THANH PHAN HOA HOC CUA DAT KHU BAO VE CANH QUAN RlTNG TRAM TRA SU- TINH AN GIANG
Tripang Thj Nga Dinh Hoai IJng
^, Nguyin Cong Thuan ' Bui Tru'ang Tho
I.GIOriTHIEU
Riling Tram Tra Su" la mot trong s6 nhu-ng viing dit ngap nLPdc npi dja quan trong co tinh da dang sinh hoc eao cua Dong bing sdng CCfu Long. Vai nhOng u'u th§ v§ dia hinh, di§u kien ty nhien, va tai nguyen thien nhien, Tra Sy la mot trong nhOng khu rii-ng Tram du-pc danh gia la khu dit ngap nydc dpc dao, co canh quan dep.
Hien tu-png nay lam cho dien tich Tram thu hep din, mit di ve my quan. Va hien trang nay n4u ti^p tuc trong t^ong lai co the m§t di noi cw trii cOa cac loai chim din d§n giam si/ da dang sinh hoc, khong con hip din khach du lich. Do do d l nghien cipu danh gia thyc trang va 6k ra giai phap thich hpp cho cong tac quan ly rij-ng Tram Tra Su-, d§ tai "Thanh phan hoa hoc cua dat
khu bao ve canh quan rung Tram Tra Stp- tinh An Giang" 6wac thijc hien nhim ti§n hanhkhao sat, danh gia thanh cac thanh phin hoa hpc ciia dat trong khu ru-ng Tram Tra Su", gop phin giai thich nguyen nhan suy thoai cua rieng Tram trong nhij-ng nam gin day va dinh hydng cho cong tac quy hoach, quan ly rifng tram Tra Su" phu hpp trong tyong lai.
2. PHUVNG PHAP NGHIEN CIJU
2.1 D§ tai du'ac ti§n hanh trong thai gian 4 thang tij' 15/01 din 20/05/2008 tai rirng Tram Tra S\r
D i t Tra Sy chia lam 2 khu, khu I: 392,7ha va khu II: 440,7ha. Xung quanh m6i khu co he thong de bao khep kin. M6i khu lai dypc phan thanh 6 khoanh rieng biet (cac khoanh la, lb, 2a, 2b, 3a, 3b thupc khu I; cackhoanh 4a, 4b, 5a, 5b, 6a, 6b thupc khu II. Mau dat dypc liy tai cac khoang noi tren a ting mat 0-20cm.
2.2 Phu'O'ng phap thu va phan tich mlu Oit sau khi mang v§ phong thi nghiem miu dypc trai deu hoae be nho, rai tren cac khay giiy (giiy cacton): dat miu nai thoang khi, mat, khong phai miu tryc ti§p dydi anh sang mat trdi. Trong di§u kien thuan Ipi m i u d i t dypc phai kho it nhat trong vong 15 ngay; nghien dat va cho qua ray 0,5mm.
Phyang tien thyc hien g6m co cac may moc thi4t bi chuyen diing nhy bg khoan dit 0,5m, 1m, 2m; dao, giiy do pH, dung dich H2O2, bang so mau dit cCia Munsell.
- May do EC, pH.
- May so may sic ke
- Hoa chit sy dung trong phan tich miu cac chi tieu hoa hoc dit.
Bang 1. Cac Phu'O'ng phap phan tich mlu
2 4
5 6 7
pH, EC A P * trao doi
Chat hu'u CO' TN TP
Hoa tan theo ti le 1:2,5. ly tarn, loc, do b^ng may
Trich bSng KCI I N , chuin do vai NAOH COIN, tao phirc vai NaF, chu^n do vai H2SO4 0,01N
Phu'ang phap Walkley-Black; oxy hoa bing H2SO4 dd - K2Cr207. Chuin bSng FeS04.
Cong pha vai H2SO4 dd - CUSO4 - Se ti le: 100-10-1 Chu'ng ck\ micro Kjeldahl.
Cong pha bSng H2SO4 dd - HCIO4 hien mau ciia phosphomolypdat vai chSt khif la ascobic axit. so mau tren may s§c ki quang pho.
