnan Thiiv Tuydn di^u
tra Tuyen 1 Tuyen 2 Tuyen 3 Tmng binh Tuyen 1 Tuyen 2 Tuydn 3 Trung binh
Lupng cac bon trong sinh khdi duoi mat dat
cua loai sii 18,29+3,78 18,31+4,68 2,97±0,68 13,19±3,05 19,24±4,73 19,49±5,86 3,02+0,91 13,98+3,83
Luong cac bon trong sinh khdi dudi mat dat
cua loai trang 6,06 ±1,87 13,22+3,08 14,28+3,34 11,18±2.76 6,54+2,35 13,73±3,59 14,97±4,03 11,74+3,32
Tdng lupng cac bon tich luy trong sinh khdi duin
mat dat cua rimg 24,35+5.65 31,53+7,76 17,25±4,02 24,37±5,81 25,78+7,08 33,22±9,45 18,17+4,94 25,72+7,15 Ket qua nghien cim eho thdy, o cae tuyen dieu
tra khde nhau thi lupng ede bon tich luy trong smh khdi dudi mat dat eua rimg ciing khac nhau phu thuoc vdo sinh khdi dudi mat ddt cua rimg. Sinh khdi dudi mat dat eua rimg cdng cao tiii lupng cdc bon tich luy trong sinh khdi dudi mat dat ciia rimg cang cao va nguoc lai. Theo do lugng cac bon tich liiy trong sinh khdi duoi mat dat theo tuyen didu tra gidm ddn theo thu tu tuyen 2 > tuyen 1 > tuyen 3 cu the: tuydn 2 cd lugng cae bon tich liiy trong sinh khdi
Bang 5. Luong cdc bon tich !uy trong sinh khdi fr^n rung ngap mdn t ^
dudi mat dat cao nhat voi 31,53+7,76 tan/ha, sau dd la tuydn 1 vdi 24,35+5,65 tan/ha va thap nhat Id tuyeh 3 vdi 17,25+4,02 tan/ha. Nhu vay tdng luong cac bon tich luy trong sinh khdi duoi mat dat tai khu vue nghien etiu la 24,37+5,81 tan/ha.
Ngodi ra, lugng cdc bon tich liiy trong sinh khdi dudi mat ddt cua loai su cao hon lodi trang, cu the loai su cd lupng cac bon tich luy trong smh khdi duoi mat dat dat 13,19+3,05 tdn/ha, eon lodi trang chi dat 11,18+2,76 tan/ha.
m$t dat, dudi mat flat vd trong sinh khdi tdng sd cua cdc tuydn di^u tra
Dot didu tra
Thang 4/2018
Thang 11/2018
Tuydn dieu h-a
Tuydn 1 Tuyen 2 Tuydn 3 Trung binh Tuyen 1 Tuyen 2 Tuydn 3 Trung binh
Lupng cac bon tich luy trong sinh khdi tren
mat dat cua rimg Tan/ha 3I,13±6,09 34,68±6,13 19,30+4,46 28,37±5,70 33,50±8,86 37,81+9,26 21,13+4,43 30,81+7,52
%
52,11 52,38 52,80 53,79 56,51 53,23 53,75 54,50
Lupng cac bon tich IQy trong smh khdi dudi mat
dat ciia riing Tim/ha 24,35±5,65 31,53+7,76 17,25±4,02 24,37+5,81 25,78±7,08 33,22+9,45 18.17±4,94 25,72±7,15
%
47,89 47,62 47,20 46,21 43,49 46,77 46,25 45,50
Lupng cac bon tich lUy trong sinh khdi tdng sd cua rimg
Tan/ha 55,48+11,74 66,21+13,89 36,55+8.48 52,74+11,51 59,28+15,94 71,03+ 18,71 39,30±9,37 56,53±14,67
%
100 100 100 100 100 100 100 100 Mat khde, trong dgt khao sat vao thang 11/2018,
lugng cdc bon tich luy trong sinh khdi duoi mat dat ciia lodi sii eao hon loai trang, cu the lodi su co luong cac bon tich luy trong smh khdi dudi mat dat dat 13,98+3,83 tan/ha, cdn loai trang ehi dat 11,74+3,32
tan/ha. Tdng lupng eac bon tich luy trung binh dudi mat dat la 25,72+7,15 tan/ha.
