No. 91 

1959 

DEVELOPMENT OF YELLOW BIRCH NURSERY STOCK 

NOT AFFECTED BY TRANSPLANTING 

In nursery seedbeds, severe root competition soon develops among seedlings of yellow birch (Betula alleghaniensis). This is due to the characteristic root system of 

the species--wide-spreading lateral growth with little downward penetration (fig. 1). 

For comparison, look at the root systems of sugar 

maple (Acer saccharurn) and white ash (Fraxinus americana). 

They reach deeper and have a marked distinction between central taproot and laterals (fig. 2). 

In densely stocked yellow birch seedbeds, transplanting or thinning appears to be desirable by the end of the 

first year. Though thinning is less expensive than transplanting, it does cause waste of many seedlings--and this is 

important if the stock is valuable (for example, in genetics 

research or when seed supply is limited). Growing interest 

in hardwood planting and the paucity of information about 

handling seedlings both in the nursery and in the field indicated a need for research on the responses of important 

northern hardwood species to transplanting. 

So, to determine the effects of transplanting, size 

of stock, and root-pruning on early survival and growth of 

1-0 yellow birch seedlings, a small transplanting study was 

made at the Burlington, Vermont, unit of the Northeastern 

Forest Experiment Station's Laconia Research Center. 

STUDY OF TRANSPLANTING 

The soil in the transplant bed was a moderately welldrained loam. The area was fertilized with 0-15-30 (NPK) at 

200 pounds per acre, primarily to correct a potassium deficiency. 

Four transplanting treatment combinations were compared: two seedling sizes, each root-pruned and not pruned, 
plus a control consisting of undisturbed seedlings thinned 

in the seedbed to allow each one at least 30 square inches 

of space. The larger seedling size averaged 2.5 (range 2.0 

to 3.0) inches, the smaller 1.5 (range 1.3 to 1.7) inches. 

In the root-pruning treatments, laterals were trimmed to 2.0 

inches on seedlings of the larger class, and to 1.5 inches 

on those of the smaller class. 

Figure 1. --Ye 1 low birch 

seedlings send their roots 

out rather thandown, resulting in early root cornpetition. Note root system on this 2-0 seedling. 

Transplanting and thinning were done during late April, 

shortly after the seedlings had broken dormancy. The transplants were lined out as bare-rooted stock soon after lifting. Spacing was 10 inches between rows and 5 inches between plants within each row. Transplants and seedlings 

were lightly mulched with pine needles and were weeded frequently during the growing sesson. 

Figure 2.--Sugar maple and white ash 

seedlings tend to develop taproots. The 

1-Omaple (left) has astronglydefined 

taproot. On the month-old ash (right) 

the taproot and the laterals already 

are clearly differentiated. 

A randomized block design was used with three replications and 90 seedlings per treatment. Final measurements 

were taken after one growing season: (1) survival and field 

height1 of all plants, and (2) stem length, oven-dry weight 

of stem and roots, and stem diameter at root collar for 18 

sample plants from each treatment. 

'Only 12 undamaged seedlings were available from the control because of deer 

browsing 2 weeks before the study ended. 
RESULTS AND RECOMMENDATIONS 

Survivals ranged from 94 to 99 percent, and mean field 

heights from 14.2 to 17.2 inches. None of the differences 

was significant at the 5-percent level. 

Nearly all plants had multiple stems, apparently 

caused by dieback of the terminal shortly after the transplanting or thinning. Since both thinned seedlings and 

transplants were afflicted, the dieback cannot be attributed 

to transplanting shock. 

Root systems of both seedlings and transplants still 

exhibited the wide-spreading characteristics typical of 1- 

year seedlings (fig. 3). Root-pruning and transplanting had 

not resulted in any notable improvement in form or structure 

of. the root systems. 

Characteristics measured on the 18-tree samples are 

summarized in table 1. None of the measured characteristics 

differed significantly among treatments and seedling sizes 

at the 5-percent level. However, trends are evident in the 

stem-length and dry-weight averages that come close to statistical significance. The 2.5-inch seedlings consistently 

averaged longer stems and greater weight than the 1.5 inch 

Table 1.--Treatment means for various measurements, based on 18-tree samples 

:comparable data not obtained for thinned seedlings because of deer damage. 

3Thinned seedlings in seedbed averaged 9/32 inch stem diameter. 

Thinned seedlings in seedbed averaged 2.63 grams oven-dry weight. 

Item 

F& Feet F& 

Stem length1 Pruned 1.12 1.34 1.23 

Not pruned 1.30 1.47 1.38 

Mean 1.21 1.40 1.31 

Inches Inches 

Stem diameter at root collar2 Pruned 7/32 9/32 -- Not pruned 9/32 9/32 -- 

Grams Grams Grams 

Oven-dry stem weight1 Pruned 1.33 2.22 1.78 

Not pruned 2.16 2.68 2.42 

Me an 1.74 2.45 2.10 

Grams Grams % 

Oven-dry root welght3 Pruned 1.60 2.65 2.12 

Not pruned 2.36 2.84 2.60 

Me an 1.98 2.74 2.36 

~oot shoot ratlo' Pruned 1.20 1.19 -- 

Not pruned 1.09 1.06 -- 

Treatment Me an Seedling size 

1.5 inches 2.5 inches 
Figure 3.--The treatment produced no change in 

the form or structure of the root systems of yellow birch. The 2-0 seedling at left and the 1-1 

transplant at right both have the characteristic 

wide-spreading root s,ys tems. 

plants; and, within size classes, seed1 ings that were not 

root-pruned averaged longer and heavier than root-pruned 

ones. These differences are in the direction that might 

logically be expected. It seems possible that, with larger 

samples, the differences would have attained statistical 

significance. 

However, regardless of statistical significance, the 

observed mean differences are relatively small and probably 

are of little importance in terms of quality of stock for 

field planting. 

Since this experiment was conducted in only one place, 

on a loam soil, and during a season of abundant and welldistributed rainfall, somewhat different results might possibly be obtained under other conditions. However, the 

present results suggest the following general guides for 

handling 1-year-old yellow birch in dense seedbeds: 

If the stock is of sufficient value to justify the cost, 

transplant seedlings of all sizes (except obvious weaklings and defectives). 

Do not root-prune other than incidental trimming of long 

roots for convenience in handling. 

If stock values do not justify transplanting costs, thin 

the seedlings in the bed, favoring the larger ones insofar as their distribution permits. 

--WILLIAM B. LEAK 

Research Forester 

Northeastern Forest Experiment Station 

Forest Service, U.S. Dept. Agriculture 

Laconia, N. H. 

4 AGRICULTURE-FOREST SERVICE-UPPER DARBY