Diel patterns of migration and migration speed were compared between reproductive timing phenotypes in female kokanee salmon Oncorhynchus nerka. Females of varying degrees of reproductive maturation were captured on their migration route to the Meadow Creek Spawning Channel (British Columbia, Canada), were tagged with passive-integrated transponders (PIT tags) and were subsequently monitored with stationary receivers. Females showed crepuscular migration timing, with approximately equal detections at dawn and dusk. In particular, peaks of movement were associated with the appearance of the sun over the mountains in the east and the disappearance of the sun over the mountains in the west. Over 25 m, migration speed was 1·0 body lengths (measured as fork length; L(F)) s(-1) and did not depend on maturation state. Over 3 km, migration speed was much slower (0·2-0·3 L(F) s(-1)) than over the short distance, with less mature females migrating more slowly than more mature females. Less mature females appeared to be in less of a hurry to reach breeding areas compared with more mature females.
from none to 17%. Bare soil was infrequent. The average thickness for the combined L and F layers was different for each of the 12 communities and varied from 0.5 inch to 0.9 inch ( Table I).The significance of the difference in the mean waterretaining capacity of the litter was determined by means of the t-test. Comparison of the two communities having the lowest and the highest mean water-retaining capacities gave a t value of 1.76 with 22 degrees of freedom and a P value of approximately 0.1. Because the ·difference proved insignificant at the 95% confidence level, it was considered appropriate to combine mean values from all commumtles. The mean of these mean values was 2.63 ± 0.06 (0.06 = 2s).The H layer and A 1 horizon make different contributions to the total water-retaining capacities of the samples, and no records were kept of the differences in the H layer. The average water-retaining capacities for the combined H and A 1 layers were similar in the various communities, ranging from 1.48 to 1.83 times the dry weight of the samples. The average value was 1.62.The weight of water held by the combined L and F layers equals approximately 0.05 inch of water. The H and associated upper part of the A 1 layer, 1 inch in total, held approximately 0.44 inch of water. Thus the total water that can be held is about 0.5 inch.The litter was a mixture of oak and pine debris. All communities had pine as a major constituent associated with one or more species of oak. Other species, especially ericaceous shrubs such as Vaccinium vacillan.r, Gaylu.r-.racia baccata, and G. frondosa, were represented in the litter, but although they had a high frequency they did not make an important contribution to litter bulk. DISCUSSION AND CONCLUSIONSThe significant facts that emerge from this study are that the differences in the litter of different forest types of the area are not significant, that the depth of the litter varies from 0.5 to 0.9 inches, and that the water retention of the litter is equivalent to approximately 0.05 inch and of the l-inch layer immediately below it to 0.44 inch. Thus the forest floor can hold approximately 0.5 inch of water, based on its ovendry condition. These relationships hold true for litter accumulated in stands control-burned as recently as 10 years previously as well as in stands unburned for several decades.Of some interest is the comparative influence of the litter in interception relative to a moss and lichen ground cover. The latter develops as a result of a persistent control-burn program that keeps the litter cover at a minimum. Moul and Buell (1955) have shown that moss mats that develop under such circumstances can intercept as much as 0.62 inch of precipitation and lichen mats as much as 0.22 inch. Since the mosses and lichens were found to cover only 33% of the ground in the burned areas while the litter in unburned areas usually covers from 90 to 100% of the ground, it would seem that the litter layer of the forest floor may be from 2 to 3 times as effective in intercepting moisture in...
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