0

\rl RESEARCH BRlT15H COLUMBIR FOREST SERVICE

0 <"..,, A ;i v,,

"

No. 42 VICTORIA, B.C., CANADA 1967

OF SCARIFIED S

SPRUCE ERATION BY

J.W.C. ARLIDGE

R e s e a r c h D h i s i o n

FOREST SERVICE D E P A R T M E N T OF LANDS, FORESTS, AND WATER RESOURCES

W T H E DURABILITY O F SCARLFIED SEEDBEDS

F O R

SPRUCE REGENERATION

BY

J , W . C . Arl idge

B. C. Forest Service Research Nates are issued at irregular intervals and distributed on the basis of their individual interest. Therefore, it may not be p s s i b l e f o r persons o r organizations t o m i n t a i n complete f i l e s i M s m c h as certain numbers may pertain only t o Forest Service problems and hence be issued o n l y to Service personnel.

Scarif ied seedbeds in 0 (Devil ' s Club) s i te type are rapidly invaded by thimbleberry(Rubus parvuflorus). Assistant is standing at cent re of scar i f ied seedbed that was bare mineral soi l 4. 9 feet wide three years before . Vegetat ion on areas not scar i f ied was one to two feet high at that time.

SUMMARY

5.

U

The effective life of machine-scar i f ied seedbeds w a s investigated 8# 17 a r e a s in the Pr ince George Forest Ois t r ic t . A l l a r e a s w e r e on si tes of average or bet ter product ivi ty for the region.

On each area f rom one up to a maximum of five sample plots were established, making a total of 33 plots distributed over a number of s i t e s , years, and methods of scarification. In each plot , seedbeds were selected at random along scar i f ied s t r ips s o that they represented a range in size from one foot square to 6 .6 feet square.

Seedbeds were seeded in the year of scar i f icat ion (SYO), and one (SYl), two (SY2), t h ree (SY3), and four (SY4) years after being scarified. When all these seeding treatments had been concluded, 310 seedbeds were under observation on each plot.

Because nature could not be relied upon to provide a constant supply of seed, seedbeds were spot-sown ar t i f ic ia l ly to s imulate an annual natural seedfal l . Thus the resul ts of the study are also an indication of what to expect after art if icially seeding strips which were scarified originally to induce natural regeneration.

The cr i ter ion of effect iveness was termed "success" and i t w a s ra ted as the per cent of seeded seedbeds with one o r more heal thy spruce seedlings in relation to the age and size of the seedbed since the date of scar i f icat ion. In addition to these main related factors, the influence of s i te-qual i ty , s ize of t ractor , and the interval of time between logging and scarifying also w a s examined.

Seeding year had a definite effect , and success decreased with the passage of t ime between scarifying and seeding. Mean success w a s 62 .8 per cen t for SYO, and 52.7, 38.7, 36.9, and 29.0 percent respect ively for SY1, SYZ, SY3, andSY4.

Success var ied direct ly with seedbed s ize . On large seedbeds, survival w a s greater and the decrease due to seeding-year effect w a s much less than on small seedbeds. The overall success was 44.0 p e r cent at the end of the f i r s t g rowing season , and 45.7, 40.1, 33.9, and 26.9 per cent respectively at the end of the second, third, fourth, and fifth growing seasons (when seeding year was ignored and the per cent of all seedbeds with one or more spruce seedl ings w a s averaged each season) .

The re were no such c lear resul ts for success in re la t ion to the s ize of the bulldozer, si te-type, and interval of time between logging and scarifying, because only a f e w confounded conditions were available for sampling. However , there are indicat ions that :

- iv - - success on p lo ts scar i f ied by l a rge t rac tors i s g rea te r than on

plots scar i f ied by medium and small t ractors , - plots on the vegetation site-type classified as Aralia-Oakfern h .I.

sl ight ly bet ter success than plots on a Devil' s Club si te, and v

- differences between pre-logging and post-logging scarification we r e not significant .

When the ' pe r cen t success ' of spruce is converted to a m o r e familiar stocking per cent for the average scarified acre on a mi l -acre bas i s , the p r inc ipa l resu l t s a re :

- a stocking of 50.5 per cent in fou r yea r s if the a rea was na tura l ly o r a r t i f ic ia l ly seeded the same year i t was scar i f ied ,

- a decrease to 3 2 . 8 per cent stocking if seeding occurs one year a f te r s i te p repara t ion , and

- unsatisfactory stocking if seeding occurs a t in tervals longer than one year af ter scar i f icat ion. In this instance, it has been predicted tha t , to ensure success , the number of viable seeds required would range from as many as 11 f o r a 6.6-foot-square plot to 25 for a one-foot-square plot.

Other species were present on the seedbeds together with the spruce. They were balsam, Douglas-fir , lodgepole pine, hemlock, aspen, cottonwood, and birch, all f rom natural seedfal l . Only balsam and birch were found on all plots.

The success of balsam and birch, ra ted in the same way as s p r u c e , varied with seedbed size but not with seeding year.

Turning now to measu res of growth, the average height of ta l les t seedlings at the end of four growing seasons was :

- spruce - 3 . 9 ins. , - balsam - 1.9 ins. , and - bi rch 11 .9 ins.

The average height of spruce seedlings did not vary with seedbed s i ze but after the second growing season the seeding-year effect resulted in decreased average height of spruce and balsam seedl ings, i . e. the average height of S Y 1 seedlings was less than S Y O seedlings of the same age, that of S Y 2 seedl ings less than S Y 1 seedlings, and so on.

The vigorous growth and the abundance of b i rch seedl ings a re a potential threat to spruce seedling survival.

