Geoscience Reference
In-Depth Information
100
Potamogeton crispus
(low NP)
Ref
A2
A2+50%
80
60
40
20
0
100
Elodea canadensis
(low NP)
Ref
A2
A2 + 50%
80
60
40
20
0
ASNDJ FMA
M
J JA
Months
S
ONDJFMAMJJ
S
O
Figure 6.7
Seasonal variation in per cent plant volume inhabited (PVI) (mean ± SE) of
the two dominant macrophytes in mesocosms receiving low nutrient loading at three
different temperature regimes in the Danish mesocosm experiment.
confirms earlier studies (Vadeboncoeur
et al
. 2003; Liboriussen & Jeppesen
2003) of shallow lakes, where a shift was observed from benthic to pelagic
production with increasing loading but only minor changes in total primary
productivity. Warming affected GPP and daytime ER differently at the two
nutrient levels. At low levels, warming had no effect in summer but stimulated
both processes during winter. The situation is different when changes over 24
hours are examined. Net ecosystem production on an annual basis was always
negative (probably due to respiration of organic matter in the sediments) and
became more negative with warming at low nutrient loading, while in the warmed
tanks with high loading, NEP first increased from the control to the A2 regime
and then decreased again in the A2+50 regime back to the control level, partly
following the pattern shown by chlorophyll
a
.
Search WWH ::
Custom Search