DET FORSTLIGE FORSØGSVÆSEN I DANMARK
THE DANISH FOREST EXPERIMENT STATION STATION DE RECHERCHES FORESTIÉRES DE DANEMARK
DAS FORSTLICHE VERSUCHSWESEN IN DÄNEMARK
B E R E T N I N G E R U D G I V N E V E D D E N F O R S T L I G E F O R S Ø G S K O M M I S S I O N
REPORTS — RAPPORTS - BERICHTE
B IN D X X X V I
HÆFTE 3 ISSN 0367-2174
I N D H O L D
J. N e c k e l m a n n : Dækrodsplanter af nåletræ. Et litteraturstudium og nogle foreløbige resultater fra danske forsøg med rødgran (Picea Abies (L.) H. Karst ) og Sitka (Picea Silchensis (Bong.) Carr.) (Ball-rooted Conifer Plants. A Survey of Literature and Preliminary Results from Danish Experiments with Norway Spruce (Picea Abies (L.) H. Karst.) and Sitka Spruce (Picea Sitchensis (Bong.) Carr.). S. 349—401. (Beretning nr. 304).
B e n t J a k o b s e n : Foreløbige resultater fra unge planteafstandsforsøg i
rødgran. (Preliminary Results from Spacing Experiments in Norway Spruce. S. 403—411. (Beretning nr. 305).
H . H o l s t e n e r - J ø r g e n s e n , V i c e n t e P. V e r a c i o n and C a l i x t o E. Y a o :
Litter Fall Studies in an Irrigation Trial in Norway Spruce. (Strøfalds- undersøgelse i et vandingsforsøg i rødgran). S. 413—432. (Beretning nr. 306).
Rettelse til beretning nr. 282. S. 433.
K Ø B E N H A V N
T R Y K T I K A N D R U P & W U N S C H ’S B O G T R Y K K E R I
1979
IN AN IRRIGATION TRIAL IN NORWAY SPRUCE
S T R Ø F A L D S U N D E R S Ø G E L S E R I E T V A N D I N G S F O R S 0 G
I R Ø D G R A N
BY
H. H O L S T E N E R -J0 R G E N S E N , VICEN TE P. VERACION, AND CALIXTO E. YAO
IN T R O D U C T IO N
I n 1944 M ø l l e r p u b lis h e d h is tr e a tis e o n a m o u n ts o f liv in g le a v e s a n d n e e d le s i n s ta n d s o f b e e c h a n d N o rw a y s p ru c e in c o n n e x io n w ith th e a s s im ila tio n a n d th e r e s p ir a tio n in th e s ta n d s . F o r b eech h e m e a s u re d th e to ta l le a f fa ll in se v e ra l s ta n d s ; h o w e v e r, in 10 s p ru c e s ta n d s h e sa m p le d 10 r e p r e s e n ta tiv e tre e s p e r s ta n d a n d w e ig h e d a n d o th e rw is e m e a s u r e d th e to ta l a m o u n t o f n e e d le s o n e a c h tre e .
H is g e n e ra l c o n c lu s io n w a s th a t th e to ta l a m o u n t o f a s s im ila tio n o rg a n s in s ta n d s o f b e e c h o r N o rw a y s p r u c e w ith clo sed c a n o p ie s is i n d e p e n d e n t o f;
1) A ge o f th e s ta n d 2) H e ig h t o f th e s ta n d 3) S ite q u a lity
4) G ra d e o f th in n in g , (p ro v id e d a c o u p le of y e a rs h a v e la p s e d sin c e la s t t h in n in g ) .
C o n c e rn in g 4 ) th i s is in a g re e m e n t w ith h is g e n e ra l s ta te m e n t, b a se d o n a n a n a ly s is o f se v e ra l th in n in g e x p e rim e n ts , t h a t w ith in w id e lim its th in n in g d o es n o t in f lu e n c e th e v o lu m e in c r e m e n t p e r h a . T h is is t r u e in m a n y c a se s, b u t i t d o es n o t h o ld w h e n w o o d d e n s ity is ta k e n in to a c c o u n t.
W ith in c re a s in g th in n in g in te n s ity , M a d s e n , M o l t e s e n , a n d O l e s e n (1978) sh o w ed th a t th e n e t d r y m a t t e r p r o d u c tio n is d e c re a s in g in N o rw a y sp ru c e . T o th e s e n io r a u th o r , M ø l l e r ’s c o n c lu s io n s h a v e sin c e lo n g b e e n a b it p u z z ling, a s a tr e a tm e n t lik e f e rtiliz a tio n o r ir r ig a tio n , w h ic h o n c e r ta in sites r e s u lts in a n in c r e m e n t in c re a s e , n o r m a lly le a v e s th e im m e d ia te im p r e s sio n th a t, a p a r t f r o m b e in g d a r k e r g re e n , n e e d le s a n d le a v e s a re a lso b e c o m in g la rg e r, a n d a f te r o n e o r tw o y e a rs e v e n th e n u m b e r o f o r g a n s seem to be h ig h e r a f te r th e tr e a tm e n t.
T h u s , th e re se e m s to be a m p le r e a s o n to m a k e in v e s tig a tio n s i n w ell d e fin e d e x p e rim e n ts w ith fo r e s t tre e s lik e th e ir r ig a tio n t r i a l u n d e r c o n s id e r a tio n in th is p u b lic a tio n .
R a th e r t h a n m a k in g a n o rm a l e x a m in a tio n o f th e l ite r a tu r e o n litte r fa ll in N o rw a y s p ru c e , th e a u th o r s p r e f e r to p r e s e n t re le v a n t fig u re s fro m th e lite r a tu r e in a ta b le in c o n n e x io n w ith th e d is c u s s io n o f o w n fin d in g s .
STU D Y M E T H O D S a. T h e l a y - o u t o f t h e i r r i g a t i o n trial.
D u rin g th e s p rin g o f 1960 a n a r e a w a s su b d iv id e d in to p lo ts s u r r o u n d e d b y p la te s o f a b e s to s -c e m e n t d u g in to th e soil. T h e p la te s o v e rla p b y a t le a s t 6 c m a n d th e o v e rla p is se ale d w ith a s p h a lt. T h e soil, a c la y e y m o - ra in e -s o il, is fre e ly d ra in e d . N o g ro u n d w a te r ta b le h a s b e e n o b se rv e d w ith in
Det fo rstlig e F o rsø g sv æ sen . XNX.VI. H. 3. 11. o k to b e r 1979.
th e to p 2.5 m . T h u s , th e p lo ts m a y be re g a r d e d a s se lf-c o n ta in e d , f r e e ly d r a in e d v essels.
A lso in th e s p r in g o f 1960, 4 -y e a r-o ld N o rw a y s p ru c e s w e re p l a n te d , th e sp a c in g b ein g 0 .9 3 X 1 -0 0 m . S u r r o u n d in g th e p lo ts tw o ro w s o f N o r w a y s p r u c e w e re p la n te d as iso la tio n . E a c h p lo t m e a s u r e s 45.5 m 2.
