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| Jansen, S.; Gortan, E.; Lens, F.; Assunta Lo Gullo, M.; Salleo, S.; Scholtz, A.; Stein, A.; Trifilò, P.; Nardini, A.. |
| • The hydraulic conductance of angiosperm xylem has been suggested to vary with changes in sap solute concentrations because of intervessel pit properties. • The magnitude of the ‘ionic effect’ was linked with vessel and pit dimensions in 20 angiosperm species covering 13 families including six Lauraceae species. • A positive correlation was found between ionic effect and vessel grouping parameters, especially the portion of vessel walls in contact with neighbouring vessels. Species with intervessel contact fraction (FC) values < 0.1 showed an ionic effect between 2% and 17%, while species with FC values > 0.1 exhibited a response between 10% and 32%. The ionic effect increased linearly with the mean fraction of the total vessel wall area occupied... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Angiosperms; Hydraulic conductivity; Intervessel pit membrane; Ionic effect; Vessel grouping; Wood anatomy; 42.41. |
| Ano: 2011 |
URL: http://www.repository.naturalis.nl/record/423644 |
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| Stein, A.; Riley, J.; Halberg, N.. |
| The value of environmental indicators largely depends upon the spatial and temporal scale that they represent. Environmental indicators are dependent upon data availability and also upon the scale for which statements are required. As these may not match, changes in scales may be necessary. In this paper a geostatistical approach to analyse quantitative environmental indicators has been used. Scales, defined in terms of resolution and procedures, are presented to translate data from one scale to another: upscaling to change from high resolution data towards a low resolution, and downscaling for the inverse process. The study is illustrated with three environmental indicators. The first concerns heavy metals in the environment, where the zinc content is... |
| Tipo: Journal paper |
Palavras-chave: Environmental aspects. |
| Ano: 2001 |
URL: http://orgprints.org/15537/1/15537.pdf |
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| Stein, A.; Georgiadis, N.. |
| Understanding the spatial distribution of species is a fundamental issue in ecology, yet quantitative descriptions of animal species’ distributions are rare. In this chapter, we use a spatialstatistics approach to describe the spatial distribution of herds of large herbivores in Laikipia, central Kenya. We used Global Positioning System technology and spatial point pattern analysis (F-, G- and J-functions) to characterise herd distributions of the 9 most abundant species comprising large herbivore communities in African savannas. F-function analysis is based on estimating the probability of a herd occurring within radius r of randomly selected focal points. G-function analysis is similar, but based on randomly selected focal herds. The J-function is... |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1536 |
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