So sdnh ket qua nghien eiiu eiia ndy vdi ket qua nghien cuu cua Nguydn Thi Hdng Hanh, Dam Trong Diic (2017) [4] ve dinh luong cac bon trong sinh khdi
KHOA HOC C 6 N G NGHl
duoi mat ddt cua rimg h-ong tiiudn loai ti-ang 18,17, 16 tiidi tai xa Da Lpe, huyen Hau Loc, tinh Thanh Hda cho thay lupng cae bon tich luy ti-ong smh khdi dudi mat dat cua rimg ti-dng thuan lodi h-ang tiiong tu vdi rimg ngap man khu vuc nghien cim, eu the: rimg trang 18 tudi cd lugng ede bon tich luy ti-ong sinh khdi dudi mat dat la Icm nhat vdi 26,83+1,03 tan/ha, tiep den la rimg 17 tudi voi 24,06+0,71 tan/ha, tiiap nhat la rimg h-ang 16 tiidi voi 21,67+0,60 tan/ha.
So sdnh luong ede bon tich luy trong smh khdi tren mat dat vdi dudi mat ddt eua rimg thay, lupng cae bon tich luy trong smh khdi tren mat dat cao hon lugng ede bon tich liiy trong sinh khdi dudi mat ddt cua rimg. Lugng cdc bon tich iQy trong sinh khdi tren mat dat cua rimg dao dong trong khoang 19,30+4,46 tan/ha den 34,68+6,13 tan/ha, chiem 52,01 - 56,84%
lupng cae bon trong sinh khdi tdng sd cua rimg (Bang 5).
Lugng cac bon tich luy trong quan the rimg tai khu vuc nghien ciru dupe xac dinh dua vao ede bon
tich luy trong smh khdi tren mat dat vd sinh khdi dudi mat ddt cua cac quan the rimg. Ket qua nghien ciru eho thay, tai dpt khao sdt 1 (thdng 4/2018) tuyen 2 cd tdng lupng ede bon tich luy lon nhat dat 66,21±13,89 tan/ha, tiiydn 1 dat 55,48+11,74 tan/ha va tuyen 3 la thap nhat dat 36,55+8,48 tdn/ha. Luong cac bon tich luy tong sd eua qudn the rimg la 52,74+11,51 tan/ha. Tai dgt khao sat 2 cd sir gia tang vd lupng ede bon trong qudn the rimg cu the: tuyen 2 cd tdng lupng cac bon tich liiy Idn nhat dat 71,03±
18,71 tan/ha, hiyen 1 dat 59,28+15,94 tan/ha va tuyen 3 la thap nhat dat 39,30+9,37 tdn/ha. Lupng ede bon tich luy tdng sd eua qudn the rung Id 56,53+14,67 tan/ha.
3.4. Lupng cdc bon tich liiy trong ddt rimg ng$p man tai VQG Xuan Thiiy
Ket qua nghien ciiu lugng cdc bon tich liiy trong dat cua rimg ngap man dugc the hien trong bang 6.