N 1
I • trees in isolationstrip
J
° tria l trees IF i g u r e 1. The lay-out of the trial.
F i g u r 1. Forsøgsplan.
D u rin g th e s p r in g o f 1974 a n ir r ig a tio n t r ia l w a s e s ta b lis h e d in t h e s ta n d , w h ic h by th e n h a d a c o m p le te ly clo sed c a n o p y . T h e m e a n h e i g h t o f th e s ta n d w a s 5.4 m . T h e la y -o u t m a y be se e n fro m F ig u r e 1. T h e t r i a l c o m p ris e s th e fo llo w in g tr e a tm e n ts —
(a ) 2 c o n tro l p lo ts
(b ) 2 p lo ts o n w h ic h , fro m A p ril 1 to S e p te m b e r 30, p a r t of th e s u r f a c e o f th e g r o u n d is s c re e n e d o ff b y p la te s , so t h a t 73.3 % o f th e t h r o u g h - fa ll is d iv e rte d . T h e q u a n tity o f c a r r ie d - o ff w a te r is m e a s u re d .
(c ) 2 p lo ts w h e re , in th e sa m e p e rio d , 20 m m o f w a te r is s u p p lie d to t h e soil w h e n e v e r th e d iffe re n c e b e tw e e n p r e c ip ita tio n -j- ir r ig a tio n w a t e r a n d a c o m p u te d e v a p o ra tio n c u rv e ( H o l s t e n e r - J ø r g e n s e n a n d H o l m s - g a a r d , 1975) ex ceed s 40 m m . H e r e a f te r c a lle d i / 2 i r r i g a t e d .
(d ) 2 p lo ts w h e re , in th e sa m e p e rio d , 40 m m o f w a te r is s u p p lie d w h e n ev er th e d iffe re n c e m e n tio n e d u n d e r (c ) ex c eed s 40 m m . H e re a fte r c a lle d 1 / 1 i r r i g a t e d .
T h e ir r ig a tio n is m a d e b y tr ic k le - ir r ig a tio n (se e H o l s t e n e r - J ø r g e n s e n a n d J o h a n s e n , 1975).
P r e lim in a r y r e s u lts o f f ie ld -m e a s u re m e n ts h a v e b een p u b lis h e d (H o l s t e n e r - J ø r g e n s e n a n d H o l m s g a a r d , 1 9 7 7 ).
b. T h e m e t h o d u s e d to o b t a i n l i t t e r s a m p l e s .
5 p la s tic f u n n e ls w e re p la c e d , ev e n ly sp a c e d , d ia g o n a lly b e tw e e n R ow 1 a n d R ow 2 a n d 5 f u n n e ls lik e w ise betw reen R o w 6 a n d Rowr 7. T h e ro w s r u n n o r th - s o u th a n d th e y w e re n u m b e re d fro m th e w e s te r n edge. T h e f u n n e ls u s e d w e re o f tw o d ia m e te r c la sse s, 140 m m a n d 175 m m . T h e fu n n e ls wrere p ro v id e d w ith a w ir e s u p p o r t a n d th e ir o u tle ts w e re fu r n is h e d w ith a n y lo n s c re e n to av o id w a te r a c c u m u la tio n . T h e a v e ra g e fu n n e l- a r e a p e r p lo t w a s 0.192 m 2, th u s re p r e s e n tin g 0.42 % o f p lo t a r e a s o f 45.5 m -.
T h e f u n n e ls wrere p la c e d in th e p lo ts o n J u n e 7, 1977. T h e y w e re e m p tie d on A u g u s t 6, O c to b e r 10, D e c e m b e r 21, 1977 a n d M a rc h 28, J u n e 2, 1978 a t w h ic h d a te th e in v e s tig a tio n w a s fin is h e d a f te r a lto g e th e r 360 d a y s.
c. L a b o r a t o r y m e t h o d s .
I n th e la b o r a to r y th e s a m p le s w e re a ir d r ie d a n d d iv id e d in to a ) n e e d les a n d b ) o th e r th in g s (tw ig s, b a rk , c o n es a n d o th e r m a t t e r ) . E a c h c a te g o ry w a s w e ig h e d a f te r k iln - d r y in g (6 0 ° C ). T h e y w e re g r o u n d (W ile y -m ill, 20 m e s h sieve) a n d a s u b -s a m p le w a s d r y a sh e d . T h e a s h w a s d isso lv e d in HC1, a n d a f te r p r e c ip ita tin g o f silic a, th e so lu te w a s a n a ly s e d fo r P (c o lo rim e tric , n itr ic a c id — m o ly b d a te — v a n a d a te ) , K (f la m e p h o to m e t r ic ) , a n d Mg (a to m ic a b s o r p tio n s p e c tr o p h o to m e tr y ) . N wra s d e te rm in e d b y a s e m i-m ic ro K je ld a h l m e th o d .
R E S U L T S a. W e i g h t s o f l i t t er .
T a b le 1 show 's g ra n d m e a n s w ith th e ir s ta n d a r d e r r o r s f o r (1 ) s p ru c e n e e d le s a n d (2 ) o th e r th in g s a t th e d if f e r e n t s a m p lin g d a te s . S ta n d a r d e r r o r s a re b a se d o n re s id u a ls a f te r a n a ly s e s o f v a ria n c e s , re m o v in g v a r ia n c e s d u e to ( a ) b lo c k s, (b ) tr e a tm e n ts , a n d (c ) fu n n e l p o s itio n in th e p lo ts. It m a y b e seen th a t, w h e re a s th e n e e d le fa ll is re a s o n a b le ev en on a n a re a -b a s is , o th e r th in g s a re fa llin g r a t h e r u n e v e n . T h is tr e n d is n o t u n e x p e c te d a n d is k n o w n fro m o th e r stu d ie s.
T a b l e 1. Survey of m eans and stan d ard e rro rs of m eans for litte r com ponents.
T a b e I 1. Oversi gt o v e r m i d d e l v æ r d i e r f or s t r ø k o mp o n e n t er n e og mi dde t f e j l på mi d d e l v ær d i e r .