^ Khoa (Vloi tru'ong va Tai nguyen thien nhien, Trifong Dai hoc C§n Tha
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Hi6n nay rii'ng Tram Tra Sy d y p c xay dyng va quan ly theo hai khu rieng biet va co dien tich g i n b i n g nhau (khu I: 392,7ha va khu II:
440 7ha) Sy phan chia nhy tren n h i m quan ly mot each chu dpng ve ch4 do nyae, rii'ng Tram, thuy sinh vat d tii'ng khu noi chung va tiJ'ng khoanh cu the noi rieng. Do do 6\ku kien t y nhien, dac diem hinh thai rii-ng Tram tii'ng phan khu, tii'ng khoanh deu co sLf khac biet tyang d6i vdi nhau Dae biet v§ tinh c h i t d i t . CO s y khac biet giii'a eac khoanh, cac khu. Do yeu c i u cua cdng tac bao ve rii'ng nen ban quan ly chu dpng quan ly ch§ dp nyde, giti' n y d c lai trong cuoi miia mya n h i m chdng chay rifng vao miia kho. Vi vay ch^ dp nydc trong khu rii'ng c6 khae biet so vdi cac khu vyc ben
ngoai va theo quy luat: Che do nydc ngap sau se dypc luan phien giOa hai khu. M6i khu giti"
nyde ngap sau mot nam, khu eon lai thong thoang ty nhien, Cao cu6i miia mya (thang 12) cac cya cdng d y p c dong giCp nydc theo ch§ dp ngap sau d khu I, trong khi do khu II con lai d y p c lyu thong nydc ra vao ty nhien trong miia mya. Vao miia kho (khoang thang 2-3) khu II can nydc, nydc tii- khu I dypc xa sang tieu khu II n h i m l^m i m , tranh chay rii'ng
3.1 Thanh ph4n hoa hpc d i t t i n g mat d cac khoanh thupc khu I
Danh gia chung thanh phan hoa hoc dat tang mat toan khu I
Bang 2. Cac chi tieu hoa hoc d§t ting mat tai cac khoanh thuoc khu
Khoanh l a l b 2a 2b 3a 3b
Cac chi tieu hoa hpc pHHjO
3,25 4,04 3,59 3,86 4,31 4,03
PHKCI
2,99 3,58 3,14 3,64 3,49 3,6
EC (pS/cm)
1430 427 814 442 417 732
CHC (%) 51,59 21,32 29,58 28,89 24,04 19,26
Axit tong (meq/IOOg)
29,51 10,49 17,5 8,99 13.5 11,99
Al"** trao d6i (meq/IOOg)
18,1 6,98 11.28
8,08 10,73
7.86
TN (%) 1,72 0,71 0,99 0,96 0.8 0,64
TP (%) 0,25 0,19 0,12 0,13 0,32 0.12
C/N 17,82 18,46 17,27 18,08 19,63 20,03 Do t i n g mSt e6 thanh p h i n c i u tao chu yeu
la xac ba thyc vat chya phan huy nen ndng do muoi hoa tan thap Ngoai ra, do nypc trong cac khoanh nhieu va eo the thong thoang, trao doi vdi nhau nen ham lypng cac mu6i hoa tan trong khu vyc d y p c ripa trdi, khuech tan vao nydc va di nai kh^c nen do bi^n dong khdng dang ke Tuy nhien do khoanh 1a cd dia hinh trung n h i t nen h i u nhy sy khuech tan eac ion muoi hoa tan di nai khac han che nen ham lypng muoi hoa tan cao hay chi sd EC cao.
Mat khac, vi dSy IS loai d i t phfen nSng nen ham lypng muoi hoa tan chu yeu la Al va Fe Tuy chi so EC t h i p nhyng gia tri nay cd the anh hydng tdi s y sinh trydng eua Tram, gay doc cho Tram. Sy tich luy dpc c h i t nhdm, s i t d r l cay Tram, cd the lam can trd sy phat then va gSy chet cSy
HSm lyang c h i t hiKU ca trong t i n g mat ciia eac khoanh toan khu deu r i t cao, h i u hk d6u tr6n 20% va thudc loai r i t giau hCru ca theo Walkley Back, Metson (Nguydn My Hoa,1998) oac biet c h i t hii'u ca cao n h i t la d khoanh l a vPi ham l y p n g hii'u c a chiem 51,59% thanh
p h i n dat (do dia diem thu m i u cd dia hinh trung nen la nai hdi tu nhidu hOu ca han khu vyc khac). Vi tri cd ham lypng hCpu ca t h i p nhit la khoanh 3b vdi 19,26% va d y p c x6p vao loai giau hii-u ca.
