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| Titel |
Trends of precipitation and streamwater chemistry at a subtropical forested catchment, northeastern Taiwan |
| VerfasserIn |
Chung-Te Chang, Jr-Chuan Huang, Teng-Chiu Lin |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130944
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| Publikation (Nr.) |
 EGU/EGU2016-11275.pdf |
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| Zusammenfassung |
| Abstract
The assessment of long-term input-output budgets has been widely used to examine
the impacts of acidic deposition on temperature forest ecosystems, but rarely in
subtropical forest ecosystem. In this study, we used weekly bulk precipitation and
streamwater chemistry data collected between 1994 and 2013 in a small catchment in
northeastern Taiwan. The long-term volume-weighted mean pH of precipitation and
streamwater were 4.64 and 6.79 respectively which indicated that the stream was
capable of neutralizing common acidic deposition. Precipitation revealed a significant
decline trend in Ca2+, NH4+, and NO3− concentration and fluxes in the summer
possibly due to decreases of local emissions in Taiwan. But the persistent high
levels of NO3− and SO42− during winter period over the past 20 years could a
potential threat to forest ecosystems in the region. Although the concentrations and
fluxes of all elements in streamwater showed high intern-annual variation, there
were no significant trends. The long-term nutrient budget indicates net loss for
Na+, Mg2+, Ca2+, NO3− and SO42−, net retention for NH4+ and Cl− and near
balance for K+. The significant trend of net export of NO3− during the study period
calls for further investigation to clarify if nitrogen saturation is occurring due to the
high acid deposition or if other factors such as typhoon disturbance are driving its
dynamics. From the comparisons between seasonal and annual budgets, it is clear that
hydrological flux instead of biological activities dominated the biogeochemical
processes and this is very different from the biotic control of biogeochemistry in
temperate forest ecosystem (e.g. Hubbard Brook Experimental Forest). Our results also
have important implications on the effects of climate change on biogeochemical
cycles.
Keywords: acid deposition, nutrient budget, biogeochemistry, forest ecosystem,
subtropical mountainous island. |
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