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 .

Palladium/Norbornene‐Catalyzed Synthesis of Heteroatom‐Containing o‐Teraryls from Aryl Iodides and Heteroarenes through Double CH Activation in Sequence

“…In our study sites, the interception loss based on the measured gross rainfall was negative especially during the fall months of April and May due to the water input from fog and clouds. In an evergreen forest of N. betuloides at 910 m a.s.l in the Andes, the annual input of cloudwater was calculated to be 1010 mm (Oyarzún et al , 2004) and in a deciduous forest of N. pumilio (P. et E.) Krasser at 1120 m a.s.l. the estimated annual interception loss was negative (Godoy et al , 1999).…”

“…In Chilean pristine forests, natural processes are dominant and nutrient cycling is not disturbed by atmospheric pollution (Godoy et al , 2001). These highly productive forest ecosystems have efficient mechanisms of conservation for essential nutrients under scenarios of higher precipitation in mountain areas (Oyarzún et al , 2004; Huygens et al , 2008). To understand, model, and predict the consequences of changing environmental conditions on ecosystem sustainability, ecological studies in these pristine forests are crucial (Huygens et al , 2008).…”

“…In general, most studies on forest interception have examined relationships to gross rainfall amount and characteristics, while fewer studies have related interception loss to forest structure (Crockford and Richardson, 2000; Tobon et al , 2000; Bryant et al , 2005) or management practices (Asdak et al , 1998). Studies in south‐central Chile showed that interception varied from 10 to 37% of annual precipitation in broadleaved forests and from 11 to 39% in coniferous plantations (Huber and Iroumé, 2001), implying that interception loss is an important component of the water balance of temperate rainforests in southern Chile (Godoy et al , 1999; Oyarzún et al , 2004). Studies on forest interception showed that throughfall, stemflow, and interception loss are closely related to the characteristics and amount of rainfall (Huber and Oyarzún, 1992).…”

Functional role of DNRA and nitrite reduction in a pristine south Chilean Nothofagus forest

“…The forest vegetation is dominated by evergreen Nothofagus betuloides with an average tree age of 325 years (Godoy et al 2001). Total annual bulk N deposition amounts to 11.8 kg N ha -1 in form of dissolved organic nitrogen (8.2 kg N ha -1 ) and dissolved inorganic nitrogen (3.6 kg N ha -1 ) (Oyarzún et al 2004). The initial mineral N concentration measured in the soil samples was 441 lg NH 4 ?…”

“…Main soil characteristics are listed in Table 1. More detailed information for the study site can be found in Huygens et al (2007) for soil characteristics and in Oyarzún et al (2004) for water and soil chemistry.…”