C. E. Magnuson

Pheromone dispersion in forests

A simple generic model for the dispersion of pheromones in a forestedecosystem is presented. Methods for the calculation of various concentration related parameters are described. The influence of different micrometeorological conditions on concentration profiles is discussed. Two separate studies from two different geographical locations lend support to the predictions of the dispersion model. For two different species of Dendroctonus beetles, aggregation behavior was correlated with meteorological condition resulting from inversion profiles.

A time-dependent mathematical expression of the münch hypothesis of phloem transport

Abstract A time-dependent mathematical expression of the Munch, osmotically driven mass flow hypothesis of phloem transport is presented. The dependent variables include concentration of solutes, pressure, velocity of phloem sap, osmotic flux of water, and concentration dependent unloading of solutes. The model meets conservation requirements during all iterations, and responds realistically to changes in independent variables. Given the same set of independent variables the time-dependent model converges to the same values as the closed-form steady-state model of Goeschl et al. (1976) regardless of the initial conditions.

Short-lived isotope kinetics: a window to the inside

An integrated approach to studying the effects of environmental factors on plants is described. The central theme of the system is the use of CO2 labelled with 11C supplied continuously to the plant and following the emitted radiation in vivo in the leaf, the phloem, and the various sinks. The system consists of six components and with minor changes can be used with other tracers such as 13N for nitrogen fixation studies. Because of the short half-life of the isotope, several experiments can be carried out on the same plant under the same environmental conditions without disturbing the plant. When this system is coupled with mathematical models of phloem transport and carbon allocation a host of ecologically, agriculturally, and genetically important questions can be answered (redundent). Carbon assimilation and allocation patterns in plant leaves were measured using this system. The concepts and analytical techniques of tracer kinetics of extended square wave (ESW) input of 11CO2 were used in calculating the parameters of carbon allocation dynamics in plant systems under different physiological conditions. Examples of the latter include (1) recovery from mechanical agitation, (2) diurnal patterns, and (3) effects of drought stress.

Measurement of carbon fixation and allocation using (super 11) C-labeled carbon dioxide.

This paper describes the use of continuously produced and applied /sup 11/C in measurements of carbon dioxide assimilation and C movement in plant research. This technique differs from the pulsing type /sup 11/C research underway in other laboratories by being continuous and on-line with computer analysis making steady-state measurements of carbon fixation and movement possible. The studies to be described here make clear the advantages of using continuously produced and applied short half-lived isotopes.