Matthias Langensiepen

Monitoring and Modeling the Terrestrial System from Pores to Catchments: The Transregional Collaborative Research Center on Patterns in the Soil–Vegetation–Atmosphere System

AbstractMost activities of humankind take place in the transition zone between four compartments of the terrestrial system: the unconfined aquifer, including the unsaturated zone; surface water; vegetation; and atmosphere. The mass, momentum, and heat energy fluxes between these compartments drive their mutual state evolution. Improved understanding of the processes that drive these fluxes is important for climate projections, weather prediction, flood forecasting, water and soil resources management, agriculture, and water quality control. The different transport mechanisms and flow rates within the compartments result in complex patterns on different temporal and spatial scales that make predictions of the terrestrial system challenging for scientists and policy makers. The Transregional Collaborative Research Centre 32 (TR32) was formed in 2007 to integrate monitoring with modeling and data assimilation in order to develop a holistic view of the terrestrial system. TR32 is a long-term research program ...

Evaluating the Influence of Plant-Specific Physiological Parameterizations on the Partitioning of Land Surface Energy Fluxes

Plantphysiologicalpropertieshaveasignificantinfluenceonthepartitioningofradiativeforcing,thespatial and temporal variability of soil water and soil temperature dynamics, and the rate of carbon fixation. Because of the direct impact on latent heat fluxes, these properties may also influence weather-generating processes, such as the evolution of the atmospheric boundary layer (ABL). In this work, crop-specific physiological characteristics, retrieved from detailed field measurements, are included in the biophysical parameterization of the Terrestrial Systems Modeling Platform (TerrSysMP). The physiological parameters for two typical European midlatitudinal crops (sugar beet and winter wheat) are validated using eddy covariance fluxes over multiple years from three measurement sites located in the North Rhine‐Westphalia region of Germany. Comparison with observations and a simulation utilizing the generic crop type shows clear improvements when using the crop-specific physiological characteristics of the plant. In particular, the increase of latent heat fluxes in conjunction with decreased sensible heat fluxes as simulated by the two crops leads to an improved quantification of the diurnal energy partitioning. An independent analysis carried out using estimates of gross primary production reveals that the better agreement between observed and simulated latent heat adopting the plant-specific physiological properties largely stems from an improved simulation of the photosynthesis process. Finally, to evaluate the effects of the crop-specific parameterizations on the ABL dynamics, a series of semi-idealized land‐atmosphere coupled simulations is performed by hypothesizing three cropland configurations. These numerical experiments reveal different heat and moisture budgets of the ABL using the crop-specific physiological properties, which clearly impacts the evolution of the boundary layer.

Typology of Smallholder Production Systems in Small East-African Wetlands

Small wetlands increasingly become important agricultural production niches in sub-Saharan Africa. Understanding the diversity of these households may help to develop guidelines for their future use. In this study a typology of households in small wetlands was developed using case studies of 275 farmers from Kenya and Tanzania. Based on a combination of production system attributes land resources, and production objectives, households were categorised into 12 farm types. Production resources, access to cropland on upland, access to market, and non-wetland related livelihood strategies differed between households and translated into different wetland use patterns. Farm types were linked to the prevailing wetland systems. The household typology captured various dimensions in values, attitudes, and goals of farmers and determined their influence on land use decisions. The wetland field: farm size ratio differed significantly between farm types. More than one-third of the households depended completely on cropland in the wetland. The variable nature of household dependence was reflected in diverse production orientations with different levels of land use intensity and subsequent pressure on wetlands. The heterogeneity induced agricultural practices among households and the complexity of the wetland system highlight the need for specific incentives to develop sustainable plans for wetland management.

Forest Management and the Water Cycle: An Integrated Introduction to Scaling

Scaling is a multifaceted methodology which can be applied in a great variety of forest hydrological and management contexts. The purpose of this introduction is to provide an overview of Part III of this book which addresses various scaling applications in forest management and hydrology. It provides an integrated overview of commonly applied scaling procedures in computer cartography and establishes links between modelling, geographic mapping and remote sensing. The following chapters provide deeper insights into the theoretical and practical concepts of scaling using information from numerous forest studies which have been performed across Europe.

Fundamentals of Model Scaling in Forest Ecology

Coping with disturbances of forest systems which result from increasing fluctuations of physical and human environments requires a better quantitative understanding of forest ecological processes at different scales. Examples of applied scaling in forest ecology are initially discussed to stress the practical relevance of scaling studies. Model-based reasoning serves as a starting point of any scaling activity. Initial cognitive processes play an important role in model conceptualizing and are thus briefly summarized. Statistical techniques for scale identification are outlined and the establishment of mathematical scaling laws explained. Structure and function are emphasized as important concepts for understanding tree responses to changing environments. Methods of translating models across spatial scales are categorized in the concluding section.