Dpt lay mau
Thang 4/2018
Thang 11/2018
Dp sau Ciia dat (cm) 0 - 2 0 2 0 - 4 0 4 0 - 6 0 6 0 - 8 0 80-100 Tdng 0 - 2 0 2 0 - 4 0 4 0 - 6 0 6 0 - 8 0 80-100 Tdng
Tuyen didu tra 1 43,28+ 0,87 33,97+0,78 31,89±0,81 27,79+0,72 22,12+1,01 159,05+4,19 44,35+0,97 34,16+1,29 32,92+0,93 28,02±1,43 22,89+0,68 162,34±4,30
Tuydn didu tra 2 48,73±1,33 41,01+1,36 36,92±1,09 30,56+1,39 26,39+1,17 183,61±4,34 50,17+1,49 42,11±1,66 37,29+1,28 31,00±1,62 28,21+1,42 187,37+4,47
Tuyen dieu tra 3 43,86±2,13 34,85+1,14 26,82+1,04 20,32+0,64 11,38+0,65 137,23+3,62 44,58+0,74 35,36+1,22 27,29±0,76 21,17+0,62 11,89+0,43 140,29±3,77
Trung binh 45,29±3,84 36,61+1,09 31,88±0,98 26,22+0,92 19,96±0,94 159,96+4,05 46,37+1,07 37,21+1,39 32,50+0,99 26,73+1,22 20,99±0,84 163,33+4,18 Ket qua a bang 6 cho thay, lupng cac bon tich
luy giam dan theo do sau cua dat, cang xudng tang dat sau lugng ede bon trong dat cang giam. Dong thdi lupng cae bon tich luy trong ddt rimg eo su khde nhau tai hai dpt lay mdu.
Dpt lay mau ddt tiiang 4/2018, lugng eac bon tich liiy trong ddt tai eac tiiyen nghien cuu cho ket qua eu the nhu sau: tuyen 2 cd lupng cdc bon tich luy trong dat la cao nhat vdi 183,61+4,34 tdn/ha, tiep theo la tuyen 1 vdi 159,05+4,19, thap nhat la tuyen 3 vdi 137,23+3,62 tdn/ha. Ket qua nghien cim lupng cac bon ti-ong dat vao tiiang 11/2018 eho tiiay, lupng
cae bon tich luy trong dat tai tuyen 2 eung cd lupng cac bon tich luy hong dat la cao nhat voi 187,37+4,47 tdn/ha, tiep theo la tuyen 1 vdi 162,34+4,30, thap nhat la myen 3 voi 140,29+3,77 tdn/ha. Trong qua trinh nghien ciru cho thay, tuyen 2 cd lugng cdc bon tich liiy trong dat rimg cao hon eac tuyen khde, nguyen nhan cd die Id do mat do cua rimg tai tuyen 2 cao hon so vdi tuyen 1 vd tuyen 3 (Bang 2), luong cdc bon trong sinh khdi tren mat dat va dudi mat dat cua rimg tai tiiyen 2 ciing cao hon tuyen 1 (Bdng 3, 4, 5), dieu nay cho thay vai trd cua rimg trong viec tich liiy cdc bon trong dat rimg. Kha nang tich luy cdc bon
244 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1+2 - THANG 2/2019
KHOA HOC C O N G NGHE
trong ddt phu thudc vao mat dp eay eua rirng. Ket qua nghien ciiu ve lupng cae bon tich liiy trong cay, trong ddt eho thay, su ddng gop eua sinh khdi re den vat chat hiiu co trong ddt rat quan trong da tao cho dat rimg la be chiia cdc bon (Nguyen Thi Hong Hanh vacpngsu,2017)[3].
Ket qua 6 bang 6 edn eho thdy, lupng cac bon hong ddt gia tang theo thdi gian, eu the thang 4/2018, lupng cac bon trong dat dao dong trong khoang 137,23+3,62 tdn/ha den 183,61+4,34 tan/ha, sau 6 thdng (thdng 11/2018) lugng cac bon dao dong h-ong khoang 140,29±3,77 tan/ha den 187,37+4,47 tdn/ha. Su gia tang lugng cdc bon trong dat rimg co
trinh thue hien cdt giam khi nha kinh nhu REDD va REDD*.
