Water chemistry and nutrient budgets in an undisturbed evergreen rainforest of Southern Chile

Abstract

In a pristine evergreen rainforest of Nothofagus betuloides, located at the Cordillera de los Andes in southern Chile (41 8S), concentrations and fluxes of nutrients in bulk precipitation, cloud water, throughfall water, stemflow water, soil infiltration and percolation water and runoff water were measured. The main objectives of this study were to investigate canopy-soil-atmosphere interactions and to calculate input-output budgets. From May 1999 till April 2000, the experimental watershed received 8121 mm water (86% incident precipitation, 14% cloud water), of which the canopy intercepted 16%. Runoff water volume amounted 9527 mm. Bulk deposition of inorganic (DIN) and organic (DON) nitrogen amounted 3.6 kg ha À1 year À1 and 8.2 kg ha À1 year À1 respectively. Occult deposition (clouds þ fog) contributes for 40% to the atmospheric nitrogen input (bulk þ occult deposition) of the forest. An important part of the atmospheric ammonium deposition is retained within the canopy or converted to nitrate or organic nitrogen by epiphytic bacteria or lichens. Also the export of inorganic (0.9 kg ha À1 year À1 ) and organic (5.2 kg ha À1 year À1 ) nitrogen via runoff is lower than the input to the forest floor via throughfall and stemflow water (3.2 kg DIN ha À1 year À1 and 5.6 kg DON ha À1 year À1 ). The low concentrations of NO À 3 and NH þ 4 under the rooting depth suggest an effective biological immobilization by vegetation and soil microflora. Dry deposition and foliar leaching of base cations (K þ , Ca 2þ , Mg 2þ ) was estimated using a canopy budget model. Bulk deposition accounted for about 50% of the total atmospheric input. Calculated dry and occult deposition are both of equal value (about 25%). Foliar leaching of K þ , Ca 2þ , and Mg 2þ accounted for 45%, 38% and 6% of throughfall deposition respectively. On an annual basis, the experimental watershed was a net source for Na þ , Ca 2þ and Mg 2þ . #

Climatic context and ecological implications of summer fog decline in the coast redwood region

“…On both interannual and interdecadal time scales, a coupling is thus apparent between upwelling-favorable conditions over the California Current and the frequency of coastal fog in northern California. The atmospheric conditions that enhance nutrient supply in the surface ocean via upwelling may provide similar benefits to coastal forests via wet deposition of nitrogen in fog water, as observed in California coast redwoods (7) and in Chile (32,33).…”

Vegetación epifita y captación de neblina en bosques siempreverdes en la Cordillera Pelada, sur de Chile

“…Además, se medirán los aportes de agua por precipitaciones dentro y fuera del bosque y la cantidad proveniente por intercepción de la neblina por un período superior a un año. Este aporte adicional de agua también fue mencionado por otros autores para los bosques templados del sur de Chile (Veblen y Ashton 1982, Pérez et al 1991, Weathers et al 2000, Oyarzún et al 2004.…”

Ecohidrology and Nutrient Fluxes in Forest Ecosystems of Southern Chile

“…Aerosol and gases can by deposited directly from the air to plant and soil surfaces during rainless periods by dry deposition. Wet deposition is defined as the input of atmospheric compounds to the earth´s surface by rain, hail, snow and/or occult deposition that occurs via fogs and clouds, which can be important in mountainous regions [3]. During rain events, dry deposition is washed off from plant parts and, together with wet deposition, reaches the forest floor as throughfall and stem flow.…”

“…The annual mean temperature is 5 to 12° C and precipitation ranges from 2000 to 7000 mm in the AMR [3]. Data from [5] reported that mean annual N composition of the rainwater in the CMR and AMR ranges (41°-43° S), varied between < 30 -43 NO 3 --N µg L -1 and 9. [7,3).…”

“…Data from [5] reported that mean annual N composition of the rainwater in the CMR and AMR ranges (41°-43° S), varied between < 30 -43 NO 3 --N µg L -1 and 9. [7,3). [6] described that the dominant form of N leaching was dissolved organic nitrogen (DON) for unpolluted forests of southern Chile.…”