title: A quantitative and statistically robust method for the determination of xylem conduit spatial distribution.
abstract: OBJECTIVE
  Because of their limited length, xylem conduits need to connect to each other to maintain water transport from roots to leaves. Conduit spatial distribution in a cross section plays an important role in aiding this connectivity. While indices of conduit spatial distribution already exist, they are not well defined statistically. •
  
  
  METHODS
  We used point pattern analysis to derive new spatial indices. One hundred and five cross-sectional images from different species were transformed into binary images. The resulting point patterns, based on the locations of the conduit centers-of-area, were analyzed to determine whether they departed from randomness. Conduit distribution was then modeled using a spatially explicit stochastic model. •
  
  
  RESULTS
  The presence of conduit randomness, uniformity, or aggregation depended on the spatial scale of the analysis. The large majority of the images showed patterns significantly different from randomness at least at one spatial scale. A strong phylogenetic signal was detected in the spatial variables. •
  
  
  CONCLUSIONS
  Conduit spatial arrangement has been largely conserved during evolution, especially at small spatial scales. Species in which conduits were aggregated in clusters had a lower conduit density compared to those with uniform distribution. Statistically sound spatial indices must be employed as an aid in the characterization of distributional patterns across species and in models of xylem water transport. Point pattern analysis is a very useful tool in identifying spatial patterns.
authors: University of Edinburgh, School of GeoSciences, Crew Building, West Mains Road, EH9 3JN Edinburgh, UK.
authors: Maurizio
authors: M
authors: Mencuccini
authors: Jordi
authors: J
authors: Martinez-Vilalta
authors: Josep
authors: J
authors: Piñol
authors: Lasse
authors: L
authors: Loepfe
authors: Mireia
authors: M
authors: Burnat
authors: Xavier
authors: X
authors: Alvarez
authors: Juan
authors: J
authors: Camacho
authors: Debora
authors: D
authors: Gil