The very slow height growth of the spruce seedl ings is a disturbing feature, especially when we reca l l tha t the sample a reas have h igh s i te - values. If a general ly poor seedl ing performance is confirmed by a survey of all scar i f ied a reas , then s i te p repara t ion and p lan t ing , ra ther than scarifying and seeding, is recommended on Devil 's Club and Aralia- Oakfern s i tes to ensure a more profitable realization of their potential productivity.

LABtiARY MINISTRY OF FORlSTS M I A M E N T BUlLDfNGS

TABLEOFCONTENTS VICTORIA, B.C. WW 3E7 Page

,TITLE PAGE i 'y

PHOTOGRAPH - Invasion of scar i f ied seedbed by thimbleberry - i i

SUMMARY ""- i i i

INTRODUCTION 1

OBJECTIVE 2 .---...-...- ........... . ....."..I..-." ____ _.".._

METHODS AND PROCEDURES" __._ 2 "-""".-.l"_.""".

ANALYSES O F DATA 5 """- "..._ ......"... " ..... .""-.-.." -.- -.-.-. I." ...... """

RESULTS AND DISCUSSION 5

Effects of Time and Seedbed Si te 6

Other Effects 9 "̂"".-..... " " .. ....... " ........................

Other Species 1 0

Height of Seedlings 12

INTERPRETATION OF RESULTS IN TERMS O F SPOT SEEDING 15

"""__ " " " ^ ........................................... ". "

11"" .. ".. ......... .̂ .... ...... ".

OBSERVATIONS 16 ................................ ..............

CONCLUSIONS AND RECOMMENDATIONS 18 " ~ . ~ "

REFERENCES .- _."._ ........................................ " ....-._.. ""." ." "._." .- I "I 2 0

APPENDIX

Tabulated Summaries of Data

FIGURES

Fig .

1. Location of sample plots ...... 3 "-" """_~"".-."

2. P e r c e n t of seeded seedbeds with spruce seedl ings (adjusted

to base year 1959) 7 "".*.. .".

Fig . P a g e

3 . Per cent of seeded seedbeds with spruce seedlings (not I_ w

adjus ted to base year ) u v 8

4. P e r cent of seeded seedbeds with spruce, balsam, and birch

seedlings - 11

5. Averaged height of ta l les t spruce , ba lsam, and b i rch

seedlings 13 ”_””

6. Averaged height of t a l l e s t sp ruce , ba l sam, and b i r ch

seedlings on AD and 0 si te types 14

t

INTRODUCTION

In the spruce-alpine f i r forests of inter ior Bri t ish Columbia scarification with a bulldozer blade is proving to be an expeditious means of

V i te preparat ion, preceding natural or ar t i f ic ia l regenerat ion.

The annual scar i f icat ion program to promote natural seeding has increased f rom t r ia l s on 243 a c r e s in 1956 to 15,530 acres during 1965, even though the treatment is genera l ly res t r ic ted to about 30 per cent of the logged acreage.

In the Pr ince George Forest . Dis t r ic t , the resul ts of a na tura l regenera t ion survey , based on 6 ,549 acres of scar i f icat ion, have been promising and indicate that white spruce should be well-represented in the new stand. In fact, Gilmour and Konishi (1965) report that the average spruce s tocking is 44 per cent by mil-acre quadrats , and that , if all species are counted, the s tocking is 49 per cent with a range f rom 4 t o 94 per cent .

This variation in natural stocking is not surprising. It s t e m s f r o m the fact that many events control the success o r fa i lure of this method of regeneration and seldom occur in an ideal sequence of desirable interact ions. Although we need not list all the events, the primary factors dictating success o r fa i lure a re abundance of seed supply, control of biot ic enemies , exposure of minera l so i l in adequate numbers of well-distributed seedbeds, absence of brush and weeds, favourable weather, and (when 10 o r m o r e do l l a r s a r e i nves t ed pe r ac re in scarification) the durabili ty of the prepared seedbed.

It i s of value to know the effective life of a seedbed because, if it spans s eve ra l yea r s , it provides a welcome leeway in the vital matter of t iming opera t iona l scar i f ica t ion programs. F i r s t , the t iming of scar i f icat ion to coincide with very good seed crops is less cr i t ical . Secondly, i t becomes more practical to cope with administrative difficult ies (p. 15 Gilmour and Konishi 1965). Thirdly, it affords an opportunity to seed art if icially in a year subsequent to the year of scarificAtion providing the prospect of successful natural seeding dims in the face of los t seed sources o r poor seed-crops.

Obviously, several quest ions ar ise . Is the l i fe-span one, two, or f ive years af ter the year of scar i f icat ion? How important is sizC of the seedbed, with par t icular reference to its re-occupation by weeds (Stettler 1958)?

Some of the answers have resul ted f rom the present study.:: Its main purpose is to advise on the length of t ime scar i f ied seedbeds remain effective media for establishment of spruce L.egeneration. It r epor t s a l so on behavioul- of the associated species of balsam and birch, and comments briefly on the influence of vegetat ion s i te- type, t ractol . s ize , and interrelat ion of t imes of logging and scarifying with the speed of vegetative invasion of prepared seedbeds.

I

*

.b ' "Based upon results fL.om Experimental Pl .oject 528 - The Influence of Time on the Effectiveness of Scar i f ied Seedbeds.

- L -

OBJECTIVE

The objective w a s to determine how long scarified seedbeds W remain effective as media for the germinat ion, survival , and growth of spruce.

METHODS AND PROCEDURES

This s tudy was carr ied out in the Pr ince George region on a number of t imber sa les scar i f ied by normal opera t iona l p rocedures . Scarifying equipment included a var ie ty of c rawler t rac tors equipped with bulldoze r blades .

