The photosynthesis of various species or even a single plant varies dramatically in time and space, creating great spatial heterogeneity within a plant canopy. Continuous and spatially explicit monitoring is, therefore, required to assess the dynamic response of plant photosynthesis to the changing environment. This is a very challenging task when using the existing portable field instrumentation. This paper reports on the application of a technique, laser-induced fluorescence transient (LIFT), developed for ground remote measurement of photosynthetic efficiency at a distance of up to 50 m. The LIFT technique was used to monitor the seasonal dynamics of selected leaf groups within inaccessible canopies of deciduous and evergreen tree species. Electron transport rates computed from LIFT measurements varied over the growth period between the different species studied. The LIFT canopy data and light-use efficiency measured under field conditions correlated reasonably well with the single-leaf pulse amplitude-modulated measurements of broadleaf species, but differed significantly in the case of conifer tree species. The LIFT method has proven to be applicable for a remote sensing assessment of photosynthetic parameters on a diurnal and seasonal scale; further investigation is, however, needed to evaluate the influence of complex heterogeneous canopy structures on LIFT-measured chlorophyll fluorescence parameters.

Quantifying heat and mass exchanges processes of plant leaves is crucial for detailed understanding of dynamic plant-environment interactions. The two main components of these processes, convective heat transfer, and transpiration, are inevitably coupled as both processes are restricted by the leaf boundary layer. To measure leaf heat capacity and leaf heat transfer coefficient, we thoroughly tested and applied an active thermography method that uses a transient heat pulse to compute t, the time constant of leaf cooling after release of the pulse. We validated our approach in the laboratory on intact leaves of spring barley (Hordeum vulgare) and common bean (Phaseolus vulgaris), and measured t-changes at different boundary layer conditions.By modeling the leaf heat transfer coefficient with dimensionless numbers, we could demonstrate that t improves our ability to close the energy budget of plant leaves and that modeling of transpiration requires considerations of convection. Applying our approach to thermal images we obtained spatio-temporal maps of t, providing observations of local differences in thermal responsiveness of leaf surfaces. We propose that active thermography is an informative methodology to measure leaf heat transfer and derive spatial maps of thermal responsiveness of leaves contributing to improve models of leaf heat transfer processes.

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fadengeheftete Broschur 64,00 € Um ein Zivilverfahren sinnvoll führen zu können, müssen die Parteien wissen, worüber sie genau streiten. Hendrik Albrecht untersucht, mit welchen Mechanismen englische Juristen den Inhalt ihres Rechtsstreits bestimmen und Klagen voneinander abgrenzen. Hierfür nutzt Hendrik Albrecht den dogmatisch unvorbelasteten Begri der Streitsache. Er erklärt unterschiedliche Vorgehensweisen bei der Bestimmung der Streitsache aus der historischen Entwicklung des deutschen und englischen Rechts heraus und analysiert die Lösungen für das sich anschließende Problem, dass es keine mehrfachen Klagen über dieselbe Streitsache geben soll. Immer deutlicher zum Vorschein kommt dabei die Suche der Verfahrensordnungen nach einer Balance zwischen Parteiherrschaft und Verfahrensökonomie. Schließlich vergleicht und bewertet der Autor die deutsche und englische Herangehensweise an die Streitsache mit der europarechtlichen Rechtsprechung, um Impulse für die zukünftige Auslegung der Streitsache zu geben.