Vi t i n g m§t hCpu ca nay d y a c hinh thanh g i n day do vat c h i t tii' rii'ng Tram rung nen c h i t hii'u CO d day ehii ydu la xac ba thyc vat dang trong qua trinh phan huy Do d i y cua Idp hii'u ca nay cung khdng cao, trung binh khoang 20cm va cao nhit la 40cm d khoanh l a .
T i n g mat hii'u ca nay cd y nghia r i t quan trpng trong den kha nang cung c i p dinh dyang cho cay cua dit, tang do xdp ciia d i t , thoang khi va la mdi trydng hoat ddng cua vi sinh vSt (Nguyen My Hoa,1998). Vdi ham lypng hu'u ca nhy tren ta cd the danh gia do phi nhieu ciia d i t la r i t cao.
Danh gi? chung v§ cac thanh phin hoa hpc d i t t i n g mat d cac khoanh thudc khu I nhy sau:
Chi sd pHH,o thudc loai ehua nh§u vdi cac gia tn biin ddng khdng Idn n i m trong khoang 3,25-4,41 Vdi gia th pH d i t nay cd the ed anh
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hydng d i n tinh c h i t d i t nhy: Gay ifc che d i n s y phat then sinh vat, tac ddng d i n nhCpng thanh p h i n hoa hpc khac, cac qua trinh sinh li hoa CLia d i t .
Ddng thdi cac chi sd EC, axit tong sd va Al^*
di dpng cung eao lam cho d i t cang trd nen chua han va dpc han doi vdi sinh vat ndi chung va Tram ndi heng.
Mat khac do da trong rirng nhiiu nam nen xac ba dpng thyc vat d y p c tich luy nhieu, tao thanh mot Idp hCfu ca t i n g mat d i y tif 20-40 cm. Chinh vi vay ma ham lypng hii'u ca cung nhy dam tong sd va Ian tong sd cung r i t t i i m nang. Tuy nhien kha nang khoang hoa chya cao nen chya that sy hii'u dung cho Tram.
Nhin chung thanh p h i n hoa hpc d i t t i n g mat d cac khoanh thudc khu I the hien cho tinh c h i t eua mdt vung d i t phen hoat ddng, ngap iing va ydm khi vdi he sinh thai Tram nhiiu nam. Tuy la mot vung d i t ed tiem nang v i c h i t hCfu ea va ngudn dinh dydng trong d i t , nhyng cac thanh p h i n hoa hoe khac trong d i t hien tai cd anh hydng tryc tiep va gian t i i p tdi sy phat trien cua Tram. Day la mot trong nhirng nguyen nhan lam han che sy sinh trydng cua Tram, lam suy thoai Tram nhy hien nay.
3.2. Thanh p h i n hoa hoc d i t t i n g mat d cac khoanh thuoc khu II
Cac khoanh thudc khu II d y p c quan ly vdi e h i do n y d c hien tai thdng thoang t y nhien.
Hien trang khao sat cho t h i y m y e n y d c dao ddng khoang 10-30cm, p h i n IPn d y d i 20cm va trong dd cd 1 khoanh hien can n y d c (4b). Do dd khu v y c nay ed sy khac biet ve cac thanh p h i n hoa hpc cung nhy tinh c h i t d i t t i n g mat so vdi khu I.
Ham lypng dam trong d i t t i n g mat trong cac khoanh nay r i t cao dao dpng tii- 0,52- 1,15%, va d y p c x i p vao loai r i t giau dam.
