RESEARCH: Shrub Propagation Techniques for Biological Control of Invading Tree Species

Cornus stolonifera, Salix petiolaris, and Spiraea alba clones already located within the corridor of an electrical power line. To establish the efficiency of treatments, we examined the statistical differences of growth traits between species and treatments. An analysis of the effects of layering shows, after the first growth season, differences for all growth traits in only one species, Spiraea alba. After the second growth season, we observed the development of new aerial stems. Layering favors horizontal expansion of shrubs over height development. The third year after treatment, the effect of layering is reduced except for Cornus stolonifera, which continuously increases, as shown by the significant progression of the clone issued from the layer even five years after treatments. With the cutting back technique, we expected a distinct vertical growth of the shrubs at the expense of increasing the crown diameter. This technique would be best associated with the rejuvenation of clones, followed by a layering of new shoots to allow a horizontal expansion of the shrubs. Therefore, the formation of a dense shrub community by layering should be considered a valuable approach for the biological control of undesirable trees in powerline rights-of-way.     

Citrulline in amniotic fluid and the prenatal diagnosis of citrullinemia

We report relatively high citrulline concentration in amniotic fluid of a citrullinemic fetus suggesting that prenatal detection of this condition could be done on this basis in conjunction with a direct or an indirect determination of argininosuccinate synthetase activity in amniotic fluid cells.     

Information Network Topologies for Enhanced Local Adaptive Management

We examined the principal effects of different information network topologies for local adaptive management of natural resources. We used computerized agents with adaptive decision algorithms with the following three fundamental constraints: (1) Complete understanding of the processes maintaining the natural resource can never be achieved, (2) agents can only learn by experimentation and information sharing, and (3) memory is limited. The agents were given the task to manage a system that had two states: one that provided high utility returns (desired) and one that provided low returns (undesired). In addition, the threshold between the states was close to the optimal return of the desired state. We found that networks of low to moderate link densities significantly increased the resilience of the utility returns. Networks of high link densities contributed to highly synchronized behavior among the agents, which caused occasional large-scale ecological crises between periods of stable and high utility returns. A constructed network involving a small set of experimenting agents was capable of combining high utility returns with high resilience, conforming to theories underlying the concept of adaptive comanagement. We conclude that (1) the ability to manage for resilience (i.e., to stay clear of the threshold leading to the undesired state as well as the ability to re-enter the desired state following a collapse) resides in the network structure and (2) in a coupled social–ecological system, the systemwide state transition occurs not because the ecological system flips into the undesired state, but because managers lose their capacity to reorganize back to the desired state. An erratum to this article can be found at .     

Dissolved organic matter fractions formed during composting of winery and distillery residues: evaluation of the process by fluorescence excitation-emission matrix

The aim of the present paper is to assess the maturity degree reached by different samples of several mixtures from winery and distillery residues composted using the Rutgers composting system, by means of excitation-emission matrix (EEM) fluorescence spectroscopy. The composts were sampled once a week for about 200d. EEM spectra indicate the presence of different fluorophores. The fluorescence intensities of these peaks show trends related to the maturity of the composting samples selected. The "contour density" of EEM maps is strongly modified through time. We have used the quantitative method of fluorescence regional integration (FRI). The EEMs were delineated into five excitation-emission regions. The degree of compost maturity could be correlated with the percentage of the volumetric integration under the EEM within each region. Further refinement of these techniques should provide a relatively rapid method for assessing the suitability of the compost to soil application.