Martin Camaj - Die albanische Mundart von Falconara Albanese in der Provinz Cosenza

Lakes have long attracted study by ecologists, and insights derived from their investigation have led to substantial advances in all branches of ecology and ecosystem science. Their scientific value stems, in part, from their position in the landscape. Their hydrological connectivity to the watershed and climatic and depositional connectivity to the airshed make them natural integrators of conditions within their catchments and beyond. Mountain ecosystems, in particular, are valuable systems to study because they possess a high degree of spatial heterogeneity superimposed on steep elevation driven gradients in soil development, vegetation cover, and precipitation and temperature patterns. High-elevation lakes are recognized as excellent indicators of regional environmental changes and are increasingly being used by regulatory agencies to establish critical loads for atmospheric pollutants. Moreover, the importance of montane snowpacks to freshwater supplies mandates that particular attention be paid to the biogeochemistry, hydrology, and ecology of these systems.

Californias iconic mountain range, the Sierra Nevada, John Muirs range of light, harbors thousands of lakes. Most are remote, at high elevations, and blanketed under snow and ice for many months each year. Hence their scientific study is challenging. Concern about acidification from atmospheric deposition in the 1980s spurred efforts to measure deposition and understand its influence on the lakes and their catchments. In more recent decades, limnological research has focused on the role of climate warming and related variations in snowfall and snowmelt in driving change in these ecosystems.

Our goal in this book is to synthesize and integrate over three decades of investigation of high-elevation lakes throughout the Sierra Nevada of California. We focus on Emerald Lake and its watershed (Sequoia National Park) because no other site has the combined long-term hydrological and limnological data for coupled lake-watershed understanding. Studies have documented recovery from mild acidification after reductions in emissions and have highlighted the vulnerability of Sierra lakes to ongoing changes in climate. Rapid warming of air temperatures and changes in precipitation have modified the timing and magnitude of hydrological and chemical fluxes, altering aquatic ecology. Experiments and models have added a mechanistic understanding of the underlying processes and provided predictive tools for managers. Comparative studies of biological and hydrochemical conditions within lakes scattered throughout the mountain range provide a regional context for examination of Sierra-wide conditions and changes.

The book begins with an introduction to the Sierra Nevada as an integrated system with characteristic climatic, geologic, topographic, ecological, and cultural features. We then introduce the lakes and watersheds that are focus of our studies. To place these lakes in context we present an analysis of the geography of water bodies throughout the Sierra based on a compilation of data from hundreds of lakes.

Chapter 3 focuses on snow, the largest input of water to Sierra watersheds with important influences on many ecological aspects of the lakes. The physical properties of snow and their relevance to remote sensing of snow are introduced. The combination of remote sensing analyses and snow survey data provides Sierra-wide descriptions of the snow cover and its interannual variability. Chapter 4 presents measurements of runoff and water balances for watershed, an essential aspect of the biogeochemical and limnological aspects treated in subsequent chapters. The combination of detailed surveys of seasonal snowpacks and monitored stream discharge and meteorological data allows estimation of all the terms in water balances for high-elevation watersheds spanning the range from north to south.

The fifth chapter examines watershed biogeochemistry based on long-term studies and mechanistic, modeling, and experimental results from the Emerald Lake watershed and elsewhere throughout the Sierra Nevada. The atmospheric deposition of ions and particulate matter represents a significant input to Sierra watersheds, which are sensitive to anthropogenic activities. In turn, the weathering of soils and rocks and the biological uptake within catchments alter the atmospheric inputs and determine loading to the lakes. We discuss biogeochemical mechanisms associated with nitrogen, phosphorus, and major solute dynamics and present mass balances of inputs and outputs for selected watersheds.