Management of natural forests might be one option to reduce the high deforestation rate in Ecuador. We therefore evaluated the response of water and nutrient cycles in a natural tropical montane forest to improvement fellings with the aim of favoring economically valuable target trees which will later be harvested with additional ecosystem impacts not considered here.

In tropical forests, the first step in the destruction cycle is usually the over-exploitation of high value timber, leading not only to extinction of the extracted species (Silva Matos and Bovi 2002) but also to the conversion of the forests into pastures in many cases (Wunder 1996b). In many highlands of Ecuador the productivity of the pastures is depleted due to the invasion of bracken fern (see Chapter 28 in this volume), which finally leads again to the conversion of primary forests by local farmers (Paulsch et al. 2001; Hartig and Beck 2003). This process usually is accompanied by loss of biodiversity (Brooks et al. 2001), increased erosion, changes of hydrology (Bruijnzel 2004), and further environmental disturbances. More information on deforestation in Ecuador is given by Mosandl et al. (Chapter 4 in this volume).

Rainfall, litter fall, and organic matter turnover are the major drivers of nutrient fluxes in forest ecosystems. During its passage through the forest, the quantity and chemical composition of water — which enters the forest via rainfall and clouds — changes (Parker 1983). The chemical quality of throughfall and stemflow is controlled by the intensity of rainfall, dry deposition, and soil fertility (Parker 1983; Schaefer and Reiners 1990). The few studies on litter leachate, i.e. the water percolating through the organic layer, in tropical forests indicate that the concentrations of all nutrients increase compared with rainfall and throughfall (e.g., Steinhardt 1979; Hafkenscheid 2000; Wilcke et al. 2001a). In stream water, nutrient concentrations are lower than in litter leachates, except for elements which are released by weathering (Bruijnzeel et al. 1993; McDowell 1998).

The Advanced Technology Development (ATD) Program is a multilaboratory effort to assist industrial developers of high-power lithium-ion batteries overcome the barriers of cost, calendar life, abuse tolerance, and low-temperature performance so that this technology may be rendered practical for use in hybrid electric vehicles (HEVs). Included in the ATD Program is a comprehensive diagnostics effort conducted by researchers at Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL), and Lawrence Berkeley National Laboratory (LBNL). The goals of this effort are to identify and characterize processes that limit lithium-ion battery performance and calendar life, and ultimately to describe the specific mechanisms that cause performance degradation. This report is a compilation of the diagnostics effort conducted since spring 2001 to characterize Generation 2 ATD cells and cell components. The report is divided into a main body and appendices. Information on the diagnostic approach, details from individual diagnostic techniques, and details on the phenomenological model used to link the diagnostic data to the loss of 18650-cell electrochemical performance are included in the appendices. The main body of the report includes an overview of the 18650-cell test data, summarizes diagnostic data and modeling information contained in the appendices, and provides an assessment of the variousmore » mechanisms that have been postulated to explain performance degradation of the 18650 cells during accelerated aging. This report is intended to serve as a ready reference on ATD Generation 2 18650-cell performance and provide information on the tools for diagnostic examination and relevance of the acquired data. A comprehensive account of our experimental procedures and resulting data may be obtained by consulting the various references listed in the text. We hope that this report will serve as a roadmap for the diagnostic analyses of other lithium-ion technologies being evaluated for HEV applications. It is our hope that the information contained in this report will lead to the development of new lithium-ion cell chemistries and designs that will meet the 15-year cell calendar-life goal established by DOE's FreedomCar and Fuel Partnership.« less

The C/25 discharge data from 18650-size cells containing LiNi0.8Co0.1Al0.1O2 cathode and graphite anode laminates were analyzed through the use of the differential voltage, dV/dQ, curves. Using half-cell data, the peaks in the dV/dQ curve of the full cell data were assigned. Analysis of the relative peak shifts allowed for the determination of the source of capacity fade. For cells formed and aged at 45 °C for 40 weeks (capacity fade = 7.5%), the analysis indicated negligible loss of accessible material at the anode and at the cathode. Capacity loss of the cell could be accounted for, largely, by side reactions at the anode. This type of analysis can be used when the introduction of a reference electrode is difficult or impractical.

Hybrid electric vehicles (HEV) need long-lived high-power batteries as energy storage devices. Batteries based on lithium-ion technology can meet the high-power goals but have been unable to meet HEV calendar-life requirements. As part of the US Department of Energy's Advanced Technology Development (ATD) Program, diagnostic studies are being conducted on 18650-type lithium-ion cells that were subjected to accelerated aging tests at temperatures ranging from 40 to 70 C. This article summarizes data obtained by gas chromatography, liquid chromatography, electron microscopy, X-ray spectroscopy and electrochemical techniques, and identifies cell components that are responsible for the observed impedance rise and power fade.

Rainfall in tropical mountain forests ranges between several hundreds and several thousands of millimeters per year (Cavelier et al. 1997; Bruijnzeel 2001). Many of these forests receive considerable cloud water inputs (Bruijnzeel 2001). During its passage through the forest, the quantity of the water entering the forest with rainfall and clouds changes because of increasing evaporation and transpiration during percolation through the ecosystem (Likens and Bormann 1995; Bruijnzeel 2001). An important water loss is the evaporation of water intercepted in the canopy. Measurements of interception loss of tropical mountain forests also vary over a broad range (Cavelier et al. 1997). The portion of throughfall and stemflow reaching the stream after its passage through the soil depends on water flow paths. The occurrence of rapid interflow is a frequent phenomenon on steep forested hill slopes (Mulholland et al. 1990; Bonell et al. 1998) and is mainly attributable to the high significance of macropores (Buttle and McDonald 2000). Therefore, the assessment of water and element fluxes in the soil requires the due consideration of fast interflow.