3.5. Ddnh gid kha nang tao hi chua cdc bon tai VQG Xuan Thuy
Dua theo huong ddn eua IPCC (2006), danh gia kha nang tao be ehiia cac bon cua rimg thong qua 3 bd ehiia: (1) be chiia cdc bon trong sinh khdi tren mat dat, (2) be chica ede bon trong sinh khdi dudi mat dat vd (3) be chiia cac bon trong dat. Dua vdo hai dpt dieu tra xdc dinh trii luong cac bon d ede be ehua, tinh toan do tang, giam binh quan eua lupng cac bon cua rimg. Ket qua nghien cuu duge the hien tai bang 7.
y nghia quan trong trong vide tham gia cae chuong
Bang 7. Banh gid Idia nang tao b^ chiia cdc bon (tdn/ha/nam) ciia VQG Xuan Thuy
Tuydn dieu tra
1 2 3 Trung binh
Bd chiia cac bon trong sinh khdi tren
mat dat Cac bon tich luy 4,74 6,26 3,66 4,89+2,26
CO2 tuong ling 17,39 22,97 13,43 17,93+
4,21
Be chiia cac bon trong sinh khdi dudi
mat dat Cac bon
tich liiy 2,86 3,38 1,84 2,69±
1,89
CO2 tuong ling 10,50 12,40 6,75 9,88+
3,08
Be chiia cac bon trong dat Cac bon tich luy 6,58 7,52 6,12 6,74+2,94
CO2 tuong ling 24,15 27,60 22,46 24,74+
8,37
Kha nang tich luy cac bon cua rimg Cac bon tich luy 14,18 17,16 11,62 14,32±
4,54
CO2 tuong ling 52,04 62,97 42,64 52,55±
11,56 Ket qua nghien ciiu trong bang 7 cho thay,
lupng cac bon tich luy tiong cac bd chiia gia tang theo thpi gian, cu thd; be chiia cac bon trong sinh khdi fren mat dat (than, canh, la) cua rimg sau mpt nam tang Idn mpt luong dang ke. Lupng cac bon tich luy cao nhat tai tuydn dieu fra 2 vai 6,26 tan/ha/nam (tuong ling vol lupng COj hap thu la 22,97 tan/ha/nam), tidp theo la tuydn didu fra 1 vdi 4,74 tan/ha/nam (tuong ling vdi lupng COj la 17,39 tan/ha/nam) va thap nhat la tuydn 3 vdi 3,66 tan/ha/nam (tupng ling vol lupng CO; hap thu la 13,43 tan/ha/nam).
Be chiia cac bon frong sinh khdi dudi mat dat (rd) ciia rimg: luong cac bon tich luy cao nhat tai hiydn didu fra 2 vdi 3,38 tan/ha/nam (hiong img voi lupng CO2 hap thu la 12,40 tan/ha/nam), tiep theo la hiyen didu fra 1 la tang 2,86 tan/ha/nam (hrong ling vdi lupng CO2 la 10,50 tan/ha/nam) va thap nhat la hiydn 3 vdi 1,84 tan/ha/nam (hiong tmg vdi lupng CO, hap thu la 2,69 tan/ha/nam).
Bd chua cac bon frong dat cua rimg: sau mdt nam tang len mpt lupng dang ke, lupng cac bon tich
luy them vao dat rimg tuong ling vdi lupng CO2 dat gia tri cao nhat la tuydn 2 vdi 7,52 tan/ha/nam (tuong ling vdi lupng CO, la 27,60 tan/ha/nam), tiep theo la tuydn 1 vdi 6,58 tan/ha/nam (tuong ling vdi lupng CO2 la 24,15 tan/ha/nam), thap nhat la tuydn 3 vdi 6,12 tan/ha/nam (tuong ling vpi lupng CO2 la 22,46 tan/ha/nam).
