Let forb(m,F ) denote the maximum number of columns possible in a (0,1)matrix A that has no repeated columns and has no submatrix which is a row and column permutation of F . We consider cases where the configuration F has a number of columns that grows with m. For a k× ` matrix G, define s ·G to be the concatenation of s copies of G. In a number of cases we determine forb(m,mα ·G) is Θ(mk+α). ...

[1] We have developed maps of dominant vegetation types, plant functional types, percent vegetation cover, aboveground plant biomass, and above and belowground annual net primary productivity for Canada north of the northern limit of trees. The area mapped covers 2.5 million km including glaciers. Ice-free land covers 2.3 million km and represents 42% of all ice-free land in the Circumpolar Arc...

Recognition is growing that besides ungulates, small vertebrate and invertebrate herbivores are important drivers of grassland functioning. Even though soil microarthropods play key roles in several soil processes, effects of herbivores-especially those of smaller body size-on their communities are not well understood. Therefore, we progressively excluded large, medium and small vertebrate and ...

Here, I describe the geographical distribution of the savanna types in Namibia and identify the factors controlling the occurrence of each savanna type in relation to the amount of annual precipitation and the various physiographical regions, including the mopane ( Colophospermum mopane) area. The different types of savanna can be distinguished on the basis of the leaf habits of the dominant ve...

A compilation of 1884 modern pollen surface samples was analyzed to explore the relationships between spatial distributions of pollen percentage data vs. climate and vegetation in western North America. Modern pollen spectra capture many of the unique traits of regional vegetation patterns and reflect regional patterns of climate diversity. Large-scale vegetation differences were identifiable b...

LANDFIRE is a large interagency project that supports national fire management and fuels treatment activities. A primary data product of LANDFIRE is a detailed vegetation type classification. This study describes how independent data from Landsat imagery, topographic data, biophysical data layers, and dependent field-collected data can be used in a hierarchical mapping approach to improve veget...

The paucity of modern pollen-rain data from the Iberian Peninsula is a signifi cant barrier to understanding the Late Quaternary vegetation history of this globally important southwestern mediterranean region. The relationships between current vegetation, the available environmental data and modern pollen are examined in Central Spain for both natural and human-induced vegetation types, as an a...