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The temperature‐determined growing season of a submerged hydrophyte
Author(s) -
MOELLER ROBERT E.
Publication year - 1980
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1980.tb01214.x
Subject(s) - biomass (ecology) , nutrient , overwintering , growing season , dry season , limiting , aquatic plant , biology , zoology , botany , ecology , eutrophication , stratification (seeds) , carnivorous plant , environmental science , agronomy , macrophyte , mechanical engineering , seed dormancy , germination , dormancy , engineering , predation
SUMMARY. Temperature determines the growing season of Utricularia purpurea , a common rootless, carnivorous plant at depths of 0–6.5 m in a dimictic oligotrophic lake (Mirror Lake, New Hampshire, U.S.A.). The dynamics of thermal stratification limit the growing season to 8 weeks at a depth of 6 m compared to 17 weeks at 2 m. Light may limit growth at 6 m during the short growing season, but is not limiting in midsummer at 2 m or 4 m. Plants of equivalent size produce 60–75% less biomass annually at 6 m than at 2 or 4 m. The seasonally maximal biomass (in mid‐August) is equivalent to the annual net production as calculated from periodic inventories of new, old and senescent tissue (thus P/B = 1.0). Uptake of nutrient elements (N, P, Ca, Mg, Na, K) is synchronous with biomass production. Nutrients do not become enriched in the overwintering tissue (52% of the maximum biomass). This species is unusually rich in Zn (1000 μg g dry wt −1 ), relatively rich in N (2.9% dry wt). but quite poor in P (0.084%).