Within selected t imber sales, plots were established after examination showed they were large enough, sufficiently uniform with r ega rd t o s i t e , and had t he r equ i r ed r ange i n s i ze of seedbeds. Figure 1 and Table 1 show the number and distribution of the plots finally selected.

Each plot consists of 310 mineral soil seedbeds produced by scarification. The individual seedbeds were selected and staked on i r regular t ransec ts t ravers ing the p lo t a rea . The min imum d imens ion of margin-to-margin width of minera l so i l w a s measured on each seedbed. The margin of a seedbed w a s e i ther forest f loor o r s l a s h accumulations. The minimum width recorded w a s one foot, and the l a r g e s t 6 . 6 fee t . Large scar i f ied a reas f requent ly had severa l maximum- sized seedbeds on them with their centres seven or more feet apart .

Within each plot, 50 seedbeds , se lec ted at random, were seeded the same year they were scar i f ied ( seeded year zero or S Y O ) . Each succeeding year 50 seedbeds were seeded (SY1, SY2, SY3, SY4), and an additional 15 seedbeds were hand-scarified and seeded each year to approximate the original conditions of scar i f icat ion.

Seeding was done each fall start ing late in September and was completed by October 15. Before seeding, all natural coniferous seedlings were removed from the seedbed. Renewed seedbeds were checked for width, cleared of vegetation with a sharpened dutch hoe, and then seeded. Seed was sown near the s take , a t the cen t re of the seedbed. The seeder w a s held about 10 inches above the ground and the seed fell within a c i rcu lar a rea averaging 10 inches in d iameter . A Swedish hand seeder (page 42, Research Review, 1958), set to deliver approximately 12 viable seeds, w a s used the f i rs t two years (1958 and 1959) . For the remaining years (1960, 1961 and 1962), the "M and B" seede r w a s used (page 34, Research Review, 1960). It delivered approximately 15 viable seeds .

c

- 3 -

Figure 1

Number and approximate location of sample plots. Inset outline of Brit ish Columbia shows general location of s tudy area.

- 4 -

Table 1. Distribution of P lo t s

F o r e s t Site (1) Type 1

0

0

0

0

0

0

0

0

0

AD

AD

AD

AD

AD

AD

Year Scarifiec

1957

1957

1957

1957

1957

1957

1957

1958

1959

1958

1958

1959

1959

1959

1959

1960

1961

( 2 ) Scarif ied

t2

"1

t l

-0

- 0

- 0

+Q

Not Logged

t5

Not Logged

- 0

t5

t1

tl

Not Logged

t o

t 1

T r a c t o r S ize

L a r g e

Medium

Smal l

Medium

Smal l

L a r g e

L a r g e

Medium

Large

Medium

Medium

L a r g e

L a r g e

Medium

Medium

Large

La rge

Vumbe r O l

Plo t s

1

2

4

3

5

1

1

2

1

1

4

2

2

1

1

1

1

c.f

Locat ion

Navor P. W.C. , Mary Lake

Aleza Lake , Fores t .Res .

1 1 I I 1 1

I I 1 1 I 1

11 II I I

Sinclair Mills

1 1 11

Aleza Lake , Fo res t Res .

Crooked River P. W.C.

Aleza Lake , Fo res t Res .

Crooked River P. W. C.

11 l l r n

Navor P. W . C. , Mary Lake

I t If Stone Creek

f i 11 r t 11

15 Mile Rd., Wells Rd.

Crooked River P. W.C.

AD = Aral ia-Dryopter is Si te Type. (1) 0 = Oplopanax Site Type.

(2) Years scar i f ied before (-) logging or after (+) logging.

- 5 -

w

The seeded seedbeds were examined in ea r ly summer ( June t o mid-July) and the fall (September) of 1959 and 1960. In 1961, 1962, and h963 they were examined only in the fall. Spruce and other t ree seedl ings were counted and recorded. On the second fall examination and on each succeeding examination, the height of the tal lest seedling of each t r ee species present was recorded.

Seedbed examinations made during the f ive years of the study totalled 17, 980.

Control data al lowed adjustment for variations in weather conditions, natural seedfall , rodent depredations, and other uncontrolled variables. I t w a s assumed that the resul ts f rom SYO seedbeds and the s e r i e s of renewed seedbeds, seeded in each of the succeeding four years , varied in response to the uncontrolled variables only, whereas all the other seeded seedbeds had the added effects of passage of t ime. Complete control w a s not attained because renewing seedbeds by hand methods did not make them identical to the newly scarified condition. The control data f rom the SYO and the renewed seedbeds permitted the adjustment of all data to a base year , thus reducing the effects of uncontrolled variables.

The year 1959 was selected as base year because monthly precipitation and mean monthly temperatures during the growing season were close to the long-term averages as measu red by weather data f rom the Pr ince George Ai rpor t weather s ta t ion .

ANALYSES O F DATA

Regress ion ana lyses of the number of seedlings on size of seedbed were made and the effects of t ime of seeding and seedbed s ize were c lear ly indicated. Analyses were then made on the basis of number of seeded seedbeds with one or more seedl ings a t the end of each of five growing seasons. Comparisons between t ractor-s izes , s i te- types, and t ime-of- scarification to t ime-of-logging were difficult because sampling w a s not orthogonal.

RESULTS AND DISCUSSION

Resul t s a re repor ted in t e rms of per cen t of seeded seedbeds with one or more seedl ings and this is termed ! success ' . Tabulated summaries of the data are presented in the appendix.

