3.2.1. S ampli ng an d Cros s -d ating Trees
Four plots , HP, K P, FP and S P were used as st ud y s it e i n t hi s st ud y (Fi g.
1-1 and Tabl e 1 -1 ). The methods of taki ng sampl e cores, m eas uri ng tree-ri ng wi dt h and evaluating error of m easurem ent s were t he s am e as
“2.2.1. Sampling and Cross-dating Trees”. To detect releases for the last 550 years we us ed tree -ri ng dat a from FP st ud y pl ot and succeeded in obt aining t wo long sampl e cores, whi l e t aki ng cores from l arge di am et er trees was s o di ffi cult t hat m ostl y i nnermos t of cores were broken. In FP stud y plot , two old -aged trees t hat mi ght be regenerat ed before t he st arti ng year of l arge s cal e l oggi ng acti vit y i n 1642 and six regenerat ed t rees t hat were expect ed t o have regenerat ed aft er 1642, were us ed t o det ect rel eas es (Tabl e s 3 -1 and 3 -2 ). A l arge data s et of t ree ring m eas urem ents was needed to cal cul at e s peci es -speci fi c rel eas e crit eri a. Therefore, we suppl em ent ed our dat a wit h 34 t ree -ri ng dat a sets from t he four st ud y s i t es (Tabl e 3-3).
3.2.2. Standi ng Tree Mon itorin g and Mappin g
Di am et er and s peci es nam e of al l li ving t rees wit h DBH ≥ 4 cm have been recorded three di fferent t im es s ince 1973 or 1974 wi thi n each s tud y pl ot (Tabl e 1 -1 ). El evati ons were m eas ured on a 20 m gri d at corners of the sub-bl ocks and posi t ion s of al l softwood and domi nant broad-l eafed t rees were mapped (Takashim a, 2009 ). For C r. japoni ca t rees in t he FP s tud y pl ot
31
Tabl e 3 -1 S am pl e t ree att ribut es: old -aged s ampl e t rees of the FP st ud y plot
32
Tabl e 3 -2 S ampl e t ree att ri but es: regenerat ed s am pl e t rees of t he FP s tud y plot
33
Tabl e 3-3 S ampl e t ree at t r i but es No .
(pl ot- 1)
Mean DB H (c m)
Mean ri n g- wi dt h ( mm)
HP 13 77. 7 1.1 8
KP 5 97. 9 1.5 5
FP 9 66. 5 1.1 9
SP 7 62. 0 1.8 3
34
regenerati on t ypes were al so recorded ; trees regenerat ed from t he ground, logs or s tump s. Wi t hin the FP s tud y pl ot Cr. japonica s nags and st um ps (DBH ≥ 10 cm) were mapped and their DBH were recorded in 2005 (Takas hi m a, 2009 ). Fi g. 3 -1 shows positi ons of l iving t rees, s nags and stumps in t he FP s tud y plot .
3.2.3. Age E s ti mation
The m et hod of age es tim ati on was s am e as “2.2.2. Age Es tim at ion , 1.
Measuring arc of inner tree -ri ng”. In t his st ud y, we es tim at ed age of 7 sampl e cores from FP st ud y pl ot . The m ean l ength of t he mi ss ing radii was 28.27 mm . One ol d -aged s ampl e t ree had a core whi ch was too short , thus we di d not calcul at e the age to avoi d a l arge m argi n of error.
3.2.4. Grow th -rate Cal cul ation
BA I was cal cul at ed using the s am e form at ion as “2.2.3. Growt h -rat e Calculation”.
3.2.5. Rel eas e Analysis
Releas e anal ys is us i ng t ree -ri ng wi dt h is a us eful approach for evaluat ing the dis turbance his tor y of a s tand wit h compl ex age st ructure (Lori m er and Frel i ch, 1989). For t he anal ysi s, the percent age growth change (%GC ), whi ch was t he percent age di f ference bet ween preceding and subs equent 10 - yr m eans of t ree -ri ng width, was calcul at ed using the formul a bel ow (Nowacki and Abram s, 1997):
%GC = (M2 - M1) / M1 × 100 (3)
where M1: precedi ng 10 - yr m ean, M2: subsequent 10 - yr m ean. A 10 - yr s pan
35
Fi g. 3 -1 Locati on of li vi ng t rees, s tumps and s nags in t he FP stud y pl ot . A and B: o ld -aged t rees . a-f: regenerat ed t rees .