D ate o f co llectio n
J n d s a m - li n g s d a t o
S p ru c e needles O ther th in g s
Mean g /m 2
S ta n d a rd e rro r M ean
g /m 2
S ta n d a rd e r ro r g /m 2
R ø d g r a n n å l e
re la tiv e g /m 2
A n d r e ti n g
re la tiv e
M i d d e l g / m 2
M i d d e l f e j l M i d d e l
g / m 2
M i d d e l f e j l
g / m - r e l a t i v g / m - r e l a t i v
6/8 -1977 60.73 2.257 3.72 11.83 0.729 6.16
10/10-1977 52.38 1.616 3.09 34.42 12.667 36.80
21/12-1977 79.65 2.121 2.66 19.57 4.322 22.08
28/3 -1978 52.77 1.324 2.51 17.40 1.240 7.13
2/6 -1978 112.44 5.395 4.80 11.70 0.197 1.68
M ean d a ily l itte r fa ll in th e 5 s a m p lin g p e r io d s c a n be se e n fro m T a b le 2. T h e r e is a s ig n if ic a n t re s p o n s e to tr e a tm e n ts (0.01 < p < 0 .0 5 ). T h e g e n e ra l tr e n d is t h a t th e a m o u n t o f l i t t e r fa ll is ris in g w ith im p ro v e d w a te r b a la n c e ; h o w e v e r, th e r e is no d if fe re n c e b e tw e e n 1 /2 ir r ig a te d a n d 1 /1 ir r ig a te d .
T a b l e 2. Average litte r fall p e r day in the collection perio d s, g /m 2.
SN = spruce needles; OT = o ther things.
T a b . e l 2. Gennemsni t l i gt dagligt st røfal d i de enkel te i n dsaml i ngspe ri ode r, g / m 2.
SN = rødgrannål e; OT = andre ting.
Period. N u m b er
o f d ay s F ra c tio n C ontrol — T h ro u iih - fa ll ‘ l / 2 - i r r i -
g ated l / l - i r r i - gated
Mean
P e r i o d e A n t a l
d a g e F r a k t i o n K o n t r o l S k æ r m e t 1/2 v a n d e t 1/1 v a n d e t M i d d e l
June 7, 1977 to
Aug. 6, 1977 60 SN
OT Sum
1.090 0.252 1.342
0.735 0.161 0.896
1.120 0.197 1.317
1.104 0.179 1.283
1.012 0.197 1.209 Aug. 6, 1977 to
Oct. 10, 1977 65
SN OT Sum
0.705 0.418 1.123
0.738 0.221 0.959
0.822 0.430 1.252
0.958 1.048 2.006
0.806 0.529 1.335 Oct. 10, 1977 to
Dec. 21, 1977 72
SN OT Sum
0.860 0.374 1.234
1.131 0.204 1.335
1.162 0.299 1.461
1.272 0.210 1.482
1.106 0.272 1.378 Dec. 21, 1977 to
M arch 28, 1978 97 SN
OT Sum
0.529 0.173 0.702
0.454 0.127 0.581
0.593 0.226 0.819
0.600 0.191 0.791
0.544 0.179 0.723
M arch 28, 1978 to SN 1.785 1.246 2.020 1.762 1.703
June 2, 1978 66 OT 0.161 0.120 0.214 0.215 0.178
Sum 1.946 1.366 2.234 1.977 1.881
T h e r e is a h ig h ly s ig n if ic a n t in te r a c tio n b e tw e e n s a m p lin g p e rio d s a n d l i tte r f a ll (p < 0 .0 0 1 ), w h ic h is d u e to d if f e r e n t a m o u n ts of l itte r fa ll fro m p e rio d to p e rio d a n d to v a ry in g r a tio s b e tw e e n n e e d le fa ll a n d fa ll o f o th e r th in g s . T h e fa ll o f n e e d le s is h ig h e s t in th e p e rio d fr o m M a rc h 28 to J u n e 2, 1978 ( s p r in g — e a rly s u m m e r ) a n d lo w e st in th e p e rio d D e c e m b e r 21, 1977 to M a rc h 28, 1978 ( w in te r ) . I t is n o ta b le th a t, f ro m A u g u s t 6 to O c to b e r 10, 1977 a n d fro m O c to b e r 10 to D e c e m b e r 21, 1977 n e e d le fa ll is r e la tiv e ly h ig h in th e p lo ts w ith c u t-d o w n th r o u g h f a ll c o m p a re d w ith o th e r p lo ts, w h ic h is p ro b a b ly d u e to th e a r tif ic ia l d ro u g h t, in good a c c o rd a n c e w ith th e f in d in g s by, a m o n g o th e rs , B o r n e b u s c h (1 9 3 7 ) a n d M o r k (1 9 4 2 ).
T h e fa ll o f o th e r th in g s is h ig h e s t d u r in g la te s u m m e r — a u tu m n a n d lo w e st d u r in g w in te r a n d s p r in g — e a rly s u m m e r. I t m u s t be k e p t in m in d th a t th e s a m p lin g e r r o r f o r o th e r th in g s is g re a t. T h e s ta n d a r d e r r o r of th e g r a n d m e a n in T a b le 2 is 13.4 % , so n o t to o m u c h im p o r ta n c e s h o u ld be a tta c h e d to th e d if fe re n c e s m e n tio n e d .
T h e c u m u la tiv e litte r f a ll d u r in g th e 360 d a y s ’ p e rio d u n d e r in v e s t
ig a tio n c a n b e se e n in T a b le 3 a n d F ig u r e 2. T h is ta b le , as w e ll a s th e fig u re , re fle c ts th e d iffe re n c e s b e tw e e n s a m p lin g p e rio d s a lre a d y m e n tio n e d . T h e n e e d le fa ll d u r in g th e w h o le p e rio d is a r o u n d 4 to n s of d r y m a tte r p e r h a in th e ir r ig a te d p lo ts , 3.4 to n s in c o n tro l p lo ts, a n d 3.0 to n s in th e
T a b l e 3. Cumulative litte r fall, g /m 2.
SN = sp ru ce needles; OT = o ther things.
T a b e l 3. Akkumul er et strøfald, g / m 2.
SN = rødgrannål e; OT = andr e ting.
P e rio d F ra c tio n C ontrol —T h ro u g h fa ll 1/2 irrig a te d 1/1 irrig a te d
P e r i o d e F r a k t i o n K o n t r o l S k æ r m e t 1/2 v a n d e t 1/1 v a n d e t
June 7, 1977 SN (55.38 44.10 67.20 66.23
to Aug. 6, 1977 OT 15.10 9.65 11.83 10.73
Sum 80.48 53.75 79.03 76.96
June 7, 1977 SN ■ 111.23 92.05 120.63 128.53
to Oct. 10, 1977 OT 42.29 24.04 39.78 78.88
Sum 153.52 116.09 160.41 207.41
June 7, 1977 SN 173.17 173.48 204.29 220.13
to Dec. 21, 1977 OT 69.19 38.74 61.34 94.02
Sum 242.36 212.22 265.63 314.15
June 7, 1977 SN 224.50 217.53 261.81 278.30
to M arch 28, 1978 OT 85.98 51.07 83.30 112.57
Sum 310.48 268.60 345.11 390.87
June 7, 1977 SN 342.34 299.79 395.16 394.61
to June 2, 1978 OT 96.62 58.97 97.41 126.73
Sum 438.96 358.76 492.57 521.34
g / m
2t / h a
5
0
days
F i g u r e 2. The cum ulative litter fall in the study period.