Kba DiiDg lao be chira cacboD tivDg rinig Dgap man
i'.is mi ^ K i »
i^ll lili iJ
• Bcduracjcbojiltoj^sinlikhailraimildal • BechiiacacttoniroiijsiiiliktHiidutniiiSliIit
• Bcdunocbontrojftlii * Bed[iiac«:boolninganliUKncua[mi;
Hinh 2. Kha nSng t&o b^ chua cac bon ciia rimg nj man tai VQG Xudn Thuy
KHOA HOC C O N G N G H £
Kha nang tich Itiy cac bon hdng nam cua rimg ngap man VQG Xuan Thiiy tuong img vm lupng CO2
"tin dung" (credit) tang theo thdi gian, hieu qua tich luy dat gia tri cao nhat trong nghien ciiu nay la tuyen 2 vdi 17,16 tan/ha/nam (tuong ling vdi lugng CO2 la 62,97 tan/ha/nam), tiep theo Id tiiyen 1 vdi 14,18 tan/ha/nam (hrong iing voi lupng CO^ la 52,04 tan/ha/nam), thap nhat tuyen 3 voi 11,62 tan/ha/nam (tuong img vdi lugng COa la 42,64 tan/ha/nam) (Hinh 2).
Voi kha nang tich luy cae bon cao trong eay vd dac biet la trong ddt rimg. Id co sd khoa hoc de tiiuc hien trdng rimg ngap man ket hpp vdi cdc bien phdp bao ton vd quan ly ben viing nhdm tang eudng trii luong cae bon hap thu, giam phdt thai khi CO2 d cdc vimg ven bien Viet Nam nhdm iing phd voi bidn ddi khi hau.
4. KET LUAN
Nghien ciiu da danh gid duoc lugng cdc bon tich luy trong shih khdi tren mat ddt, dudi mat dat vd lugng cdc bon trong dat cua rimg ngap man VQG Xuan Thuy:
Tai hai thdi didm dieu ti-a (thang 4/2018 vd thdng 11/2018), lugng cac bon tich liiy trung binh trong sinh khdi tren mat dat eua RNM dao dong 28,37 - 30,81 tan/ha, trong sinh khdi dudi mat dat cua RNM dao dgng 24,37 - 25,72 tan/ha, ti-ong dat RNM dao dong trong khoang 159,96 - 163,33 tan/ha.
Luang cac bon tich liiy trong ddt eao hon khoang 3,11 - 9,40 lan lugng cac bon trong sinh khdi dudi mat dat va 1,01 -1,20 lan so vdi luong eac bon trong sinh khdi tren mat dat cua rimg.
Lugng ede bon tich luy cua rimg ngap man VQG Xuan Thuy tuong iing vdi luong CO2 "tin dung"
(credit) cd khuynh hudng tang theo thdi gian. Lupng cac bon tich luy cua rimg thong qua 3 be chica (be ehiia eac bon trong sinh khdi tren mat ddt, dudi mat dat vd trong dat eua rimg) dat gia tn tiimg binh la 14,32±4,54 tan/ha/nam (tuong iing voi luong CO^ la 52,55+11,56 tan/ha/nam).
Vdi kha nang tich luy cac bon cao trong cay va dac biet la trong dat rimg. Id eo so- khoa hpe de thue hien trdng rimg ngdp man ket hop vdi eac bien phdp bdo tdn vd quan ly ben viing giiip tang eudng trii lupng eac bon hap thu, giam phat thai khi CO2 d' cdc viing ven bidn Viet Nam nhdm iing pho vdi bidn ddi khi hau.
LOI CAM ON
Nghidn CUV duoc hoan thanh dudi su hd ti-a kinh phi cua de tai ma sd TNMT.2018 05.06. Cae tac gia xin tiin trong cam on.
TAI L B I THAM KHAO
1. Nguyen Thanh Ha, Yoneda R., Ninomiya I., Harada K., Tan D. V., Tuan M. S., Hong P. N., 2004.
The effects of stand-age and inundation on the cae bon accumulation in soil of mangrove plantation in Nam Dmh, Northern Vietnam, The Japan society of ti-opical ecology, 14 (2004): 21-37.