- 6 -

Effects of Time and Seedbed Size W

The decreasing effectiveness of the seedbeds with passage of * t ime after scarification, due mainly to regrowth of vegetation, is apparent in the success by seeding years. Mean success of the seedbeds seeded the s ame yea r as scar i f ied (SYO) is 62.8 per cent ; and 52.7, 38.7, 36.9, and 29.0 per cent respect ively for SY1, SY2, SY3, and SY4.

Size of seedbed had an important effect on success . Success w a s lower on small seedbeds than on larger ones, and the decrease with successive years and with t ime of seeding w a s a l so g rea t e r on sma l l seedbeds than on large ones. Figure 2 shows the effects of seedbed size and the adverse effects on the establishment of seedlings with the passage of t ime between scar i f icat ion and seeding.

Overal l success in terms of per cent of seeded seedbeds with one or more seedl ings was 44.0 per cent at the end of the f i rs t growing season, and 45.7, 40.1, 33.9 and 26.9 per cent respectively at the end of the second, third, fourth, and fifth growing season.

The seeding year with the best results is SYO. The year ly decline in success of these seedbeds seeded during the scar i f icat ion year is c lear ly shown for a per iod of four years . At the end of four growing seasons, 23.3 per cent of the smal les t s ize-c lass seedbeds have one or more seedlings, while 51.7 per cent of the l a rges t s ize- c lass have one or more seedl ings. There is no s ign of a levelling off of the annual decrease in number of seedbeds with seedlings.

The s teady decrease in success f rom year to year with no s ign of levelling off may be cause for concern. However , the above resul ts a re der ived f rom da ta ad jus ted to min imize the e f fec ts of the uncontrolled var iables (weather , natural seedfal l , rodent depredat ions) and i t i s assumed that these results depict the si tuation that would prevail under a continuous regime of the base year , 1959. But weather, natural seedfall , and other conditions varied from year to year. The data without adjustment, presented in Figure 3, shows an increase in average success with the passage of t ime, due to the seeding in of natural seedl ings, 46.0 per cent at the end of the f i rs t growing season, and 54.5, 55.1, 57.4 and 62.0 per cent respect ively a t the end of the second, third, fourth, and f if th growing season. However, the decrease in germination and survival with the passage of t ime between scar i f icat ion and seeding (seeding year effect) and the effect of s eedbed s i ze a r e as prominent as in the adjusted data, a further indication of the lasting effectiveness of the larger seedbeds.

- 7 -

W

80

60

40

20

0

80

60

40

20

0 3 r d . G r o w i n g S e a s o n

I I I I I I I

80

60

40

20

0

80

60 - - I I I 9

- I 4 0 - - .I 1 5 .....

..... ..... ..... ..... 9 - - .i

Figure 2

Pe r cen t of seeded seedbeds with spruce seedlings (adjusted to base year 1959) at the end of the f i rs t , second, third and fourth growing seasons, by seedbed size-classes and seed- ing yea r s . SYO - seeded same year as scar i f ied; S Y 1 - seeded one vear af ter scar i f icat ion, and s o on.

- 8 -

1 Seedbed Siz

1.7 3 -2 4.7 I 4 2 I

1 st . G r o w i n g Season

I m I I I-SYO I

60

40

20

0

I 60

40

20

0 I 1 I

t 60

40

20

0

I

In

3rd. Growina Season

8 0 I 60 9-

- 9 I l r ..... ..... ..... I

..... ..... ..... ..... ..... 4 0 ..... - - 9 I I i;;;; ..... I - I I !iEii I

..... ..... ..... ..... ..... ..... ..... ..... 20 -

..... ..... ..... ..... 0

u

Figure 3

P e r c e n t of seeded seedbeds with spruce, seedlings (not adjusted to base year) a t the end of the f i rs t , second, third, and fourth growing seasons, by seedbed size-classes and seeding years.

- "

- 9 -

Other Effects

L r ' Analyses of the data for the effects of t rac tor s ize , vege ta t ion s i te types, and interrelat ion of t imes of logging and scarification w e r e l imited. Comparisons were made between sets of plots that were t reated a l ike in all respects except for the factor examined. These compar isons a re no t en t i re ly sa t i s fac tory because of small and varying numbers of samples in the sets . In addition there exists a locali ty bias. For ins tance , on ly a t Aleza Lake Fores t reserve w a s the smal les t t ractor (TD6) used; a lso s i te types tended to be concentrated by locality. Hence the following results, adjusted to base year, are presented with the reservation that they indicated trends rather than demonstrate differences.

Mean success for large t r a c t o r s (D9, D8, TD14) was 44.0 per cent, for medium tractors (D6, TD9) w a s 27 .0 per cen t , and for smal l t ractors (TD6) 21.9 per cent . The large t ractor mean differs s ignif- -

icantly (P =-., 01) f rom medium and smal l t rac tor means . The d i f fe rence between medium and small t ractor means is not significant (P = .05) . This resul t i s a t t r ibuted to the higher proport ion of large-s ized seedbeds on plots scar i f ied by the large t ractors . The average percentage of large-sized seedbeds (width over 5 feet) on plots scarified by large t r a c t o r s w a s 7 1 per cent , and for plots scar i f ied by medium and small t r a c t o r s w a s 38 and 27 per cent , respect ively.

During the study the author had a dis t inct impression that the results were better on plots in the AD (Aralia-Oakfern) si te type than on plots in the 0 (Devil 's Club) si te type. Analysis of the data , however , support this impression only partially. Mean success for plots scarified by medium tractors in unlogged stands w a s 61.6 per cent in AD site type, and 41. 1 per cent in 0 site type. Mean success for plots scarified immediately before scarifying was 34.7 per cent in AD site type, and 26.3 per cent in 0 si te type. These differences are s ignif icant (P.= .Os), Other combinations of t ractor s ize and t ime-of-scar i f icat ion to t ime-of- logging showed no significant differences.