F i g n r 2. Det s u m m e r e d e st røf ai d i u nde rsøgel sespe ri ode n ( se i øvr i gt tabel- t ekster).
s h ie ld e d p lo ts . T h e fa ll o f o th e r th in g s is 1.3 to n s p e r h a in 1 /1 ir r ig a te d p lo ts , a r o u n d 1.0 to n i n 1 /2 ir r ig a te d a n d c o n tro l p lo ts, a n d 0.6 to n in s h ie ld e d p lo ts . T h e to ta l litte r fa ll is a r o u n d 5.2 to n s p e r h a in 1 /1 i r r i g a te d p lo ts, 4.9 to n s i n 1 /2 ir r ig a te d p lo ts , 4.4 to n s in c o n tr o l p lo ts, a n d 3.6 to n s in sh ie ld e d p lo ts . I t s h o u ld be n o tic e d t h a t th e la s t tw o d iffe re n c e s b e tw e e n 1 /2 ir r ig a te d a n d 1 /1 ir r ig a te d o rig in a te m a in ly f ro m th e la rg e a m o u n t o f o th e r th in g s in th e 1 /1 ir r ig a te d p lo ts co lle c te d in th e p e rio d A u g u s t 6 to O c to b e r 10, 1977.
b. N u t r i e n t c o n c e n t r a t i o n s in t h e l i t t er .
A su rv e y o f th e n u tr ie n t c o n c e n tr a tio n s in th e tw o c o m p o n e n ts o f th e l i t t e r is s h o w n in T a b le 4.
T a b l e 4. C oncentrations (% ) of ash and n u trien ts in the litte r fall com ponents at the differen t sam pling dates.
T a b e l 4. I n d h o l d e t ( % ) af aske og næri ngss t off er i strøfaldets f r akt i oner p å de forskel lige indsamli ngsdage.
L itte r co m p o n en t
C ontrol —T h ro u g h fa ll
S t r ø - f r a k t i o n
E lem ent 6/8-77 10/10-77 21/12-77 K o n t r o l
28/3-78 2/6-78 6/8-77 10/10-77 21/12-77 S k æ r m e t
28/3-78 2/6-78
E l e m e n t 6/ 8 -77 1 0 /1 0 -7 7 2 1 / 1 2 -77 28 /3 -7 8 2 / 6 -7 8 6 /8 - 7 7 10 /10 -77 2 1 /1 2 -7 7 2 8 /3 -7 8 2/6 -7 8
Spruce Ash 6.9 8.4 6.5 6.5 6 .2 7.3 8.5 6.8 7.2 6.4
needles N 1.32 1.24 1.10 1.45 1.24 1.21 1.16 0.97 1.30 1.16
Rødqran- nåle
P 0.16 0.15 0.17 0.16 0.16 0.16 0.15 0.16 0.16 0.16
K 0.32 0.38 0.45 0.37 0.61 0.34 0.39 0.36 0.30 0.57
Mg 0.09 0.13 0.10 0.10 0.10 0.10 0.16 0.10 0.09 0.09
Otlier Ash 16.3 16.6 16.5 25.6 23.9 29.4 20.0 20.1 26.7 29.6
things N 1.88 1.62 1.51 1.93 1.83 1.94 1.90 1.37 2.37 1.76
An d r e P 0.23 0.21 0.34 0.26 0.29 0.30 0.23 0.26 0.33 0.29
ting K 0.31 0.45 0.29 0.24 0.36 0.27 0.41 0.33 0.16 0.29
Mg 0.14 0.19 0.16 0.12 0.11 0.13 0.18 0.12 0.10 0.12
T a b l e 4 (co n tin u ed ).
T a b e l 4 (fort sat) .
L itte r
com ponent 1 /2 irrig a te d 1/1 irrig a te d
S t r ø f r a k t i o n
E le m e n t 6/8-77 10/10-77 21/12-77
1/2 v a n d e t
28/3-78 2/6-78 6/8-77 10/10-77
i f l
21/12-77 v a n d e t
28/3-78 2/6-78
E l e m e n t 6 / 8 - 7 7 1 0 /1 0- 7 7 21 /1 2-7 7 28 /3 -7 8 2/6-78 6 /8 - 7 7 1 0 / 1 0 -77 2 1 /1 2 -7 7 28 /3 -7 8 2/6 -7 8
Spruce Ash 7.9 8.9 7.1 7.8 7.4 7.6 9.6 8.0 8.3 6.8
needles N 1.23 1.15 1.01 1.43 1.12 1.40 1.24 1.18 1.34 1.24
Rødgr an P 0.16 0.16 0.17 0.16 0.18 0.17 0.17 0.17 0.17 0.19
nåle K 0.37 0.40 0.42 0.33 0.65 0.35 0.37 0.36 0.30 0.60
Mg 0.10 0.14 0.10 0.10 0.10 0.10 0.14 0.10 0.10 0.10
O ther Ash 19.2 22.3 19.8 34.1 33.9 22.7 54.2 23.3 36.7 33.8
things N 1.87 1.64 1.45 2.07 2.16 1.85 1.78 1.90 2.06 2.35
An d r e P 0.31 0.25 0.27 0.35 0.37 0.29 0.34 0.37 0.41 0.29
ting K 0.29 0.47 0.29 0.20 0.37 0.28 0.30 0.30 0.19 0.31
Mg 0.13 0.17 0.13 0.12 0.15 0.13 0.19 0.13 0.13 0.11
Det fo rs tlig e F o rsø g sv æ sen . XXXVI. H . 3. I I . o k to b e r 1979. 6
In th e s p ru c e n e e d le s, c o n c e n tra tio n s a r e v a ry in g -with th e s a m p lin g p e rio d s . G e n e ra lly th e d iffe re n c e s a re h ig h ly s ig n if ic a n t (p < 0 .0 0 1 ). T h e o n ly e x c e p tio n is i n th e P -c o n c e n tra tio n s (0.01 < p < 0 .0 5 ).
T h e tr e a tm e n ts h a v e a h ig h ly s ig n if ic a n t in flu e n c e o n th e a s h c o n c e n tr a tio n s (p < 0 .0 0 1 ). T h e a s h c o n c e n tr a tio n s a re h ig h e r in th e n e e d le s in th e tr e a te d p lo ts t h a n in th e c o n tro ls .
A lso N - c o n c e n tr a tio n s i n th e n e e d le s a r e s ig n if ic a n tly in flu e n c e d b y tr e a tm e n ts (0.001 < p < 0 .0 1 ). I n th is c a se sh ie ld e d p lo ts a n d 1 /2 i r r i g a te d p lo ts h a v e , o n a n a v e ra g e , lo w e r c o n c e n tr a tio n s t h a n c o n tr o ls a n d 1 /1 ir r ig a te d p lo ts . T h e o v e ra ll d iffe re n c e b e tw e e n th o s e tw o g ro u p s is 0.10 % N.