36
for radi al -growth averaging was used t o det ect sust ained growt h i ncreas es in percent age to di s count the influence of cl im at e and ot her short -t erm growt h pert urbat ions (Leak, 1987). %GC of ei ght Cr. j aponi ca s ampl e trees in FP s tud y plot were cal cul at ed t o det ect growth i ncreas es caus ed b y gap form ati ons from hum an or natural disturbance.
To obt ain rel eas e cri teri a, the boundar y l ine m et hod was us ed (Bl ack and Abram s , 2003) becaus e t hi s m et hod s ol ved the dendroecol ogical probl ems of ring wi dt h decreasing caused b y agi ng and narrow ring wi dt h s howi ng ext rem el y l arge %GC. Thi s m et hod uses two st eps : (1) em pi ri cal esti mati on of t he m axi mum g rowt h change bas ed on prior growth, and (2) s cali ng of t he rel eas es rel ati ve to t he boundar y li ne (Splecht na et al., 2005).
In t he fi rst st ep t he boundar y l i ne m et hod i s det erm ined based on the rel at ions hi p between %GC and prior growth values, whi ch was m e an growth over t he pri or 10 yea rs . For cal cul at ing t he speci es -specifi c boundar y l ine, a large dat a s et of t ree ri ng m easurem ents was needed. Therefore, we suppl em ent ed t ree -ri ng dat a from the FP st ud y s it e wi th dat a from another three perm anent st ud y plot s on Yakus him a Is l and; tot al number of individual s used was 34 (Tabl e 3-3). We divided t he dat a s et i nto ni ne pri or growt h cl ass es (cl ass wi dt h 0.5 m m), averaged the t en hi ghest growt h change values for ever y growth cl as s, and fit l inear, power, l ogari thm i c and exponenti al curves and s el ect ed t he functi on t hat yi elded the hi ghest R2 value. In t he s econd st ep, all t he rel eas es were eval uat ed rel ative t o t he boundar y li ne. We i dent i fi ed pot ent i al rel eas es according to a procedure devel oped b y Bl ack and Abrams (2003) as fol lows. Onl y %GC val ues great er than 10% were ret ained. A t i me seri es graph of %GC shows increases at poi nts of pot enti al rel ease, and onl y t he m axi mum %GC for each ascent was used so that each peak woul d be considered onl y once as a
37
pot ent i al rel eas e. Onl y t hes e pot ent i al rel eas es were then eval uat ed rel ati ve to the boundar y l ine. We i denti fi ed an y %GC peak more t han 20% of t he boundar y li ne at the gi ven pri or growth rat e as m oderate rel eas e and an y peak ex ceeding 50% of t he val ue of the bounda r y l ine as a m ajor rel eas e.
3. 3. Resul ts
3.3.1. Bou ndary Lin e
The best fitt ed equat ion as t he boundar y l ine was:
%GC = –91.88 l n (P G) + 137.56 (4)
where P G: prior growt h. The R2 val ue of above equati on was 0.9 6 (Fi g.
3-2(A)). All cal cul at ed %GC rang ed from – 77.7 to 277.9% for pri or gro wth from 0.12 to 4.71 mm (Fi g. 3 -2(B) ). Fi g. 3 -2 (B) als o i ncl udes the li nes indi cati ng 50% and 20% of the boundar y l ine, whi ch are t hresholds us ed to define m aj or and m oderat e rel eases , respect ivel y.
3.3.2. Dis turban ce His tory
Fi g. 3 -3 s hows t he dis t ribut ion of rel ease for s am pl e t rees (A) and (B).