Y i u to d i n d i n s y khac biet v i nong dp dam chu y i u la do s y khac biet v i ham lypng hii'u ca trong d i t . Tir k i t qua dd cho t h i y ham lypng dam d khu I cao han so vdi khu II. Va vdi ham lypng dam t i i m tang nay se cung c i p cho d i t ngudn dinh d y d n g r i t Idn n i u cd d i i u kien thich hpp.
Ngoai ra chi sd C/N con the hien kha nang khoang hoa eua d i t , kha nang thanh thuc cua d i t cung nhy dp phi nhieu cua d i t . T i t ca cac khoanh d i u cd ti sd C/N Idn han 16 thudc loai trung binh. VPi ehi sd C/N nhy tren cho thiy hien trang kem hCru dung cua chat hCru ca, hay d i t kem phi nhieu.
Bang 3. Cac ehi tieu hoa hoc d i t t i n g mat tai cac khoanh thudc khu II
Khoanh 4a 4b 5a 5b 6a 6b
Cac chi tieu hoa hoc pHH^o
3,73 3,67 3,93 3,94 3,66 4,25
PHKCI
3,55 3,55 3,55 3,55 3,50 3,63
EC (pS/cm)
733 884 481 553 2010
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CHC (%) 34,39 24,76 17,88 28,89 15,66 14.66
Axit tong (meq/IOOg)
13,49 13,01 10,49 12,99 14,99 9,01
A P * trao doi (meq/IOOg)
12,75 12,44 7,42 6,67 10,06
6,31
TN {%) 1,15 0,83 0,60 0,96 0,52 0,40
TP (%) 0,32 0,18 0,14 0,19 0,12 0,14
C/N 19,64 17,78 16,43 19,01 19,68 18,23 Dam tdng (TN)
Lan tong sd trong t i n g d i t mat cua toan bd khu la r i t cao, toan bd cac khoanh deu thudc loai giau Ian. Khoanh cao n h i t la khoanh 4a vdi ham lypng Ian chiem 0,32%, va t h i p nhat la khoanh 6a vdi ham lypng chiem 0,12%. Cd s y bien ddng tyang doi vdi nhau va cd tri sd tyang t y nhy cac khoanh khu I.
Nguyen nhan chinh d i n den ham lypng Ian d t i n g mat cac khoanh nay r i t cao la do ham lypng c h i t hyu co thudc loai giau d t i n g mat.
Va t y a n g t y nhy cac khoanh khac chu y i u la Ian hiru ca; va khdng ngoai trir nguyen nhan la do tir xac ba hCru ca thyc vat va tir c h i t thai ddng vat, chim, dai... Ham lypng c h i t hCru ea d p h i n Idn cac khoang d y p c x i p nhdm r i t
giau, cac khoanh con lai cung d y p c xep vao loai giau. Tuy nhien ham lypng hCru ea nay chi the hien d gia tri t i i m tang, chya hCru dung ddi vdi Tram (do ti sd C/N edn cao). Mat khac, do mdi tyang quan vdi hCru ca ma ham lypng dam tong sd va Ian tong sd cung cao. Chi sd dam tong va lari tong nay cung the hien kha nang t i i m tang v i dinh dydng trong d i t cho Tram.
Tom lai vdi dieu kien hien tai thi cac khoanh d i t thupc khu II dang trong trang thai khir, y i m khi. Tinh c h i t d i t chua phen vdi nhiiu doe td.
Ngudn dinh dydng trong d i t dang d trang thai t i i m tang, chya hiru dung ddi vdi Tram, H i u h i t cac thanh p h i n hoa hoc d i t d y a c danh gia la y i u td gidi han sy sinh trydng cua Tram.
Day la mot trong nhyng nguyen nhan chinh gay suy thoai Tram.
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KET LUAN VA KIEN NGHj
Tra S y la mdt viing d i t phen nang vdi chi so pH d y p c danh gia la r i t chua d khoanh l a (3,25) va chua n h i i u d t i n g mat d t i t ca cac khoanh edn lai. Cac khoanh thudc khu I ed pH cao han cac khoanh thudc khu II. Dao ddng trong khoang: 3,25-4,31 doi vdi PHHJO, va 2,99- 3,64 ddi vdi PHKCI
Ham l y p n g mudi hoa tan (chi sd EC) bien ddng kha rd d cac vi tri khae nhau va d y a c danh gia la it anh h y d n g ddi vdi cay trdng d t i n g mat. EC cao n h i t la d khoanh 6a (2010 pS/cm) k i den la khoanh 1a (1430 pS/cm); cac khoanh edn lai dao ddng tir 262-884 pS/cm.
