North America

Map 1 shows the distribution of forests in North America. Mexico was included with Central America. The difference in sources between the U.S. dataset and the Canadian one resulted in some mis-matches between forest types across the border, most obvious perhaps between Maine and New Brunswick and between Montana and Alberta. The tropical forest types listed in the legend to the map were both in Hawaii. The Great Plains of the U.S. and up into Saskatchewan was mainly not forested. The Appalachians appeared quite forested, and taking into account that the eastern states are the more populated ones, there was a considerable amount of forest still remaining in these states. Between the Rocky Mountains and the coastal ranges of California was less forested than in the mountains, and where it was forested the forest types were dry. Towards the very south and the north of the continent the land was less forested, as in Texas and Florida, and northern Alaska, the Northwest Territories and northern Quebec. In Canada the datasets showed the sparser forest types where boreal forest blends into tundra.

Map 2 shows how the ecological zones relate to the distribution of forest. The Great Plains region that does not have forest extends into the cool temperate moist forest zone, where one would expect to find forest. The absence of forest in this zone may be due to human activity. In south Florida the subtropical moist forest zone is actually a herbaceous swamp area where the Everglades are located, so edaphic conditions are a factor in the lack of forest.

Fig. 2 shows that Canada had a greater amount of forest than did the U.S., but a smaller percentage of it was protected (see also Table 1). Of the nine types of forest that occurred in the region only four occurred in Canada. The two tropical types were restricted to Hawaii (U.S.), and only one of these was natural (Map 1, Table 2). Evergreen needleleaf forest had by far the greatest cover, more than twice that of each of the next most abundant three (Fig. 1). This also had the greatest percentage protected at 9.9%. Of the non-tropical types deciduous broadleaf forest had the least cover and freshwater swamp forest the least protection (Fig. 1). The latter mainly occurred in the southern U.S., particularly in Louisiana, Mississippi, Alabama, Georgia, Florida and South Carolina (Map 1).

There were 29 ecological zones in this region that were to some degree forested (Fig. 3, Table 3). The zones with the greatest amount of forest were the boreal moist forest and the boreal wet forest (Fig.3). These occurred mainly in Canada (Map 2). The cool temperate moist forest had the next greatest amount of forest, much of which was in the U.S. The tropical dry forest zone, which had very little forest, had the greatest percentage of forest protected (Fig. 3, 45%). Eighteen of the 29 zones had less than 10% of the forest protected. The warm temperate moist forest zone, although it had quite high forest cover in comparison to many of the other zones, only had 1.6% under protection. There were five different forest types in this zone (Table 3), only one of which had close to 10% protected (sparse trees and parkland). Excluding the tropical forest types that only occurred in Hawaii, all forest types occurred in five or more ecological zones. This combined to make many different possible forest type variants. The subtropical dry forest zone had very few of its forests protected (0.1%, Fig. 3), and there were five different forest types in this zone. Some of these covered quite substantial areas, none less than 3000 km and one even up to 18 285 km. These had very insignificant amounts protected, ranging from 0 to 16 km. The warm temperate desert zone supported only one forest type, sclerophyllous dry forest, but none of this was protected. In the polar moist tundra zone, although there was a total percent of 5.5 of the forests protected (Fig. 3), there were five forest types, two of which had minimal or no protection: mixed needleleaf/broadleaf forest and sparse trees and parkland (Table 3). The cool temperate desert bush followed a similar pattern with no protection for the mixed needleleaf/broadleaf forests and minimal forest protected in the other types.

In an attempt to impartially indicate natural, undisturbed forest variants which may be under the most immediate threat of destruction, a list was drawn up that pinpointed those under 100 km² in extent with none protected. These are variants of relatively limited extent and which do not even have any legal protection; possibly much less actual protection. Some of these forest variants may indeed be truly rare and unprotected types, others are clearly fragments of forest at the end of their ranges, as for example certain types of dry forest should not normally occur in moist ecological zones, or vice versa. An in-depth analysis of these forest variants is outside the scope of this study. There were 4 of the 123 variants in North America that met these criteria, and these are listed below (T=tropical forest type, N=non-tropical forest type):

Deciduous broadleaf forest (N) in the Warm temperate desert bush zone

1. Sclerophyllous dry forest (N) in the Subtropical moist forest zone
2. Evergreen needleleaf forest (N) in the Subtropical desert bush zone
3. Mixed needleleaf/broadleaf forest (N) in the Polar dry tundra zone

Ten of the 29 ecological zones that supported forest in the region were more than 50% covered by forest. The highest percentage cover was 87%, in the boreal desert zone. This and the boreal rain forest zone had 14% of the area of the zone covered with protected forest.