Sam pl e t ree (A) s howed m aj or rel eas es i n 1751, 1774, 1778 and 1996, and sampl e t ree (B) s howed them i n 1629, 1687, 1689, 1691, 1821, 1845, 1892, 1905 and 1939. The BA I val ue of sam pl e tree (A) increas ed from the mi ddl e of 1700s t o t he begi nni ng of 1900s. The BA I of s ampl e t ree (B) i ncreas ed from t he begi nning of 1800s to the end of 1900s . Thes e i ncreas es of BAI value occurred aft er t he frequent m ajor rel eas es from the m i ddl e o f 1700s for sampl e t ree (A) and from t he beginni ng of 1800s for sampl e t ree (B).
Tabl e 3-2 shows t he es tim at ed age from regenerat ed l iving t rees and
38
Fi g. 3 -2 Li near approxim at ion of averaged value of t en hi ghest growt h change for ever y growt h cl ass (A). Boundar y l ine and pl ot of percent growt h change (%GC ) val ues wit h respect to pri or growt h for 34 sam pl e t rees (B).
39
Fi g. 3 -3 P ercent growth change (%GC ) and bas al area i ncrement (BA I) for sampl e t rees (A) and (B).
40
regenerati on t ypes . Even t hough t he y were l ocat ed in t wo different areas (Fi g. 3 -1 ), regeneration years were wit hin t he rel ati vel y n arrow range bet ween t he years 1791 and 183 5 . This t imi ng was consi st ent wit h a m aj or rel eas e foll owed b y hi gh BAI values for bot h s am pl e t rees (A) and (B).
Fi g. 3 -4 s hows the number of s ampl e t rees showi ng moderat e and m ajor rel eas es wi thin each of 10 - year cl as s for ol d -aged and rege nerat ed t rees . Ol d -aged t rees showed m aj or and m oderat e rel eas es from the 1450’s to 1990’s. Regenerated trees showed major and mode rate releases from the 1820’s to 1990’s.
3. 4. Dis cu ss ion
The present s tud y a tt em pt ed t o pi npoi nt the t im e of di st urbance of C r.
japoni ca on Yakus him a Is l and over l as t s everal hundred years usi ng tree-ri ng anal ys i s . Ol d -aged sampl e t rees (A) and (B) s howed i ncreasi ng growt h alt hough they were approxim at el y 5 00 to 600 years old, whil e t he growt h rat e of t rees norm all y decli nes as a tree ages (Gower et al., 1996).
The s am pl e t ree (A) showed m ajor rel eas e from the mi ddl e of 1700s and the sampl e t ree (B) s howed m aj or rel ease fro m the beginni ng of 1800s (Fi g.
3-3). Both t rees s howed a rel ati vel y hi gh BAI val ue for about 150 years aft er t hes e r el eas es (Fi g. 3 -3). In old growt h natural Cr. j aponi ca fores t i n Akit a, the growt h of 160 –200 years old Cr. japoni ca i ncre as ed aft er thi nning (Nis hiz ono et al ., 2006). This stud y cl arifi ed that m uch ol der Cr.
japoni ca trees o n Yakushi m a Isl and al so increas ed their growth rat e s aft er dis turbances.
Est im at ed germi nat i on years of regenerated t rees were bet ween 1791 and 1835, whi ch were aft er the m ajor rel ease of ol d -aged s ampl e t rees foll owed b y l ong-l as ti ng hi gh BA I val ue s , and al l of t hem regenerat ed on st um ps or
41
Fi g. 3-4 Decadal dist ribut ion of m aj or and m oderat e releases of t wo old -aged and six regenerat ed t rees for FP st ud y plot . Tot al number of rel ease (A), and rel ease for each sam pl e t ree s (B).
42
logs (Tabl e 3 -2 ). Hence, t hese regenerat ed t rees m i ght have grown up in improved l i ght and bett er condi tion s of com peti tion on nei ghbori ng t rees becaus e of loggi ng act ivit y. Eve n though the regenerat ed s am pl e t rees were locat ed in t wo s eparate pl aces, germi nat ion year of s am pl e t rees cent ered on a short peri od of t im e (Tabl e 3-2 and Fi g. 3-1). This res ult s how s t here was loggi ng acti vi t y in t he s am e t im e point i n bot h thes e areas o f the st ud y si t e.