T h e tr e a tm e n ts h a v e h a d a s ig n ific a n t in flu e n c e o n P -c o n c e n tra tio n s in th e n e e d le s (0.001 < p < 0 .0 1 ). T h e g e n e ra l tr e n d is t h a t P -c o n c e n tra - tio n s a re h ig h e r i n th e ir r ig a te d p lo ts th a n in th e c o n tro ls a n d th e sh ie ld e d p lo ts . T h e m e a n d iffe re n c e b e tw e e n th o s e g ro u p s is 0.009 % P .
T h e d e te r m in a tio n o f K -c o n c e n tra tio n s i n f a lle n n e e d le s is o f m a r g in a l in te r e s t o n ly , a s m o s t o f th e p o ta s s iu m in p l a n t tis s u e is w a te r s o lu b le a n d m a y be w a s h e d o u t o f th e tis s u e b y th e r a in f a ll, b o th w h e n th e tis s u e is aliv e a n d w h e n , a s in litte r , i t is d e a d ( T a m m 1951, M a d g w i c k a n d O v i n g - t o n 1 9 5 4 ). T h e r e is no s ig n if ic a n t d iffe re n c e b e tw e e n K -c o n c e n tra tio n s (0.05 < p < 0 .1 0 ), b u t th e g e n e ra l te n d e n c y is t h a t c o n c e n tr a tio n s a re lo w e r in th e sh ie ld e d p lo ts a n d th e 1 /1 ir r ig a te d p lo ts th a n i n th e c o n tr o ls a n d th e 1 /2 ir r ig a te d p lo ts.
M g -c o n c e n tra tio n s in n e ed le l i t t e r seem to be f u lly in d e p e n d e n t o f th e tr e a tm e n ts .
C o n c e rn in g th e se c o n d litte r c o m p o n e n t, o th e r th in g s , th e v a r ia tio n in n u t r i e n t c o n c e n tr a tio n s is c o n s id e ra b le , a n d th e r e a re n o g e n e ra l s ig n ific a n t tr e n d s . T h e r e a re s ig n ific a n t d iffe re n c e s b e tw e e n s a m p lin g d a te s fo r N -co n c e n tr a tio n s (0.001 < P < 0 .01), f o r K -c o n c e n tra tio n s ( p < 0 .0 0 1 ), a n d fo r M g -c o n c e n tra tio n s (p < 0 .0 0 1 ). T r e a tm e n ts h a v e h a d no s ig n ific a n t i n flu e n c e o n th e c o n c e n tra tio n s .
c. A m o u n t s o f n u t r i e n t s r e t u r n e d w i t h t h e l i t t er .
T a b le s 5 to 9 sh o w th e c u m u la tiv e n u t r i e n t c o n te n t in th e l itte r d u r in g th e in v e s tig a tio n p e rio d , a n d in F ig u r e 3 th e fig u re s fro m T a b le 6 (N -con- te n t in l i t t e r f a ll) a r e p lo tte d a g a in s t tim e to i l lu s tr a te th e r e t u r n of N to th e soil s u rfa c e .
T h e re is a g e n e ra l tr e n d in th e fig u re s w h ic h is in a g re e m e n t w ith th e tr e n d s in th e b a s ic f ig u re s on w h ic h th e y a re fo u n d e d , w e ig h t o f l itte r a n d n u tr ie n t c o n c e n tr a tio n s i n litte r. T h e a s h a n d n u t r i e n t r e t u r n wTith th e litte r is lo w e st in th e sh ie ld e d p lo ts, c o n tro ls a r e in te r m e d ia te , a n d ir r ig a te d p lo ts
T a b e l 5. Ak k u mu l e r e t i n d h o l d af aske i strøfaldet, g / m 2.
SN = r ødgrannål e; OT = andr e ting.
T a b l e 5. Cumulative content of ash in litter fall, g /m 2.
SN = spruce needles; OT = other things.
P e rio d F ra c tio n C ontrol —T h ro u g h fa ll 1 /2 ir rig a te d 1/1 irrig a te d
P e r i o d e F r a k t i o n K o n t r o l S k æ r m e t 1/2 v a n d e t 1/1 v a n d e t
June 7, 1977 SN 4.51 3.23 5.30 5.01
to Aug. 6, 1977 OT 2.47 2.84 2.27 2.43
Sum 6.98 6.07 7.57 7.44
June 7, 1977 SN 8.35 7.28 10.08 10.98
to Oct. 10, 1977 OT 6.99 5.72 8.51 39.35
Sum 15.34 13.00 18.59 50.33
Ju n e 7, 1977 SN 12.40 12.82 16.05 18.29
to Dec. 21, 1977 OT 11.43 8.67 12.79 42.88
Sum 23.83 21.49 28.84 61.17
Ju n e 7, 1977 SN 15.72 16.00 20.54 23.12
to M arch 28, 1978 OT 15.72 11.96 20.29 49.68
Sum 31.44 27.96 40.83 72.80
Ju n e 7, 1977 SN 22.98 21.26 30.46 31.03
to June 2, 1978 OT 18.26 14.30 25.07 54.46
Sum 41.24 35.56 55.53 85.49
T a b l e 6. Cum ulative co n ten t of N in litte r fall, g /m 2.
SN = spruce needles; OT = o th er things.
T a b e l 6. A k k u mu l e r e t i n d h o l d af N i strøfaldet, g / m 2.
SN = rødgrannål e; OT = a n d r e ting.
P e rio d F ra c tio n C ontrol —T h ro u g h fa ll 1 /2 irrig a te d 1/1 irrig a te d
P e r i o d e F r a k t i o n K o n tr o l S k æ r m e t 1/2 v a n d e t 1/1 v a n d e t
June 7, 1977 SN 0.86 0.53 0.83 0.93
to Aug. 6, 1977 OT 0.28 0.19 0.22 0.20
Sum 1.14 0.72 1.05 1.13
June 7, 1977 SN 1.43 1.09 1.44 L70
to Oct. 10, 1977 OT 0.72 0.46 0.68 1.41
Sum 2.15 1.55 2.12 3.11
June 7, 1977 SN 2.11 1.88 2.28 2.78
to Dec. 21, 1977 OT 1.13 0.66 0.99 1.70
Sum 3.24 2.54 3.27 4.48
Ju n e 7, 1977 SN 2.85 2.45 3.10 3.56
to M arch 28, 1978 OT 1.45 0.95 1.44 2.08
Sum 4.30 3.40 4.54 5.64
Ju n e 7, 1977 SN 4.31 3.40 4.59 5.00
to June 2, 1978 OT 1.64 1.09 1.74 2.41
Sum 5.95 4.49 6.33 7.41
T a b e l 7. A k k u mu l e r e t i n d h o l d af P i s t r øf aldet, g / m 2.
