Abundancia De Macroalgas
Enviado por nohep3 • 3 de Diciembre de 2012 • 4.540 Palabras (19 Páginas) • 391 Visitas
On the abundance of epiphytic green algae in relation to the
nitrogen concentrations of biomonitors and nitrogen deposition
in Finland
J. Poikolainena*, H. Lippo”, M. Hongistob, E. Kubin”, K. Mikkola’, M. Lindgrend
‘Muhos Research Station, Finnish Forest Research Institute, FIN-91500 Muhos, Finkmd
bFinnish Meteorological Institute, FIN-00101 Helsinki, Finland
CRovaniemi Research Station, Finnhh Forest Research Institute, FIN-96301 Rovaniemi, Finland
*Vantaa Research Centre, Finnish Forest Research Institute, FIN-013OI Vantaa, Finland
Received 27 March 1998; accepted 10 September 1998
Abstract
Green algae have become considerably more abundant in the years 19851995 in Finland and their distribution area has expanded
northwards. Green algae on conifers were most abundant in southern Finland where the nitrogen deposition is highest. Correlations
were observed between the abundance of green algae and a modelled nitrogen and sulphur deposition as well as the nitrogen
concentration of the biomonitors. The increased abundance of green algae in Finland may be caused by several concurrent changes
which have taken place in the environment and which have all promoted the occurrence of green algae. A slight rise in mean annual
temperature, the long-term stability of nitrogen deposition, and the clear fall in the amount of sulphur deposition have probably all
increased the growth and abundance of green algae. At a local level, the differences in microclimate have also effect on the
abundance of green algae and the microclimate varies, inter alia, by the nutrient-richness of the habitat, the predominant tree
species, stand age and stand density.
Keywords: Green algae; moss; lichen; pine bark; nitrogen deposition
Introduction
The deposition of nitrogen has increased in a large
part of Europe during the past few decades while at the
same time, that of sulphur has considerably diminished
(Barrett et al., 1995; Mylona, 1996). The emissions of
oxides of nitrogen in Finland have remained approximately
at the same annual level, 250 000 tonnes, and
those of ammonium, 50 000 tonnes, in the years 19&G
1995 (Ymptiristtikatsaus, 1995). Emissions of sulphur
dioxide have diminished during the same period from
about 300 000 tonnes to 100 000 tonnes. The total deposi-
* Corresponding author. Tel.: +358-B-531-2200, fax: +358-8-531-
2211; e-mail: jarmo.poikolainen@metla.fi
tion of oxidized nitrogen exceeds 3-4 kg (N) ha-’ year-’
and of the total reduced nitrogen 2-3 kg (N) ha-’ year-’ in
southern Finland (YmptiriWkatsaus, 1995; Hongisto,
1998). Both the oxidized and the reduced nitrogen deposition
decrease to the north and they are in northern
Finland correspondingly only l-l.5 kg (N) and 0.5-l kg
(N). Dry deposition varies 20-50% of total with the
seasons.
Atmospheric nitrogen in wet deposition is in nitrate
and ammonium form (NO,, NH,-) while in dry deposition
it is mainly in the form of gaseous nitric acid
(HNO,), ammonium (NH,) or nitrogen dioxide (NO,)
(Pitcairn et al., 1995; Hongisto, 1998). Nitrogen deposition
has a twofold ecological impact. On the one hand,
nitrogen causes acidification of the soil due to leaching of
base cations. On the other hand, it is a vital plant
86 J. Poikolainen et al. I Environmental Pollution 102, Sl (1998) 85-92
nutrient, which, when in excess, causes eutrophication. It
has been observed that increased deposition has caused
changes in vegetation, especially in areas of high
deposition in Central Europe, to the extent that
eutrophic plant species have increased at the expense of
oligotrophic species (e.g. Bobbink et al., 1992; Sutton et
al., 1993). If the vegetation is not able to bind free
nitrogen in the biological cycle, leaching will increase. In
areas where nitrogen deposition exceeds about lo-15 kg
N ha-* forested catchments show increased leaching of
nitrate (Grennfelt and Hultberg, 1986).
Research on nitrogen deposition and its impacts on
forest ecosystems has been relatively modest with respect
to the use of bioindicators when compared to the
research done on sulphur deposition. Part of the reason
probably lies in the fact that, due to it being an important
plant nutrient, it is more difficult to separate its effects
on vegetation than when dealing with sulphur. Green
algae have been used a little during the past few years as
bioindicators when examining nitrogen deposition
because
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