A m aj or rel eas e of t he old -aged sampl e t ree (A) was det ect ed duri ng t he 1990 ’s , but s ampl e t ree (B) did not show rel eas e for t he 1990 ’s (Fi gs. 3-3 and 3 -4 ). M ajor rel eases of regenerated t rees for t he 1970 ’s and 1980 ’s were al so det ect ed (Fi g. 3-4). These releases mi ght have been caused b y nat ural dis turbance, because the FP st ud y pl ot has been s t ri ct l y prot ect ed since 1971. The m ajor natural dist urbance in Yakus him a Is land mi ght be l and sli de and t yphoon. S him okawa and Jitousono (1984) report ed that l and s li de ma y happen ever y 1000 years i n st eep or d rai nage basin in Yakushim a Is l and. In FP st ud y pl ot on gentl e sl ope, however, land sli de m i ght not happen at l east l as t 600 years, j udgi ng from the number of t ree -ri ng for t he sampl e trees (Tabl e 3-1 ) and the exist ence of m an y l arge t rees and s tumps (Fi g. 3 -1 ). Yakushi ma Is l and i s s uscept ibl e t o t yphoons , which m a y caus e the canop y gaps i n t he st ud y plot . The weather s t ati on of Yakushim a recorded wi nd veloci ti es exceedi ng 55 m s- 1 ei ght tim e s from 1938 t o 2012 (J apan M et eorologi cal Agenc y, 2013), m eaning powerful t yphoons hi t about ever y 10 years in Yakushi m a Is l and. However, Takas him a (2009) reported that onl y a few Cr. j aponi ca have been recruit ed in perm anent s tud y pl ot s incl uding FP st ud y plot bas ed on m onit oring res ult s si nce 1973. In thes e plots, som e l os s es of api cal parts of the crowns were observed ( Ishii et al ., 2010), whil e whol e crown dam aged or uproot ed t rees are rarel y observed, especi al l y i n l arger t rees . Onl y one bi g C r. japoni ca wi th a DBH of 250 cm
43
in K P st ud y plot was fel l ed b y t he t yphoon (No. 19) in 1997 , but no recrui tm ent of Cr. j aponi ca was observed. This s uggest s di st urbances s ince 1970 ’s mi ght have been sm al l er s cal e t han previ ous loggi ng acti vit y and happened at t he i ndi vidual tree l evel . In addi ti on, s uch sm al l s cal e nat ural dis turbance m a y als o occur all the ti me even before 1970 ’s and during the large s cal e logging a ct ivit y.
There are hi st ori cal des cri pti on s s howing t he earli es t l oggi ng occurred i n 1563 and t he s t arti ng year of s ys t em ati c loggi ng act ivit y was 1642. In the FP st ud y s it e som e moderate rel eases were det ect ed si nce 1450 ’s , but no major rel eas es occurred unti l 1629. Ba sed on t he t ree -ri ng anal ys i s of stumps, there m a y have been som e loggi ng acti vi ti es bef ore 1642 (Ushij im a et al ., 2006), and s o t hes e moderat e rel eas es before 1642 m a y have been caus ed b y logging as well as natural dis turbances . However, thes e loggi ng act ivi ti es mi ght have been s m all er scal e than l at er s ys t emati c l oggi ng act ivi ti es, becaus e onl y m oderate rel eases occurred .
In concl us ion, t hi s s tud y emphasiz ed t hat s ys t em at i c large s cal e l oggi ng act ivi ti es of Cr. japoni ca occurred as part of t he hist ori cal record. In our stud y s it e, logging act ivi t y st art ed about 1630 and l arge scal e loggi ng act ivi t y occurred from the mi ddle of 1700s . Large s cal e loggi ng acti vi t y encouraged growth rat e s i n older t rees about 500 t o 600 years ol d ; gap form ati on m a y be i m port ant for regenerat ion of Cr. japoni ca and sm all s cal e dis turbance as soci at ed wi th indi vidua l t ree l evel mi ght be inadequat e to stim ul at e regenerati on of Cr. j aponi ca. Low l evels of dis t urbances als o occurred before 1630 and these rel eases were li kel y t o be caus ed b y l oggi ng but mi ght have been sm al l scal e. These res ul ts suggest past l oggi ng act ivi ti es are im port ant t o encourage growt h and regen erati on of C r.
japoni ca.