SN = rødgrannål e; OT = andr e ting.
T a b l e 7. Cumulative content of P in litter fall, g /m 2.
SN = spruce needles; OT = other things.
P e rio d F ra c tio n • C ontrol —T h ro u g h fa ll 1/2 ir rig a te d 1/1 irrig a te d
P e r i o d e F r a k t i o n K o n t r o l S k æ r m e t 1 /2 v a n d e t 1 /1 v a n d e t
June 7, 1977 SN 0.10 0.07 0.11 0.11
to Aug. 6, 1977 OT 0.03 0.03 0.04 0.03
Sum 0.13 0.10 0.15 0.14
Ju n e 7, 1977 SN 0.17 0.14 0.19 0.22
to Oct. 10, 1977 OT 0.09 0.06 0.11 0.26
Sum 0.26 0.20 0.30 0.48
June 7, 1977 SN 0.27 0.27 0.33 0.37
to Dec. 21, 1977 OT 0.18 0.10 0.17 0.32
Sum 0.45 0.37 0.50 0.69
Ju n e 7, 1977 SN 0.35 0.34 0.42 0.47
to M arch 28, 1978 OT 0.42 0.14 0.25 0.40
Sum 0.77 0.48 0.67 0.87
June 7, 1977 SN 0.54 0.47 0.65 0.69
to June 2, 1978 OT 0.45 0.16 0.30 0.44
Sum 0.99 0.63 0.95 1.13
T a b l e 8. Cum ulative co n ten t of K in litte r fall, g /m 2.
SN = spruce needles; OT = o th e r things.
T a b e l 8. A k k u mu l e r e t i n d h o l d af K i strøf aldet, g / m 2.
SN = rødgrannål e; OT = a n d r e ting.
P e rio d F ra c tio n C ontrol —T h ro u g h fa ll 1/2 irrig a te d 1/1 irrig a te d
P e r i o d e F r a k t i o n K o n t r o l S k æ r m e t 1/2 v a n d e t 1 / 1 v a n d e t
June 7, 1977 SN 0.21 0.15 0.25 0.23
to Aug. 6, 1977 OT 0.05 0.03 0.03 0.03
Sum 0.26 0.18 0.28 0.26
June 7, 1977 SN 0.38 0.34 0.46 0.46
to Oct. 10, 1977 OT 0.17 0.09 0.16 0.23
Sum 0.55 0.43 0.62 0.69
June 7, 1977 SN 0.66 0.63 0.81 0.79
to Dec. 21, 1977 OT 0.25 0.14 0.22 0.28
Sum 0.91 0.77 1.03 1.07
June 7, 1977 SN 0.85 0.76 1.00 0.96
to M arch 28, 1978 OT 0.29 0.16 0.26 0.32
Sum 1.14 0.92 1.26 1.28
June 7, 1977 SN 1.57 1.23 1.87 1.66
to June 2, 1978 OT 0.33 0.18 0.31 0.36
Sum 1.90 1.41 2.18 2.02
T a b e l 9. Ak k u mu l e r e t i n d h o l d af Mg i strøfaldet, g / m 2.
SN = rødgrannål e; OT = andr e ting.
T a b l e 9. Cumulative content of Mg in litter fall, g /m 2.
SN = spruce needles; OT = other things.
P e rio d F ra c tio n C ontrol — T h ro u g h fa ll 1/2 irrig a te d 1/1 irrig a te d
P e r i o d e F r a k t i o n K o n t r o l S k æ r m e t 1 / 2 v a n d e t 1 / 1 v a n d e t
June 7, 1977 SN 0.06 0.04 0.07 0.07
to Aug. 6, 1977 OT 0.02 0.01 0.02 0.01
Sum 0.08 0.05 0.09 0.08
June 7, 1977 SN 0.12 0.12 0.15 0.15
to Oct. 10, 1977 OT 0.07 0.04 0.07 0.14
Sum 0.19 0.16 0.22 0.29
June 7, 1977 SN 0.18 0.20 0.23 0.24
to Dec. 21, 1977 OT 0.11 0.06 0.10 0.16
Sum 0.29 0.26 0.33 0.40
June 7, 1977 SN 0.23 0.24 0.29 0.30
to M arch 28, 1978 OT 0.13 0.07 0.13 0.18
Sum 0.36 0.31 0.42 0.48
June 7, 1977 SN 0.35 0.31 0.42 0.42
to June 2, 1978 OT 0.14 0.08 0.15 0.20
Sum 0.49 0.39 0.57 0.62
s h o w th e h ig h e s t v a lu e s. I n m o s t in s ta n c e s 1 /1 ir r ig a te d p lo ts sh o w h ig h e r v a lu e s t h a n 1 /2 ir r ig a te d p lo ts (a s h , N, P , a n d M g ). I t s h o u ld o n ce m o re b e n o te d t h a t o n ly m a r g in a l a tte n tio n c a n be p a id to K -v a lu e s b e c a u s e of th e w a s h in g -o u t o f th is e le m e n t b y th e ra in fa ll.
T h e tu r n - o v e r o f n u tr ie n ts o n a y e a r ly b a s is is as fo llo w s:
N : 45 — 74 k g / h a P : 6 .3 — 11.3 k g / h a ( K) : 14 — 22 k g / h a M g: 3 .9 — 6.2 k g / h a
d. I n c r e m e n t a n d n e e d l e fall.
O n e re a s o n f o r c a r r y in g th r o u g h th is in v e s tig a tio n w a s to e lu c id a te w h e th e r th e tr e a tm e n ts in th e ir r ig a tio n t r ia l h a v e a n y in flu e n c e o n th e n e e d le fa ll. I t m a y be p r e s u m e d t h a t a n y in flu e n c e o n in c r e m e n t re fle c ts tr e a tm e n t- in d u c e d d iffe re n c e s in le a f a r e a in d e x , w h ic h in t u r n r e s u lt in p a r a lle l d iffe re n c e s in n e e d le fall. In F ig u r e 4 n e e d le fa ll v a lu e s ( t / h a ) a re p lo tte d a g a in s t m e a n a n n u a l b a s a l a r e a in c r e m e n t ( m 2/ h a ) in th e 5 -y e a r p e rio d d u r in g w h ic h th e tr e a tm e n ts h a v e so f a r b een c a r r ie d th r o u g h . T h e
N k g / h a 100
N
g /itv *o control + - th ro u g h fa ll
*1/2 irrig a te d
#1/1 irrigated --- Spruce needles --- Other things
► Total litterfaU
5 0 -
10
days
F i g u r e 3. The cum ulative con ten t of N in litter fall.
F i g u r 3. Det s u mme r e d e N-i ndhol d i st r øfal det ( se i øvr i gt tabeltekster).
