267 
Groom.—Remarks on the Oecology of Co?iiferae. 
and are admittedly of such importance as to be included in the small work 
on ‘Forest Protection ’ by Fiirst; the results are given in column 8 of the 
same table. The results of both methods of estimating agree in showing 
the larger number of insects menacing the existence of coniferous species. 
NUMBER OF SPECIES OF INSECTS ATTACKING. 
Species. 
Young trees. 
Old trees. 
Grand Total 
(young and 
old). 
No. of species 
of prime 
importance 
attacking. 
Abies pectinat a .... 
Severe. 
3 
Total. 
20 
Severe. 
6 
Total. 
27 
Severe. 
9 
Total. 
47 
16 
Picea excelsa .... 
21 
64 
10 
57 
3 i 
121 
30 
Pinus sylvestris .... 
33 
67 
20 
67 
53 
*34 
3 2 
Larix decidua .... 
8 
14 
7 
37 
15 
5 i 
20 
Fraxinus excelsior 
2 
2 
0 
18 
2 
20 
6 
Fagus sylvatica .... 
T 4 
8 
46 
22 
63 
19 
Betula alba ..... 
5 
13 
1 
50 
6 
63 
13 
Carpinus Betulus 
0 
3 
0 
16 
0 
19 
6 
Alnus glutinosa .... 
5 
6 
4 
42 
9 
48 
5 
Ultnus campestris and U. montana 
0 
0 
2 
37 
2 
37 
9 
(The number of slight diseases is obtainable by subtracting the 1 severe ’ 
from the ‘ total ’ in the respective cases. The total number of insects listed 
was 385.) 
Columns 6 and 8 are worthy of special comparison. 
Of the insects mentioned here as attacking young trees, 102 species 
attack the Conifers only, 18 attack the Conifers and dicotyledons, and 15 
species attack the dicotyledons only. Thus, on the average, each Conifer 
has 25*5 exclusive foes or 30 inclusive foes, while each dicotyledon has 
2*5 exclusive foes or 5-5 inclusive foes. Similarly, attacking old trees, 
121 are confined to the Conifers, 8 damage the Conifers and dicotyledons, 
while 131 are confined to the dicotyledons. On the average each conifer 
is attacked by 30-25 exclusive foes or 32*25 inclusive foes, and each 
dicotyledon by 21-8 exclusive or 23-1 inclusive foes. 
Thus dicotylous trees (at least in north-temperate climes) may owe 
their victory over Coniferae in the majority of favourable sites largely to 
their power of resisting or repairing injury caused by sudden hostile 
influences, including animal and fungal foes. It is possible, too, that in 
secular changes of climate Coniferae suffered more than dicotyledons, 
though certain coniferous genera, such as Pinus, betray no signs of inability 
to secular acclimatization. So far as the chief forest trees are concerned, 
insect-pollination appears to have played but a small part in aiding the 
north-temperate dicotyledons. 
