A taxonomic and horticultural review of Erythronium L. (Liliaceae)

MATHEW, B., 1992. A review of Erythronium L. (Liliaceae). The morphology, distribution and horticultural value of the genus is reviewed and a tentative key to the identification of the species is provided.     

COMPUTER ANALYSIS OF BIRD SOUNDS: A GUIDE TO CURRENT METHODS

ABSTRACT

Bioacoustics researchers can use a computer as a powerful tool to measure, classify, compare and synthetise sounds. Vocalisations on tape are commonly converted to a digital format suitable for a computer by using an analogue to digital converter and then a Fourier transformation. Alternatively, sonagrams can be measured, for example by using a digitising pad or an image analysis system. Correlations and indices of similarity have been used to compare sounds, but variations in both the time and frequency dimensions of a noise are a problem. A solution may be the use of pattern recognition methods such as elastic matching and time warping. These methods are briefly described and assessed.     

The response of an Eastern Amazonian rain forest to drought stress: results and modelling analyses from a throughfall exclusion experiment

Warmer and drier climates over Eastern Amazonia have been predicted as a component of climate change during the next 50–100 years. It remains unclear what effect such changes will have on forest–atmosphere exchange of carbon dioxide (CO₂) and water, but the cumulative effect is anticipated to produce climatic feedback at both regional and global scales. To allow more detailed study of forest responses to soil drying, a simulated soil drought or 'throughfall exclusion' (TFE) experiment was established at a rain forest site in Eastern Amazonia, Brazil, for which time-series sap flow and soil moisture data were obtained. The experiment excluded 50% of the throughfall from the soil. Sap flow data from the forest plot experiencing normal rainfall showed no limitation of transpiration throughout the two monitored dry seasons. Conversely, data from the TFE showed large dry season declines in transpiration, with tree water use restricted to 20% of that in the control plot at the peak of both dry seasons. The results were examined to evaluate the paradigm that the restriction on transpiration in the dry season was caused by limitation of soil-to-root water transport, driven by low soil water potential and high soil-to-root hydraulic resistance. This paradigm, embedded in the soil–plant–atmosphere (SPA) model and driven using on-site measurements, provided a good explanation ( R ² > 0.69) of the magnitude and timing of changes in sap flow and soil moisture. This model-data correspondence represents a substantial improvement compared with other ecosystem models of drought stress tested in Amazonia. Inclusion of deeper rooting should lead to lower sensitivity to drought than the majority of existing models. Modelled annual GPP declined by 13–14% in response to the treatment, compared with estimated declines in transpiration of 30–40%.