No indication of an interrelationship between t imes of scar i f icat ion and logging arose f rom the few comparisons that could be made. In other words , these l imi ted t es t s de tec ted no d i f fe rence in resu l t s be tween pre- logging and post-logging scarification.

- 10 -

Other Species

Seedlings of other tree species found on seedbeds seeded to * spruce were tal l ied. Balsam, Douglas-fir , lodgepole pine, hemlock, aspen, cottonwood, and birch, all f rom natural seedfal l , were found; but only balsam and birch seedlings were found on all plots and the results reported. The percent of seedbeds with one or more seedlings a r r anged by seeding years is shown in Figure 4. Spruce is included for comparison.

Note that , unlike spruce, there does not appear to be a seeding year effect upon balsam and birch. The age of the birch seedlings cannot be related to seeding year because birch seedlings were not removed before the seeding. Perhaps the passage of t ime does not decrease the "receptiveness" of the scar i f ied seedbeds for balsam to the same extent i t does for spruce.

Balsam seedlings were few in number in 1960 and 1961 (1 5 . 7 per cent and 7 . 5 per cent success respectively) and confined to plots adjacent to or in unlogged stands. In 1961 there was a good seed crop for balsam and seedl ings were numerous in 1962 and 1963 (37.4 per cent and 43.4 per cent success , respect ively) .

The species other than spruce occurred with high frequency on seedbeds that had spruce seedlings - only 16 per cent of the balsam seedlings were on seedbeds without spruce seedlings, and 24 per cent of the birch occurrences were on seedbeds without spruce and/or balsam seedlings.

An analysis of the effect of seedbed s ize was not made for balsam and birch, but a relationship is indicated f rom a sample of 1 ,000 seedbeds drawn a t random from the data . Balsam successes ( i .e . , seedbeds with one or more seedl ings) occurred in a ra t io of about 3:4:6 for small , medium, and large seedbeds; b i rch in a ra t io of about 2:3:4, and spruce about 4:5:9. It i s assumed f rom these resu l t s tha t successes va ry with seedbed size.

No relationships of t rac tor s ize , s i te type , o r t ime-of -scar i fy ing to time-of-logging, to the occurrence of ba lsam o r birch seedlings were found.

- 11 -

f .- 3 v)

Lu n

P m

Lu Lu v)

Y 0

+ Lu Z V

SPRUCE I I I I

BALSAM 81 RC H

2nd. G r o w i n g S e a s o n

- S Y O

80

6 0

4 0

20

0 3 r d G r o w i n a S e a s o n

80

6 0

4 0

20

0 I

I

I I

111 j I ..... ..... ..... ..... ..... ..... ..... ..... ..... .....

.... .... .... 4 t h . G r o w i n a S e a s o n

Figure 4

Pe r cen t of seedbeds seeded with spruce, balsam, and birch seedlings at the end of the second, third, and fourth growing seasons, by seeding years .

- 12 -

Height of Seedlings

A t the end of the second growing season and each examination- thereafter the tal lest seedling of each tree species found on a seedbed was measured . F igure 5 is a bar g raph of the averaged heights arranged by seeding years.

Average height of tallest seedlings decreases with seeding year at the end of the third and fourth growing season for spruce and balsam. The i r regular i ty of seeding year effect on spruce and balsam at the end of the second growing season is thought to be the result of differences in growth in various years, due principally to weather. By the end of the third growing season these differences are less and do not mask the seeding year effect . The reversal of seeding year effect shown by birch heights is the result of seedling age not being related to seeding year. Most birch S Y 3 seedl ings are not 2 years o ld , but 4 o r 5 yea r s old.

It is important to notice that growth (difference between averaged height at the end of the third and second growing season, and at the end of the fourth and third growing season) decreases with seeding year for all spec ies .

Spruce height was not found to be related to seedbed size, and it is assumed that the same condition holds true for balsam and birch height growth. Neither was there any indication that tractor size, nor time-of-scarifying to time-of-logging had an effect on height growth. T h e r e is evidence that averaged heights of spruce and birch, but not ba l sam, a r e g rea t e r i n AD site type than in 0 si te type. Figure 6 shows the averaged heights for plots in AD and 0 s i te types a r ranged by seeding years . These resul ts are no doubt responsible in part for the impression that AD s i te types were more successfu l than 0 s i te types.

V'

Spruce grew bet ter than balsam, and balsam is perhaps not a serious competitor with spruce. On the other hand, the vigorous growth and abundance of b i r ch s eed l ings a r e a threat to the survival and development of spruce seedlings. The poor height growth of spruce and balsam seedlings is noteworthy.

- 1 3 -

W

1 5.0

l a 0

5.0

0

1 50

1 a0

5.0

0

1 5.0

1 0 9

SO

0

SPRUCE I 6 ALSAM I 6 I RCH

2nd. Growina Season

1

3rd. Growina Season

4 t h . Growing Season

I I

0 I I - ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... I n n ..... ..... ..... I Figure 5

..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... .....

,....

Averaged height (in inches) of t a l l e s t sp ruce , ba l sam, and birch seedlings at the end of the second, third, and fourth growing seasons, by seeding years.

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6.0

4.0

t 2.0

0

4.0 I- I (3 Lu

2.0

0

6.0

4.0

2.0

0

SPRUCE I 0 ALSAM 1 2nd. Growing Season

I 4 I i I 4 I i

I I

I -I I 4

I ._.....

I 4th. Growina Season

Figure 6

I

Averaged height (in inches) of ta l les t spruce , ba lsam, and birch seedlings at the end of the second, third, and fourth growing seasons on AD and 0 si te types, by seeding years .

