. The Canadian field-naturalist. K. 0 1 2 3 4 5 6cm. I LJ \ I i I Figure 2. Various seedlings which developed from the alpine soil cores. G, H. and L could not be identified; tentative identification of the other plants is given in Table 2. organic terrain in central Alaska is considerably higher than data from comparable sites at Rankin Inlet. Here, seedling emergence rates of lO/m^ and 78/m- were recorded for wet and hummocky tundra respectively, with 157 and 118 non-germination seeds/m- also found. At Churchill, no seedlings emerged, although non-germinating seeds were esti- mated at 600/m-
. The Canadian field-naturalist. K. 0 1 2 3 4 5 6cm. I LJ \ I i I Figure 2. Various seedlings which developed from the alpine soil cores. G, H. and L could not be identified; tentative identification of the other plants is given in Table 2. organic terrain in central Alaska is considerably higher than data from comparable sites at Rankin Inlet. Here, seedling emergence rates of lO/m^ and 78/m- were recorded for wet and hummocky tundra respectively, with 157 and 118 non-germination seeds/m- also found. At Churchill, no seedlings emerged, although non-germinating seeds were esti- mated at 600/m- in the wet bog. Because of the presence of permafrost, the tundra region is particularly sensitive to disturbance and several studies have investigated the impact of increased resource exploration activity on the vegeta- tion. Hernandez (1973) concluded that vegetative spread was the principal method of plant development on disturbed sites. Seedling establishment was not abundant, although Younkin (1973) noted that under laboratory conditions seed of all of the species com- monly found in disturbed areas had relatively high rates of germination. Where disturbance has been severe, recolonization is slow and studies by Dabbs et al. (1974) on the progress of natural recolonization of backfilled sites showed that after two years the cover of vascular plants remained sparse. The majority of the seed reserves are found in the surface organic soil layers (Gartner et al. 1983; Lachenbruch 1981; McGraw 1980). Hence, careful removal, storage and replacement of this organic material during construc- tion programmes may accelerate recolonization, although a rapid loss in viability could be expected. Without a source of viable seed, natural revegetation can only occur through gradual vegetative spread: the results of the present study suggest that this must ultimately be the dominant process in tundra Please note that these images are extracted from scanned page images that
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