Chi sd Al^* trao doi va acid tong sd d i u cao, eao n h i t la khoanh l a (18,10 meq/IOOg A\^*
trao doi va 29,21 meq/IOOg acid tong), cac khoanh edn lai cung kha cao Ca hai chi tieu nay d i u d y p c danh gia la cao d t i n g mat.
Thanh p h i n c h i t hiru ca, dam tong d y p c danh gia la cao d t i n g mat cua h i u h i t cac khoanh. Gia tn hCru ca va dam cao nhat la d t i n g mat khoanh l a (51,59%). Tuy nhien gia tri tren chi ed y nghTa la d dang t i i m tang (do ti le C/N cao).
Trir lypng Ian thi ehi cao d t i n g m f t cac khoanh, khdng cd sy dao ddng Idn giCra eac khoanh. Rieng chi cd 3 khoanh l a , 3a va 4a thi trtr lypng Ian tang eao so vdi eac khoanh edn lai.
S y b i i n ddng cac thanh p h i n hoa hpc d i t theo vi tri chu yeu phu thudc vao c h i do quan ly n y d c va mye n y d c hien tai d cac khoanh.
TAI LIEU THAM KHAO 1. Chi cue Kiem lam tinh An Giang, 12/2004. Bao
cao: "Lugn chirng khoa hoc thanh lap Khu bao ve canh quan Tra Sy, tinh An Giang (giai doan 2005-2010)" So Nong nghiep va Phat trien nong thon An Giang.
2. Edward J. Plaster. 2003 Soil science and Management. Thopmson Delmar learning.
3. Le Van Khoa, 2000. Oat va moi tru'dng. NXB Giao dye.
4. Le Van Khoa, 2005. O l t ngap nu'dc. NXB Giao Due.
5. Ngo Ngoc Hung, 2005.Giao trinh Phi nhieu d i t Oai hoc Clin Tho.
6. Vien Tho nhuovg Nong hoa. 1998 So tay phan tich Oat-Nyoc-Phan bon-cay tr6ng NXB Nong nghiep.
7. A Basic Elements. G.H Bolt and M.G.M Bruggen Wert, 1998 Soil Chemistry. Elsevier Scientific publishing company
Summary
THE CHEMICAL CHARACTERISTICS SOIL IN TRA SU MELALEUCA FOREST
Truong Thi Nga Dinh Hoai Ung Nguyen Cong Thuan
Bui Truong Tho These two parameters are evaluated high at surface.
Organic, N total and P total are high at surface in almost plots. The organic and N value are highest at the surface of plot l a (51,59%). P content is not high changed between plots. N and P content particular high at the zone which many birds. Meanwhile, organic has high value because of the forest botanical carpet. The fluctuation of chemical composition of soil follow by position is conditional upon the regulation concerning management of state at plots. Therefore, the managers need particular care about regulation concerning management of state at TraSu to develop the forest.
In order to evaluating actuality and proposing suitable solution for management TraSu Melaleuca forest in An Giang province, "The chemical characteristics soil in Tra Su Melaleuca forest-An Giang province" was carry out to survey and assess chemical characteristics soil in Tra Su Melaleuca forest Twelve samples of soil at two different water management zones (divided to twelve plots) are collected and measured about physical and chemical parameters of soil. The result showed that TraSu is a heavy acid soil which acid to heavy acid pH values at all plots Exchanged Ap* and total acid are both high, the highest plot is plot l a ((18,10 meq/100g exchanged Al^* and 29,21 meq/IOOg total acid).
MONG CAC D 6 N G CHI VA CAC BAN LIOJ Y : KEM THEO BAI BAO CAN PHAI CO T^N BAI BAO B I N G T I £ N G A N H V A P H A I CO SUMMARY BANG TlfiNG ANH
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