2. Nguyen Thi Hong Hanh, Pham Hong Tinh, Mai Sy Tuan, 2016. Allometry and biomass accounting for mangroves ICandeUa obovata Sheue, Liu & Yong and Sormeratia caseolaris (L.) Engler planted in coastal zone of red river delta, Vietnam, International Journal of Development Research.
Vol.06, Issue, 05 (2016): 7804-7808.
3. Nguydn Thi Hdng Hanh (ehii biSn), Pham Hdng Tinh, 2017. Sach chuySn khdo "Dinh lugng cdc bon trong rimg ngap man trdng viing ven bien mien Bde Viet Nam". NXB Khoa hoc Tu nhien vd Cong nghe.
4. Nguydn Thi Hong Hanh, Ddm Trgng Diic, 2017. Danh gia kha nang tao be chiia cac bon rimg trdng tiiudn loai trang 18, 17, 16 hjoi tai xa Da Loc, huyen Hau Lpe, tinh Thanh Hoa. Tap chi Khoa hpc - Dai hpc Qudc gia Hd Ngi (33); 14-25.
5. IPCC, 2006. IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by National Greenhouse Gas Inventones Programme, Eggleston H. S., Buendia L, Miwa K., Ngara T , Tanabe K., (eds). Pubhshed: IGES, Japan.
6. Kauf&nan J. B., & Donato D., 2012. Protocols for the measurement, monitorring and reporting of structure, biomass and carbon stocks m mangrove forests. Bogor, Indonesia: Center for International Foresti7 Research (CIFOK).
7. Komiyama A., Ong J. E., Poungpam S., 2008.
Allometry, biomass, and productivity of mangrove forests: A review. Aquatic Botany, 89:128-137.
8. Le Van Khoa, Nguyin Xuan Cu, Biii Thi Ngpc Dung, Le Dire, Trdn Khde Hiep, Cdi Van Tranh, 2000.
Phuong phdp phan tich dat, nude, phan bdn, cdy trdng. NXB Giao due: 71-74.
246
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1+2 - THANG 2/2019
KHOA HOC CONG NGHfi
STUDY ON CARBON STOCK IN MANGROVE FOREST OF XUAN THUY NATIONAL PARK, NAM DINH Nguyen I h i Hong Hanh\ Nguyen Hoang Tung^, Pham Hong TinhS
Le Dac TruongS Nguyen Khac Thanh^
'Hanoi University of Natural resource and Environment
^EJC Joint Stock Company Summary
Caron stock in three carbon pools of the mangrove forests at Xuan Thuy NaUona! Park (aboveground biomass, belowground biomass and soil carbon pools) was quantified in 2018. Tbe results showed that soil carbon pool (159.96 -163.33 tons per hectare) was about 3.11 - 9.40 times larger than that of above ground biomass carbon pool (24.37 - 25.72 tons per hectare) and 1.01-1.20 times larger than that of below ground biomass carbon pool (28.37 - 30.81 tons per hectare). The average carbon accumulation rate of the mangrove ecosystem was 14.32+4.54 tons per hectare per year (corresponding to 52.55+11.56 tons COg per hectare per year). Tbe relative high carbon stock accumulated m the biomass, especially in tbe soil of mangrove ecosystem at Xuan Thuy National Park could be a bard scientific basis of mangrove rehabitabon, sustainable conservation and management for increasing carbon sequetrabon and reducing COj emission in coastal areas of Vietnam.
Keywords: Carbon, mangroves, biomass, Xuan Thuy National Park.
Ngudi phan bien: PGS.TS. Pham Mmh Toai Ngdy nhan bdi: 7/12/2018
Ngdy thong qua phan bi0n: 9/01/2019 Ngdy duy^t dang: 16/01/2019