1 6.0

1 2.0

8.0

4.0

0

16.0

12.0

8.0

4.0

0

16-0

12.0

8.0

4.0

0

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INTERPRETATION O F RESULTS IN TERMS O F SPOT SEEDING

On the basis of this study and several assumptions, the results x o m spot seeding scarified areas when natural seed is unavailable or inadequate can be predicted. Scarification as pract iced in the Prince George region results in mineral soi l exposure that averages 34 p e r cent of the area, or 15,000 sq. f t . per acre (Gilmour and Konishi , 1965, page 7 ) . Assuming that seedbed s izes occur in the same ra t io as found for the plots of this study there is room for 660 seedbeds per acre dis t r ibuted as fol lows:

I Seedbed Size-Class - ( feet) 1

1. 0-2.4 5.5-6.6 4.0-5.4 2.5-3.9

Number of seedbeds 282 97 136 14 5

This corresponds to the average distribution of seedbeds found by Gilmour and Konishi - that is , 65 per cent (= 650) of the mil-acres on an acre have one square foot or more of seedbed.

Assuming that the 660 available seedbeds are spot-seeded and applying the resul ts f rom summary 2 in the appendix, the number of stocked seedbeds w a s calculated and converted to a stocking f igure for SYO and SY1 seedbeds at the end of the fourth growing season and for S Y 2 seedbeds at the end of the third growing season. These resul ts are presented in Table 2 on page 16. Included is the number of viable seeds requi red to produce two surviving seedlings at the end of the fourth growing season, estimated from data not used in this report .

I t is evident from these results that seeding the same year as scarification is essential to obtain the best results. The predicted number of stocked seedbeds at the end of the fourth growing season following seeding produces adequate stocking of 50.5 per cent on a mi l -acre bas i s and the quantity of seed requi red is small . Seeding one growing season after scarification reduces stocking to 32.8 per cent, and doubles the amount of viable seed required. When seeding is delayed until two growing seasons have passed af ter scar i f icat ion, s tocking is unsatisfactory and the quantity of viable seed required is large. I t should be noticed that the SY 2 stocking of 28.7 per cent is at the end of the third growing season after seeding. Advance regeneration, regeneration of other coniferous species , and regenerat ion occurr ing on seedbeds other than mineral soi l would improve stocking slightly.

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Table 2. P e r cent Stocking on Average Scarified Acre

SYO SY1 s Y 2 ~ SYO SY1 SY2

89 38 31 8 16 25

87 52 4 2 5 13 13

71 53 45 3 11 13

258 185 169 2 9 11

505 328 287

I Seedbed I I Success 1. I. No. of Viable

Seeds per Seedbed

V

Milacre Per Cent Stocking I

50.5 32.8 28.7 I

1. Success - per cent of seeded seedbeds with one or more seedlings and is rated at the end of the fourth growing season for SYO and SY 1 and the end of the third growing season for SY2.

Scarification can be made more effective by increasing the area of exposed mineral soil . This would not only provide more seedbeds, but would also increase the proport ion of the l a rge seedbeds tha t a re more effective. Cost of scarifying could be expected to increase by this pract ice .

OBSERVATIONS

A study such as this with repeated examinations of the same areas engenders in the examiner a familiarity with the plots and their responses. The following observations are based on familiari ty and not experimental evidence but I hope they add to this study.

Plots on sandy loam soi ls had more seedl ings in SYO and SY1 years than plots on silty and clay soils. However, sandy loam plots were quickly overgrown with vegetation. Especially is this the case in Oplopanax (Devil’s Club) si te type where sandy loam plots were obli terated in th ree yea r s with a rank growth of thimbleberry (Rubus parviflorus) three feet tall. (See photograph page ii)

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Seedbeds with a rough surface had more seedlings than smooth W seedbeds. Even the sl ight roughening made by tractor tracks improved

d e seedling catch. On the other hand, so-called mixed seedbeds, that i s , a mixture of duff and mineral soi l rol led up by the bulldozer blade and then spread out , were poor seedbeds in terms of establishment of

seedbeds appeared bet ter than average. To produce the ideal seedbed requi res an implement tha t sc reefs , that is , s c r a p e s off the vegetation and most of i ts roots, and that cult ivates or harrows the bare mineral soi l to produce a rough seedbed.

seedlings; but height growth of the few seedlings established on mixed

Frost heaving occurred on seedbeds on heavy-textured soils, but is not considered a ser ious fac tor in spruce es tab l i shment . A r eco rd of frost heaving w a s kept for severa l p lo ts ear ly in the s tudy . Frost heaving of spruce seedlings was recorded on 267 seedbeds. Two growing seasons la ter 243 of these seedbeds s t i l l had spruce seedl ings on them. Many of the seedlings had exposed [ 'hockey st ick" roots, but otherwise did not appear to differ in vigor or average height f rom normal seedlings.