44
Current l y, loggi ng of C r. japoni ca i s basi call y not all owed in t he core area i n FEPA. However, s el ect ive loggings are carried out for Cr. j aponi ca pl ant ati ons i n t he buffer area i n FEPA and i n t he producti on area outsi de FEPA. Our findi ngs sugges t that group selection s ys t em is m ore appropri at e rat her than s ingl e -t ree s el ecti on in order t o encourage natural regenerat ion and growth of rem aining t rees i n such areas. Int eres ti ngl y, Im a da (1986) had al read y propos ed the group s el ect ion sys t em wit h 240 yea r rot ati on for product ion area of C r. j aponi ca forest on Yakus hi ma Is l and, and t hi s s ys t e m has been experim ent al l y i mpl em ent ed. Thus, i t coul d be very val uabl e t o evaluat e such an ex peri m ent al pract i ce to furt her confi rm t he effect s of loggi ngs.
45
4. Comparing 3 0 - ye ars Diame te r Cens use s a nd Tree -ring Chronologies on O ld-grow th Cry ptome ria ja ponica from Yak us hima Is la nd , Ja pan
4.1. In trodu cti on
Cons ervat ion of t he old -growt h forest requi r es an underst andi ng of long-t erm growth i n C r. japoni ca, becaus e i denti fi cati on of l ong -t erm patt erns in fores t growth is needed t o underst and fores t dynam i cs , wi th di rect i mpli cati ons i n fores t m anagem ent and sil vi cul ture (Biondi , 1999).
However, growth o f nat ural forest is not well known, becaus e forest st ructure of nat ural forest i s compl ex and its growth process i s various . Conti nuous di am eter cens us or t ree -ri ngs m eas urem ents are required to estim at e long -t erm pat t erns i n forest growt h .
The most comm on m ethod of growt h es tim ati on is m easuri ng t ree di am et ers repeat edl y and cal cul ati ng di amet er change (C l ark et al., 2007).
This approach has t he advant ages t hat diam et ers can be m easured rapidl y (Cl ark et al., 2007), it is possibl e to coll ect dat a i n prot ec t ion area wi thout dam aging t rees, and it i s eas y t o get inform at ion about surroundi ng actual sit uati on , but not possi bl e to get past i nform ati on before st art ing census.
However t here are several di s advant ages t o di am et er m eas urem ents . The di am et er m easurem ents have substant i al error (Barker et al ., 2002; Kit ahara et al., 2009), and negati ve growt h coul d be obs erved (Cl ark et al ., 2007) al though posi tive gr owth should occur each year. Annual gr owth rat es are oft en unknown, becaus e i nt ervals bet ween m eas urem e nts can be long (C l ark et al., 2007). Especiall y i t is di ffi cult t o m easure bi g C r. j aponi ca t rees because of i rregul ar s hape, covering t hi ck moos of t ree surface, and poor foot ing caus ed b y man y bi g stumps and logs on forest fl oor. Thus, it i s
46
concerned t hat as t he di am et ers are bi gger, m eas urem ent s m a y be l es s accurate.
In comparis on, advant age of t ree -ri ng m eas urem ent is t hat t ree -ring dat a provide an accurat e repres ent ati on of yea r -t o- year growth pat t erns (Bi ondi , 1999), and negati ve growth can ’t be observed. Tree-ring inform ati on al so represent s past growth back to t he year of germ inati on of t he t ree. However, there are s om e di s advant ages . Tree -ri ng dat a mi ght i ncl ude fal s e or mis si ng ri ngs. As one or two s ample cores are t aken general l y from one t ree, t he act ual t ree circum ference i s not known (Cl ark et al ., 2007). S am pl e cores shri nk aft er t aki ng from t rees and are not be abl e t o be t aken from prot ect ed areas or pl aces where t rees do not produce ident ifi abl e annual rings .
