. The ecology and life history of the common frog (Rana temporaria temporaria) . 16 26 JANUARY I 5 25 FEBRUARY 17 27 MARCH APRIL Fig. 24. The Course of Phosphate Concentration in Spawn Ponds and Non-spawn Ponds, from January to April The first two points of the non-spawn ponds are fi-om single records. The thick line and solid dots indicate the non-spawn ponds, the thin line and open dots the spawn ponds. The non-spawn level is about twice that of the spawn pond level. Note that the rain affects the non-spawn ponds more than the spawn ponds. ponds where the plants are growing rapidly, and is r
. The ecology and life history of the common frog (Rana temporaria temporaria) . 16 26 JANUARY I 5 25 FEBRUARY 17 27 MARCH APRIL Fig. 24. The Course of Phosphate Concentration in Spawn Ponds and Non-spawn Ponds, from January to April The first two points of the non-spawn ponds are fi-om single records. The thick line and solid dots indicate the non-spawn ponds, the thin line and open dots the spawn ponds. The non-spawn level is about twice that of the spawn pond level. Note that the rain affects the non-spawn ponds more than the spawn ponds. ponds where the plants are growing rapidly, and is replenished when rain washes it into the pond from the land. It is therefore interesting to note that it was just this reciprocal relation that was observed. Fig. 24 shows the results. The first two points for the non-spawn ponds may not be reliable, because they were based on only one pond, but at all other dates the values for the non-spawn ponds lie above those for the spawn ponds. Moreover, both curves tended downwards all through the dry January and February, and when rain fell in March, the phosphates, replenished by the run-off, rose more in the non- spawn ponds. After the middle of March, both tended downwards. This suggests that plant activity was higher in the spawn ponds, and it was, of course, these that tended to have high potassium. The result
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