NovEMBEa 24, 1888.] 



THE GARDENERS* CHRONICLE. 



599 



old has a mean height of 90 feet ; mean annual height 

 growth (from thirty-second to fifty-seventh year) 

 = 14 inches; both grown in Perthshire. (3). Mature 

 Douglas Firs in the most favourable localities of 

 North America are reported to reach a mean height 

 of 213 feet; such trees are often up to 500 years 

 old, but it is not known, at what age the height 

 growth ceases : let us assame that it is very slight 

 after the age of 250 years. With these facts before 

 us, the heights up to an age of 140 years may be 

 estimated as follows : — 



! of 32 ye 



Hil 



150 



(c.) Form Figure. — The form figures for Silver Fir 

 are : — 



At the age of 32 yean "65 



50 -47 



The form figure of the Taymount plantation 

 shows '30 for an age of thirty-two years. This is 

 very considerably below the form-figure for Silver 

 Fir, and it is in accordance with the facts of the case. 

 The Douglas Fir is a much more tapering tree than 

 the Silver Fir, and the highest form figures which 

 can be expected may perhaps be placed as follows : — 



At the age of 32 years = -39 



By utilising the figures thus estimated the following 

 table for the Douglas Fir has been calculated ; — 





No. 

 of 



fan 

 lit. 



feet. 



Section- 

 al area 



at 

 height 

 of chest, 



•^nare 

 feet. 



Form 

 ligure 

 for 

 solid 



Volume of 

 solid wood 



(3 inches 

 diam.and 

 upwards), 

 cubic feet, 



per acre. 



Mean Tree. 



Age, 

 yrs. 



Section- 

 al area, 

 square 

 feet. 



Duim. 



3-' 



202 



60 



153 



•39 



3.738 



•782 



1-1-0 



50 



150 



82 



16! 



•38 



5,204 



l'llo 



U-3 



;s 



125 



105 



831 



■33 



9,217 



1-817 



131 



100 



100 



125 



288 



•37 



13.322 



2-885 



230 



125 



8S 



HI 



3 7 



■36 



16,599 



3.715 



26-1 



Hi 



80 



150 



315 



•35 



13.112 



1 307 



28-1 



Let us now compare the volume of the Douglas 

 Fir with that of the Silver Fir :— 





1 Growing stock, per acre 

 in cubic feet. 



Mean annual increment 

 in cubic feet per acre. 





' Douglas 

 Fir. 



Silver 

 Fir. 



Douglas 

 Fir. 



Silver 

 Fir. 



50 



5,201 



3,458 



101 



69 



75 



9,217 



8,532 



123 



111 



100 



13.322 



13,291 



133 



133 



125 



16,599 



16,291 



138 



130 



110 



1^,112 



17,720 



129 



127 



This table indicates that under a rotation of up 

 to about ninety years the Douglas Fir, owing to its 

 more rapid development in early growth, yields 

 larger returns of solid wood than the Silver Fir. 

 Under a rotation of 90 to 120 years the returns 

 in volume are about equal. Under a rotation of 

 more than 120 years the Douglas Fir will again yield 

 larger returns of volume than the Silver Fir. The 

 latter is of little consequence in this country, because 

 no landed proprietor would think of working his 

 plantations under a rotation of more than 120 years, 

 unless he had a particular fancy to see large trees on 

 his estate. Attention must also be drawn to the 

 fact that the mean annual increment culminates 

 between the years 100 and 125, so that a rotation of, 



say, 110 to 120 years will yield, in the long run, a 

 larger number of cubic feet of solid wood, than either 

 a shorter or longer rotation, both in the case of 

 Silver Fir and, as far I can judge, also of Dougias 

 Fir. 



The above data, it must always be remembered, 

 refer only to the final cuttings. I have no data 

 whatever which would enable me to compare the 

 intermediate returns (thinnings) of Douglas Fir and 

 Silver Fir. I may also draw attention to the lact, 

 that the numbers of cubic feet given above refer to 

 the actual volume of solid wood. In order to obtain 

 the number t-f cubic feet calculated from the quarter 

 girth, as is usual in this country, the numbers must 

 throughout be reduced by about one- fourth (more 

 accurately 22 per cent.). 



I have compared the returns of the Douglas Fir 

 with those of the Silver Fir, because we possess 

 accurate tables giving the volume-yield of the latter 

 at d liferent ages. It would have been more to the 

 purpose to substitute the Larch for the Silver Fir, 

 but unfortunately the laws of increment of the 

 former have not as yet been so minutely studied and 

 recorded as in the case of the latter. So much, 

 however, is known, that the Larch developes much 

 more rapidly than the Silver Fir during youth, and 

 that it yields larger returns of solid wood under a 

 rotation of seventy-five years, and perhaps even 

 eighty years, in favourable localities; under a higher 

 rotation the volume yield of the Silver Fir is greater 

 than that of Larch. Hence it may be safely said 

 that under a rotation ot seventy-five and perhaps 

 even eighty years the Larch will yield as much solid 

 wood as the Douglas Fir whenever they are grown 

 in regular fully stocked woods, and in localities of 

 equal quality — with this difference, that the material 

 yielded by the Douglas Fir will consist of a smaller 

 number of trees per acre, with a greater mean diameter 

 per tree. 



The laws of increment of Scotch Pine are well 

 known. On good localities, like that of Taymount, 

 the growing stock of a fully stocked acre compares 

 as follows with that of Douglas Fir: — 



Age. 



Volume 

 per acn 



of solid Wood 

 , in cubic feet. 



Mean annual 

 per acre, in 



increment 

 :ubic feet. 





Dougla 

 Fir. 



s Scotch 

 Pine. 