Relati vel y l itt l e res earch has focused on com pari ng inventori es and dendrochronol ogi cal records (Biondi, 1999; C l ark et al ., 2007). Biondi (1999) reported that tree -ri ng data was cl osel y m at ched with repeat ed fores t invent ori es . We focus ed on 30 years di am et er cens us and t ree -ri ng chronol ogi es on ol d -growt h Cr. j aponi ca fores t from Yakushi m a Isl and, whi ch cons is ts of few hundred year old trees. The obj ective of t hi s st ud y was t o compare growt h from di am et er census es and t ree -ri ng dat a t o know error range i n order to consi der about the r ol e of cens us for nat ural old -growt h Cr. japonica forest on Yakus him a Is l and .
4.2. Materi al and M eth ods 4.2.1. Di ameter Cen sus
DBH of al l li ving t rees wit h DBH ≥ 4 cm were recorded three di fferent tim es since 1973 in the fi ve plots (Tabl e 1 -1). DBH m easu rem ent was conduct ed usi ng cal iper in 0.5 cm round bas ed up to 90 cm or 100 cm cal iper s iz e. Two m eas urem ents from di fferent di rections at ri ght angl es t o
47
each ot her were ob t ai ned for each t ree, and the m easurem ent val ues were averaged. Di am eter tape was u s ed for each t ree that was not abl e t o be measured usi ng caliper, in 0.5 cm round based. P ol e was us ed for each t ree that was st andi ng on poor footi ng caus ed b y m an y bi g s tum ps and logs on forest fl oor, in 5 cm round based. At t he breast hei ght we placed n um ber pl at es and m easured DBH ever y census at s am e pl ace. Furthermore, the rest lengths of t he nai ls , whi ch att ached t he num ber pl at es t o the s tems (Fi g.
4-1 ), were randoml y sel ect ed and m eas ured i n 0.1 cm round based during at thi rd m eas urem ent for 224 t r ees i n st ud y plots of HP, FP and S P (Fi g. 1 -1 and Tabl e 1 -1 ).
4.2. 2. S ampli ng an d Cros s -d ating Trees
Tree-ring width of s ampl e c ores from 49 i ndi vi duals from st udy pl ot s HP, KP, FP and SP, were m eas ured (Fi g. 1 -1 and Tabl e 1 -1 ). The m ethods of taki ng s am pl e cores , m easuri ng t ree -ri ng wi dth and eval uating error of measurem ent s were t he s am e as “2 .2.1. S am pl ing and C ros s -dat ing Trees ”.
In T P s tud y pl ot (Fi g. 1 -1 and Tabl e 1 -1 ), 12 sampl e cores from 11 individual s were t aken in 2012. To know percent age of sh ri nk, cores were ins erted i nto st raw and t he siz e of core (wit hout bark) was m arked on the st raw i mm edi at el y a ft er t he t aki ng cores and t he l engt h were m eas ured . Aft er ai r dri ed, l ength of cores w ere m easured and percent age of s hri nk is cal cul at ed. The res ult s from t ree -ring m eas urem ent were i ncreas ed b y average shrink percent age 1.5%, whi ch were added t o the res ult of t ree -ring measurem ent .
4.2. 3. An al ys is
The period bet ween t he fi rst and second measurem ent s of di amet er census
48
Fi g. 4 -1 Dri vi ng a nail i n to t he st em (Yoshida, 2007 ).