W

Thimbleber ry is the most vigorous plant invader of scar i f ied seedbeds in the study area. It g rows f rom root sprouts , p ro l i fe ra tes rap id ly f rom i t s rh izomes and can ob l i te ra te a large seedbed in three years . It competes with spruce seedlings for moisture and nutrients and produces a dense shade. Most spruce seedlings that survive i ts competit ion are smothered by i ts heavy leaf fall. Thimbleber ry is most plentiful in the 0 site type, especially after logging. Birch seedlings are vigorous competitors, too. The abundance of birch seedlings varies with number of s eed t r ee s , and one b i r ch s eed t r ee pe r ac re can e s t ab l i sh s eed l ings on a la rge number of scarified seedbeds. The fell ing of birch res iduals would greatly reduce the number of birch seedl ings, a l though there would st i l l be a seed sou rce in the unlogged margins. After the third year many birch seedlings a re browsed sufficiently to check their growth, but not, unfortunately, to reduce the threat to survival of sp ruce s eed - l ings. Western coolwort (Tiarella unifoliata) is the herbaceous plant most frequently found on scarified seedbeds in 0 and AD site types. I t begins to occupy seedbeds af ter two or three years . I t i s , of c o u r s e , a competitor, but more in the sense that i t occupies space and is thus more ser ious on small seedbeds than large ones. Oak fern (Gymnocarpium d r y o p t e r i s ) , s a r s a p a r i l l a (Aralia nudicaulis) , woods' horsetail (Equisetum sylvat icum) and bunchberry (Cornus canadensis) are a l so , more o r l e s s , the same kind of competi tors , become es tabl ished on seedbeds a f t e r two o r t h ree yea r s , but occur less f requent ly than T ia r e l la .

"

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Occas iona l ly smal l a reas occur red in sl ightly concave posit ions that received surface drainage f rom the surrounding terrain. These places usually had low success. The seedbeds tended to be definite v depressions that f looded from spring snow melt , and in the fall in yea r s when there were heavy rains. The few successful seedbeds in these places were mounds or hummocks. Vegetation offered serious competit ion on the mounds. Sedges (Carex spp.) , Indian reed grass (Cinna latifolia), bluejoint grass (Calamagrost is canadensis) and horsetai ls (Equisetum spp.) not only became active competitors within two or three growing seasons, but the i r l i t t e r smothered seedl ings .

I_

Unfortunately no plots in Cornus-Moss site type were found for this study. The Cornus-Moss si te type is well-suited for scarification. I t has a l iv ing-moss and raw-humus layer severa l inches th ick , l esser vegetation is relatively poor in species and abundance, approximately 7 0 per cent of the plant roots are in the humus and top inch or two of the soi l . Furthel-more, observat ions show that in the C-M s i te type scar i f ied (screefed) seedbeds remain free from vegetation for four to f ive years. Glew (1963) found scarification costs to be low on C-M s i te types .

CONCLUSIONS AND RECOMMENDATIONS

For bes t r e su l t s s ca r i f i ed a r eas shou ld be s eeded na tu ra l ly o r ar t i f ic ia l ly the same year , and not la ter than one growing season af ter scarification. At present , predict ion of good seed crops is uncertain, and it is impractical to schedule scarification to years of good seed crops for i t means a crash program to scar i fy the backlog of unregenerated areas bui l t up between good seed years. Artificial seeding is an al- ternative when seed crops fail, but this also presents difficulties. Broadcast seeding requires large quant i t ies of seed which is expensive and often is not available at any price. Spot-seeding greatly reduces the quantity of seed requi red , a l though labour cos ts a re increased .

Improved scar i f icat ion to increase exposure of minera l so i l is recommended. The maximum area possible is l imited to 60 to 7 0 per cent of the to ta l a rea because of the space occupied by stumps and s lash accumulat ions, and an i r regular dis t r ibut ion of regenerat ion is unavoidable.

The lack of a difference in results from pre-logging and post- logging scarification suggests that both leave and cut strips on a l te rna te c lear-cut s t r ip t imber sales be scar i f ied. The leave s t r ips should be winter-logged as soon as regeneration is established.

*::

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*v

W

The height of spruce seedlings in this investigation averaged only 3 . 9 inches at the end of four growing seasons. This height growth w e average of the ta l les t seedl ings on each seedbed) seems poor for s i tes of as high potential growth as the AD and 0 si te types. Re- surveying is recommended for some of the scarified areas on which regeneration surveys have been made. The main purpose would be to assess the g rowth of the regeneration and incidentally any change in stocking, If the resurvey confirms the poor growth shown in this investigation, then a strong case has been made for planting these s i tes ra ther than scar i fying them. To realize the high potential productivity inherent in 0 and A D site types, quick and adequate restocking with welldistributed thrifty spruce seedlings is essential.

Investigation of mechanical methods of s i te p repara t ion for planting is warranted. Site preparation for planting can increase survival and growth of planted stock by reducing competit ion from vegetation, reduce planting costs , and improve spacing and stocking. With adequate si te preparation the possibil i ty of bullet or tube planting should not be overlooked,

On the basis of the resul ts of this study and experience, I suggest that cut-over areas in 0 site type be regenerated by planting, accompanied by s i te preparat ion, in order to real ize the high growth potential of these s i tes . Scar i f icat ion is suggested for AD si te types provided further study shows growth of regenerat ion to be sat isfactory. Although there were no plots in CM site types in this study, I believe that regeneration can be satisfactorily established on this si te type by scar i f icat ion.

Decie, T. P . , and F ra

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REFERENCES

. s e r , A. R . , 1961. Miscellaneous note s on Y

scar i f ica t ion t r ia l s , Pr ince George Fores t Dis t r ic t , 1956-59. B. C. Fores t Serv ice , Research Note No. 36.

G i lmour , J. R. and Konishi, J. , 1965. Scarification in spruce-alpine f i r type of the Pr ince George Fores t Dis t r ic t . B. C. Forest Service, Forest Management Note No. 4.

Clew, D. R . , 1963. The results of s tand t reatment in white spruce-alpine f i r type of the northern inter ior of Brit ish Columbia. B. C. Fores t Serv ice , Fores t Management Note No. 1.

Illingworth, K. and Arlidge, J. W . C . , 1960. Interim report on some forest si te types in lodgepole pine and spruce-alpine f i r s tands . B. C. Fores t Serv ice , Research Note No. 35.