4,00
3,50
3,00
, y e a r
F i g u r e 4. Needle fall p lotted against average basal area in crem en t in the fore
going 5 y ears’ period.
F i g u r 4. Nål ef al d lagt o p over årlig grundf l ade t i l v æks t i den f orudgående 5 års-periode.
re g re s s io n -lin e is e s tim a te d ; h o w e v e r, th e c o r r e la tio n c o e ffic ie n t r = 0.816 is s ig n ific a n t (0.01 < p < 0 .0 2 ), w h ic h is a s tro n g s u p p o r t o f th e w 'o rk in g h y p o th e s is .
D ISC U SSIO N
A s m e n tio n e d in th e in tr o d u c tio n , th e a u th o r s h a v e f o u n d i t p r e f e r a b le n o t to m a k e a t r a d itio n a l re v ie w of th e lite r a tu r e . In T a b le 10 so m e p u b lis h e d f ig u r e s a re p r e s e n te d to g e th e r w ith a few r e m a r k s a n d w ith th e c o m p a ra b le f ig u r e s f r o m th e p r e s e n t in v e s tig a tio n . T h e r e is o n e r e m a r k to b e m a d e a b o u t th e fig u re s , th e y all com e fro m s ta n d s w ith clo sed c a n o p ies, b u t a p a r t fro m th is th e ir o r ig in s a re d if f e r e n t c o u n tr ie s in E u ro p e , a n d a sin g le N o r th A m e ric a n s ta n d is in c lu d e d , too. A lso, th e s ta n d s h a v e v a ry in g ages, a n d site f a c to r s a s w e ll a s h e ig h t above se a level v a r y a good deal.
T h e fig u re s in th e ta b le v a ry v e r y m u c h . T h e lo w e s t fa ll o f n ee d le s h a s b e e n fo u n d b y B o r n e b u s c h (1 9 3 7 ), th e h ig h e s t b y G l o a g u e n a n d T o u f f e t
i d n e e d l e fal l
4 '9mL
T a b l e 10. Sum m ary of results from litte r fall studies in N orw ay spruce stands.
T a b e l 1 0 . Samme n f a t ni ng af pu b l i c e r e d e str øfal ds undersøgel ser i rødgran.
k g litte r kg N
R eference p e r h a
a n d y e a r k g s tr ø
% n eed les p e r h a a n d y e a r k g N
R e m a rk s
F o r f a t t e r p r . h a
og å r
% n å l e p r . h a og d r
B e m æ r k n i n g e r
Aussenac, 1969 2924 85.6 1 stand, average of 2
years. Needle fractio n 1 year.
Bonnevie-Svendsen
and Gjems, 1957 2996 75.8 29.0 Average of 4 stands and
2 years. The am ount of litte r seems to be co r
related w ith stand den
sity (basal area).
Bornebusch, 1937 1499 _ — Average of 3 stands and
2 years, needles only.
C handler, 1943 3767 -- 38.6 1 stand an d 1 year,
needles only.
D ietrich, 1963 3217 79.5 32.0 Average of 4 stands and
2 years.
Duvigneaud et al. 1972 3141 86.4 — 1 stand an d 1 year.
Gloaguen et Touffet,
1976 7369 91.9 68.5 1 stand, average of 4
years.
Gossuin, 1974 2632 83.2 — 1 stand, average of 3
years.
H unger, 1975
Control 2678 74.6 33.2 1 stand \ average of
F ertilized 2746 77.7 35.9 1 stand J 3 years.
Kollist, 1967 3300 — — Quoted from F o restry
abstracts, 1969.30:597.
L indberg och Nor-
m ing, 1943 3089 — 29.7 1 stand and 1 year,
needles only.
Mork, 1942 2989 81.8 35.5 Best stan d out of 4,
average of 3 years.
N ihlgård, 1972 5720 76.2 58 1 stand average of
3 years.
R ok’yanis, 1974 2328 63.7 13.3 Average of 5 stands,
1 year.
Viro, 1955 2524 72.9 21.2 Average of 3 stands and
4 years.
T he p resen t investigation:
— T hroughfall 3588 83.6 44.9 I
Control 4390 78.0 59.5 1 Average of 2 plots,
1 /2 irrig ated 4926 80.2 63.3 1 1 year.
1/1 irrig ated 5213 75.7 74.1
(1 9 7 6 ). I n b o th c a se s th e s tu d ie s w e re c o n tin u e d f o r m o r e th a n o n e y e a r ; th e r e f o r e th e r e is h a r d ly a n y re a s o n to believe t h a t th o s e tw o in v e s tig a tio n s r e p r e s e n t a ty p ic a l in s ta n c e s , f o r in s ta n c e d u e to sev ere d ro u g h ts , w h ic h c o u ld c a u s e h e a v y n e e d le fa ll in th e d r o u g h t y e a r a n d d e c re a s e d n e e d le fa ll i n th e fo llo w in g y e a r.
In m o s t o f th e p u b lic a tio n s , e s tim a tio n s o f th e s a m p lin g e r r o r s a re p re s e n te d , a n d th e y sh o w t h a t th e m e th o d s u s e d a re good e n o u g h to w a r r a n t s ig n ific a n t d iffe r e n c e s b e tw e e n th e in v e s tig a tio n s ; h o w e v e r, n o th in g c a n be s a id a b o u t a n y b ia s d u e to th e s a m p lin g m e th o d s u s e d . A b ia s m a y b e e x p e c te d to be n e g a tiv e in th e se n se th a d n e e d le s a n d o th e r th in g s p a s s th r o u g h th e w a te r d r a in s in th e c o lle c tin g d ev ices, le a d in g to lo w e r l itte r fa ll v a lu e s th a n th e tr u e l i t t e r fall. C o n c e rn in g th e p r e s e n t s tu d y , f r e q u e n t in s p e c tio n s o f th e f u n n e ls h a v e m a d e th e p o s s ib ility of lo s in g n e e d le s i n
s ig n if ic a n t; h o w e v e r, a lo ss o f m in o r p a r tic le s of o th e r th in g m a y o c c u r.
In th is c o n n e c tio n i t sh o u ld b e n o te d t h a t th e r e la tiv e n e e d le f r a c tio n s of th e to ta l l itte r fa ll, a lth o u g h v a ry in g a m o n g in v e s tig a tio n s a n d w ith in i n v e s tig a tio n s , give n o s u p p o r t f o r a n y h y p o th e s is a b o u t b ia s e d e s tim a te s of o th e r th in g s .
A t th is sta g e o f l itte r fa ll s tu d ie s i t seem s f a ir to s ta te t h a t th e r e a re g r e a t v a r ia tio n s w ith in a re g io n lik e N o r th e r n E u ro p e , w h ic h c a n n o t be e x p la in e d b u t m u s t be ta k e n a s p la in f a c ts . It c a n b e seen fr o m th e f ig u re s i n T a b le 10 th a t th e la te s t D a n is h f in d in g s fa ll w ith in th is v a r ia tio n r a n g e , a lth o u g h , o n a n a v e ra g e , th e y a re s o m e w h a t h ig h e r th a n th e g e n e ra l m e a n .