49
is t erm ed as ‘fi rst peri od’, between t he second and thi rd m eas urem ents as
‘second period’, and between the first and third measurements as ‘all period’. The first period and second period were termed 10 -19 years and all period was t erm ed 28 -30 years . For fi rs t , second and al l peri od s, di am et er growt h per 10 years (wit hout bark) was cal cul at ed from t he cens us records . The percent age of bark t hi ckness was esti mat ed us ing t he rel at ions hi p bet ween di am et er and bark thi ckness of di s c from s t em anal ys i s (Togo, 1981). We cal cul at ed the di am et er growth of 4 9 indi vi duals , whi ch were identi cal t o t rees whos e s am pl e cores were t aken from 4 s tud y plots (HP, KP, FP and SP) (Tabl e 4 -1 ). For t he s am e peri od, di am et er growt h per 10 years was cal cul at ed from t he sum of t ree -ri ng wi dt hs . Diam et er growt h per 10 years from 14 i ndivi dual s, for which res t lengths of the nail s were m eas ured and als o s am pl e cores were t aken, was calcul at ed.
Pai red t t es t was appl i ed to t es t t he null h ypot hesi s of no di fference bet ween di am et er cens us/ nai l m easurem ent and t ree -ring m easurem ent . For the cont inuous vari abl es , we cal cul at ed average di fference (AD), average percent age di fference (APD), s t andard devi ati on (SD) of the di fferences , whi ch are commonl y us ed m ea sures of random m easurem ent error (Kit ahara et al ., 2009). For t he cal cul at ion t ree -ri ng measurem ent s were defined as true value. AD defi ned as the average of t he di am et er cens us /nai l measurem ent mi nus t he t ree -ri ng meas urem ent, and AP D defined as the average of t he abs ol ut e di fference divided b y the t ree -ring measurem ent . Di am et er growth per 10 years from diam et er cens us , t ree -ring m eas urem ent and rest l engths of t h e nai ls were grouped into each di am et er class , and AD, AP D and S D for each di am et er cl ass we re also cal cul at ed.
From t he all dat a of res t l engt h of nai l, percent age t hat nails have fall en awa y from t he st em and nai ls have been pushed out of the st em, were
50
Tabl e 4-1 S ampl e t ree att ri but es at the 3rd moni tori ng year
51
cal cul at ed.
4.3. Resul t s
4.3.1. Di ameter Cen sus vs. Tree -rin g Measu remen t
Fi g. 4 -2 shows s catt er pl ot of di am et er growth (cm 10- 1 years ) from di am et er cens us and t ree -ring m eas urement . Li near approximation and det ermi nati on coeffi ci ent were; for 1st peri od y = 0.24 x + 1.85, R2 = 0.01, for 2nd period y = 1.12 x – 1.51, R2 = 0.06 and for al l peri od y = 0.47 x + 0.73 , R2 = 0.0 4. N egati ve growt h s were obs erved at di am et er cens us for ever y peri od, and t here was great vari abilit y bet ween di am et er cens us and tree-ri ng m easurem ent (Fi g. 4 -2). The res ul ts of pai red t t est showed no si gni fi cant di fferences in di am et er census and t ree -ri ng m eas urem ent. Tabl e 4-2 shows t he devi ations of di am et er cens us from t ree -ring measurem ent . The AD, AP D and S D were hi gh, but the values of all period wer e l ower than 1s t and 2nd period. Tabl e 4 -3 s hows t he devi at ions of di am et er cens us from t ree -ri ng m eas urem ent for DBH clas s. About the hal f of AD of all DBH cl ass were negat ive di fferences . The AP D and S D were hi gher for DBH ≥ 70 cm . Fi g. 4-3 s hows di am et e r growt h (cm 10- 1 years ) from di am et er cens us and t ree-ring m easurem ent for each of DBH cl as s. The res ul t of t ree -ri ng measurem ent s howed cons t ant growt h for ever y di am et er class for ever y period, but the res ul t of di am et er cens us showed negative growt h an d l arge range of di fference especi all y for di am et er cl as s of 80 and 110 cm.
4.3.2. Nail Meas u remen t vs . Tree -ring Measu remen t
Fi g. 4-4 s hows scatt er pl ot of di am et er growth (cm 10- 1 years ) from nail measurem ent and t ree -ring m easurem ent. Li near approxi m a tion was y = 1.00 x + 0.68 (R2 = 0.25). There was great variabi lit y bet ween nail