Rieche, K . W . , 1961. A prel iminary s tudy of the economic use of c rawler t rac tor equipment for scar i f icat ion. B. C. F o r e s t Service, Engineering Services Division. Unpublished Report .

S te t t le r , R . F . , 1958. Development of res idual s tand of in te r ior spruce-alpine f i r dur ing the f i rs t 28 years following cutting. B. C. Forest Service, Research Note No. 34.

W

t

A P P E N D I X

Tabulated Summaries of Data

W

W

Summary No. 1. P e r cent of seeded seedbeds with spruce seedlings (adjusted to base year, 1959)

L I I Seedbed Size-class (feet)

At the end of Seeded Year

I Firs t growing s e a s on

Me an

SY 0 S Y 1 SY2 SY 3 SY4

1.0-2.4

67.4 37.0 31.4 21.2 20.1

2.5-3.4 Mean 5.5-6.6 4.0-5.4

58.7

29.0 47.8 21.8 19.6 37.5 58. 0 29.2 20.7 45 .2 58.7 48.5 30.4 46.1 57.4 45.2 33.7 75.3 79.1 75 .9

44.0

Second growing season 72. 2 72.2 51.3 49 .5 S Y 0 67. 5

SY 1

36.1 51.6 40 .2 31.8 20.3 SY 3 40. 0 53.0 48.2 31.6 18.5 SY 2 49.6 63.6 49.2 39. 8 32.3

Me an 45.7

Third Growing season 62. 1 68. 0 69.2 46.6 34.9 SY 0

SY 1 26.4 41 .3 37.7 18.5 10.5 SY 2 4 2 . 0 55.6 50.5 32. 8 20.1

Me an 40.1

Fourth growing season 51.7 46 .5 24.6 23.3 SY 0 45.1

SY1 27. 9 41.7 42.5 20 .8 11.2

Mean 33.9

Fifth' growing season 26.0 18. 8 11.7 SY 0 39.8 26.9

Summary No. 2. P e r c e n t of seeded seedbeds with spruce seedlings (not - adjus ted to base year )

u

Y

Seedbed Size-Class ( feet)

I I seeded Year 1.0-2.4 2.5-3.9 4.0-5.4 Mean 5.5-6.6

I I Firs t g rowing season S Y 0

SY 1 S Y 2 S Y 3 SY4

70 .4 37 .9 33.0 1 9 . 8 12.5

67.2 36.7 38 .9 28.9 20.5

79.7

24. 3 39.6 20.3 39.4 53.5 44.3 49.1 61.4 53.0 48. 1 59.7 46 .4 84. 3 90.4

46 .0 Me an

Second growing seas on 70.9

52.3 38. 0 32.4

S Y O 38.6 SY 1 59.4

19 .3 S Y 3 22.4 SY 2

80.3 83.5 90.1 54.4

39.4 60.7 44.4 48. 2 66.7 50.7 59. 8 73.1

Mean 54.5 L r '

Third growing season 66.0

45.1 31.0

SY 0

S Y 2 32.3 S Y 1 59.0

21.6

Me a n

Fourth growing s e a s on S Y 0

37 .9 25.9 SY 1 64 .3 61 .8 72.7

45. 8 65.6 55.1 83.1 91.6

Me an 57.4

Fifth growing season 62.0 75.0 50.0 75.0 41.7 SY 0

Summary No. 3. P e r Cent of seedbeds with spruce, balsam and birch seedlings.

Y

A t the end of

Second growing seas on

Spruce Bi rch Balsam Seeded

Year I

SY 0 54.7 20.4 83. 5 SY 1 SY2 SY 3

59. 8 48. 2 39.4

11.4 26.7 35.2

43.2 50. 1 35.2

Mean 54.5 22.6 44. 9

Third growing season SYO

48. 3 35.1 39.6 SY 2 55.2 26.9 57.1 SY 1 41.4 35.2 80. 8

Mean 55.1 31.. 3 50. 3

Fourth growing season

Me an 57.4 41.3 48.4 47.6 34.7 45. 8 S Y 1 50. 2 55.1 83.1 S Y 0

.

Summary No. 4. Averaged height (in inches) of tallest seedlings

Spruce Birc ' Ba l sam W

At end of Seeded Year

Second growing seas on 3.99 1.53 1.60 SYO

SY 1

14.72 1.47 1.56 SY 3 10.73 1.80 1.57 SY 2

6.74 1.69 1.47

Me an 1.54 1.54 5.32

Third growing seas on 9.72 1.90 3.20 SYO

SY 1

13.69 1 .52 2.54 S Y 2 11.01 1.80 2.70

1

Mean 2. 80 1. 84 10.55

Fourth growing season 12.26 2.08 4.81 SYO

SY 1 13.68 1.13 3.18

Me an 3.93 1.94 11.87

S u m m a r y No. 5. Averaged Height of tal lest seedlings by si te types

Balsam Birch Spruce

Site Type ~~ ~

Site Type Site 'I rPe

0 AD AD AD

1.70 2.03 1 .72 1.60

0

1.20 1. 51 1 .39 1.56

0 At the end of Seeded

Year

Second growing seas on SY 0

SY 1 SY 2 SY 3

2. 18 1.98 1.66 1.34

1.44 1.18 1.93 1.37

6.20 9.96

11.27 18.10

2. 98 3. 50 8. 84

13.60

Third growing s e a s on SY 0

SY 1 SY 2

3.18 3. 56 2. 88

2. 98 1.75 2.46

8. 53 12.37 18.70

2. 94 11.76 15.86

2.50 1.95 1.75

4.13 1.56

.99 1.95 1.42

1.31 1.49

Fourth growing season SY 0

SY 1 14.19 19.13

7.62 LO. 56

5.99 3.64

3.11 3.02

W