T a b le 10 also, sh o w s th e N -tu rn o v e r in th o s e s tu d ie s w h e re N -a n a ly se s h a v e b e e n c a r r ie d th r o u g h . T h e D a n is h in v e s tig a tio n s h o w s r e la tiv e ly h ig h a m o u n ts o f N. As to th e D a n is h fin d in g s , th e tr e a tm e n t- in d u c e d d if f e r e n ce s in k g N p e r h a a re m a in ly c a u s e d b y th e d iffe re n c e s in a m o u n t o f l i t te r. I t is w o r th m e n tio n in g , to o , t h a t th e D a n is h s ite is r a t h e r fe rtile .
A s to th e level o f o th e r n u tr ie n ts , th e tu r n o v e r in th e D a n is h s tu d y is a lso h ig h e r t h a n th e fig u re s fro m o th e r s tu d ie s , w h ic h is u n d e r lin in g t h a t th e f e r tility o f th e s ite u n d e r c o n s id e r a tio n is h ig h .
M o r k (1942) c la im s t h a t th e a m o u n t o f l i tte r p e r y e a r is d e p e n d e n t on site q u a lity , age o f s ta n d , a n d h e ig h t ab o v e sea level. 4 o b s e rv a tio n s c a n h a r d ly s u p p o r t th is w id e c o n c lu sio n .
H u n g e r (1975) s ta te s t h a t th e d iffe re n c e b e tw e e n h is 2 p lo ts is close to b e in g s ig n ific a n t (0.05 < P < 0 .1 0 ). H e also d e m o n s tr a te s t h a t th is d if fe re n c e is d u e to a la r g e r l i t t e r fa ll j u s t a f te r th e fe r tilis a tio n .
A p a rt f ro m th o s e tw o re f e re n c e s a n d in c o n tr a d ic tio n to M ø l l e r’s (1 9 4 4 ) c o n c lu s io n s m e n tio n e d in th e in tr o d u c tio n , it is f a ir to s tre s s t h a t th e p r e s e n t s tu d y d e m o n s tr a te s a p o sitiv e c o r re la tio n b e tw e e n in c r e m e n t a n d a m o u n t o f litte r fa ll, w h ic h is n ew a n d in c lo se r a g r e e m e n t w ith c o m m o n se n se e x p e c ta tio n s th a n M ø l l e r ’s s ta te m e n ts a re .
SUMMARY
In an irrig a tio n tria l in 21-year-old N orw ay sp ru ce on fertile clayey m oraine (Holstener-Jørgensen a n d Hol msgaard, 1977) the am ount of litte r fall w as meas
u re d and its chem ical com position determ in ed over a p erio d of a year (1977/78).
The tables an d figures of the re p o rt show the follow ing —
The am ount an d chem ical com position of the litte r fall are d ep en d en t on th e treatm ents ap p lied in the trial. In screened-off plots w h ere p a rt of th e sum
m er p re c ip ita tio n is diverted, the litte r fall is th e poorest, 3.6 tons p e r ha, of w h ic h 3.0 tons are needles. The am ounts are in creasin g w ith the im provem ent of the w a te r supply to the plots. In 1/1 irrig a te d plots the litte r fall is 5.2 tons p e r ha, of w h ic h 3.9 tons are needles.
W ith the litter, p la n t n u trien ts are retu rn e d to th e soil. T hus, in screened-off plots 44.9 kg N p e r h a is retu rn e d , in fully irrig a te d plots 74.1 kg p e r ha.
Møll er (1944) on the basis of his studies in closed stands concluded th a t the am ount of needles is in d ep e n d en t of —
(1) age of stand (2) heig h t of stan d (3) site quality
(4) grade of th in n in g w hen m easured a couple of years afte r the last th in ning.
In the irrig a tio n trial, w h ic h is un th in n ed an d has fully closed canopy, there is a correlation betw een needle fall and basal a re a increm ent (Figure 4 ), w hich is in closer agreem ent w ith com m on sense than M øller’s conclusions are.
DANSK SAMMENFATNING
I et vandingsforsøg i 21-årig rø d g ran på fru g tb a r lerm oræ ne (Hol s t ener- Jørgensen an d Hol msgaard, 1977) er strøfaldets størrelse m ålt og dets kem iske sam m ensæ tning bestem t over en p erio d e p å et å r (1977/78).
B eretningens tab eller og fig u rer v iser følgende:
Strøfaldets stø rrelse og kem iske sam m ensæ tning er afhæ ngige af forsøgets behandlinger. I skæ rm ede p arceller, h v o r en del af som m ernedbøren ledes bort, e r strøfaldet m indst, nem lig 3.6 t p r. ha, hvoraf 3.0 t er nåle. M ængderne stiger m ed fo rb ed rin g af p a rcellern es vandforsyning. I 1/1 vandede p arc e lle r er strø
faldet 5.2 t p r. ha, h v o raf 3.9 t er nåle.
Med strø et re tu rn e re s p lantenæ ringsstoffer til jorden. I skæ rm ede p a rceller retu rn e res således 44.9 kg N p r. ha, i fu ld t vandede 74.1 kg N p r. ha.
Møller (1944) konkluderede p å grundlag af sine stu d ier i sluttede bevoks
ninger, at nålem æ ngden er uafhæ ngig af 1) bevoksningsalder
2) bevoksningshøjde 3) b onitet
4) ty ndingsstyrke ved undersøgelse et p a r å r efter sidste tynding.
I vandingsforsøgets behandlingsled, hvor bevoksningerne er fu ld t sluttede og utyndede, er d e r en k o rrelatio n mellem nålefald og grundfladetilvæ kst (figur 4), som e r i bedre overensstem m else m ed sund fo rn u ft end Møllers konklusioner.
Oxford Classific. No. 114.351, 160.21, 561.25 Picea abies.
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R e t t e l s e til n r . 282. H. C. O ls e n : V e d m a s s e ta b e l fo r rø d g r a n i D a n m a r k . B in d XXXIV.
D a fo rm le rn e ( 1 3 ) , (1 4 ) og (1 5 ) v ed e n b e k la g e lig fe jl er a n f ø r t u d e n k o r r e k tio n s v a re n d e til, a t d m å le s i cm , b e d e s fø l
g e n d e r e tte ls e r fo r e ta g e t:
sid e 380: i (1 3 ) r e tte s „— 2 log d “ til „— 2 log ( d / 1 0 0 ) “ s id e 381: i (1 4 ) r e tte s „0.000977“ til „4.000977“
sid e 381: i (1 5 ) r e tte s „ 0 .105887“ til „4.105887“