Douglas 

 Fir. 



Scotch 

 Pine. 



5M 

 100 



6,201 



9.217 

 13.322 



5,600 

 7,900 



9,300 



101 

 123 



133 



112 

 105 

 93 



Under a rotation of fifty years Scotch Fine may 

 even yield a little more material than the Douglas 

 Fir, but later on it drops considerably behind. 



Quality of the Timber. — The next point of im- 

 portance is the quality of the timber. The wood 

 of the Douglas Fir has a great reputation, and 

 in America its quality is believed to be equal 

 to that of Larch timber. In how far the Douglas 

 Fir grown in this country will come up to that 

 standard remains to be seen. The larger sized 

 trees so far cut on the Scone estate have been freely 

 bought at the same rates as those usually paid for 

 Larch, but sufficient time has not elapsed to show 

 the comparative merits of home grown Douglas Fir 

 and Larch timber. 



A few words must now be added with regard to 

 the safety of production. First of all it is an undis- 

 puted fact that Douglas Fir can, in this country, only 

 be successfully grown in sheltered localities, because 

 its leading shoot, and even the lateral branches, are 

 very liable to be broken by wind. This reduces the 

 area suitable for its cultivation very considerably. 



Then there can be no doubt that the Douglas Fir, 

 in order to yield large volume returns, requires good 

 fertile and fresh or moist soil, in fact, soil on which 

 any other species will produce a large volume of 

 timber. Such land can, moreover, be used to greater 

 advantage for field crops. What we specially re- 

 quire are species which will do well, or at any rate 

 fairly well, on lands which are not suitable for field 

 crops. 



Finally, it has been said that the Douglas Fir is 

 not exposed to any disease, while the Larch, for 

 instance, suffers so much in this respect. With 

 regard to this point, it will be as well not to shout 

 until we are safely out of the wood. It will be re- 

 membered that the Larch disease did not show itself 

 in Scotland until about sixty years ago. Only quite 

 lately Mr. McGregor, who has been on His Grace 

 the Duke of Athol's estates for more than forty 

 years, pointed out to me, that he has never seen the 

 Larch cancer on any of the old Larch trees, except 

 on those parts of the trees which have been formid 

 during the last sixty years. This certainly seems 

 to indicate that the disease did not exist before about 

 the year 1820. 



No doubt exists now that the Larch cancer is the 

 result of the ravages of a fungus ( Peziza Willkommii), 

 the spores of which enter the tree through wounds 

 which were caused by insects (aphis), frosts, violence, 

 &c. Only a few days ago, and after I had com- 

 menced this article on the Douglas Fir in Scotland, 

 I saw in a German forest journal a notice of the dis- 

 covery of an injurious fungus on the Douglas Fir. 

 Dr. von Tubeuf, a pupil of the celebrated pathologist, 

 Dr. li. Hartig, of Munich, has now described a fungus, 

 Botrytis Douglasii, which is parasitic on the 

 Douglas Fir : it has been noticed during the last ten 

 years in several widely separated localities in Ger- 

 many on the trees in the experimental plantations 

 which have been made of late years. As far as is 

 known at present the fungus attacks in the first 

 place the young shoots, the needles of which turn 

 brown or gray, the whole being ultimately spun over 

 with mycelium ; it then extends and kills ultimately 

 the plants. It has also been found that this same 

 fungus can be cultivated on two to six year old 

 plants of Silver Fir, Spruce, and Larch. Dr. von 

 Tubeuf found, as a general rule, that those Douglas 

 Firs were specially attacked which grow in fully 

 stocked areas, so that the branches of the trees 

 interlaced; and in these cases the lower branches 

 were more attacked than those higher up. He also 

 noticed that free standing trees were free of the 

 disease, and he naturally draws the conclusion, that 

 infection depends on a high degree of moisture, 

 such as is found in dense woods, while free-growing 

 trees, exposed on all sides to drying air currents 

 escaped. Now, what does this mean ? Simply that 

 the Douglas Fir must be grown in thin open woods, 

 and if so, good-bye to any high returns per acre, such 

 as Silver Fir, Larch, or even Scotch Pine will yield. 

 Generally Dr. von Tubeuf adds some very sen- 

 sible remarks, of which I give the following extracts. 

 He 6ays : — 



"In introducing an exotic species, the first ques- 

 tion should be whether, if grown in the same localitv, 

 it possesses any real advantages over our indigenous 

 species, either in consequence of a superior quality of 

 wood, rapid growth, large dimensions, active repro- 

 ductive power, &c, or by more successfully resisting 

 any unfavourable conditions of the soil or climate, or 

 by being less subject to natural enemies, such as 

 game, animal or vegetable parasites, &c. A further 

 most important question is, whether with the exotic 

 tree we are likely to introduce new enemies to our 

 indigenous trees ; and in this respect we need only 

 remind the reader of the imported enemies of the 

 Potato, the Colorado beetle, the enemies of the 

 Vine, &c 



" Of our own enemies of trees, a large number 

 attack without distinction the exotics lately intro- 

 duced, Curculio, Bostrychus, cockchafers, cater- 

 pillars and beetles attack exotics like indigenous 

 trees ; Trametes radiciperda (one of the most for- 

 midable of fungi) destroys the wood of the Douglas 

 Fir like that of any other species." 



These words deserve serious consideration. It is 

 more than probable that the Douglas Fir will, with 

 us, in the course of time, develope its full share of 

 enemies, if not more, considering that it is an exotic 

 species. 



Before concluding I desire to express a hope that 

 my object in publishing these notes on the Douglas 

 Fir may not be misunderstood. The cultivation of 



