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regular research paper |
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Acclimation of silver fir (Abies
alba Mill.) seedlings to
irradiance conditions under canopies of different tree species in Sudety Mts.
(Southern Poland) |
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Zdzisław Kajak1 and Paweł Prus2 |
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1Centre for Ecological
Research PAS (formerly Institute of Ecology PAS) Dziekanów Leśny, 05-092
Łomianki, Poland
2Centre
for Ecological Research PAS, Dziekanów Leśny ,05-092 Łomianki, Poland and The
Stanisław Sakowicz Inland Fisheries Institute, Department of River Fisheries,
Główna 48, Żabieniec, 05-500 Piaseczno, Poland, e-mail: rzeki@infish.com.pl (present address) |
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Abstract:
During 9 years of studies very regular Chironomus population dynamics was
stated in a eutrophic, lowland dam reservoir. There were usually two peaks of
the abundance: the higher one at spring (up to 80 thousands ind. m –2)
and the much lower in autumn. The duration of the spring Chironomus generation was about 3 weeks. The constant presence of
young larvae during the summer did not result in the high total abundance of
larvae, mainly due to the strong predation of fish and swallows on various
stages of Chironomus. The smaller
predators pressure in the spring (due to fish breeding) and in the autumn
(due to lower temperatures) resulted in the mentioned two peaks. The spring peak abundance was
positively correlated with the chlorophyll concentration in water (feeding
resource for larvae) and negatively with the water flow. There was also negative
correlation of the water flow and the chlorophyll concentration, as well as
abundance of Chironomus and
Tubificidae during the vegetation season (April–October). Tubificidae
correlated strongly positively with the spring Chironomus numbers (with a month lag). The slight positive
correlation of these benthic components abundance occurred for the whole
vegetation season. Tubificidae occurred in generally high numbers - up to 400 thousands m–2, but
various in different years, and with no regular changes during the season. |
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Key words: Chironomus, Tubificidae, population dynamics, long-term
studies, dam-reservoir |